NASA/TP–2015-217532

July 2015

Karen D. Baver, Dirk Behrend, and Kyla L. Armstrong

National Aeronautics and 

Space Administration 

Goddard Space Flight Center

Greenbelt, Maryland 20771

International VLBI Service for Geodesy and Astrometry

2014 Annual Report
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NASA/TP–2015-217532

July 2015

Karen D. Baver (ed.)

NVI, Inc., Greenbelt, Maryland

Dirk Behrend (ed.)

NVI, Inc., Greenbelt, Maryland

Kyla L. Armstrong (ed.)

NVI, Inc., Greenbelt, Maryland 

International VLBI Service for Geodesy and Astrometry

2014 Annual Report
Level of Review: This material has been technically reviewed by technical management

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Preface

This volume of reports is the 2014 Annual Report

of the International VLBI Service for Geodesy and

Astrometry (IVS). The individual reports were contributed by VLBI groups in the international geodetic

and astrometric community that constitute the permanent components of IVS.

The IVS 2014 Annual Report documents the work

of the IVS components for the calendar year 2014,

our sixteenth year of existence. The reports describe

changes, activities, and progress of the IVS. Many

thanks to all IVS components who contributed to this

Annual Report.

With the exception of the first section, the contents

of this Annual Report also appear on the IVS Web site

at

http://ivscc.gsfc.nasa.gov

/publications/ar2014

This book and the Web site are organized as follows:

• The first section contains general information about

IVS, a map showing the locations of the components, information about the Directing Board members, and the annual report of the IVS Chair.

• The second section holds two special reports. The

first report, “Foundation of the Asia-Oceania VLBI

Group for Geodesy and Astrometry”, describes the

progress towards establishing a new subgroup of

the IVS, the Asia-Oceania VLBI Group (AOV),

that will focus on the regional community of AsiaOceania. Progress in 2014 has included development of Terms of Reference, election of a Chair

and appointment of a Secretary, and a survey of regional resources, such as schedulers, antennas, correlators, and analysis centers. The group’s goal is to

IVS 2014 Annual Report

begin the first Asia-Oceanian VLBI network observations in early 2015. The activities of the AOV are

expected to enhance the quality of Asia-Oceanian

data products and to contribute to the construction

of Asia-Oceanian reference frames. The establishment of the AOV is a necessary and exciting development not only for Asia-Oceanian VLBI but

also for the IVS. The second report, “VGOS Data

Transmission and Correlation Plan”, discusses the

transmission of data from IVS Network Stations to

IVS Correlators and the correlation and fringe fitting of the data within the VLBI Global Observing

System (VGOS). This report covers topics such as

e-transfers and physical shipment of media, playback systems at the correlators, and correlator CPU

and storage requirements. The report then assesses

current and planned correlator resources and issues

recommendations.

• The next seven sections hold the reports from the

Coordinators and the reports from the IVS Permanent Components: Network Stations, Operation

Centers, Correlators, Data Centers, Analysis Centers, and Technology Development Centers.

• The next section contains a compilation of publications in the field of geodetic and astrometric VLBI

during 2014.

• The final section provides reference information

about IVS. Following the current version of the IVS

Terms of Reference, a reference table is provided

with links to the IVS Member and Affiliated organizations, the IVS Associate Members, and the IVS

permanent components.

iii

Table of Contents

Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iii

About IVS . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

IVS Organization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

IVS Component Map . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

IVS Directing Board . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

IVS Chair’s Report . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Special Reports . . . . . . . . . . . . . . . . . . . . . . 9

VGOS Data Transmission and Correlation Plan . . .11

Foundation of the Asia-Oceania VLBI Group for

Geodesy and Astrometry . . . . . . . . . . . . . . . . . . . . . . . 20

IVS Coordination . . . . . . . . . . . . . . . . . . 27

Coordinating Center Report . . . . . . . . . . . . . . . . . . . . 29

Analysis Coordinator Report . . . . . . . . . . . . . . . . . . . 32

Network Coordinator Report . . . . . . . . . . . . . . . . . . . 35

IVS Technology Coordinator Report . . . . . . . . . . . . 41

Network Stations . . . . . . . . . . . . . . . . . . . 45

Badary Radio Astronomical Observatory 2014 IVS

Annual Report . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

Effelsberg Radio Observatory 2014 Annual Report 50

Fortaleza Station 2014 Annual Report . . . . . . . . . . . 53

Goddard Geophysical and Astronomical Observatory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

Hartebeesthoek Radio Astronomy Observatory (HartRAO) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

AuScope VLBI Project and Hobart 26-m Antenna 63

Kashima 34-m VLBI Station . . . . . . . . . . . . . . . . . . . 67

Kokee Park Geophysical Observatory . . . . . . . . . . . .71

Kashima and Koganei 11-m VLBI Stations . . . . . . 75

Matera CGS VLBI Station 2014 Annual Report . . 79

Medicina Station Status Report . . . . . . . . . . . . . . . . . 82

IVS 2014 Annual Report

Metsahovi Radio Observatory Network Station 2014  ̈

Annual Report . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83

VERA 2014 Geodetic Activities . . . . . . . . . . . . . . . . 87

Noto Station Status Report . . . . . . . . . . . . . . . . . . . . . 90

Ny-Alesund Geodetic Observatory 2014 Annual  ̊

Report . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .92

German Antarctic Receiving Station (GARS)

O’Higgins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95

Onsala Space Observatory – IVS Network Station

Activities during 2014 . . . . . . . . . . . . . . . . . . . . . . . . . 98

Parkes 2014 IVS Report . . . . . . . . . . . . . . . . . . . . . . 102

Korea Geodetic VLBI Station, Sejong . . . . . . . . . . 103

Shanghai Station Report for 2014 . . . . . . . . . . . . . . 106

Simeiz 22-m Radio Telescope as an IVS Network

Station . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109

Svetloe Radio Astronomical Observatory 2014 IVS

Annual Report . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113

JARE Syowa Station 11–m Antenna, Antarctica . 116

Last Year of Operation of the TIGO VLBI Station in

Concepcion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120  ́

Tsukuba 32-m VLBI Station . . . . . . . . . . . . . . . . . . .124

Nanshan VLBI Station Report 2014 . . . . . . . . . . . . 128

New Zealand VLBI Station, Warkworth . . . . . . . . 130

Westford Antenna 2014 Annual Report . . . . . . . . . 134

Geodetic Observatory Wettzell - 20-m Radio Telescope and Twin Telescopes . . . . . . . . . . . . . . . . . . . . 137

Instituto Geografico Nacional of Spain . . . . . . . . . 141  ́

Zelenchukskaya Radio Astronomical Observatory

2014 IVS Annual Report . . . . . . . . . . . . . . . . . . . . . . 145

Operation Centers . . . . . . . . . . . . . . . . . 149

Bonn Geodetic VLBI Operation Center . . . . . . . . . 151

CORE Operation Center 2014 Annual Report . . . 153

NEOS Operation Center . . . . . . . . . . . . . . . . . . . . . . 157

v
vi Table of Contents

Correlators . . . . . . . . . . . . . . . . . . . . . . . 159

The Bonn Astro/Geo Correlator . . . . . . . . . . . . . . . .161

Haystack Observatory VLBI Correlator . . . . . . . . .164

IAA Correlator Center 2014 Annual Report . . . . . 168

Shanghai VLBI Correlator . . . . . . . . . . . . . . . . . . . . 171

Tsukuba VLBI Correlator . . . . . . . . . . . . . . . . . . . . . 175

Washington Correlator . . . . . . . . . . . . . . . . . . . . . . . . 179

Data Centers . . . . . . . . . . . . . . . . . . . . . . 181

BKG Data Center . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183

CDDIS Data Center Summary for the IVS 2014

Annual Report . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 185

Italy INAF Data Center Report . . . . . . . . . . . . . . . . 188

Data Center at NICT . . . . . . . . . . . . . . . . . . . . . . . . . .189

Paris Observatory (OPAR) Data Center . . . . . . . . . 192

Analysis Centers . . . . . . . . . . . . . . . . . . 195

Analysis Center of Saint Petersburg University . . 197

Geoscience Australia Analysis Center 2014 Annual

Report . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 199

Report for 2014 from the Bordeaux IVS Analysis

Center . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .200

BKG/DGFI Combination Center Annual Report

2014 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 204

Matera CGS VLBI Analysis Center . . . . . . . . . . . . 208

DGFI Analysis Center Annual Report 2014 . . . . . 210

GFZ Analysis Center 2014 Annual Report . . . . . . 213

BKG/IGGB VLBI Analysis Center . . . . . . . . . . . . .217

GSFC VLBI Analysis Center Report . . . . . . . . . . . 221

Haystack Observatory Analysis Center . . . . . . . . . 225

IAA VLBI Analysis Center Report 2014 . . . . . . . . 229

Italy INAF Analysis Center . . . . . . . . . . . . . . . . . . . 233

JPL VLBI Analysis Center Report for 2014 . . . . . 235

KASI Combination Center 2014 Annual Report . 239

KTU-GEOD IVS Analysis Center Annual Report

2014 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 240

Analysis Center at the National Institute of Information and Communications Technology . . . . . . . . . . 243

NMA Analysis Center 2014 Annual Report . . . . . 247

Paris Observatory (OPAR) Analysis Center . . . . . 249

Onsala Space Observatory – IVS Analysis Center

Activities during 2014 . . . . . . . . . . . . . . . . . . . . . . . . 252

PMD Analysis Center 2014 Annual Report . . . . . 256

Pulkovo IVS Analysis Center (PUL) 2014 Annual

Report . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 260

SAI VLBI Analysis Center 2014 Annual Report . 264

SHAO Analysis Center 2014 Annual Report . . . . 266

Tsukuba VLBI Analysis Center . . . . . . . . . . . . . . . . 269

U.S. Naval Observatory VLBI Analysis Center . . 273

USNO Analysis Center for Source Structure Report . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 276

Vienna Special Analysis Center Annual Report

2014 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 278

Technology Development Centers . . 283

Canadian VLBI Technology Development Center

Report . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 285

GSFC Technology Development Center Report . .286

MIT Haystack Observatory Technology Development

Center . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .289

IAA Technology Development Center Report

2014 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 292

NICT Technology Development Center 2014 Annual

Report . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 296

Onsala Space Observatory – IVS Technology Development Center Activities during 2014 . . . . . . . . . . 300

IGN Yebes Technology Development Center . . . . 304

Bibliography . . . . . . . . . . . . . . . . . . . . . . 309

Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .311

IVS Information . . . . . . . . . . . . . . . . . . . 329

IVS Terms of Reference . . . . . . . . . . . . . . . . . . . . . . 331

Links to Additional IVS Information . . . . . . . . . . . 338

IVS 2014 Annual Report
About IVS
2

IVS Organization

Objectives

IVS is an international collaboration of organizations which 

operate or support Very Long Baseline Interferometry 

(VLBI) components. The goals are:

1. To provide a service to support geodetic, geophysical 

and astrometric research and operational activities.

2. To promote research and development activities in 

all aspects of the geodetic and astrometric VLBI 

technique.

3. To interact with the community of users of VLBI 

products and to integrate VLBI into a global Earth 

observing system.

The IVS

• Interacts closely with the IERS, which is tasked by 

IAU and IUGG with maintaining the international 

celestial and terrestrial reference frames (ICRF

and ITRF),

• coordinates VLBI observing programs, 

• sets performance standards for the observing stations, 

• establishes conventions for data formats and products, 

• issues recommendations for analysis software,

• sets standards for analysis documentation,

• institutes appropriate product delivery methods in 

order to insure suitable product quality and timeliness.

Realization And Status Of IVS

IVS consists of

• 32 Network Stations, acquiring high performance 

VLBI data,

• 3 Operation Centers, coordinating the activities of a 

network of Network Stations,

• 7 Correlators, processing the acquired data, providing feedback to the stations and providing processed 

data to analysts,

• 5 Data Centers, distributing products to users, 

providing storage and archiving functions,

• 28 Analysis Centers, analyzing the data and producing 

the results and products,

• 7 Technology Development Centers, developing new 

VLBI technology,

• 1 Coordinating Center, coordinating daily and long 

term activities.

Altogether

• 83 Permanent Components, representing 43 institutions in 21 countries,

• ~300 Associate Members.

In addition the IVS has:

• Directing Board, determining policies, standards and 

goals; the board is composed of 16 members (elected 

and ex officio), including

• Coordinators for the network, analysis and technology.

ORGANIZATION OF INTERNATIONAL VLBI SERVICE
3

IVS Affiliated Organizations

The following organizations cooperate with IVS on issues 

of common interest, but do not support an IVS component. 

Affiliated Organizations express an interest in establishing 

and maintaining a strong working association with IVS to 

mutual benefit. Listed alphabetically by country. 

Products

The VLBI technique contributes uniquely to

• Definition and realization of the International Celestial 

Reference Frame (ICRF)

• Monitoring of Universal Time (UT1) and length of day 

(LOD)

• Monitoring the coordinates of the celestial pole (nutation and precession)

Further significant products are

• All components of Earth Orientation Parameters at 

regular intervals

• Station coordinates and velocity vectors for the realization and maintenance of the International Terrestrial 

Reference Frame (ITRF)

All VLBI data and results in appropriate formats are archived in data centers and publicly available for research 

in related areas of geodesy, geophysics and astrometry.

IVS Member Organizations

The following organizations contribute to IVS by supporting 

one or more IVS components. They are considered IVS 

Members. Listed alphabetically by country.

Organization Country

Geoscience Australia Australia

University of Tasmania Australia

CSIRO Australia

Vienna University of Technology Austria

Centro de Rádio Astronomia e Aplicações 

Espaciais

Brazil

Geodetic Survey Division, Natural 

Resources Canada

Canada

Dominion Radio Astrophysical 

Observatory

Canada

Universidad de Concepción Chile

Instituto Geográfico Militar Chile

Chinese Academy of Sciences China

Finnish Geodetic Institute, Aalto University Finland

Observatoire de Paris France

Laboratoire d’Astrophysique de Bordeaux France

Deutsches Geodätisches 

Forschungsinstitut

Germany

Bundesamt für Kartographie und Geodäsie Germany

Institut für Geodäsie und Geoinformation 

der Universität Bonn

Germany

Forschungseinrichtung Satellitengeodäsie, 

TU-Munich

Germany

Max-Planck-Institut für Radioastronomie Germany

GeoForschungsZentrum Potsdam Germany

Istituto di Radioastronomia INAF Italy

Agenzia Spaziale Italiana Italy

Politecnico di Milano DIIAR Italy

Geospatial Information Authority of Japan Japan

National Institute of Information and 

Communications Technology

Japan

National Astronomical Observatory of 

Japan

Japan

National Institute of Polar Research Japan

Auckland University of Technology New 

Zealand

Norwegian Mapping Authority Norway

Astronomical Institute of St.-Petersburg 

University

Russia

Institute of Applied Astronomy Russia

Pulkovo Observatory Russia

Sternberg Astronomical Institute of 

Moscow State University

Russia

Organization Country

Hartebeesthoek Radio Astronomy 

Observatory

South 

Africa

Korea Astronomy and Space Science 

Institute

South 

Korea

National Geographic Information Institute S. Korea

Instituto Geográfico Nacional Spain

Chalmers University of Technology Sweden

Karadeniz Technical University Turkey

Main Astronomical Observatory, 

National Academy of Sciences, Kiev

Ukraine

Laboratory of Radioastronomy of Crimean 

Astrophysical Observatory

Ukraine

NASA Goddard Space Flight Center USA

U. S. Naval Observatory USA

Jet Propulsion Laboratory USA

Organization Country

Australian National University Australia

University of New Brunswick Canada

FÖMI Satellite Geodetic Observatory Hungary

Joint Institute for VLBI in Europe (JIVE) Netherlands

Westerbork Observatory Netherlands

National Radio Astronomy Observatory USA
4

IVS Component Map

IVS Components by Country

Country Qty.

Australia 3

Austria 1

Brazil 1

Canada 1

Chile 1

China 4

Finland 1

France 3

Germany 10

Italy 7

Japan 12

New Zealand 1

Norway 2

Russia 9

South Africa 1

South Korea 2

Spain 2

Sweden 3

Turkey 1

Ukraine 2

USA 16

Total 83
5
6

IVS Directing Board

NAME: Hayo Hase

AFFILIATION: Bundesamt für 

Kartographie und Geodäsie/

TIGO, Germany/Chile

POSITION: Networks 

Representative

TERM: Feb 2011 to Feb 2015

NAME: Rüdiger Haas

AFFILIATION: Chalmers 

University of Technology, 

Sweden

POSITION: Technology Development Centers Representative

TERM: Feb 2013 to Feb 2017

NAME: Dirk Behrend

AFFILIATION: NVI, Inc./Goddard 

Space Flight Center, USA

POSITION: Coordinating Center 

Director

TERM: ex officio

NAME: John Gipson

AFFILIATION: NVI, Inc./Goddard 

Space Flight Center, USA

POSITION: Analysis Coordinator

TERM: permanent

NAME: Patrick Charlot

AFFILIATION:Laboratoire 

d’Astrophysique de 

Bordeaux, France

POSITION: IAU Representative

TERM: ex officio

NAME: Alessandra Bertarini

AFFILIATION: University 

of Bonn, Germany

POSITION: Correlators

and Operation Centers

Representative

TERM: Feb 2011 to Feb 2015

NAME: Axel Nothnagel

AFFILIATION: University 

of Bonn, Germany

POSITION: Chair, Analysis and 

Data Centers Representative

TERM: Feb 2013 to Feb 2017

NAME: Ed Himwich

AFFILIATION: NVI, Inc./Goddard 

Space Flight Center, USA

POSITION: Network

Coordinator

TERM: permanent
7

NAME: Shinobu Kurihara

AFFILIATION: Geospatial 

Information Authority, Japan

POSITION: At Large Member

TERM: Feb 2013 to Feb 2015

NAME: Chopo Ma

AFFILIATION: NASA Goddard 

Space Flight Center, USA

POSITION: IERS Representative

TERM: ex officio

NAME: James Lovell

AFFILIATION: University of 

Tasmania, Australia

POSITION: Networks 

Representative

TERM: Feb 2013 to Feb 2017

NAME: Fengchun Shu

AFFILIATION: Shanghai 

Astronomical Observatory, 

China

POSITION: At Large Member

TERM: Feb 2013 to Feb 2015

NAME: Alexander Ipatov

AFFILIATION: Institute of 

Applied Astronomy, Russia

POSITION: At Large Member

TERM: Feb 2013 to Feb 2015

NAME: Arthur Niell

AFFILIATION: MIT Haystack 

Observatory, USA

POSITION: Analysis and Data 

Centers Representative

TERM: Feb 2013 to Feb 2015

NAME: William Petrachenko

AFFILIATION: Natural 

Resources Canada, Canada

POSITION: Technology

Coordinator

TERM: permanent

NAME: Harald Schuh

AFFILIATION: GFZ German 

Research Center for 

Geosciences, Germany

POSITION: IAG Representative

TERM: ex officio
8

IVS Chair’s Report

Axel Nothnagel

Institute of Geodesy and Geoinformation of the University 

of Bonn 

The IVS Annual Report 2014 is again a vital means of 

documenting the success of the IVS in both its operational 

capacities and its progress in development. I would like 

to thank all contributors for their efforts in writing down 

their activities. This is sometimes considered a futile and 

superfluous endeavor; however, just the opposite is the 

case. The IVS Annual Report is a valuable document 

and a good reference of what everyone is doing for and 

within the IVS. One of the key reasons for the high level 

of acceptance of the IVS Annual Reports has always 

been that they have a very low latency of publication 

and guarantee a high level of actuality. But where would 

our timely contributions end up if we hadn’t our diligent 

team of editors, Karen Baver, Dirk Behrend, and Kyla 

Armstrong, who take care of all the nitty-gritty details 

of queries, formatting, type-setting, and administrative 

hurdle-jumping before we have the printed issues in our 

hands? A special thanks to the three of them. 

Still talking of the IVS Annual Report and its importance, 

let me mention that one of our parent organizations, the 

International Association of Geodesy (IAG), has launched 

a review campaign of its services starting with a very 

detailed questionnaire. Having the continuous series 

of annual reports at hand largely simplified the task of 

answering the request for information and giving a presentation at one of the IAG review meetings in Vienna 

in April 2014. 

In 2014, the IVS and its components continued to operate 

at the best of their capacities making everything possible 

that was needed for the specific task at hand. One of the 

key activities to name here certainly is CONT14, which 

was observed in May 2014, with its tremendous load on 

(wo)manpower and hardware. CONT14 was the first Continuous VLBI Campaign that was processed in its entirety 

at the Bonn MPIfR1/BKG2 Correlator by the staff of IGG3

with a DiFX software correlator. Due to the dedication of 

the correlator staff and help from many other places, the 

task was completed as planned, and I expect that some 

fine publications will result from this endeavor in 2015.

In March 2014, the 8th IVS General Meeting was hosted 

by our colleagues of the Shanghai Astronomical Observatory with a wealth of presentations and plenty of time for 

discussions at splinter meetings and other pleasant side 

events. Thank you once again for this unique experience. 

The proceedings of the meeting were printed at the end 

of last year, and participants should have received a copy 

long before they read these lines. The timeliness of publishing the IVS General Meeting Proceedings is another proof 

of the very good functionality of the IVS, which remains 

unrivalled among the IAG services.

The IVS Directing Board (DB) met twice in 2014, once 

in Shanghai, China, in March in connection with the 8th 

General Meeting and once in Tsukuba, Japan, in October 

where the DB had the pleasure to witness the formal inauguration ceremony of the Ishioka VGOS telescope. We 

congratulate our colleagues at the Geospatial Information 

Authority of Japan (GSI) on their nice new instrument and 

look forward to receiving the first real VLBI data soon. We 

are also glad to report that the IGN Yebes Observatory 

was accepted as an IVS Technology Development Center 

and that the Korean Sejong radio telescope produced its 

first usable data in 2014. 

Another noteworthy item is that the VGOS Project Executive Group, with approval of the IVS Directing Board, 

finalized both the VGOS Observation Plan and the VGOS 

Data Transfer and Correlation Plan. The two documents 

describe the path of VGOS into the future and are a valuable reference for IVS colleagues and decision makers 

alike. They are available on the IVS Web site.

Once again we can look back on a very successful year 

for the IVS. I trust that you will have an interesting and 

informative read while going through the individual reports 

of this volume.

————————————————————————————

1 Max Planck Institute for Radio Astronomy, Bonn, Germany

2 Federal Agency of Cartography and Geodesy, Frankfurt am Main, Germany

3 Institute of Geodesy and Geoinformation of the University of Bonn, Germany 
Special Reports

11

VGOS Data Transmission and Correlation Plan

Version: November 18, 2014

Bill Petrachenko, Alessandra Bertarini, Walter Alef, Dirk Behrend, Roger Cappallo,

Hayo Hase, Chopo Ma, Arthur Niell, Axel Nothnagel, Xiuzhong Zhang

Abstract. The establishment of the VLBI Global Observing System (VGOS) requires a 

projection of the needs for data transmission as well as for correlation to achieve the best 

possible results and a smooth implementation phase from the very beginning. In this 

document we outline the requirements and possible developments, which are related to 

(a) the transport of the raw VLBI data from the stations to the correlators and (b) the 

correlation and fringe fitting process itself. 

1. Introduction

The implementation of the VLBI Global Observing System (VGOS) is being guided by 

the VGOS Program Executive Group (VPEG), which documents its discussions and 

considerations in a series of VGOS plans. Following the VGOS Observation Plan

(Petrachenko et al. 2014), this document now addresses the requirements for VGOS data 

transmission and correlation. In technical terms, a fundamental assumption for this plan is 

that the observation cycle of one source has a duration of 30s including a typical onsource integration time of 7.5 s. Data is acquired at 16 Gbps. Assuming that the sequence 

of observations can be realized as set forth in the VGOS Observation Plan, the VGOS 

data production rates increase from 58 TeraByte (TB) per day in the year 2015 to 1037 

TB/day in 2020 (Tab. 1). The last column, “data/day at correlator”, assumes that there is 

only one monolithic correlator in use. With more than one correlator, sessions would be 

distributed such that, on average, the total correlator load would be divided in proportion 

to the available capacity at each correlator. Although interesting from the point of view of 

data transmission and cost sharing, a highly distributed correlator is not discussed here.

Year # of sites hours of 

obs/day

data/day/site 

(TB)

data/day at correlator 

(TB)

2015 8 4 7.2 58

2016 10 8 14.4 144

2017 16 8 14.4 230

2018 20 10 18.0 360

2019 24 12 21.6 518

2020 24 24 43.2 1037

Table 1. Estimates of VGOS data production rates for the years 2015 to 2020.
12

This document will attempt to predict VGOS requirements for e-transfer, disk pack 

shipping, media requirements per station, number of playback units at the correlator, 

correlator cores, internal correlator network, and on-line correlator memory for the years 

2015 to 2020. In this version of the document, the increased data transmission and 

correlation load related to multi-antenna sites has not been taken into account. For twin 

(VGOS) telescope sites this could lead to as much as a doubling of the data production 

rate if the most aggressive observing scenarios are assumed for both antennas. For sites 

that will continue to operate a legacy antenna along with the new VGOS antenna(s), the 

added data production rate will typically be significantly less severe than for twin 

telescope sites due to the slower slew speed of the legacy antenna. Furthermore no 

attempt will be made here to estimate power requirements for the correlator although this 

could become an important aspect of correlator operational costs; hence it may be 

considered in a later version of this document. It is assumed that the correlator will be a 

software correlator and that its architecture will be similar to existing software 

correlators.

2. e-Transfer Rates

Based on the information in Table 1 it is possible to calculate requirements for sustained 

data transmission rate from each site and for a cumulative sustained reception rate at the 

correlator. These are calculated simply as the total daily data production divided by the 

number of seconds in a day. The cumulative sustained reception rate at the correlator in 

column five of the table assumes that all stations transmit data to the correlator via etransfer and hence is the maximum value expected. When specifying a requirement for 

network data rate it is common to account for network overhead by applying about a 40% 

margin above the sustained data rate to arrive at the required network data rate. Stations 

planning to transfer data over the Internet have to increase their capacity from 1.0 Gigabit 

per second (Gbps) in 2015 to 5.6 Gbps in 2020 (Tab. 2). If the data of all stations would 

be transferred over the Internet, the correlator(s) need an increase in network capacity 

from 8 Gbps to 134 Gbps. For some stations and correlators where direct inexpensive 

access to a high speed network is not practical, it may be cost effective and efficient to 

physically transport modules to or from a nearby node on a network trunk and then etransfer from that point onward.

Year

data rate at 

each site 

(Gbps)

network data rate at 

each site (Gbps)

data rate at 

correlator 

(Gbps)

network data rate at 

correlator (Gbps)

2015 0.7 1.0 5 8

2016 1.3 1.9 13 19

2017 1.3 1.9 21 30

2018 1.7 2.4 34 48

2019 2.0 2.8 48 68

2020 4.0 5.6 96 134

Table 2. Estimates of sustained e-transfer rates and network data rates.
13

3. Record Media Shipment

The other alternative for data transmission is to physically ship record media. By 2015 it 

is expected that new 8-pack recording modules will be based on 6 TB disks (i.e. 48 TB 

total for each 8-pack module). In Table 3, the data production rates from Table 1 are reexpressed in terms of the number of 8-pack record modules required per day. In most 

cases disk packs will be significantly less than full at the end of 24 hours.

Year 8-pack module capacity

(TB)

data produced per day

(# of 8-pack modules)

2015 48 0.15

2016 48 0.30

2017 48 0.30

2018 48 0.37

2019 48 0.45

2020 48 0.90

Table 3. Estimates of the number of 8-pack record modules required per day at each 

station.

4. Media Requirements per Station

There are three cases that need to be considered for estimating a stations media 

requirements: 

 All stations ship disk packs. Any station that ships disk packs needs enough media 

to handle about eight weeks of recording (one week for shipping to the station, 

one week for shipping to the correlator, two weeks for correlator schedule 

slippages and post-processing, and four weeks to reduce costs at the correlator 

through bulk monthly shipment of media to the stations);

 Some stations ship disk packs and some stations e-transfers data. In this case, the 

stations that ship disk packs still need eight weeks of media; but the stations that 

e-transfer data only need enough media to handle three weeks of recording before 

modules can be erased for re-use (one week while the shipped disks travel to the 

correlator and two weeks for correlator schedule slippages and post-processing) 

[An alternative for stations that e-transfer is to have enough on-line RAID storage 

to store the raw data for three weeks.]; 

 All stations e-transfer data. For a network where all stations e-transfer data there 

are two cases:

o Non real time. In this case each station needs two weeks of media to 

account for correlator schedule and data transmission slippages, and to 

allow for completion of post-processing
14

o Real time. In this case correlator schedule slippages are not tolerated and 

only limited buffering is required to account for network overhead and 

unexpected network outages.

In Table 4, the media requirements per station are shown. As in the previous section, it is 

assumed that 48 TB modules will be used. Even though some stations will have more 

than adequate network capability, it is recommended that they still maintain a capability 

for removable data recording media since correlators may not be able to handle the 

required network traffic especially during early operations. It is further recommended that 

the IVS decide on a compatibility standard for record media so that correlators will not 

need to support more than one type of media.

Year module 

size 

(Tbytes)

Data per 

day

(# of 

modules)

Days/

module

(modules/

year 1-way 

shipped) 

Sites that 

ship data 

(modules

needed/

site)

Sites that etransfer in a 

mixed 

network

(RAID TB)

All sites

e-transfer -

not real time

(RAID TB)

2015 48 0.15 6 (21) 7 4 (151) 3 (101)

2016 48 0.30 3 (122) 19 7 (302) 5 (202)

2017 48 0.30 3 (122) 19 7 (302) 5 (202)

2018 48 0.37 2 (183) 28 11 (373) 7 (249)

2019 48 0.45 2 (183) 28 11 (453) 7 (303)

2020 48 0.90 1 (365) 56 21 (907) 14 (605)

Table 4. Media requirements per station assuming the case where data are shipped only 

when media is nearly full. As an alternative to removable disk modules for e-transfer 

data, the numbers in brackets in the last two columns of the table represent the amount of 

on-line RAID storage (TB) that would be needed to store all e-transferred data from a 

single station until it can be released.

5. Playback systems at the correlator

It is assumed that the number of playback units at the correlator will be large enough to

make possible a semi-automated operating mode where recorded modules never need to 

be exchanged more often than once per day. In this section, Mk6 units are used as 

examples although other types of compatible and competitive playback units may also be 

developed in the course of time. It is assumed that a data acquisition duty cycle of less 

than 25% will be used so that no more than a single disk pack at a time needs to be 

mounted at a station and that each Mk6 playback unit at the correlator will be able to 

mount up to four recorded modules. There are three cases that need to be considered: 

 All stations ship data. In this case three criteria need to be met:
15

o There needs to be a place for a recorded module from each station to be 

loaded. For example, since each Mk6 can handle four recorded modules, 

an eight station network would require at least two Mk6s.

o The cumulative sustained data rate of the correlator needs to be met. For 

example, since each Mk6 can play back at 16 Gbps (or somewhat more) 

when four disk packs are loaded, a sustained data rate of 21 Gbps would 

require at least two Mk6s.

o It must be possible to store the total volume of data acquired in 24 hours. 

For example, since each Mk6 fully loaded with four 48-TB record 

modules can store 192-TB of data, a 230 TB session would require at least 

two Mk6s.

 All stations e-transfer data. In this case only the latter two criteria need to be met 

but now an equal number of Mk6s is required to record data from the network and 

to play it back to the correlator so that the number of units is doubled. For 

example, for a sustained data rate of 21 Gbps and a total volume of 230 Tbytes, 

two Mk6s would be required to record from the network and two to play back to 

the correlator, for a total of 4 Mk6s.

 Some stations ship data and some stations e-transfer data. In this case, the 

number of Mk6s required will lie somewhere between the cases where all stations 

ship and all stations e-transfer. The final number will depend on the ratio of 

stations shipping and e-transferring.

See Table 5 for an estimate of the number of Mk6s required at the correlator.

Year # of sites

Data rate at 

correlator

(Gbps)

Data volume 

(TB)

# of Mk6s 

(all sites ship 

data)

# of Mk6s

(all sites etransfer data)

2015 8 5 58 2 2

2016 10 13 144 3 4

2017 16 21 230 4 4

2018 20 33 360 5 6

2019 24 48 518 6 8

2020 24 96 1037 6 16

Table 5. Estimate of number of Mk6s required at correlator.

6. Correlator Cores

In principle, it should be easy to estimate the VGOS correlator CPU requirements since 

the processing load of a DiFX correlator (or any software correlator with a similar 

architecture) increases more or less linearly with the number of stations in a scan. [With a 

typical DiFX correlator this linear relation is valid up to about 15 stations which is in line 

with the vast majority of scans expected for the VGOS network even up to 2020 and 
16

beyond.] As a result, the number of CPU operations required to keep up with data 

acquisition should simply be proportional to the cumulative sustained input data rate of 

the correlator. (See Table 2.) Unfortunately, performance benchmarks that relate 

correlator input data rate to required number of correlator cores are often misleading 

when used to extrapolate to other correlator architectures, generations of technology, and 

observing scenarios. This is largely due to the fact that complex real time interactions 

amongst various hardware components and software processes lead to bottlenecks that 

move from location to location in the system and change in severity depending on 

correlator size, architecture, technology, and observing configuration. In the absence of 

something better to do, a universal scaling factor of about 40 correlator cores per Gbps

was derived based on the processing of a single broadband session at the Haystack DiFX 

correlator and that scaling factor was then used to extrapolate to the VGOS correlator 

configurations shown in Table 6. For the reasons described above it is not expected that 

the estimates in the table will be accurate to better than about a factor of three in either 

direction. 

Year # of correlator cores

2015 200

2016 600

2017 900

2018 1400

2019 2000

2020 3900

Table 6. Estimates of correlator cores required. It is expected that these 

values are not accurate to better than a factor of about three.

7. Internal data rate at the correlator

As a lower limit, the internal data rate of the correlator needs to handle the sustained data 

acquisition rate. However, since data may at times need to be transmitted more than once 

before they arrive at their final destination for correlation, an efficiency factor needs to be 

applied to arrive at a realistic recommendation for internal data rate. It is difficult to be 

exact about the size of this factor since it will change both with correlator architecture 

and session configuration. However, for the purpose of this document, a factor of 40% is 

considered reasonable. If data is e-transferred, then double that rate is required so that 

transfers from the network to storage and storage to the correlator cores can be handled 

simultaneously (Tab. 7). Although current correlators are built around 10 Gbps network 

technology, modern equipment is increasingly able to handle higher data rates. It is 

recommended that a move to higher rate (e.g., 40 Gbps) technology be considered. 
17

Year

Data rate at 

correlator

(Gbps)

Internal data rate 

(all sites ship data)

(Gbps)

Internal data rate 

(all sites e-transfer data)

(Gbps)

2015 5 7 14

2016 13 19 37

2017 21 30 59

2018 34 48 96

2019 48 68 135

2020 96 135 269

Table 7. Estimates of required internal data rates at correlator.

8. Local storage at the correlator

In addition to the correlation playback units, each correlator needs sufficient local storage 

capacity for buffering data. Taking into account the data streams coming in by e-transfer 

and a correlation backlog of two observing days, correlators need local storage capacity 

of at least 500 TB. For this, either commercial RAID systems or dedicated VLBI units 

are available. For the dedicated VLBI units, the current MK6 units are used as examples. 

Along with high storage density and data rates they also have the advantage of removable 

media. 

9. Current and Planned IVS Correlator Resources

Location Correlator Cores Mk6s External Network 

(Gbps)

Now Planned Now Planned Now Planned

Bonn 488 1000-1500 2 6 (2 slot) 1 no plan

USNO 512 1024 0 ? 1 10

Haystack 100 ~300 3 6 20 no plan

Shanghai 64 1000 2 ? 1 no plan

Tsukuba 92 256 (24.9 TB) (513 TB) 10 no plan

Table 8. Current (2014) and planned correlator resources.

Table 8 shows the current and planned resources available for IVS processing at existing 

software correlators. In most cases these correlators will be shared with other 

astronomical and/or space programs so only a fraction of the capability will be available 

for geodesy. Although other aspects of the correlator are important, e.g. internal network 

resources and internal storage, the table only considers correlator cores, Mk6s and the 

external network connection. In the case of the Tsukuba correlator, there are no plans for 
18

Mk6s so internal storage is displayed and it should be noted that their planned upgrade 

has in fact recently been implemented. Correlators that might be of interest but are not 

included in the table are the VLBA correlator which is used for processing RDV sessions, 

the Curtin correlator used for AUSTRAL sessions, the Kashima correlator and the 

Russian correlator. Their use for VGOS sessions will have to be discussed. Available 

correlator resources in Table 8 can be compared with projected correlator requirements in 

Tables 6, 5 and 2 respectively.

Station Network Data Rate(Gbps)

Noto 10

Kokee 0.1

Westford 20

GGAO 1

Ishioka 10

Sheshan 1

Wettzell 1

Yebes 10

Table 9. Network data rates at sites most likely to be ready 

for broadband observing in 2015.

Table 9 shows network data rates currently available at the VGOS stations most likely to 

be ready for the broadband test campaigns in 2015. In general data rates vary 

considerably from site to site. These values should be compared with the projected 

requirements in Table 2.

10. Recommendations

 Correlator Cores. Within the next year or two there could be significantly more 

than 3000 correlator cores available at IVS correlators. According to Table 6 this 

would satisfy VGOS correlator core requirements up to about 2019. However, 

this takes into consideration neither the fact that most IVS correlators are shared 

with other applications (including legacy S/X observing) nor the fact that the 

estimates in Table 6 are only reliable to within a factor of about three. 

Furthermore, since most correlators are currently being upgraded with respect to 

correlator cores it is unlikely that sponsors will fund further upgrades in the near 

future. As a result it is recommended that the current set of upgrades be 

completed and that the situation with respect to correlator cores be reviewed in 

about two years. Over that time, broadband data will have routinely been 

processed using modern correlator cores so that better estimates of the relation 

between data throughput and correlator cores can be made. At the same time, 

more accurate schedules for the roll out of VGOS stations and 24/7 operation will 

be known making predictions of correlator core requirements more realistic.
19

 Dedicated VLBI disk units. At the moment, no VLBI disk unit with competing 

capacity to the MK6 units is available. For this reason, MK6 units are used as 

examples. At present only a few Mk6s units are deployed at observing sites and at 

correlators. It is recommended that correlators aim to have at least four Mk6s (or 

equivalent) on the short term and as many as eight on the longer term.

 External network connections at correlator. To achieve high precision low 

latency results, network connections at correlators should be upgraded to at least 

10 Gbps on the short term with significantly higher rates (40 Gbps) required in the 

future to support 24/7 operations with the full network.

 Network connections at stations. If real time processing is a priority, network 

VGOS stations should be upgraded to handle at least 2 Gbps on the short term 

with 5.6 Gbps required for full 24/7 operations.

 Even though some stations will have more than adequate network capability, it is 

recommended that they still maintain a capability for removable data recording 

media since correlators may not be able to handle the required network traffic 

during early operations. 

 It is recommended that the IVS decide on a compatibility standard for record 

media so that correlators will not need to support more than one type of media.

 Internal network technology at the correlator. Although current correlators are 

built around 10 Gbps network technology, modern equipment is increasingly able 

to handle higher data rates. It is recommended that a move to higher rate (e.g., 

40 Gbps) technology be considered.

References

Petrachenko B, Behrend D, Hase H, Ma C, Niell A, Nothnagel A, Zhang X (2014): 

VGOS Observing Plan (February 13, 2014) http://ivscc.gsfc.nasa.gov/technology/vgosdocs/vgos_observing_plan_140213.pdf
Foundation of the Asia-Oceania VLBI Group for Geodesy and

Astrometry

Shinobu Kurihara 1, Jim Lovell 2, Jungho Cho 3, Sergei Gulyaev 4, Fengchun Shu 5, Ryoji Kawabata 1

Abstract The Asia-Oceania VLBI Group for Geodesy

and Astrometry (AOV), which is a group of scientists

in the Asia-Oceania region supporting geodetic and astrometric Very Long Baseline Interferometry (VLBI),

was newly established in 2014. Like the European

VLBI Group for Geodesy and Astrometry (EVGA),

it is a subgroup of the International VLBI Service for

Geodesy and Astrometry (IVS). This article traces the

beginning and progress toward the inauguration of the

AOV.

1 Background

The International VLBI Service for Geodesy and

Astrometry (IVS) is an international collaboration of

organizations which operate or support Very Long

Baseline Interferometry (VLBI) components. Since its

foundation in 1999, the IVS has provided a service to

support geodetic and astrometric research and operational activities, promoted technology development for

VLBI and facilitated interaction between individuals

in the VLBI community.

However two decades before the establishment

of the IVS, European countries had organized the

European VLBI Group for Geodesy and Astrometry

(EVGA) and held the first European VLBI meeting

in April 1980 in Bonn, Germany [1]. The EVGA was

1. Geospatial Information Authority of Japan, Japan

2. University of Tasmania, Australia

3. Korea Astronomy and Space Science Institute, South Korea

4. Auckland University of Technology, New Zealand

5. Shanghai Astronomical Observatory, CAS, China

IVS 2014 Annual Report

mainly devoted to geodetic, or rather geodynamic, and

astrometric research, but was open also to subjects of

general interest that were relevant to VLBI. It is safe

to say that the EVGA was the prototype of today’s

IVS. The EVGA has implemented regional VLBI

observations on a regular basis with a permanent network of fixed stations (now called EUROPE session)

and encouraged cooperation and personnel exchanges

among member organizations through holding a

biennial meeting. Their approach has paid off and they

continue to play a leading role in the international

VLBI community.

In the Asia-Oceania region, there has been cooperation between relevant VLBI organizations in each

country, but less international collaboration. Up until

the early days of the IVS, there were few VLBI telescopes devoted to geodetic observations in this region.

According to the 1999 IVS Annual Report, only five

organizations from the region (one from China and four

from Japan) were listed as the IVS Member Organizations. In the last ten years or so, several organizations

from Australia, New Zealand, and South Korea became

IVS Member Organizations and many telescopes for

geodesy such as the AuScope array, Warkworth, and

Sejong were newly erected. Today, the IVS Member

Organizations in Asia-Oceania play a crucial part in

geodetic and astrometric VLBI activities in the world.

In 2013 we proposed that Asia-Oceania should also establish a regional community for geodetic and astrometric VLBI along the lines of the EVGA.

20
Foundation of the AOV 21

2 Progress

In March 2013, several researchers from East Asian

countries participated in the 21st EVGA Meeting held

at Aalto University in Finland. Jungho Cho, Fengchun

Shu, and Shinobu Kurihara discussed the idea of regional collaboration on geodetic VLBI among South

Korea, China, and Japan sitting at the same table in

the dinner of the meeting (Figure 1). We concurred on

the need for establishing a new regional community for

VLBI and discussed what action should be taken to fulfill the idea. We three brought it back home and encouraged VLBI colleagues in each country to agree with

the plan and to be involved in the community. In subsequent further discussions, we came to the conclusion

that the involvement of VLBI institutions in Oceanian

countries was also necessary for more effective cooperation in this region.

We solicited colleagues in Australia and New

Zealand to take part in the regional VLBI community.

They already have started a series of VLBI sessions

called AUSTRAL with a network including AuScope,

Warkworth, and HartRAO and organized a cooperative

framework in the Southern Hemisphere. Oceanian

colleagues were interested in the plan and favored

being involved in the new regional community with

East Asian countries.

In September 2013, colleagues from several VLBI

institutions in Australia, New Zealand, and Japan met

after the IAG Scientific Assembly held at Potsdam,

Germany. We agreed on the foundation of a regional

VLBI community and confirmed that it should be a

subgroup of the IVS in the same way that the EVGA

is. The community was named the Asia-Oceania VLBI

Group for Geodesy and Astrometry, and its acronym

was tentatively called AOV. Jim Lovell undertook to

draft the Terms of Reference. In the IVS Directing

Board Meeting on September 7th, Shinobu Kurihara

reported that Asian and Oceanian countries intended to

establish a regional VLBI group similar to the EVGA,

and the Board fully approved this notion.

Though the Terms of Reference are similar to those

of the EVGA, they focus on issues particular to the

region. In particular, the Terms of Reference stipulate

that the AOV plays an important role through measurement of tectonic plate motion, atmospheric variation

and the determination of the Geodetic Reference Frame

for the region in order to better understand the risks and

reduce the effect of destructive earthquakes, tsunamis,

typhoons and cyclones which frequently cause serious

damage to the region.

We continued to work toward establishing the AOV

and held our inaugural meeting in conjunction with the

8th IVS General Meeting in Shanghai, China in March

2014. As of the end of 2013, while the draft of the

Terms of Reference were almost completed, we determined the need for strong leadership from a publicly elected Chair and Secretary so as to formally inaugurate the group. Since the election took a couple

of months, we decided to hold the election after the

Shanghai meeting. The announcement of the Shanghai

meeting was sent out to all the IVS Associated Members in the Asia-Oceania region (more than 80 individuals) at the beginning of January, and many researchers

and engineers expressed their interest. At the Shanghai

meeting on March 1st, more than 30 participants discussed the draft of the Terms of Reference, the process

to appoint the Chair and Secretary and their duties, and

plans for initial AOV activities (Figure 2).

At the opening of the IVS General Meeting on

March 2nd, Dr. Axel Nothnagel, the Chair of the IVS

Directing Board, introduced the foundation of the

AOV to the IVS community in general as one of the

three important activities with GGOS, together with

the UN Global Geospatial Information Management

(UN-GGIM) and data referencing through Digital

Object Identifiers (DOI) initiatives.

In September 2014, the election of the first AOV

Chair was held, led by five members of the Election Committee (Shinobu Kurihara, Stas Shabala,

Fengchun Shu, Sergei Gulyaev, and Jungho Cho). The

call for nomination was sent out to all AOV members,

and a special web site for the election was set up at the

Shanghai Astronomical Observatory. There were two

candidates for the Chair position, and 12 institutions

(Table 1) cast one vote each. But it ended in a tie,

thus the final decision went to the vote by the Election

Committee. As a result, Jim Lovell from the University

of Tasmania was elected as the first Chair of AOV.

According to the Terms of Reference approved on

September 1st, the Chair is to appoint the Secretary,

and considering geographical balance, if the Chair is

from Oceania, the Secretary must be appointed from

Asia – and vice versa. Jim appointed Ryoji Kawabata

from the Geospatial Information Authority of Japan

(GSI).

IVS 2014 Annual Report
22 Kurihara et al.

Fig. 1 The dinner time discussion in Finland on March 6th, 2013.

Fig. 2 The meeting at Shanghai Astronomical Observatory on March 1st, 2014.

The Chair and Secretary held a face-to-face meeting at Tsukuba, Japan just after the inauguration ceremony of the Ishioka VGOS Station and discussed

how to organize and coordinate regional VLBI obserIVS 2014 Annual Report
Foundation of the AOV 23

Table 1 Member Organizations of the Asia-Oceania VLBI Group for Geodesy and Astrometry. Shanghai and Xinjiang are registered

as CAS in the list of IVS Member organizations, but in consideration of balance of population they are counted as two institutes in

AOV.

Name of Member Organizations Country

Geoscience Australia Australia

University of Tasmania Australia

Commonwealth Scientific and Industrial Research Organisation Australia

Shanghai Astronomical Observatory China

Xinjiang Astronomical Observatory China

Geospatial Information Authority of Japan Japan

National Astronomical Observatory of Japan Japan

National Institute of Information and Communications Technology Japan

National Institute of Polar Research Japan

Auckland University of Technology New Zealand

Korea Astronomy and Space Science Institute South Korea

National Geographic Information Institute South Korea

vations. It was decided that a survey to grasp resources

of telescopes, correlators, and analysis centers in the

Member Organizations would be carried out.

As a result of the survey sent in December, the representatives of the AOV Member Organizations offered

their resources including three schedulers, 16 network

stations, three correlators, and two analysis centers to

the observations for AOV. The first regional VLBI observations by the Asia-Oceanian VLBI network will

commence early in 2015.

3 Expected Activities of the AOV

Here we describe the expected activities of the AOV

that have been discussed in past meetings and in some

email discussion.

3.1 Regular Regional VLBI Observations

Regional VLBI observations in Asia-Oceania on a regular basis will produce the most tangible and practical

results in the initial activities of the AOV. Until now, the

international VLBI sessions have been implemented

under the IVS. However the Asia-Pacific Space Geodynamics program (APSG), which has two sessions

in a year, is the only VLBI series optimized to AsiaOceania region. We will conduct six 24-hour sessions

in a year. A large number of AUSTRAL sessions have

already been planned for 2015 and so our strategy is to

expand six of these to include as many Northern Hemisphere Asia-Oceania telescopes as possible. These sessions should be renamed AOV sessions. Details such

as frequency sequence, bandwidth, rate of sampling,

and time of the session start are to be determined as

soon as possible. The observed data should be correlated at one of the correlators in this region. The Shanghai VLBI Correlator, the Tsukuba VLBI Correlator,

and the National Geographic Information Institute have

offered to process the AOV data. The observed data

will be e-transferred to the correlator via network, not

media shipping. For the baseline between Hobart and

Tsukuba, the real-time data transferring and near realtime data processing are available at the Tsukuba Correlator [2].

The correlated data in these AOV sessions will be

analyzed and compared by more than two analysis centers and these results will be fed back to the schedulers

to improve the quality of data products in following

AOV sessions. The results will also contribute to the

construction of the regional reference frames in this

area.

3.2 Scientific Meeting

It is essential to hold a plenary scientific meeting on

VLBI like the EVGA meeting and the IVS General

Meeting for sharing and discussing technical matters

and giving researchers a chance to get to know each

IVS 2014 Annual Report
24 Kurihara et al.

other. A new inter-agency and international project

might happen from such an opportunity. In many cases,

meetings connected to VLBI and other related areas

have been held in Europe and America. If we can hold

such a meeting in Asia-Oceania, we expect many researchers from the region will be able to participate

given the relatively smaller travel budgets and given

the fact that they will not be exhausted by long flights

or suffer from jet lag.

3.3 Regular Working Meeting

Additionally, more frequent regular working meetings

by the Chair, Secretary, and representatives from each

Member Organization will be required. A teleconference might be convenient because of less time difference. The progress of VGOS projects in each country

should also be shared in these meetings.

Acknowledgements

The AOV has now formally started a year and a half

after initial discussion. This would not have been possible without contributions from all individuals and institutions in Asia-Oceania, and its future growth will

not be possible without their further contributions. We

wish to extend many thanks to them and hope that the

AOV can contribute to the promotion of VLBI operations, research, and technology development in this

region.

References

1. Campbell, J., EVGA — Looking back at the early beginnings, Proceedings of the 20th Meeting of the European

VLBI Group for Geodesy and Astronomy, edited by W. Alef,

S. Bernhart, and A. Nothnagel, 1-8, 2011.

2. Kurihara, S., K. Nozawa, R. Haas, J. Lovell, J. McCallum,

J. Quick, and T. Hobiger, 4-station Ultra-rapid EOP Experiment with e-VLBI Technique and Automated Correlation/Analysis, Proceedings of the 21st Meeting of the European VLBI Group for Geodesy and Astronomy, edited by N.

Zubko and M. Poutanen, 233-236, 2013.

Terms of Reference

for the Asia-Oceania VLBI

Group for Geodesy and

Astrometry (AOV)

The AOV is a group of scientists in the Asia-Oceania

region supporting geodetic and astrometric Very Long

Baseline Interferometry (VLBI). It is a subgroup

of the International VLBI Service for Geodesy and

Astrometry (IVS).

The Asia-Oceania region is highly dynamic in geophysics and climate, with a large number of destructive

earthquakes, tsunamis, typhoons and cyclones. Many

countries in the region will experience the effects of

climate change much sooner or to a greater degree

than other regions, due to more frequent extreme

weather events and rising sea levels for example. In

order to better understand the risks and reduce the

effects of these phenomena, the AOV has an important

role to play through measurement of tectonic plate

motions, atmospheric variations and determination

of the Geodetic Reference Frame for the region. The

AOV seeks to:

1. foster the use of VLBI, with a particular focus

on producing high quality data and science results in geodesy and astrometry from the AsiaOceania region.

2. form and strengthen links between the different Asia-Oceania VLBI components in technology development and from observations to data

analysis.

3. promote and represent Asia-Oceania geodetic

and astrometric VLBI within the broader international scientific communities.

4. provide and archive information and scientific

results of Asia-Oceania geodetic and astrometric VLBI.

5. organize regular working meetings to improve

communication and cooperation between members of the AOV.

IVS 2014 Annual Report
Foundation of the AOV 25

6. support and promote education and training in

geodetic and astrometric VLBI and related technology in the region.

Membership of the AOV is naturally comprised of IVS

Member Organizations and IVS Associate Members

in the Asia-Oceania region.

The AOV also accepts applications for (non-voting)

Corresponding Membership from individuals working

on geodetic and/or astrometric VLBI at non-IVS

Member Organizations in the Asia-Oceania region.

Membership is institution-based with each institution

carrying one vote in the election of a Chair. Upon

election, the Chair will appoint a Secretary of their

choice. If the Chair is from Asia, the Secretary must

be from Oceania and if the Chair is from Oceania,

the Secretary must be from Asia. The Chair and

Secretary must be from AOV Member Organizations

or be Corresponding Members. These appointments

are for a term of 4 years each. There is no cost for

membership.

Roles of AOV Chair and Secretary

The Chair will:

• Set agendas and chair AOV meetings

• Arrange face-to-face meetings and regular telecons

• In consultation with Members, set the science

goals of the AOV

• Seek funding for AOV activities

• Represent the AOV within other related groups

(IVS, EVGA etc)

• Organize regional observations

The Secretary will be responsible for management and

coordination, including:

• Collating and maintaining information on the

range of expertise and people within the AOV

for purposes of collaboration.

• Management of the AOV website

Approved 1 September 2014

IVS 2014 Annual Report

IVS Coordination

Coordinating Center Report

Dirk Behrend

Abstract This report summarizes the activities of the

IVS Coordinating Center during the year 2014 and

forecasts activities planned for the year 2015.

1 Coordinating Center Operation

The IVS Coordinating Center is based at the Goddard Space Flight Center and is operated by NEOS

(National Earth Orientation Service), a joint effort for

VLBI by the U.S. Naval Observatory and the NASA

Goddard Space Flight Center.

The mission of the Coordinating Center is to

provide communications and information for the IVS

community and the greater scientific community and

to coordinate the day-to-day and long-term activities

of IVS.

The Web server for the Coordinating Center is provided by Goddard. The address is

http://ivscc.gsfc.nasa.gov.

2 Activities during 2014

During the period from January through December

2014, the Coordinating Center supported the following

IVS activities:

• Directing Board support: Coordinated, with local committees, two IVS Directing Board meetings,

NVI, Inc.

Coordinating Center

IVS 2014 Annual Report

in Shanghai, China (March 2014) and Tsukuba,

Japan (October 2014). Notes from each meeting

were published on the IVS Web site.

• VGOS: Supported the activities for establishing

the VLBI Global Observing System (VGOS)

through participation in the VGOS Technical Committee (VTC) and the VGOS Project Executive

Group (VPEG).

• Communications support: Maintained the Web

pages, e-mail lists, and Web-based mail archive

files. Maintained the 24-hour and Intensive session

Web pages including the data acquisition, correlation, analysis, and performance summaries.

• Meetings: Coordinated, with the Local Committee,

the eighth IVS General Meeting, held in Shanghai,

China in March 2014. Chaired the Program Committee for the meeting and prepared the program

booklet.

Fig. 1 Participants of the eighth IVS General Meeting.

• Publications: Published the 2013 Annual Report in

summer 2014. Published three editions of the IVS

Newsletter in April, August, and December 2014.

Published the Proceedings volume of the eighth

IVS General Meeting in cooperation with the Chinese publishing house Science Press in December

29
30 Behrend

2014. All publications are available electronically

as well as in print form.

• Observing Program Committee (OPC): Coordinated meetings of the OPC to monitor the observing

program, review problems and issues, and discuss

changes.

• 2014 Master Schedule: Generated and maintained

the Master Observing Schedule for 2014. Coordinated VLBI resources for observing time, correlator usage, and disk modules. Coordinated the usage

of Mark 5 systems at IVS stations and efficient deployment of disk modules.

• 2015 Master Schedule: Generated the proposed

Master Schedule for 2015 and received approval

from the Observing Program Committee.

3 CONT14 Campaign

The Continuous VLBI Campaign 2014 (CONT14) was

successfully observed in early May 2014. Seventeen

IVS stations at sixteen sites (see Figure 2) observed

for fifteen consecutive days at a rate of 512 Mbps from

6–20 May 2014. The observing was done on the basis

of UT days with each CONT14 day running from 0 UT

to 24 UT. UT day observing allows for the most accurate combination and comparison of results with other

techniques.

Badary

Fortaleza

Kokee

Matera

Onsala

Westford

Wettzell

Yebes

Zelenchukskaya

Hartebeesthoek

Hobart

Katherine

Ny−Alesund

Tsukuba

Warkworth

Yarragadee

Fig. 2 Geographical distribution of the sixteen CONT14 sites.

The sites in red (circles) mostly e-transferred their data to the

correlator, whereas the blue sites (triangles) physically shipped

their recording modules.

All CONT14 data were correlated at the Bonn Correlator, easing the logistics involved with module handling at the correlators and the stations, and ensuring

the creation of a homogeneous data set.

The Coordinating Center, in collaboration with the

OPC, was responsible for:

• the overall planning and coordination of the campaign,

• the media usage and shipment schedule, and

• the preparation of the detailed observing schedules

and notes.

More information about the CONT14 campaign

can be found on the IVS Web site under the URL

http://ivscc.gsfc.nasa.gov/program/

cont14.

4 Staff

The staff of the Coordinating Center is drawn from individuals who work at Goddard. The staff and their responsibilities are listed in Table 1.

Table 1 IVS Coordinating Center staff.

Name Title Responsibilities

Dirk

Behrend

Director Web site and e-mail system maintenance,

Directing Board support, meetings, publications, session Web page monitoring

Cynthia

Thomas

Operation

Manager

Master schedules (current year), resource

management and monitoring, meeting

and travel support, special sessions

Frank

Gomez

Web

Manager

Web server administration, mail system

maintenance, Data Center support, session processing scripts, mirror site liaison

Karen

Baver

General

Programmer

and Editor

Publication processing programs, LaTeX

support and editing, session Web page

support and scripts, Data Center support

Kyla

Armstrong

Data Technician and

Editor

Publications support and Web site support

5 Plans for 2015

The Coordinating Center plans for 2015 include the

following:

• Maintain IVS Web site and e-mail system.

• Publish the 2014 Annual Report (this volume).

• Coordinate, with the local committee, the eighth

IVS Technical Operations Workshop to be held at

IVS 2014 Annual Report
Coordinating Center Report 31

the MIT Haystack Observatory, MA, USA in May

2015.

• Support Directing Board meetings in 2015.

• Coordinate the 2015 Master Observing Schedules

and IVS resources.

• Publish Newsletter issues in April, August, and December.

• Support the VGOS activities within the VTC and

the VPEG.

IVS 2014 Annual Report
Analysis Coordinator Report

John Gipson

Abstract I present the IVS analysis coordination issues of 2014. The IVS Analysis Coordinator is responsible for generating and disseminating the official IVS

products. This requires consistency of the input data by

strict adherence to models and conventions.

1 IVS Analysis Workshop and Software

Demonstration

The IVS Analysis Workshop was held on March 7,

2014 in Shanghai, China in conjunction with the IVS

General Meeting. As usual, the Workshop provided

a useful forum for analysts to discuss various issues.

Space limitations preclude a full discussion, but it is

worthwhile mentioning a few ‘action items’ and what

subsequently happened.

1.1 Analyst Comments

The Goddard VLBI group has been producing session

reports for all IVS sessions since 2000. These reports

summarize what was discovered in the process of analyzing the sessions, and they contain information about

clock breaks, station performance, etc. I have heard

that other IVS analysts use these reports, particularly

if they notice something ‘funny’ with the data. David

Gordon of GSFC suggested that the other ACs which

NVI, Inc.

IVS Analysis Coordinator

IVS 2014 Annual Report

are responsible for particular sessions take over the task

of writing the Analyst Comments for their sessions.

USNO agreed to serve as a test case and expects to start

submitting the comments for the R4s in early 2015. I

look forward to other Analysis Centers which are responsible for specific sessions taking part in this effort.

1.2 Multi-tone Phase Cal

Arthur Niell suggested that the correlators should begin

using Multi-tone Phase Cal. Alessandra Bertarini from

the Bonn Correlator agreed to process a set of sessions

using Multi-tone. These sessions would be compared

to sessions processed ‘normally’. In the summer and

fall of 2014 Alessandra processed the CONT14 sessions using both single-tone and multi-tone phase-cal.

David Gordon edited and analyzed these sessions. I

compared the results of the two data sets. The multitone results tended to be better from several criteria.

The number of observations was larger in the multitone databases, indicating that the correlator was able

to recover more observations. The average session fit

was lower, indicating that the data was more consistent

within a session. The baseline scatter over CONT14

was lower with multi-tone, indicating that the data was

more consistent across the sessions. But it turned out

that the vertical position for Zelenchukskaya changed

by about 1 cm in the multi-tone sessions compared to

the single-tone. This shift was consistent across all of

the sessions.

32
Analysis Coordinator Report 33

1.3 UT1 at Finer Intervals

At short time scales UT1 exhibits stochastic variation.

The error in extrapolated UT1 given an initial offset

and rate grows as 35 μs T(3/2)

, where T is measured

in days. For 24-hour sessions, current VLBI software

produces either A) an overall offset and rate for UT1

for each session or B) UT1 at 24-hour tabular points

surrounding and including the session. The UT1 formal errors for the best sessions is on the order of 2 μs.

This suggests that we could accurately measure UT1 at

intervals of six hours. It was decided to pursue this on

a trial basis although no results are in yet.

2 IAG/GGOS/IERS Unified Analysis

Workshop

The Unified Analysis Workshop was held at Caltech

in June 2014 and chaired by Tom Herring. There were

representatives from all of the Geometric Techniques

and talks about many subjects. I will restrict myself

here to two issues of the most relevance to VLBI. First

there was an extended discussion of the scale of the

TRF. The scale is important because GPS, which provides densification of the ITRF, is relatively insensitive

to scale. Hence the scale must be set by other techniques, and in practice it is set by VLBI and SLR. John

Ries who works in SLR gave an overview of this issue. The scale determined by VLBI and SLR differs by

about 1 ppb, which translates to a difference in local

up of 6 mm. This result has been more or less consistent over the last 15 years. As we strive for millimeter

level accuracy it is important that we resolve this issue.

One possible explanation advanced by Ries is that this

may be due to differences in how the techniques model

the effects of General Relativity. This should certainly

be re-examined. Dan MacMillan of GSFC gave a talk

about various things that can affect the scale of the TRF

as measured by VLBI, for example the effect of not

modeling gravitational deformation in VLBI antennas.

Neglecting this effect will change the estimate of local

up which will go directly into the scale. But the sign

and magnitude of this effect depend on the characteristics of the antenna, and there is no compelling reason why the effect would be positive for all or most of

the antennas. One can determine the effect of gravitational deformation either through direct measurement

or structural modeling of the antenna. (See the references which list papers by Artz, Nothnagel, Sarti, and

Abbondanza discussing this issue.) Neither approach

is inexpensive. But I encourage groups that have resources to make these measurements on the antennas

for which they are responsible. Johannes Bohm gave  ̈

a talk about the effect of Glacial Isostatic Adjustment

(GIA) models on the difference in scale between VLBI

and SLR. If all of the VLBI and SLR sites were colocated with each other, these models would affect both

techniques identically. But because this is not the case,

changing the models will affect the techniques differently and could in principle result in scale differences.

But the magnitude of the effect seems too small. Another issue that affects all of the techniques is modeling of High Frequency Earth Orientation Parameters

(HF-EOP). The importance of this effect was predicted

in the early 1990s, [Herring and Dong], and the first

models were adapted in the mid 1990s (see for example [Gipson 1996]). I gave a talk comparing empirical HF-EOP models derived from Space Geodesy

[Artz 2011, Bockmann 2010, Gipson 2009, Steigenberger 2006] to Tidal models derived from satellite altimetry data [Ray 1994, Ray 1996, Egbert 1994]. Once

the effects of Libration are included, both the Space

Geodesy models and the Tidal models generally agree

with each other. But if you look at the models in more

detail, it is clear that the Space Geodesy models cluster

together, with the RMS difference being ∼2 μs, as do

the Tidal models, also with an RMS difference of 2 μs.

The RMS difference between the Space Geodesy and

the Tidal Models is ∼4 μs, suggesting there is room

for improvement. Harald Schuh gave a talk “Combined

short period EOP model” that reported on a collaboration that plans to derive a new and improved High Frequency Earth Orientation (HF-EOP) model based on

better tidal modeling. It is possible that this model will

agree better with the empirical data.

3 ITRF2013 Becomes ITRF2014

In March 2013, Zuheir Altamimi issued a call for participation in ITRF2013. This was to include data from

the geometric techniques through December 2013. Because of some quality control issues, the IGS had not

submitted a solution as of early December 2014. Zuheir

IVS 2014 Annual Report
34 Gipson

asked the Analysis Coordinators of the different techniques if they would be willing to extend their data by

submitting a contribution through December 2014. The

end product would be not ITRF2013 but ITRF2014.

The hard deadline for the submission would be February 28, 2015. I contacted Sabine Bachmann of the

IVS Combination Center to see if this was feasible on

her end. When she replied in the affirmative I polled

the various IVS Analysis Centers that had submitted

VLBI solutions to ITRF2013 to see if they were willing and able to process another year of data with a

deadline of January 31, 2015. All of the ACs agreed

to do this. Ten IVS Analysis Centers submitted solutions for ITRF2013 and ITRF2014 using five software

packages. The software and the number of ACs were,

in order of popularity: A) Calc/Solve, five ; B) VieVS,

two; C) Geosat, one; D) Occam, one; E) Quasar, one.

Calc/Solve continues to be the most widely used software package, but it is good to have other packages

to which to compare results. As a side-effect of doing

the combination, in the course of comparing the results

from different ACs with each other, many discrepancies were found. Sabine Bachmann notified the respective ACs about this, and many bugs and setup errors

were found and corrected. This sort of feedback is crucial to making the VLBI products better.

References

1. Artz T., Springer A., and Nothnagel A. (2014). A complete

VLBI delay model for deforming radio telescopes: the Effelsberg case, J. Geod. 88:1145-1161.

doi 10.1007/s00190-014-0749-1.

2. Artz, T., S. Tesmer nee B  ́ ockmann, A. Nothnagel (2011)  ̈

“Assessment of periodic sub-diurnal Earth rotation variations at tidal frequencies through transformation of VLBI

normal equation system”, Journal of Geodesy, 85 (9). p.

565-584. doi: 10.1007/s00190-011-0457-z.

3. Nothnagel A., Springer A., Heinz E., Artz T., and de Vicente

P. (2014), Gravitational deformation effects: The Yebes 40-

m telescope. IVS 2014 General Meeting Proceedings. D.

Behrend, K. Baver, K. Armstrong (eds). 158-162.

4. Sarti P., Abbondanza C., Vittuari L. (2009), Gravitydependent signal path variation in a large VLBI telescope

modelled with a combination of surveying methods. J. Geod.

83(11):1115-1126.

doi 10.1007/s00190-009-0331-4

5. Abbondanza C., Sarti P. (2010), Effects of illumination functions on the computation of gravity-dependent signal path

variation models in primary focus and Cassegrainian VLBI

telescopes. J Geod 84(8):515-525.

doi:10.1007/s00190-010-0389-z.

6. Herring T. A., Dong D. (1994) Measurement of diurnal and

semidiurnal rotational variations and tidal parameters of

Earth. J Geophys Res 99(B9):18051-18071.

doi:10.1029/94JB00341

7. Gipson J. M. (1996) Very long baseline interferometry determination of neglected tidal terms in high-frequency earth

orientation variation. J Geophys Res 101(B12):28051-

28064.

doi:10.1029/96JB02292

8. Bockmann S., Artz T., Nothnagel A., Tesmer V. (2010)  ̈ International VLBI service for geodesy and astrometry: Earth

orientation parameter combination methodology and quality of the combined products. J Geophys Res 115:B04404.

doi:10.1029/2009JB006465

9. Steigenberger P., Rothacher M., Dietrich R., Fritsche M.,

Rulke A., Vey S. (2006),  ̈ Reprocessing of a global GPS network. J Geophys Res 111:B05402.

doi:10.1029/2005JB003747

10. Gipson J. M., Ray R. D. (2009) A new model

of tidal EOP variations from VLBI data spanning

30 years. In: EGU General Assembly 2009, 19–

24 April 2009, Vienna, vol 11, p 13096. http://

meetingorganizer.copernicus.org/EGU2009/EGU2009-

13096.pdf

11. Ray J. R. (1996) Measurements of length of day using the

Global Positioning System. J Geophys Res 101(B9):20141–

20149. doi:10.1029/96JB01889

12. Ray R. D., Steinberg D. J., Chao B. F., Cartwright D. E.

(1994) Diurnal and semidiurnal variations in the Earth’s

rotation rate induced by oceanic tides. Science 264(5160):

830–832.

doi:10.1126/science.264.5160.830

13. Egbert G. D., Bennett A. F., Foreman M. G. G.

(1994) TOPEX/POSEIDON tides estimated using a global

inverse model. J Geophys Res 99(C12):24821–24852.

doi:10.1029/94JC01894

IVS 2014 Annual Report
Network Coordinator Report

Ed Himwich, Rich Strand

Abstract This report includes an assessment of the

network performance in terms of lost observing time

for calendar year 2014. Overall, the observing time loss

was about 12%, which is an improvement of about 4%

over the previous year due primarily to fewer antenna

issues at the observatories and less data loss assigned to

the DAS terminal. A table of relative incidence of problems with various subsystems is presented. The most

significant identified causes of loss were the scheduled

VGOS testing, which accounted for 28 IVS sessions

being missed, and bad weather (accounting for about

35% of the loss assigned and reported as miscellaneous problems). After miscellaneous, antenna issues

were next at about 15% of data loss, followed by receiver problems at 14%. RFI was 13%, which is 6.6%

higher than in 2013. Problems with the electronics rack

amounted to 12%. Less than 1.5% of the losses occurred for unknown reasons.

1 Network Performance

The overall network performance was for the most part

very good. RFI in S-Band continues to be a source of

loss and increased by 6.6%. Bad weather in the Pacific

Rim caused wind stows. Antennas with moving parts

fail or require system maintenance. The Mark 5 recording system accounted for 4% of data loss, and most

of that can be assigned to failed disk modules. Overall, operator performance was very good with generNASA Goddard Space Flight Center

IVS Network Coordinator

IVS 2014 Annual Report

ally quick responses to system errors reported by the

Field System or local station equipment such as their

antenna control units.

This network performance report is based on correlator reports for experiments in calendar year 2014.

The report includes results for the 154 24-hour sessions

that had detailed correlator reports available as of January 27, 2015. The data set examined includes approximately 632,594 dual frequency observations. Results

for 94 experiments were omitted because either they

were correlated at the VLBA, they were not correlated

yet by CRTN, or correlation reports were not available

on the IVS data centers. Experiments processed at the

VLBA correlator were omitted because the information provided for them is not as detailed as that from

Mark IV correlators. The experiments that were not

correlated or did not have correlator reports available

yet include some JADE, CRF, APSG, AUST14, OHIG,

R&D, T2, RV, CRDS, EUR, and all the A14 sessions.

In summary, roughly 70% of the data from scheduled

24-hour sessions for 2014 are included in this report.

That is similar to the coverage of reports for many previous years.

An important point to understand is that in this

report, the network performance is expressed in terms

of lost observing time. This is straightforward in

cases where the loss occurred because operations

were interrupted or missed. However, in other cases,

it is more complicated to calculate. To handle this, a

non-observing time loss is typically converted into an

equivalent lost observing time by expressing it as an

approximate equivalent number of recorded bits lost.

As an example, a warm receiver will greatly reduce the

sensitivity of a telescope. The resulting performance

will be in some sense equivalent to the station having

a cold receiver but observing for (typically) only one35
36 Himwich and Strand

third of the nominal time and therefore recording the

equivalent of only one-third of the expected bits. In a

similar fashion, poor pointing can be converted into an

equivalent lost sensitivity and then equivalent fraction

of lost bits. Poor recordings are simply expressed as

the fraction of total recorded bits lost.

Using correlator reports, an attempt was made to

determine how much observing time was lost at each

station and why. This was not always straightforward

to do. Sometimes the correlator notes do not indicate

that a station had a particular problem, while the quality code summary indicates a significant loss. Reconstructing which station or stations had problems—and

why—in these circumstances does not always yield accurate results. Another problem was that it is hard to

determine how much RFI affected the data, unless one

or more channels were removed and that eliminated the

problem. It can also be difficult to distinguish between

BBC and RFI problems. For individual station days,

the results should probably not be assumed to be accurate at better than the 5% level.

The results here should not be viewed as an absolute evaluation of the quality of each station’s performance. As mentioned above, the results themselves

are only approximate. In addition, some problems such

as weather and power failures are beyond the control

of the station. Instead the results should be viewed in

aggregate as an overall evaluation of what percentage

of the observing time the network is collecting data

successfully. Development of the overall result is organized around individual station performance, but the

results for individual stations do not necessarily reflect

the quality of operations at that station.

Because stations typically observe with more than

one other station at a time, the average lost observing

time per station is not equal to the overall average loss

of VLBI data. Under some simplifying assumptions,

the average loss of VLBI data is roughly twice the average loss of station observing time. This approximation is described in the Network Coordinator’s section

of the IVS 2001 Annual Report. For 2014, this agrees

very roughly with the number of (single frequency: S

or X) single baseline observations on which the correlator reported failure, approximately 17%, but other

factors, particularly the dual frequency nature of useful

geodetic observations, complicate the picture. One significant issue this year was that the correlators did not

report losses for some stations (notably Westford) that

did not observe in experiments they were scheduled

for. If we omit those losses from the observing time

loss, the overall observing time loss is reduced (artificially) to about 10%. Twice that is closer to 17% than

doubling 12% is, but the 17% value is still about 25%

less than expected. A similar but somewhat smaller discrepancy also occurred for 2012. Some work would no

doubt find the issues that caused this, but the factor of

two is just a rough approximation, so not getting agreement is not too large an issue of concern.

For 2014, the actual percentage of data (dual frequency) that was not included by the analysts was

approximately 23%. This is even larger (by approximately 7%) than the single baseline observations reported lost by the correlator. It is expected that this

number should be higher both because of the dual

frequency nature of the final observable and the fact

that analysts use additional criteria beyond what is discussed here to decide when to exclude observations.

However, it means in effect that only about 77% of the

observations we attempted to collect were useful.

For the 154 experiments from 2014 examined here,

there were 1,404 station days or approximately 8.2 stations per experiment on average. This compares to 159

experiments considered in the report for 2013, which

included 1,432 station days with nine stations per experiment. The number of analyzed experiments and

the average number of stations per experiment has remained about the same for 2014. Of the station days for

2014, approximately 12% (or approximately 168 days)

of the observing time was lost, which is about 4% lower

than last year. Removing VGOS testing from this assessment the overall observing time loss for 2014 was

10%. This is 6% lower than in 2013, but 2013 included

many sessions lost to scheduled antenna maintenance.

Removing antenna maintenance as a loss reduces the

year 2013 value by 3% to 13% overall loss. By this

measure 2014 is about 3% lower than 2013. For comparison to reports from earlier years, please see Table

1.

The lost observing time for 2014 is in line with results from 2013 and years before 2009. The results for

2009 may be artificially high due to a change in the

way the results were tabulated for that year. We believe

this year’s calculations are more in line with how they

were made before 2009.

An assessment of each station’s performance is

not provided in this report. While individual station

information was presented in some previous years, this

practice seemed to be counter-productive. Although

IVS 2014 Annual Report
Network Coordinator Report 37

Table 1 Lost observing time. The percentage applies to a subset

of the 1999-2000 experiments. Percentages for 2010 and 2011

are omitted but should be 10-20%.

Year Percentage

1999-2000* 11.8

2001 11.6

2002 12.2

2003 14.4

2004 12.5

2005 14.4

2006 13.6

2007 11.4

2008 15.1

2009 21.5

2012 12.3

2013 16.2

2014 11.9

many caveats were provided to discourage people

from assigning too much significance to the results,

there was feedback that suggested that the results were

being over-interpreted. Additionally, some stations

reported that their funding could be placed in jeopardy

if their performance appeared bad, even if it was for

reasons beyond their control. Last and least, there

seemed to be some interest in attempting to “game”

the analysis methods to apparently improve individual

station results. Consequently, only summary results

are presented here. Detailed results are presented to

the IVS Directing Board. Each station can receive its

own results by contacting the Network Coordinator

(Ed.Himwich@nasa.gov).

For the purposes of this report, the stations were

divided into two categories: large N: those that were

included in 24 or more network experiments among

those analyzed here and small N: those in 17 or fewer

(no stations were in the 18-23 experiment range). The

distinction between these two groups was made on the

assumption that the results would be more meaningful for the stations with more experiments. The average observing time loss from the large N group was

much smaller than the average from the small N group,

11.9% versus 22.1%. There are many more station days

in the large N group than the small N group, 1,025 versus 122, so the large N group is dominant in determining the overall performance.

There are 17 stations in the large N group. Ten

stations observed in 49 or more experiments. Of the

17 stations, 13 successfully collected data for approximately 92% or more of their expected observing time.

The four other stations collected 70%, 68%, 65%, and

42% or more of the time. These results are not significantly different from previous years.

There are 21 stations in the small N group. The

range of lost observing time for stations in this category was 0%—100%. The median loss rate was approximately 22%, a little worse than last year.

The losses were also analyzed by sub-system

for each station. Individual stations can contact the

Network Coordinator (Ed.Himwich@nasa.gov) for

the sub-system breakdown (and overall loss) for

their station. A summary of the losses by sub-system

(category) for the entire network is presented in Table

2. This table includes results since 2003 sorted by

decreasing loss in 2014.

The categories in Table 2 are rather broad and require some explanation, which is given below.

Antenna This category includes all antenna problems, including mis-pointing, antenna control computer failures, non-operation due to wind through

2013, and mechanical breakdowns of the antenna. It

also includes scheduled antenna maintenance. Wind

stows have been moved to Miscellaneous for 2014.

Clock This category includes situations in which

correlation was impossible because the clock offset

either was not provided or was wrong, leading

to “no fringes”. Maser problems and coherence

problems that could be attributed to the Maser are

also included in this category. Phase instabilities

reported for Kokee are included in this category.

DBBC clock errors are included in this category.

Miscellaneous This category includes problems that

do not fit into other categories, mostly problems beyond the control of the stations, such as power (only

prior to 2012), (non-wind) weather through 2013,

wind stows (moved here from the Antenna category

starting in 2014), cables, scheduling conflicts at the

stations, and errors in the observing schedule provided by the Operation Centers. For 2006 and 2007,

this category also includes errors due to tape operations at the stations that were forced to use tape

because either they did not have a disk recording

system or they did not have enough media. All tape

operations have since ceased. This category is dominated by weather and scheduling conflict issues.

IVS 2014 Annual Report
38 Himwich and Strand

Table 2 Percentages of observing time lost by sub-system. Percentages for 2010 and 2011 were not calculated.

Sub-System 2014 2013 2012 2009 2008 2007 2006 2005 2004 2003

Miscellaneous 35.11 9.4 6.9 15.3 12.8 7.6 18.0 8.0 8.0 6.0

Antenna 14.81 39.6 18.1 29.4 19.2 34.6 19.0 24.4 32.9 17.8

Receiver 13.89 7.7 11.7 18.6 13.8 14.9 20.8 24.2 18.0 25.2

RFI 13.24 6.4 11.8 5.9 14.8 10.4 11.6 6.2 5.0 9.3

Rack 12.02 19.5 21.8 6.6 8.7 11.4 16.3 5.1 6.8 5.0

Recorder 4.10 3.3 5.7 2.9 4.1 4.6 3.3 8.9 11.1 10.9

Operations 4.08 2.5 2.0 1.2 2.3 0.0 2.0 4.7 6.1 3.6

Unknown 1.3 5.7 14.2 14.2 17.7 14.9 4.0 3.3 10.1 12.6

Power 0.4 2.1

Clock 0.2 3.5 1.8 1.9 0.5 0.3 4.9 14.5 0.5 3.4

Software 0.17 1.0 0.3 0.1 0.1 0.4 0.1 0.5 0.1 0.1

Shipping 0.0 0.9 3.6 4.0 5.4 1.0 0.0 0.2 1.4 6.1

Westford VGOS testing, 28 station days, has been

assigned to Miscellaneous for this year, 2014.

Operations This category includes all operational errors, such as DRUDG-ing the wrong schedule, starting late because of shift problems, operator (as opposed to equipment) problems changing recording

media, and other problems.

Power This category includes data lost due to power

failures at the sites. Prior to 2012, losses due to

power failures were included in the Miscellaneous

category.

Rack This category includes all failures that could be

attributed to the rack (DAS), including the formatter

and BBCs. There is some difficulty in distinguishing

BBC and RFI problems in the correlator reports, so

some losses are probably mis-assigned between the

Rack category and the RFI category.

Receiver This category includes all problems related

to the receiver, including outright failure, loss of

sensitivity because the cryogenics failed, design

problems that impact the sensitivity, LO failure, and

loss of coherence that was due to LO problems. In

addition, for lack of a more clearly accurate choice,

loss of sensitivity due to upper X-band Tsys and

roll-off problems are assigned to this category.

Recorder This category includes problems associated with data recording systems. Starting with

2006, no problems associated with tape operations

are included in this category.

RFI This category includes all losses directly

attributable to interference, including all cases

of amplitude variations in individual channels,

particularly at S-band. There is some difficulty

in distinguishing BBC and RFI problems in the

correlator reports, so some losses are probably

mis-assigned between the Rack category and the

RFI category.

Shipping This category includes all observing time

lost because the media were lost in shipping or held

up in customs or because problems with electronic

transfer prevented the data from being correlated

with the rest of the experiment’s data.

Software This category includes all instances of software problems causing observing time to be lost.

This includes crashes of the Field System, crashes

of the local station software, and errors in files generated by DRUDG.

Unknown This category is a special category for

cases where the correlator did not state the cause

of the loss and it was not possible to determine the

cause with a reasonable amount of effort.

Some detailed comments on the most significant issues for this year’s data loss are given below.

• The largest source of data loss for 2014 was Miscellaneous at 35% which was due to moving wind

stows and weather related issues into this category.

VGOS testing at Westford was also assigned to

Miscellaneous as that station did not participate in

28 previously scheduled R1 sessions.

• The Antenna was the next largest source of loss at

14.8%, and the Receiver was next at 13.9%, with

Fortaleza observing warm for 28 scheduled days.

• RFI contributed about 13%, almost all in S-band

due to commercial systems. The stations with the

most significant RFI losses are Fortaleza, Medicina,

and Matera.

IVS 2014 Annual Report
Network Coordinator Report 39

• The data rack was the next largest source of loss

at 12%, about 7.5% lower than in 2013. This improvement is the result of bringing all stations up to

14 working converters and what seems like a better

operational handle on digital back-ends and better

grounding at the sites.

• The proportion of losses attributed to Unknown,

1.3%, decreased this year, primarily because of improvements in classifying the cause of losses. Assigned maintenance for this year was 22 station

days, 14%, with about half for repair of the antenna

across the network.

Overall, while the network operated well for the

most part, there are a few notable issues (in alphabetical order of station), for stations that lost more than

120 total observing hours regardless of the number of

scheduled sessions for 2014.

• Fortaleza had a significant cryogenic problem again

this year, and a new compressor was shipped to the

station in 2015.

• Hobart12 and Hobart26 have a new and serious RFI

issue. Hobart12 had multiple wind stows, and Hobart26 had DAS issues.

• Katherine12 had wind stows and DBBC issues

since repaired.

• Matera had serious RFI and DAS issues since repaired.

• Medicina had required antenna maintenance and

weather issues.

• Warkworth had multiple antenna controller issues

and antenna repair.

• Westford lost scheduled R1 sessions due to VGOS

testing.

• Yarragadee had Mark 5 module and timing issues.

• Yebes40 lost data due to their data rack until repaired.

2 CONT14

The CONT14 session ran from May 6—20, 2014.

There were 15 sessions using 17 stations for a total

of 114,522 scans in 255 station days. 18 station days

were lost, 7% overall. RFI accounted for 3%, and the

weather caused 2.5% data loss, usually due to wind

stows.

3 New Stations

There are prospects for new stations on several fronts.

These include (in approximate order of how soon they

will start regular observations):

• At Wettzell in Germany, the new Twin Telescope

Wettzell (TTW) for VGOS has been commissioned.

• At GSFC in the USA, a new 12-m antenna is undergoing testing. While this antenna is primarily for

use in the development of the VGOS system, it is

expected that it will eventually join the network for

regular observing.

• South Korea has a new antenna for geodesy at Sejong, built by the National Geographic Information

Institute (NGII). This antenna is now used for normal operations. There is also interest in geodetic

use of the Korean VLBI Network (KVN), which

consists of three stations intended primarily for astronomy.

• In Spain/Portugal, the RAEGE (Atlantic Network

of Geodynamical and Space Stations) project aims

to establish a network of four fundamental geodetic

stations including radio telescopes that will fulfill

the VGOS specifications: Yebes (1), Canary Islands

(1), and Azores (2).

• In Norway, the Norwegian Mapping Authority

(NMA) is in the civic construction phase for a twin

telescope system.

• In Sweden, Onsala Space Observatory has ordered

a twin telescope system.

• In Russia, VGOS antennas have been built at the

QUASAR sites Badary and Zelenchukskaya.

• There is interest in India in building a network of

four telescopes that would be useful for geodesy.

• Saudi Arabia is investigating having a combined

geodetic observatory, which would presumably include a VLBI antenna.

• Colombia is investigating having a combined

geodetic observatory, which would presumably

include a VLBI antenna.

Many of these antennas will become available for

use in the next few years. Efforts are being made to

ensure that these antennas will be compatible with

VGOS.

IVS 2014 Annual Report
40 Himwich and Strand

4 Network Coordination Activities

Network coordination involved dealing with various

network and data issues. These included:

• Reviewing all experiment “ops” messages, correlator reports, and analysis reports for problems and

working with stations to resolve them.

• Responding to requests from stations for assistance.

• Identifying network station issues and working

with the IVS Coordinating Center and the stations

to resolve them. This year these included:

– Encouraging timely delivery of log files

– Validating DBBCs replacing existing systems

– Maintaining the FS PC kernel

• Participating in development of the new VEX2

schedule file standard.

• Providing catalog update information for station

equipment and track lay-outs.

• Recognizing and reporting DBBC issues to station

observing staff.

• Reviewing Mark 5 recording error checks for problems and informing correlator staff and station staff.

• Resolving Kokee GPS/NTP timing issues.

• Troubleshooting power supplies and identifying the

correct parts for shipping.

• Troubleshooting video converters and organizing

shipments to stations.

• Providing telescope pointing analysis and advice.

• Support, including software development, for the

12-m antenna at GSFC and the VGOS observing

system.

5 Future Activities

Network coordination activities are expected to continue next year. The activities will largely be a continuation of the previous year’s activities:

• Reviewing all experiment “ops” messages, correlator reports, and analysis reports for problems and

working with stations to resolve them.

• Responding to requests from stations for assistance.

• Identifying network station issues and working

with the IVS Coordinating Center and the stations

to resolve them.

• Updating Network Station configuration files.

• Helping to coordinate a Mark 5A/5B firmware update for large module directories and bigger disks.

• Providing support, including software development, for the 12-m antenna at GSFC and the VGOS

observing system.

• Other activities as needed.

IVS 2014 Annual Report
IVS Technology Coordinator Report

Bill Petrachenko

Abstract The main focus of IVS technology development over the past year was to achieve operational

readiness for broadband observing. This includes not

only the development and proliferation of broadband

systems but also the development of software and processes to enable efficient, and eventually automatic,

operation of the VGOS stations and correlators. Already, a number of fully compliant (or nearly compliant) VGOS antennas have been constructed (many

of these having already achieved first light and first

fringes) with several more expected to come on line

in the next year or two. The looming challenge is to

ensure: that signal chains are available for these antennas; that operating modes of the various systems are

VGOS compliant, interoperable, and sufficiently robust

against RFI, and that systems can be controlled and

thoroughly monitored remotely.

1 VGOS Compliant Signal Chain

Although the definition of the official VGOS signal

chain has never been formalized in a single document,

it has been discussed in some detail in the collection

of talks presented at the IVS VLBI2010 Workshop

on Technical Specifications held at Bad Koetzting/Wettzell on March 1-2, 2012. Earlier discussions

can also be found in the talks presented at the IVS

VLBI2010 Workshop on Future Radio Frequencies

and Feeds held at Wettzell/Hollenstein on March

Canadian Geodetic Survey, Natural Resources Canada

IVS Technology Development Coordinator

IVS 2014 Annual Report

18-20, 2009 and in the reports “Design Aspects of

the VLBI2010 System: Progress Report of the IVS

VLBI2010 Committee”, June 2009, and “VLBI2010:

A Vision for Geodetic VLBI”, 2005. Links to all of

these talks and reports can be found on the IVS Web

site.

So that there is no confusion about the expectations

for a VGOS system, the most important system parameters are summarized below:

• The input frequency range is 2.2—14 GHz. But

because it is expected that there will be stations

that have RFI in the 2.2—3 GHz range that is

strong enough to saturate their front ends, VGOS

frequency sequences will typically use only the 3—

14 GHz range. Use of the full 2.2—14 GHz range

will however be important to allow interoperability

with legacy S/X systems and stations with S/X/Kaband receivers.

• There will be four 1024 MHz bands in a system,

each of which can be situated anywhere within the

input frequency range. [Resolution for setting the

frequency will be 400 KHz or a sub-multiple.] Because most systems will operate in an RFI environment, a digitizer with at least 8-bit resolution

should be used to provide adequate dynamic range.

• Each of the four 1024 MHz bands will be divided into channels. This is required to protect

against RFI within the band. Although there has

been no formal discussion of acceptable channel

bandwidths, all channelized systems incorporate

a 32 MHz option making this, in practice, the

standard. VDIF output format is expected with

2-bit requantization of either real or complex

data. It will be possible to select any subset of the

channels for output.

41
42 Petrachenko

• The instantaneous output data rate will be 16 Gbps.

But because VGOS observing involves short integrations (less than about 15 s) and frequent slewing between sources, the sustained data rate is not

expected to be greater than about 4 Gbps. Provided

that a RAM buffer of at least 30s at 16 Gbps is available, sustained record or e-transfer rates greater

than about 4 Gbps will not be required.

• To minimize systematic effects, calibration systems

are required:

– A phase calibration (Pcal) signal needs to

be injected into the receiver frontend so that

interferometric phases between bands can

be aligned. The same signal is also be used

to calibrate the downlink delay through the

signal chain and transmission lines. For optimal

performance the Pcal signal should be a series

of very narrow pulses with pulse repetition rate

of 5 or 10 MHz.

– The delay of the cable carrying the maser reference signal to the Pcal generator needs to be calibrated because that delay is reflected directly

in the measured interferometric delay once Pcal

has been applied. This is referred to as cable cal.

It needs to achieve a stability roughly equal to

that of the maser in order to avoid degradation

of the time scale.

– The total power of the receiver needs to be accurately measured in order to support investigations into source structure. This is done by measuring the change in receiver power as a calibrated noise signal is coupled into and out of the

signal chain. In order for this to be done simultaneously with observing, it is necessary that the

noise signal be relatively weak, and in order to

track rapid changes in power, it is necessary that

the switching be done several times per second.

A switching rate of 80 Hz is common in astronomy.

Although there are many other detailed recommendations, systems that include these basic characteristics have a very good chance of working successfully

together.

2 Automation and Remote Control

Automation and remote control are very important aspects of VGOS. With the expectation of 24/7 operations and a sharp rise in the number of observations per

day, it is necessary (to keep operating costs at a reasonable level) to make all processes (including schedule

generation, station operation, correlation, fringe processing, and analysis) as automated as possible.

A necessary step to achieve automation and remote

control is to have a language to concisely and completely describe the instrumentation, operating modes,

and schedule for a session. This has been the role of

the VEX language over the past decades. But, with

the advent of VGOS and the new broadband systems,

instrumentation and operating modes which had not

been conceived of when the original version of VEX

was developed now need to be handled. As a result,

over the past few years, a new version of VEX, VEX2,

was developed. VEX2 was completed this year; it went

through a brief period of community consultation, and

it is now being used to write software to control instrumentation and processes in the complete VGOS operational chain.

The real workhorse for monitor and control at the

stations has always been the Field System. This will

continue to be true in the future, but, with the growing

emphasis on automation and remote control, a significantly larger amount of data will need to be collected

continuously at the stations. This is needed to evaluate

remotely whether or not all systems are working optimally or perhaps to even indicate when systems are just

beginning to show signs of failure. As a result, processes are being put in place to monitor continuously

and store locally a wide variety of parameters including

such things as temperatures throughout the site, motor

currents, Pcal, total power, stream stats, raw data captures, plus much more. These data can be accessed remotely to get a detailed view of the state of all station

equipment.

Although this additional data will be invaluable for

evaluating the health of stations, the volume of data

will be too large for a remote operator to continuously

scan it. As a result, intelligent software and display processes will be required to study the data and inform the

operator through warnings, alarms, and displays when

significant performance deficiencies or dangerous conditions are detected.

IVS 2014 Annual Report
IVS Technology Coordinator Report 43

3 VGOS Innovation

As the operational phase of VGOS approaches, focus is

shifting to the deployment of signal chains at stations.

But significant VGOS related innovation continues at

IVS Technology Development Centers. A few significant highlights are listed below:

• Circular polarized conical feeds are being developed at Yebes. Up until this year, all broadband

feeds considered for use in VGOS have used dual

linear polarization. This is in spite of the fact that

linear polarization has complications for VLBI due

to inhomogeneity of parallactic angles caused by

the wide separation of antennas in the network. Although a solution to the parallactic angle problem

has been found, there continues to be interest in

circular polarized feeds because they are a more

natural fit for VLBI. If the conical feeds being developed at Yebes can achieve low noise, high efficiency, and good polarization separation, they may

become a preferred solution for the VGOS community.

• Progress continues to be made at Noto on the

DBBC3L. The DBBC3L is a data acquisition system that, due to its digitizers with wide bandwidth

and high clock frequency, can direct sample 4

GHz chunks of data. Although each sampler of

the DBBC3L is not capable of directly sampling

the entire 2—14 GHz VGOS bandwidth (as was

the intention with the DBBCH), when eight of

these are combined with fixed frequency down

converters, the full 2—14 GHz band can be sampled in both polarizations. This enables optimal

placement of each channel anywhere within the

full VGOS range, which is an added capability

beyond currently used band-constrained systems.

• The Mark 6 data systems developed at Haystack

are entering operational service. These data systems are ideally suited for use in VGOS observing. Their large input RAM buffers allow data to be

input at the full VGOS data acquisition rate of 16

Gbps and then recorded at a slower rate as the antenna slews to the next source. This capability along

with the advent of disk packs based on 4 Tbyte or

larger individual disks opens the possibility of efficiently recording a complete VGOS 24-hour session onto a single disk pack.

• A new cooled broadband front end based on a Sterling cycle refrigerator is the joint project of Auscope and Callisto. Sterling cycle refrigerators are

small and light; they require very little maintenance and have long times between failures. Although these systems cannot achieve as low physical temperatures as the usual GM-refrigerators, calculations indicate that Tsys for the new front end

system meets the VGOS recommendation while at

the same time being less expensive, lighter, and

more operationally efficient. Collaborative funding

strategies have left sufficient funds to also acquire

a full VGOS back end for Auscope.

• A new cable delay measurement system was developed at Haystack to replace the old Mark III cable

cal units. Although based on similar principles, the

new units are in detail very different and perform

with significantly better stability, matching roughly

the performance of a maser. Initially it had been

thought that an ultra-stable Pcal uplink cable could

be found, but experience has shown that a back-up

monitoring system is prudent to guarantee the specified VGOS temporal performance.

• Significant work was done in the past year to

move the DiFX correlator and fringing software

towards an operational configuration for VGOS. In

the correlator itself several compatibility features

have been implemented to allow correlation of

data streams with incompatible characteristics,

e.g. different bandwidths, different LO settings,

real vs. complex encoding, etc. In addition, the

fringing software has been extended to combine

multiple bands (including the use of a TEC search

to handle the phase curvature of the ionosphere)

and polarizations. With these capabilities in place,

the focus has moved to improving the operational

efficiency of the correlator so that correlator runs

become easier to set up and extraction of data

from Mark 6 units into native correlator storage

is less time consuming. When this development

phase is complete, it will be important to export the

VGOS enhancements to other correlators so that

experience can be gained with processing VGOS

sessions.

• A cost effective direct sampling digital back end

is being developed at NICT. This system uses a

broadband sampler along with a lower rate sample clock. Using aliasing, a number of bands can

be overlapped onto the same frequency region. AlIVS 2014 Annual Report
44 Petrachenko

though very cost effective, this system does not

currently support channelization and hence is incompatible with the VGOS recommendation. It has

been used successfully on the baseline between

Kashima and Ishioka for broadband tests but is

mainly intended for internal use with the NICT time

transfer project.

4 VGOS Observing Plan

During 2013, the VGOS Project Executive Group

(VPEG) developed an observing plan to guide the

transition from current S/X to future VGOS broadband

operations. The plan spans five years and begins with a

series of test campaigns in 2015. In 2014, the plan was

accepted by the IVS Directing Board and presented

to the IVS membership at the IVS GM in Shanghai.

In the meantime the plan was augmented by a Data

Transmission and Correlation Plan.

Two main initiatives are underway to support the

test campaigns of 2015.

First, a number of VGOS antennas have now been

constructed and have achieved first light and first interferometric fringes. Westford and GGAO have implemented front and back end receivers that are very

nearly VGOS compliant. At the same time, a number

of other international sites are working hard to put in

place VGOS signal chains, with Wettzell, Yebes, and

Kokee expected to be ready before the end of the year.

Second, a series of bi-weekly VGOS sessions have

been initiated between Westford and GGAO, the goal

being to establish a fully operational VGOS methodology. To support this, a so-called “parallel universe”

has been put in place at Goddard that completely imitates the Master Schedules, ops mailing list, etc. that

have been used for years for the legacy S/X-band operations. In addition, processes are being put in place to

automate as much as possible the full operational chain

from schedule generation to analysis. The importance

of this effort cannot be overemphasized in the quest to

move from a VGOS test footing to a full VGOS operational capability.

With these two initiatives underway, the IVS can

be optimistic that it will be ready for the VGOS Pilot

Project planned for 2016.

IVS 2014 Annual Report
Network Stations

Badary Radio Astronomical Observatory 2014 IVS Annual Report

Sergey Smolentsev, Valery Olifirov, Dmitry Ivanov

Abstract This report provides information about the

Badary network station: general information, facilities,

staff, present status, activities during 2014, and outlook.

1 General Information

The Badary Radio Astronomical Observatory (Figure 1) was founded by the Institute of Applied

Astronomy (IAA) as one of three stations of the

Russian VLBI network QUASAR. The sponsoring

organization of the project is the Russian Academy

of Sciences (RAS). The Badary Radio Astronomical

Observatory is situated in the Republic Buryatia

(East Siberia) about 130 km east of Baikal Lake

(see Table 1). The geographic location of the observatory is shown on the IAA RAS Web site

(http://www.ipa.nw.ru/PAGE/rusipa.htm). The basic

instruments of the observatory are a 32-m radio

telescope equipped with special technical systems for

VLBI observations and a 13.2-m VGOS antenna. The

observatory is also equipped with co-location instruments such as GPS/GLONASS/Galileo receivers, a

“DORIS” beacon, and an SLR system. In 2014 a WVR

was installed.

Institute of Applied Astronomy of RAS

Badary Network Station

IVS 2014 Annual Report

Table 1 Badary Observatory location and address.

Longitude 102◦14′

Latitude 51◦46′

Republic Buryatia

671021, Russia

oper@badary.ipa.stbur.ru

2 Technical Staff

Table 2 Staff related to VLBI operations at Badary.

Valery Olifirov observatory chief

Alex Maklakov chief engineer, FS, pointing system control

Roman Kuptsov engineer

Andrey Mikhailov FS, pointing system control

3 Component Description

3.1 Technical and Scientific Information

Characteristics of the radio telescope are presented in

Table 3.

3.2 Co-location of VLBI, GPS/GLONASS,

DORIS, and SLR System

Badary observatory is equipped with the Javad

GPS/GLONASS/Galileo receiver, The SLR system

“Sazhen-TM” (Figure 3), “DORIS” beacon, and

47
48 Smolentsev et al.

Fig. 1 Badary observatory.

Table 3 Technical parameters of the radio telescope.

Year of construction 2005

Mount AZEL

Azimuth range ±270◦(from south)

Elevation range from −5

◦

to 95◦

Maximum azimuth

- velocity 0.83 ◦/s

- tracking velocity 2.5

′

/s

- acceleration 12.0

′

/s

2

Maximum elevation

- velocity 0.5

◦

/s

- tracking velocity 0.8

′

/s

- acceleration 12.0

′

/s

2

Pointing accuracy better than 10′′

Configuration Cassegrain (with

asymmetrical subreflector)

Main reflector diameter 32 m

Subreflector diameter 4 m

Focal length 11.4 m

Main reflector shape quasi-paraboloid

Subreflector shape quasi-hyperboloid

Main reflector surface accuracy ± 0.5 mm

Frequency range 1.4–22 GHz

Axis offset 3.7±2.0 mm

automatic meteorological station WXT-510 are in

operation (Figure 2).

4 Current Status and Activities during

2014

Badary observatory participates in IVS and domestic

VLBI observing programs. During 2014, Badary staFig. 2 Javad GPS/GLONASS/Galileo receiver and“DORIS”

beacon at the Badary observatory.

tion participated in 49 24-hour IVS sessions — 25 IVSR4, two IVS-T2, two EUROPE, five R&D, and 15 IVSCONT.

Badary participated in 48 24-hour sessions in the

framework of the domestic Ru-E program for determination of all Earth orientation parameters and in 361

one-hour Ru-U sessions for obtaining Universal Time

using e-VLBI data transfer. e-VLBI data transfer is

used for Badary observation data for Ru-E sessions too.

Finally, the installation of the 13.2-m antenna system and all necessary equipment is finished. RT-13

(Figure 4) saw “first light” (Figure 5).

In 2014 a WVR was installed and successfully

worked (Figure 6).

IVS 2014 Annual Report
Badary IVS Annual Report 49

Fig. 3 “Sazhen-TM” SLR system at Badary observatory observed 2,803 passes of LAGEOS, GLONASS et al. and obtained

22,834 normal points during 2014.

Fig. 4 RT-13 antenna at Badary observatory.

5 Future Plans

Our plans for the coming year are the following:

• To participate in IVS sessions,

Fig. 5 “First light” of RT-13 antenna at Badary observatory.

Fig. 6 WVR at Badary observatory.

• To carry out domestic observing programs for

obtaining Universal Time daily and for obtaining

Earth orientation parameters with e-VLBI data

transfer weekly,

• To carry out SLR observations of geodetic and navigation satellites,

• To participate in EVN and RADIOASTRON observing sessions,

• To continue geodetic monitoring of the RT-32 parameters,

• To perform WVR measurements on a regular basis,

• To comission RT-13,

• To begin regular observations with RT-13 in 2015.

References

1. Finkelstein A., Ipatov A., Smolentsev S. The Network

“Quasar”: 2008-2011 // “Measuring the future”, Proc. of the

Fifth IVS General Meeting, A. Finkelstein, D. Behrend (eds.),

St. Petersburg, “Nauka”, 2008. pp. 39–46.

IVS 2014 Annual Report
Effelsberg Radio Observatory 2014 Annual Report

Uwe Bach, Alex Kraus

Abstract The 100-m radio telescope of the MaxPlanck-Institut fur Radioastronomie (MPIfR) is one of  ̈

the largest fully steerable single-dish radio telescopes

in the world and a unique high-frequency radio

telescope in Europe. The telescope can be used to

observe radio emissions from celestial objects in a

wavelength range from 90 cm (300 MHz) down to

3.5 mm (90 GHz).

1 General Information

The Effelsberg radio telescope was inaugurated in 1971

and was (for almost 30 years) the largest fully steerable single-dish radio telescope in the world. It is situated in a protected valley near Bad Munstereifel (about  ̈

40 km southwest of Bonn) and operated by the MaxPlanck-Institut fur Radioastronomie (MPIfR) on behalf  ̈

of the Max-Planck-Society (MPG). To this day, it is the

largest radio telescope in Europe and is mostly used for

astronomical observations.

This extremely versatile and flexible instrument can

be used to observe radio emissions from celestial objects in a wavelength range from about 1 m (corresponding to a frequency of 300 MHz) down to 3.5 mm

(90 GHz). The combination of the high surface accuracy of the reflector (the mean deviation from the ideal

parabolic form is ∼0.5 mm rms) and the construction

principle of ‘homologous distortion’ (i.e., the reflector in any tilted position has a parabolic shape with a

Max-Planck-Institut fur Radioastronomie, Bonn, Germany  ̈

Effelsberg Network Station

IVS 2014 Annual Report

well-defined, but shifted, focal point) enables very sensitive observations to be made at high frequencies (i.e.,

ν >10 GHz).

The wide variety of observations with the 100-m

radio telescope is made possible by the good angular

resolution, the high sensitivity, and a large number of

receivers which are located either in the primary or in

the secondary focus. Together with a number of distinct backends dedicated to different observing modes,

this provides excellent observing conditions for spectroscopic observations (atomic and molecular transitions in a wide frequency range), high time-resolution

(pulsar observations), mapping of extended areas of

the sky, and participation in a number of interferometric networks (IVS, mm-VLBI, EVN, and Global VLBI

etc.).

Table 1 Telescope properties.

Name Effelsberg

Coordinates 6:53:01.0 E,+50:31:29.4 N

Mount azimuthal

Telescope type Gregorian (receivers in primary

and secondary focus)

Diameter of main reflector 100 m

Focal length of prime focus 30 m

Focal length of secondary 387.7 m

focus

Surface accuracy 0.55mm rms

Slew rates Azi: 25 deg/min, Elv: 16 deg/min

Receivers for Geodetic 3.6 cm/13 cm secondaryobservations focus (coaxial)

Tsys (3.6 cm/13 cm) 25 K, 200 K

Sensitivity (3.6 cm/13 cm) 1.4 K/Jy, 0.5 K/Jy

HPBW (3.6 cm/13 cm) 81 arcsec, 350 arcsec

Tracking accuracy ∼ 2 arcsec

50
Effelsberg 2014 Report 51

Fig. 1 Aerial image of the Effelsberg radio observatory. Shown are the 100-m Effelsberg antenna and the institute’s building (left of

the antenna). Effelsberg hosts also a station of the European Low Frequency Array (LOFAR), seen in the lower part of the picture.

2 Staff

The staff at Effelsberg consists of about 40 people, including telescope operators, technical personnel for receivers, electronics, and mechanics, scientists, and administrative personnel. Involved in IVS activities are,

beside the telescope operators, Dr. Alexander Kraus

as station manager and scheduler for the 100-m Effelsberg telescope, Dr. Uwe Bach as support scientist and

VLBI friend, and Thomas Georgi for VLBI support.

3 Activities during the Past Year

Effelsberg has participated regularly in the EUROPE

IVS sessions since 1991. In 2014, the experiments

EUR129 and EUR132 were observed. About 30% of

the observing time of the Effelsberg antenna is used

for VLBI observations. Most of them are astronomical observations for the European VLBI Network

(EVN), High Sensitivity Array (HSA), Global MM

VLBI Array (GMVA) or other global networks, but

also geodetic VLBI observations within the IVS are

performed. Since 2011, the Russian Astro Space

Center has been operating a 10-m space radio antenna

on board the satellite SPEKTR-R (RadioAstron) to

perform VLBI observations. Effelsberg is highly

involved in the ground based support of this mission,

and 262 of a total of 455 VLBI observations in 2014

were connected to RadioAstron observations.

To reduce the gain elevation dependence for secondary focus observations, the 6.5-m diameter subreflector of the Effelsberg antenna consists of 96 individual panels with actuators. The panels are adjusted

for each elevation via a look-up table based on the finite element model that describes the gravitational deformations of the main dish. To further improve the

look-up table, a holography technique which can produce low resolution maps of the wavefront-errors in an

antenna surface using astronomical observations was

tested at Effelsberg. This “out-of-focus (OOF)” holography requires — in contrast to traditional holography

measurements — only several focused and out of focus

IVS 2014 Annual Report
52 Bach and Kraus





	





	





	




	





	









 !	


!
"

	


Fig. 2 Picture of the secondary focus cabin with several astronomical receivers, e.g. the new K-band with two horns and the

geodetic SX system with the 3.6-cm horn and the tertiary mirror

for the 13-cm horn.

images of a compact source at a good signal to noise

ratio. The study is still in progress, but some promising measurements were obtained and were reported at

the EVN Symposium (Bach U., 2014, PoS (12th EVN

Symposium) 036, in press).

A new K-band receiver (18 to 26 GHz) was

installed in the secondary focus in 2014 (see Figure 2).

The commissioning is in progress, and first VLBI

fringes were obtained in the second EVN Session

in June 2014. The system will soon replace the old

K-band VLBI receiver.

4 Current Status

Effelsberg uses the DBBC2 and a Mark 5B+ recorder

for all EVN, global, and geodetic VLBI observations. In addition there are two NRAO RDBEs and a

Mark 5C recorder that are used for observations with

the VLBA, HSA, and GMVA. Both VLBI backends

and their recorders are controlled by the Field System (current release FS-9.11.6). The observatory is

connected via a 10 GE optical fiber to the e-VLBI

network and can do real time e-VLBI observations and

e-transfer of data to Bonn and JIVE.

5 Future Plans

Upgrades for several receiving systems are planned for

2015. A new C-band system (4-8/9.3 GHz) for wideband observations has been constructed and will be installed in the secondary focus within the next month.

The installation of a new Q-band receiver (38 to 50

GHz) is planned for autumn 2015. The new receivers

will provide wideband IF signals of 2.5 GHz and 4 GHz

bandwidth which can be used with the next generation

of digital VLBI backends and recorders (e.g. DBBC3

and Mark 6) to record data at recording rates of up to

32 Gbps.

Two Mark 6 recorders are currently tested in the

lab in Bonn and will be installed in Effelsberg soon.

The installation of a DBBC3 is planned for summer

2015. It is planned to replace the shipment of modules

for all EVN observations to JIVE by e-transfers via the

e-VLBI network using a Mark 6 recorder in raid mode.

IVS 2014 Annual Report
Fortaleza Station 2014 Annual Report

Pierre Kaufmann 1, A. Macilio Pereira de Lucena 2, Adeildo Sombra da Silva 1

Abstract This is a brief report about the activities carried out at the Fortaleza geodetic VLBI station (ROEN:

Radio Observat  ́ orio Espacial do Nordeste), located in  ́

Eusebio, CE, Brazil, during the period from January  ́

until December 2014. The total observed experiments

consisted of 118 VLBI sessions and continuous GPS

monitoring recordings. About 90% of VLBI recorded

data was transmitted through the high speed network.

1 General Information

The Radio Observat  ́ orio Espacial do Nordeste, ROEN,  ́

located at INPE facilities in Eusebio, nearly 30 km east  ́

of Fortaleza, Ceara State, Brazil, began operations in  ́

1993. Geodetic VLBI and GPS observations are carried out regularly, as contributions to international programs and networks. ROEN is part of the Brazilian

space geodesy program, which was initially conducted

by CRAAE (a consortium of the Brazilian institutions

Mackenzie, INPE, USP, and UNICAMP) in the early

1990s. The program began with antenna and instrumental facilities erected, with activities sponsored by

the U.S. agency NOAA and the Brazilian Ministry of

Science and Technology’s FINEP agency.

ROEN is currently coordinated by CRAAM, Center of Radio Astronomy and Astrophysics, Engineering School, Mackenzie Presbyterian University, Sao ̃

Paulo, in agreement with the Brazilian National Space

1. Universidade Presbiteriana Mackenzie, CRAAM and INPE,

Radio Observat  ́ orio Espacial do Nordeste, ROEN  ́

2. Instituto Nacional de Pesquisas Espaciais, INPE

Fortaleza Network Station

IVS 2014 Annual Report

Research Institute, INPE. The activities are currently

carried out under an Agreement of Cooperation which

was signed between NASA—representing research interests of NOAA and USNO—and the Brazilian Space

Agency, AEB and which was extended until 2021.

Under the auspices of the NASA-AEB Agreement,

a contract was signed between NASA and CRAAM,

Mackenzie Presbyterian Institute and University to partially support the activities at ROEN. In 2014, the contract was renewed for four more years.

The counterpart of the operational costs, staff, and

support of infrastructure are provided by INPE and by

Mackenzie.

2 Main Instruments

The largest instrument at ROEN is the 14.2-m radio

telescope on an alt-azimuth positioner. It is operated at

S- and X-bands, using cryogenic radiometers. The system is controlled by the Field System, Version 9.11.6.

Observations are recorded with a Mark 5A system

and transmitted through a high speed network either

to the U.S. (WACO and Haystack correlators) or to

the Bonn correlator in Germany at rates about 220

Mbps. The 1 Gbps link was accomplished in 2007.

It integrates and is sponsored by the Brazilian Research Network — RNP. One Sigma-Tau hydrogen

maser clock standard is operated at ROEN. GPS monitoring is performed within a cooperative program with

NOAA (USA). There is a Leica System 1200 installed

at the station that operates continuously. The collected

data are provided to the NOAA/IGS center and to the

Brazilian IBGE center. ROEN has all basic infrastruc53
54 Kaufmann et al.

Fig. 1 14.2-m radio telescope.

tures for mechanical, electrical, and electronic maintenance of the facilities.

3 Staff

The Brazilian space geodesy program is coordinated

by one of the authors (Pierre Kaufmann), who is

Brazil’s AEB representative in the NASA-AEB Agreement. The coordination receives support from the Sao ̃

Paulo office at CRAAM/Instituto and Universidade

Presbiteriana Mackenzie, with administrative support

from Valdomiro M. S. Pereira and Luc ́ıola Melissa

Russi. The Fortaleza Station facilities and geodetic

VLBI and GPS operations are managed on site by Dr.

Antonio Macilio Pereira de Lucena (INPE), assisted

by Eng. Adeildo Sombra da Silva (Mackenzie), and

the technicians Avicena Filho (INPE) and Francisco

Renato Holanda de Abreu (Mackenzie).

4 Current Status and Activities

4.1 VLBI Observations

In addition to the regular experiments, Fortaleza participated in the CONT14 campaign during 2014. It consisted of 15 days of continuous observations whose

main goal was to acquire state-of-the-art VLBI data

over a time period of about two weeks to demonstrate

the highest accuracy of which the current VLBI system

is capable. All sessions of geodetic VLBI are described

in Table 1.

Table 1 2014 session participation.

Experiment Number of Sessions

IVS-R1 37

IVS-R4 50

IVS-T2 03

R&D 04

CONT14 15

CRF 03

OHIG 06

4.2 Operational and Maintenance

Activities

The summary of activities performed in the period is

listed below:

1. Repair and maintenance of the following equipment: cryogenic system, Mark IV video converters,

Mark 5A recorder, antenna control electronic system, angle encoder system.

2. Adjustment in cavity control system of SigmaTau

maser.

3. Field system updating.

4. Mark 5A recorder operational system and software

restoration.

5. Installation of a new UPS system.

6. Operation and maintenance of geodetic GPS

(NOAA within the scope of NASA contract).

7. Operation and maintenance of power supply equipment at the observatory (main and diesel driven

standby).

IVS 2014 Annual Report
Fortaleza 2014 Report 55

8. Transferring of recorded data through high speed

network part of and sponsored by the Brazilian Research Network — RNP.

4.3 GPS Operations

The IGS network GPS receiver operated regularly at all

times during 2014. Data were collected and uploaded

to an IGS/NOAA computer.

IVS 2014 Annual Report
Goddard Geophysical and Astronomical Observatory

Ricardo Figueroa, Jay Redmond, Katherine Pazamickas

Abstract This report summarizes the technical parameters and the technical staff of the VLBI system at the

fundamental station GGAO. It also gives an overview

about the VLBI activities during the 2014 report year.

The outlook lists the outstanding tasks to improve the

performance of GGAO.

1 GGAO at Goddard

The Goddard Geophysical and Astronomical Observatory (GGAO) consists of a 5-meter radio telescope for

VLBI, a new 12-meter radio telescope for VLBI2010

development, a 1-meter reference antenna for microwave holography development, an SLR site that

includes MOBLAS-7, the NGSLR development

system, a 48′′ telescope for developmental two-color

Satellite Laser Ranging, a GPS timing and development lab, a DORIS system, meteorological sensors,

and a hydrogen maser. In addition, we are a fiducial

IGS site with several IGS/IGSX receivers.

GGAO is located on the east coast of the United

States in Maryland. It is approximately 15 miles NNE

of Washington, D. C. in Greenbelt, Maryland (Table 1).

NASA Goddard Space Flight Center

GGAO Network Station

IVS 2014 Annual Report

Table 1 Location and addresses of GGAO at Goddard.

Longitude 76.4935◦ W

Latitude 39.0118◦ N

MV3

Code 299.0

Goddard Space Flight Center (GSFC)

Greenbelt, Maryland 20771

http://cddisa.gsfc.nasa.gov/ggao/vlbi.html

2 Technical Parameters of the VLBI Radio

Telescopes at GGAO

The 5-m radio telescope for VLBI at MV3 was originally built as a transportable station, but it was moved

to GGAO in 1991 and has been used as a fixed station. In the winter of 2002 the antenna was taken off its

trailer and permanently installed at GGAO.

In October of 2010, construction of the new

12-meter VLBI2010 developmental antenna was completed. This antenna features all-electric drives and a

Cassegrain feed system. Integration of the broadband

receiver and the associated sub-systems is underway

as a joint effort between Exelis and the MIT Haystack

Observatory.

The technical parameters of the radio telescopes are

summarized in Table 2.

3 Technical Staff of the VLBI Facility at

GGAO

GGAO is a NASA R&D and data collection facility

and is operated under the Space Communication Network Services (SCNS) contract by Exelis Inc. The staff

56
GGAO IVS Report for 2014 57

Fig. 1 Goddard Geophysical and Astronomical Observatory.

Table 2 Technical parameters of the radio telescopes at GGAO.

Parameter 5-m 12-m

Owner and operating agency NASA NASA

Year of construction 1982 2010

Diameter of main reflector d 5m 12m

Azimuth range +/−270◦ +/−270◦

Azimuth velocity 3

◦/s 5◦/s

Azimuth acceleration 1

◦/s2 1◦/s2

Elevation range +/−90◦ 5−88◦

Elevation velocity 3

◦/s 1.25◦/s(Avg.)

Elevation acceleration 1

◦/s2 1◦/s2

Receiver System

Focus Cassegrain Cassegrain

Receive Frequency 2−14GHz 2−14GHz

Tsys 100K 50K(T heoretical)

Bandwidth 512MHz, four bands 512MHz, four bands

G/T 26dB/K 43dB/K

VLBI terminal type CDP VLBI2010

Recording media Mark IV Mark 5C

at GGAO consists mainly of two operators and one

backup engineer. The Exelis staff includes Jay Redmond and Katherine Pazamickas conducting VLBI operations and maintenance at GGAO with the support of

Ricardo Figueroa.

4 Status of MV3 and VLBI2010 at GGAO

Having ceased VLBI operations in May 2007, MV3

continues on a full time basis to be a major component in the program to demonstrate the feasibility of the

VLBI2010 broadband delay concept. Under the guidIVS 2014 Annual Report
58 Figueroa et al.

ance of the Exelis team, the majority of MV3’s S/X

components were upgraded, and antenna refurbishing

should be completed by early 2015 to provide additional support to the VLBI2010 System. Tasks started

in 2013 and finished in 2014 for the 5-m antenna included the following:

• The 017 Electronic Box was refurbished, and new

wiring and upgraded components were installed.

• The Cryogenic Dewar and its components were restored for X-band operations. Also, the cryogenic

thermometer, vacuum gauge, and bias voltage box

were installed and tested.

• The FSS Subreflector and Feed assembly, including the FSS, was recoated with a highly reflective

surface, repaired, and placed back on the antenna.

• The ACU and control panel are in the process of

upgrade and troubleshooting.

• Two of the Sargent Welch Directorr Model 8816-

Bs were refurbished using a repair kit. One was

mounted and tested in the antenna.

Much of the 2014 activities at GGAO focused on

performance testing and upgrading of the VLBI2010

12-m antenna. But some other activities worth noting

included:

• Continued wideband system testing and characterization of the 12-m antenna.

• Procurement of new test equipment for characterization of the wideband RF hardware.

• Continued broadband phase cal and cable cal performance testing.

• Integration of RDBEs, Mark 6 recorder, UDC, and

Field System computer software.

• Installation of RDBE-G hardware.

• VLBI observations between Westford and GGAO

with RDBE-G hardware/software and the Mark 6

recorder.

• Upgrade of timing distribution and standardization

of broadband rack cables.

• Additional testing of 16 Gbps VLBI recording,

demonstrated using the Mark 6 recorder.

• Refurbishing of the 5-meter antenna control unit

and vacuum system.

5 Outlook

GGAO will continue to support VLBI2010, e-VLBI,

and other developmental activities during the upcoming year. Tentative plans for 2015 include plans to:

• Continue to upgrade the VLBI2010 broadband receiver system on the 12-m antenna.

• Conduct IVS observations using the Mark 6

recorders to demonstrate the VLBI2010 capabilities on a regular twice a month schedule.

• Continue testing of the new broadband phase calibrator for the VLBI2010 system.

• Continue the upgrade of the 5-m antenna and initiate testing in S/X band.

• Continue to measure the baseline between the 5-

m and the 12-m antennas for position ties to the

reference frame.

• Try to understand the source of the azimuth and elevation gearboxes’ oil contamination.

• Try to understand why the antenna will not move in

elevation under computer control when first started

up on cold mornings.

IVS 2014 Annual Report
Hartebeesthoek Radio Astronomy Observatory (HartRAO)

Marisa Nickola, Jonathan Quick, Ludwig Combrinck

Abstract HartRAO provides the only fiducial geodetic site in Africa and participates in global networks for

VLBI, GNSS, SLR, and DORIS. This report provides

an overview of geodetic VLBI activities at HartRAO

during 2014, including the 15-m radio telescope taking over from the 26-m for the majority of sessions,

progress with the VGOS project, and preparations for

hosting the 9th IVS General Meeting in 2016.

1 Geodetic VLBI at HartRAO

Hartebeesthoek is located 65 km northwest of Johannesburg, just inside the provincial boundary of Gauteng, South Africa. HartRAO is located 32 km away

from the nearest town, Krugersdorp. The telescopes

are situated in an isolated valley which affords protection from terrestrial radio frequency interference.

HartRAO currently operates both a 15-m and a 26-m

radio telescope. The 26 m is an equatorially mounted

Cassegrain radio telescope built by Blaw Knox in 1961.

The telescope was part of the NASA deep space tracking network until 1974 when the facility was converted to an astronomical observatory. The 15 m is an

alt-az radio telescope built as a Square Kilometre Array (SKA) prototype during 2007 and converted to an

operational geodetic VLBI antenna during 2012. The

telescopes are co-located with an ILRS SLR station

(MOBLAS-6), an IGS GNSS station (HRAO), a seismic vault, and an IDS DORIS station (HBMB) at the

HartRAO

HartRAO Network Station

IVS 2014 Annual Report

adjoining South African National Space Agency Earth

Observation (SANSA EO) site. HartRAO is also a full

member of the EVN.

Fig. 1 Please join us for the 9th IVS General Meeting to be held

in South Africa in March 2016!

2 Technical Parameters of the 15-m and

26-m Telescopes of HartRAO

Table 1 contains the technical parameters of the

HartRAO 15-m and 26-m radio telescopes, while

Table 2 and Table 3 contain technical parameters of

the HartRAO 15-m and 26-m receivers, respectively.

The current data acquisition systems consist of a

DBBC terminal and a Mark 5B+ recorder for both

the 15-m and the 26-m antennas. A Mark 5B and a

Mark 5C recorder are used for e-transfer of data and

conditioning and testing of disk packs. Three hydrogen

masers are available for use, namely the EFOS-28,

59
60 Nickola et al.

which is currently employed for VLBI on the 15-m

antenna, as well as two spares – iMaser 72, currently

employed on the 26-m antenna, and the resuscitated

EFOS-6.

Table 1 Antenna parameters.

Parameter Hart15M HartRAO

Owner and operating agency HartRAO HartRAO

Year of construction 2007 1961

Radio telescope mount Az-El Offset equatorial

Receiving feed Prime focus Cassegrain

Diameter of main reflector d 15m 25.914m

Focal length f 7.5m 10.886m

Focal ratio f /d 0.5 0.42

Surface error of reflector (RMS) 1.6mm 0.5mm

Short wavelength limit 2cm 1.3cm

Pointing resolution 0.001◦ 0.001◦

Pointing repeatability 0.004◦ 0.004◦

Slew rate on each axis Az: 2◦s

−1 HA: 0.5◦

s

−1

El: 1◦s

−1 Dec: 0.5◦

s

−1

Table 2 Parameters of the 15-m co-axial receiver.

Parameter X-band S-band

Feeds stepped horn wide-angle corrugated horn

Amplifier type cryo HEMT cryo HEMT

Tsys (K) 40 42

SSEFD (Jy) 1400 1050

PSS (Jy/K) 35 25

3 dB beamwidth (◦) 0.16 0.57

Table 3 Parameters of the 26-m receiver (degraded performance

due to dichroic reflector being used for simultaneous S-X VLBI).

Parameter X-band S-band

Feeds dual CP conical dual CP conical

Amplifier type cryo HEMT cryo HEMT

Tsys (K) 52 40

SSEFD (Jy) 849 1190

PSS (Jy/K) 16.3 29.8

3 dB beamwidth (◦) 0.096 0.418

3 Current Status

During 2014, the 15-m antenna took over much of

the 26 m’s workload with the number of sessions involving HART15M more than doubling the previous

year’s number. The 15-m antenna joined in its first

OHIG sessions in February and successfully participated in its first CONT campaign during May 2014,

taking over from the 26-m antenna, which was involved in previous CONT02, CONT05, CONT08, and

CONT11 campaigns. During September 2014, the 15-

m antenna also participated in its second AUSTRALCONT campaign. In contrast to the increased number

of sessions run on the 15-m antenna, the 26 m’s workload nearly halved compared to that of 2013. Eight

dual experiments, four R1s, and four AUSTs, with

both the 15-m and 26-m antennas observing, were performed during the year. On the 4th of August 2014 at

10:22:33 UT during one of these dual sessions, R1647,

the Orkney earthquake occurred approximately 100 km

from HartRAO, registering a magnitude of 5.5 on the

Richter scale. The 15-m and 26-m antennas each also

partcipated in two Chinese Lunar Lander Chang’E-3

RD/OCEL sessions during 2014. Geodetic VLBI data

for all but the RDV sessions were e-transferred to

the correlators. Telescope time allocation for geodetic

VLBI in 2014 consisted of 122 sessions for the 15-m

and 31 sessions for the 26-m antenna (Table 4). On the

23rd of April 2014 the 22 GHz receiver was installed

on the 26-m antenna. It will be used for astrometric

VLBI to help improve the ICRF. During observation

of the bright AGN J1427-4206 with the HartRAO 26-

m, Hobart 26-m, and Tidbinbilla 70-m antennas during a 24-hour astrometric VLBI on 4-5 May, intereference fringes were detected. The process of procuring

the VGOS antenna started in 2014 with the granting

of exemption from an EIA, the completion of a DC

resistivity ground survey, and an RFI study showing

no activity in the requisite bands. During April 2014,

Ludwig Combrinck installed a seismometer and accelerometer on Marion Island, repaired the DORIS system, surveyed it in and tied it to the GNSS receiver

with GPS. As part of the development of the new Lunar Laser Ranger, the laser systems from Ekspla were

commissioned from 18-22 November 2014.

4 Personnel

On the 14th of August 2014 our director,

Dr. Mike Gaylard, passed away. Space geodesy

program leader, Professor Ludwig Combrinck, is

IVS 2014 Annual Report
HartRAO 61

Table 4 Geodetic VLBI experiments in which HartRAO participated during 2014.

Experiment No. of sessions on 15 m No.of sessions on 26 m

R1 36 5

AUST 26 7

AUST14 17 0

CONT14 15 0

R4 15 0

RD 7 5

OHIG 4 2

RDV 2 1

CRDS 0 6

CRF 0 3

T2 0 2

Total 122 31

currently HartRAO’s acting director. Table 5 lists the

HartRAO station staff involved in geodetic VLBI.

Jonathan Quick (VLBI friend) provides technical

support for the Field System as well as for hardware

problems. Philip Mey, project manager of the VGOS

radio telescope, has joined the geodetic VLBI team

as a trainee operator at the end of 2014. Ludwig

Combrinck, Aletha de Witt, Denise Dale, Sayan Basu,

Glenda Coetzer, and Marisa Nickola attended the 8th

IVS General Meeting in Shanghai, China held 2-7

May 2014, and all contributed with presentations or

posters. Ludwig invited the IVS family to join us under

African skies for the 9th IVS General Meeting to be

held in South Africa in March 2016. Alet represented

HartRAO in the IAU’s ICRF-3 working group during

this meeting and the subsequent ‘REFAG, Symposium 2014 on Reference Frames for Applications in

Geosciences’ held in Luxembourg in October 2014.

Philip and Ludwig visited the Wettzell Observatory in

Germany during September 2014 to learn about the

VGOS Twin Telescope and discuss antenna design.

5 Future Plans

200 sessions are scheduled for 2015, 30 of those on

the 26-m antenna with the remainder having been

allocated to the 15 m. Hart15M will participate in

AUSTRAL-CONT campaigns during February and

June 2015. VGOS activities planned for 2015 include

core drilling to determine the depth to bedrock, digging of trenches and laying of cables, award of tender

for construction and laying of foundation, and the

Table 5 Staff supporting geodetic VLBI at HartRAO.

Name Function Program

L. Combrinck Program Geodesy

Leader

J. Quick Hardware/ Astronomy

Software

R. Botha Operator Geodesy

J. Grobler Operator Technical

P. Mey Operator Geodesy

R. Myataza Operator Technical

M. Nickola Logistics/ Geodesy

Operations

P. Stronkhorst Operator Technical

C. Zondi Operator Technical

subsequent construction of the VGOS antenna. Work

on the Lunar Laser Ranger (LLR) project will continue

during 2015. Alet will attend the 22nd Working

Meeting of the European VLBI Group for Geodesy

and Astrometry in Sao Miguel, Azores in May 2015 as  ̃

well as the 2015 IAU General Assembly in Honolulu,

Hawaii in August 2015, representing HartRAO at the

IAU’s ICRF-3 working group meetings. Preparations

for hosting the 9th IVS General Meeting in March

2016 will also be a priority during 2015.

Acknowledgements

HartRAO is a National facility operating under

the auspices of the National Research Foundation

(NRF), South Africa. The Space Geodesy Programme

is an integrated program, combining VLBI, SLR,

and GNSS, and it is active in several collaborative

projects with GSFC, JPL, and GFZ (Potsdam) as

well as numerous local institutes. Collaboration also

includes CNES/GRGS/OCA and the ILRS community in a Lunar Laser Ranger (LLR) project with

local support from the University of Pretoria and

the National Laser Centre (CSIR), among others.

General information as well as news and progress

on geodesy and related activities can be found at

http://geodesy.hartrao.ac.za/.

IVS 2014 Annual Report
62 Nickola et al.

Fig. 2 Hamba kahle, Mike.

Fig. 3 The 15 m antenna in action during CONT14.

Fig. 4 The 22 GHz receiver, installed on the 26 m on 23 April

2014.

Fig. 5 Pieter, Alet, Jon and Keith getting ready for K-band’s welcoming celebration — Hello Kitty!

Fig. 6 Philip’s rig for measuring RFI at the proposed VGOS site.

Fig. 7 Seismometer installation on Marion Island with DORIS

hut in background.

IVS 2014 Annual Report
AuScope VLBI Project and Hobart 26-m Antenna

Jim Lovell 1, John Dickey 1, Brett Reid 1, Jamie McCallum 1, Stas Shabala 1, Lucia Plank 1, Elizaveta

Rastorgueva-Foi 1, Imogen Jones 1, Christopher Watson 2, Simon Ellingsen 1, Anthony Memin 1

Abstract This is a report on the activities carried out

at the University of Tasmania in support of the three

AuScope VLBI observatories and the Hobart 26-m antenna. In 2014 the antennas participated in 185 IVS

sessions for a total of 551 antenna days of observing,

289 more than in 2013. An increase in operations funding in 2013 enabled us to increase our observing load,

including 73 days per year for AUSTRAL, which is

focused on high priority geodetic and astrometric programs in the southern hemisphere. All four antennas

participated in the 15-day CONT14 campaign as well

as a similar AUSTRAL 15-day session in September.

In this report we also briefly highlight our research activities during 2014 and our plans for 2015.

1 General Information

As part of AuScope (www.auscope.org.au), the University of Tasmania (UTAS) operates the AuScope VLBI

Array (Lovell et al., 2013), three 12-m diameter radio telescopes on the Australian continent (Figure 1),

located near Hobart (Tasmania), Yarragadee (Western

Australia), and Katherine (Northern Territory).

The Hobart telescope (Hb) is co-located with the

existing 26-m telescope (Ho) to preserve the more than

20 year VLBI time series at the site. Midway between

the 26-m and 12-m telescopes is the HOB2 GNSS installation which has been a core site of the International

GNSS Service (IGS) since its conception. A hut capa1. School of Mathematics and Physics, University of Tasmania

2. School of Land and Food, University of Tasmania

Hobart 12 m and 26 m, Katherine, and Yarragadee

IVS 2014 Annual Report

ble of housing a mobile gravimeter is also co-located

on the site. The Yarragadee telescope (Yg) provides a

far western point on the continent and is co-located

with multiple existing geodetic techniques including

SLR, GNSS, DORIS, and gravity. The Katherine site

(Ke) is new and provides a central longitude, northern site. The telescope at Katherine is co-located with a

new GNSS site that forms part of the AuScope GNSS

network.

Each AuScope VLBI observatory is equipped with

a 12.1-m diameter main reflector. The telescope specifications include: 0.3 mm of surface precision (RMS),

fast slewing rates (5 deg/s in azimuth and 1.25 deg/s

in elevation), and acceleration of 1.3 deg/s/s. All three

sites are equipped with dual polarization S- and X-band

feeds with room temperature receivers covering 2.2 to

2.4 GHz at S-band and 8.1 to 9.1 GHz at X-band. System Equivalent Flux Densities (SEFDs) are 3500 Jy in

both bands. Data digitization and formatting is managed by the Digital Base Band Converter (DBBC) system, and data are recorded using the Mark 5B+ system.

Each site is equipped with a Hydrogen maser time and

frequency standard.

All three observatories were designed and constructed to be remotely controlled and monitored to

keep operating costs at a minimum. The operation of

the AuScope VLBI array is being carried out from a

dedicated operations room on the Sandy Bay campus

of the University of Tasmania.

2 Staff

The staff at UTAS consist of academics, Prof. John

Dickey (director), Dr. Simon Ellingsen, Dr. Christo63
64 Lovell et al.

Fig. 1 The AuScope VLBI array and Hobart 26 m.

pher Watson, and Prof. Peter McCulloch. Dr. Jim

Lovell is Project Manager for the AuScope VLBI

project. Dr. Jamie McCallum, Dr. Stas Shabala, Dr.

Lucia Plank, Dr. Elizaveta Rastorgueva-Foi, and Dr.

Anthony Memin are post-doctoral fellows who are

carrying out research aimed at improving geodetic

solutions in the southern hemisphere. Mr. Brett

Reid is the Observatory Manager whose position is

funded by the university, and Ms. Imogen Jones is

employed to assist in operations and media logistics in

particular. In addition we have an electronics technical

officer, Mr. Eric Baynes. For the operation of the

observatories during geodetic observations we rely

heavily on support from the astronomy PhD and post

graduate students. Logistical and maintenance support

at Katherine is provided by Mr. Martin Ephgrave and

at Yarragadee by Mr. Randall Carman and team at the

MOBLAS5 SLR station.

3 Geodetic VLBI Observations

In 2014 the AuScope and Hobart 26-m antennas participated in 185 IVS sessions (up from 111 in 2013 and

72 in 2012) for a total of 551 antenna days of observing, 289 more than in 2013 and 404 more than in 2012.

All antennas participated in the 15-day CONT14 campaign. A summary of the observations is presented in

Table 1

Table 1 AuScope and Hobart 26-m antenna participation (number of days) in IVS sessions in 2014. The AUST14 series of observations was a 15-day CONT-like session as part of the AUSTRAL program, divided into 17 sessions (some lasted less than

24 hours).

Session Antenna

Ho Hb Ke Yg

APSG 2 2 2

AUST14 17 17 17

AUSTRAL 3 55 56 54

CONT14 15 15 15 15

CRDS 6 6 6 6

CRF 3 3 3

OHIG 5 6 6

R&D 9 2 2 2

R1 31 29 30

R4 36 34 35

T2 1 2 2

Total 33 173 172 172

3.1 The AUSTRAL Program

The ∼ 60day per year AUSTRAL Program commenced in July 2013. Observations are being made

with the three AuScope antennas as well as the Warkworth 12 m and Hartebeesthoek 15 m. The Hobart

26 m and Hartebeesthoek 26 m also participate for

some AUSTRAL observations. Scheduling is carried

out in VieVS, and data are correlated at the Curtin

University software correlator.

IVS 2014 Annual Report
AuScope VLBI 65

The AUSTRAL observing program is divided into

three streams focused on high priority geodetic and astrometric aims in the southern hemisphere:

1. astrometric observations to monitor and enhance

the southern hemisphere reference frame in preparation for ICRF3;

2. regular observations to improve the density of the

geodetic time series for the southern antennas and

to measure and monitor the motion and deformation of the Australian plate;

3. four 15-day CONT-like sessions over two years to

demonstrate the full capabilities of the array, characterize the level of systematic errors caused by

the troposphere and source structure and develop

and trial error mitigation strategies. One session

was held in 2013 and another in 2014, and two are

scheduled for 2015.

The AUSTRAL sessions are subject to steady

improvements. Thanks to improved scheduling (in

cooperation with the Vienna University of Technology), more frequent observations with four and five

station networks and improved observations, results

in terms of baseline length repeatabilities have been

improved significantly. Figure 2 shows the dramatic

improvement in baseline repeatability in AUSTRAL

sessions following a change in scheduling strategy

after AUST30 in July 2014.

2 4 6 8 10 12

0

5

10

15

20

25

30

wrms in mm

length of baseline 103 km

Hb−Ke

Hb−Yg

Ke−Yg

Hb−Ww

Ke−Ww

Ww−Yg

Ht−Ke

Ht−Yg

Ht−Hb

Ht−Ww

before AUST30 (41 sess.)

AUST30 and after (21 sess.)

Fig. 2 Baseline length repeatabilities of the AUSTRAL sessions

before and after a change in the scheduling strategy.

3.1.1 Post-correlation Data Processing

Starting in late 2012, the University of Tasmania began

handling the post-correlation processing of the AUSTRAL experiments correlated at Curtin University. All

AUSTRAL data are now post-processed at UTAS and

submitted to the IVS as version 1 databases.

4 Research Activities

We have made further progress in investigation of the

effects of quasar structure on geodetic solutions. Using the VieVS source structure simulator (Shabala et

al. 2015) developed in close collaboration with the TU

Wien group led by Johannes Bohm, we have performed  ̈

simulations to confirm that source structure contributes

at the millimeter level to present-day station position

determination. Hence the accuracy of present-day measurements is dominated by the stochastic wet troposphere, but quasar structure will become important in

the VGOS era. We have also investigated via simulations the possibility of modifying scheduling strategies

to include source structure information. This approach

appears promising once tropospheric noise is reduced

from being the single dominant component in geodetic

solutions.

An active area of current investigation is the impact

of structure on the CRF, where this effect appears to be

much stronger than on the TRF. We have run a number

of simulations for various levels of structure, and a paper (Plank et al.) is currently in preparation. Observationally, the thesis work of Rob Schaap (2014) found

a strong relationship between the quasar structure index, flux density, and astrometric stability: for a given

variable quasar, its astrometric position is most stable

and its structure minimized when its flux density is at

a maximum. This may be a useful tool for selecting

suitable quasars for IVS observations.

A new area of research started last year is the use

of sibling telescopes, i.e. the 26-m and the 12-m antennas at Hobart, to determine the local baseline (tie)

as measured by VLBI. Several sessions including the

12-m and the 26-m telescopes were observed in 2014,

with the analysis ongoing at the moment.

IVS 2014 Annual Report
66 Lovell et al.

5 References

1. Lovell, J. E. J. et al., 2013, J. Geod. 87, 527.

2. Schaap et al. 2014, J. Geod. 88, 575.

3. Shabala et al. 2015, J. Geod. in press.

IVS 2014 Annual Report
Kashima 34-m VLBI Station

M. Sekido, E. Kawai

Abstract The Kashima 34-m diameter radio telescope

is maintained by Space Time Standards Laboratory of

NICT. Development of its broadband VLBI system has

been conducted in the frequency transfer project. Its

narrow beam width broadband feed was originally developed for a Cassegrain type 34-m antenna, and the

first light observation was performed successfully in

January 2014. In addition to the R&D VLBI experiments for frequency transfer and astronomical observations, the 34-m radio telescope has been regularly

participating in IVS sessions.

1 General Information

Fig. 1 The Kashima 34-m radio telescope.

NICT Space-Time Standards Laboratory/Kashima Space Technology Center

NICT Kashima Network Station

IVS 2014 Annual Report

The 34-m diameter radio telescope has been maintained and operated by the VLBI group of Space Time

Standards Laboratory (STSL) in the National Institute of Information and Communications Technology

(NICT). It is located in the Kashima Space Technology

Center (KSTC), which is at the east coast of the main

island of Japan. Development of VLBI technology for

distant frequency transfer (project name: GALA-V) is

the current main mission of the VLBI project in NICT.

Development of a broadband VLBI observation system

is conducted in the GALA-V project. The observation

frequency range and data acquisition system (DAS) of

the GALA-V project are designed in the scope of joint

VLBI observations with a VGOS system.

2 Component Description

2.1 Receivers

The Kashima 34-m antenna has multiple receiver systems from L-band up to Q-band. The performance parameters for each frequency are listed in Table 1. Receiving bands are changed by exchanging receiver systems at the focal point of the antenna. Each receiver is

mounted on one of four trolleys, and only one trolley

can be at the focal position. The focal point is adjusted

by the altitude of the sub-reflector via motion of five

axes actuators. When a feed system is newly mounted,

the sub-reflector position is adjusted for that. The detail

of each receiver status is as follows:

L-band: Influence of Radio Frequency Interference

(RFI) caused by a cell phone base station was reduced by installation of a superconductor filter in

67
68 Sekido and Kawai

Table 1 Antenna performance parameters of the Kashima 34-m telescope.

Receiver Pol. Frequency SEFD [Jy]

L-band RHCP/LHCP 1405-1440MHz, 1600-1720MHz ∼ 500

S-band RHCP/LHCP 2210-2350MHz ∼ 250

X-band RHCP/LHCP 8180-9080MHz ∼ 370

Wideband V-Linear Pol. 6.4-15GHz ∼ 1000 – 2000

K-band LHCP 22 - 24 GHz ∼ 1300

Ka-band RHCP 31.7-33.7GHz NA

Q-band 42.3-44.9GHz ∼4500

front of the LNA by the end of 2013. The L-band receiver performance almost recovered and has been

used for pulsar observations.

S-band: Although there are some RFI signals in Sband, that is not so strong to saturate the LNA

at the first stage. Thus the signal at an unncessary frequency is supressed by bandpass filter after the LNA. This bandpass filter was exchanged

from a superconductor filter, which has been used

for ten years, to a standard one in the end of 2013.

Consequently, its observation frequency range was

slightly changed to 2,210—2,350 MHz.

Wideband: One of the important components of the

GALA-V project is the development of a broadband receiver for a large diameter antenna. Because

the well-known Eleven-feed [1] and QRFH [2]

broadband feeds have broad beamwidths (90-120

degrees), thus they cannot be used for the 34-m antenna, whose viewing size of subreflector from the

focal point is 34 degrees. Thus, a new broadband

Fig. 2 Broadband (IGUANA) feed installed in the receiver room

of the Kashima 34-m telescope.

feed with a narrow beam width has been originally

developed. A prototype of the new broadband feed

(code name: IGUANA) was mounted on the trolley

of the C-band receiver with a room temperature

LNA. The receiver has one linear (V) polarization

property, and its system equvalent flux density

(SEFD) is 1000—2000 Jy at the 6.5—15 GHz

frequency range. A more improved feed with a

broader frequency range and higher efficiency is

under development.

22 GHz: This receiver has one Left Hand Circular

Polarization (LHCP). The receiver performance is

stable and the receiver has been used for astronomical observations.

43 GHz: Re-adjustment of the subreflector position

was performed at the end of 2014, and this receiver

system was re-activated.

2.2 Data Acquisition System

Several VLBI data acquisition systems have been developed and installed at the Kashima 34-m station.

K5/VSSP32: is a multi-channel data acquisition

system [3] and is compatible with a Mark 5 system

via data format conversion. Thus most of geodetic

VLBI observations are perfomed with this DAS.

K5/VSI: is a data recording system composed of a

PC-VSI data capture card (PCI-X interface) and

a PC with RAID disk systems. This system is

used in combination with samplers (ADS1000,

ADS2000, ADS3000, and ADS3000+) with a VSIH interface. The ADS3000+ sampler is capable

of broadband observations (1024 Msps/1ch/1bit,

128 Msps/1ch/8bit) and multi-channel digital BBC

function. Thus combination use of ADS3000+ and

IVS 2014 Annual Report
Kashima 34-m Station 69

K5/VSI is essentially compatible with K5/VSSP32

and Mark 5 DAS.

K6/OCTAD-G (code name GALAS): is the newly

developed sampler for the GALA-V project [4].

Output data streams come out from 10 Gbit-Ether,

and are recorded by a PC system composed of 10

Gbit-Ether and RAID disk system. A new design

aspect of GALAS is so called direct sampling,

which directly captures the data without frequency

conversion. The sampling rate of GALAS is

selectable from 16.384 GHz and 16.0 GHz. The

former sampling rate is used for capturing a signal

with 1024 MHz bandwidth at an arbitrary frequency

via a digital filter. The latter sampling rate is designed for an experimental data acquisition mode,

which captures four pre-filtered RF frequency

signals with 1.6 GHz bandwidth at 3.2, 4.8, 9.6 and

12.8 at once. More details are discussed in “NICT

Technology Development Center 2014 Annual

Report” in this volume.

K4/VSOP terminal: has been used in domestic astronomical observations.

10 Gbps Network Connections and Data Server

A local area network (LAN) connecting data acquisition systems and software correlator PCs inside NICT

(Kashima and Koganei) has been upgraded to 10GbitEthernet. The outgoing network for IVS e-transfer was

upgraded from 1 Gbps to 10 Gbps through JGN-X1and

APAN2 network. The data servers operated for e-VLBI

data exchanges are listed in Table 2. Currently only

k51c.jp.apan.net has 10 Gbps NIC (Network Interface

Card), but others have 1 Gbps. This situation will be

improved in 2015.

Table 2 Data servers at Kashima Station and its capacity.

Hostname Path Disk Size Network Speed

vlbi2.jp.apan.net /vlbi2/ 12 T Bytes 1 Gbps

k51b.jp.apan.net /vlbi3/ 26 T Bytes 1 Gbps

k51c.jp.apan.net /vlbi4/ 24 T Bytes 10 Gbps

1 Next generation Network Testbed http://www.jgn.

nict.go.jp/

2 Asia-Pacific Advanced Network http://www.apan.net/

3 Staff

KAWAI Eiji: is the main engineer in charge of the

hardware maintenance and the operation of the

Kashima 11-m and 34-m antennas. He is responsible for routine geodetic VLBI observations for

IVS.

HASEGAWA Shingo: is the supporting engineer for

IVS observation preparation and maintenance of file

servers for e-VLBI data transfer.

TSUTSUMI Masanori: is the supporting engineer

for maintenance of data acquisition PCs and

computer network.

TAKEFUJI Kazuhiro: is a researcher using the 34-m

antenna for the GALA-V project and the Pulsar observations. He performed startup work of the broadband IGUANA receiver including adjusting the subreflector position and measurement of the SEFD of

the new receiver.

UJIHARA Hideki: designed the new broadband

IGUANA feed.

ICHIKAWA Ryuichi: is in charge of keeping GNSS

stations and routine GNSS observations.

TAKIGUCHI Hiroshi: is a researcher for analysis of

T&F transfer and geodesy with GNSS observations

and VLBI data.

SEKIDO Mamoru: is responsible for the Kashima

34-m antenna as the group leader. He maintains FS9

software for this station and operates the Kashima

and Koganei 11-m antennas [6] for IVS sessions.

4 Current Status and Activities

The main mission of the VLBI project of NICT is the

development of VLBI systems for distant frequency

transfer. In that project, named GALA-V [4], upgrading the receiver of the 34-m telescope to enable broadband observation in frequency range 3.2 — 15 GHz is

being conducted. Because the beamwidths of known

broadband feeds [1, 2] are too wide to be used in the

34-m radio telescopes, where the beamwidth has to be

34 degrees in diameter, we have developed our original broadband feed with narrow beamwidth property.

The first prototype of the IGUANA feed, which has

sensitivity at the 6.5 — 15GHz frequency range, was

installed in the 34-m anntena. Its first light observation

was made in January 2014. Simultaneous observation

IVS 2014 Annual Report
70 Sekido and Kawai

Fig. 3 Frequency spectrum of methanol maser line at 6.7 GHz

and 12.2 GHz from radio source W3OH. The two spectral lines

are simultaneously observed in the first light observation with

broadband feed mounted on the 34-m antenna.

of spectral lines at 6.7 GHz and 12.2 GHz (Figure 3)

demonstrated the impact of the broadband feed in astronomical observation. This new feed enables upgrading of the existing Cassegrain type antenna for broadband observation.

The broadband system is of course intended to

make joint observations with VGOS [7] systems. Joint

observations and compatibility with the VGOS system

developed by Haystack Observatory is being discussed.

5 Future Plans

International test observations with the broadband feed

is being planned under collaboration among Haystack,

NASA/GSFC, and NICT. The first test observing was

successfully finished in January 2015.

T&F observations with broadband VLBI will be

conducted in 2015 as the main mission of the GALAV project. In 2014, small diameter antennas were installed at NICT Koganei and NMIJ (National Metrology Institute of Japan) Tsukuba, where optical frequency standards are being developed. VLBI experiments for frequency comparison between UTC[NICT]

and UTC[NMIJ] will be conducted with the 34-m antenna for boosting the sensitivity.

Acknowledgements

The development of the broadband feed was supported

by the “Joint Development Research” fund provided

from the National Astronomical Observatory of Japan

in 2013—2014. We acknowledge Professor K. Fujisawa of Yamaguchi University and M. Honma and

M. Matsumoto of NAOJ for supporting this development. We thank the research network JGN-X and the

Information System Section of NICT for supporting

the network environment in this project.

References

1. Yang, J., et al, “Cryogenic 2–13 GHz Eleven Feed for Reflector Antennas in Future Wideband Radio Telescopes”,

IEEE Trans. on Ant. & Prop., Vol.59, No.6, pp.1918-1934,

2011.

2. Akgiray, A., et al., “Circular Quadruple-Ridged Flared

Horn Achieving Near-Constant Beamwidth Over Multioctave Bandwidth: Design and Measurements”, IEEE Trans.

on Ant. & Prop., Vol.61, No.3, pp.1099-1108, 2013.

3. Kondo,T., Y. Koyama, R. Ichikawa, M. Sekido, E. Kawai,

and M. Kimura, Development of the K5/VSSP System, J.

Geod, Soc. Japan, Vol. 54, No 4, pp. 233-248, 2008.

4. Sekido M., et al., Development of Wide-band VLBI system

(GALA-V), IVS NICT-TDC News No 33, pp.11-14, 2013.

5. Takefuji, K., et al., “NICT Technology Development Center

2014 Annual Report”, this volume, 2015.

6. Sekido, M., E. Kawai, “Kashima and Koganei 11-m VLBI

Stations”, this volume, 2015.

7. Petrachenko, B.: VLBI2010: Progress and Challenges, IVS

2012 General Meeting Proceedings, edited by D. Behrend

and K. D. Baver, NASA/CP-2012-217504, p.42-46, 2012.

IVS 2014 Annual Report
Kokee Park Geophysical Observatory

Ron Curtis

Abstract This report summarizes the technical parameters of the VLBI system at the Kokee Park Geophysical Observatory and provides an overview of the activities that occurred in 2014.

1 Location

The Kokee Park Geophysical Observatory (KPGO) is

located in Kokee State Park on the island of Kauai

in Hawaii at an elevation of 1,100 meters near the

Waimea Canyon, often referred to as the Grand Canyon

of the Pacific. KPGO is located on the map at longitude

159.665◦ W and latitude 22.126◦ N.

2 Technical Parameters

The receiver is of NRAO (Green Bank) design (a dual

polarization feed using cooled 15 K HEMT amplifiers). The antenna is of the same design and manufacture as those used at Green Bank and Ny-Alesund. A  ̊

Mark 5B+ recorder is currently used for all data recording.

Timing and frequency is provided by a Sigma Tau

Maser with a NASA NR Maser providing backup.

Monitoring of the station frequency standard performance is provided by a CNS (GPS) Receiver/Computer

1. USNO

2. NASA GSFC

Kokee Park Network Station

IVS 2014 Annual Report

system. The Sigma Tau performance is also monitored

via the IGS Network.

3 Staff

The staff at Kokee Park consists of six full time people

employed by ITT Exelis under the SCNS contract to

NASA for the operation and maintenance of the observatory. Chris Coughlin, Lawrence Chang, Kiah Imai,

and Ron Curtis conduct VLBI operations and maintenance. Ben Domingo is responsible for antenna maintenance, and Amorita Apilado provides administrative,

logistical, and numerous other support functions. Kelly

Kim also supports VLBI operations and maintenance

during 24-hour experiments and as backup support.

4 Mission Support

Kokee Park has participated in many VLBI experiments including IVS R4 and R1. KPGO also participates in the RDV, CRF, and OHIG experiments. KPGO

averaged two experiments of 24 hour duration each

week, with weekday Intensive experiments in 2014.

Kokee Park hosts other systems, including the following: a Doppler Orbitography and Radiopositioning Integrated by Satellite (DORIS) beacon and remote control, a Quasi-Zenith Satellite System (QZSS)

monitoring station, a Two-Way Satellite Time and Frequency Transfer (TWSTFT) relay station, and a TurboRogue GPS receiver. Kokee Park is an IGS station.

71
72 Curtis

5 Recent Activities

The KPGO 20-m antenna has been in service for

22 years and continues to show signs of its age. The

frequency of the maintenance activities for monitoring,

lubricating, and greasing antenna components was

increased to minimize wear and tear on the aging

antenna. One of the major signs of wear on the 20-m

antenna is axial play in the azimuth bearing. This puts

additional strain on the azimuth drive components, especially in high wind conditions. In April 2014, KPGO

technicians lowered the south azimuth motor/brake

assembly to replace the leaking seals between the

gearbox and the brake housing to prevent the oil leak

from compromising the brake and/or the motor performance. Plans are in progress to repair and upgrade

many of the 20-m antenna components. The plans

to upgrade the KPGO 20-m telescope for broadband

observation are on hold until after the installation of

the new 12-m high-precision VLBI2010-style radio

antenna. The new 20-m antenna broadband receiver

box built by MIT is in storage in the KPGO operations

building. The digital backend has been rack mounted

until future use with four RDBEs, four UP/DOWN

Converters, one of four Mark 5C recorders, and an

Optical ReCeiver/splitter/Amplifier (ORCA). New

timing and frequency distribution equipment was

installed at KPGO in advance to support the new 20-m

digital backend.

The installation of the InterTronic Solutions 12-m

high-precision VLBI2010-style radio antenna at

KPGO passed the Preliminary Design Review and

Critical Design review in 2014. The MIT-designed

broadband feed to be used on this 12-m telescope

has completed its System Requirement Review in

2014. The project is on schedule for completion by

the end of 2015. The e-transfers of the INT1 sessions

from KPGO to USNO were being transmitted over

the microwave infrastructure provided by the Pacific

Missile Range Facility (PMRF) connecting KPGO

to DREN. In June 2014, there was an upgrade to the

DREN network which requires an upgrade at KPGO to

utilize the DREN connectivity. MIT and USNO were

working on the required KPGO upgrades and the INT1

sessions were sent via FedEx to USNO beginning in

June 2014 through the end of 2014. MIT and USNO

will continue to work on the KPGO network upgrades

and the plans to migrate to a dedicated fiber connection

for KPGO. MIT is working with the Hawaii Internet

Consortium (HIC) and DREN to improve the KPGO

e-transfer rate. Long term plans are still to make

real-time VLBI data transfers from KPGO a reality.

6 Outlook

KPGO will continue with efforts to upgrade the 20-

m antenna signal path to VLBI2010 specifications.

KPGO staff, Exelis personnel at GSFC, USNO personnel, and MIT personnel are in the process of planning the 20-m antenna modifications and the installation of a new broadband frontend for the KPGO 20-m

antenna after 2015. USNO, NASA, InterTronic Solutions, MIT, and Exelis will continue to work throughout 2015 on the construction process for the high precision VLBI2010-style 12-m radio telescope at KPGO.

Facility upgrades and construction of a new antenna

pad for the 12-m telescope are planned for the first

half of 2015. The installation of the new 12-m antenna

and signal path is planned for the second half of 2015.

The internal network architecture at KPGO will be upgraded to support the network requirements of the new

12-m telescope.

IVS 2014 Annual Report
Kokee Park 2014 Report 73

Fig. 1 The KPGO 20-m radio telescope (foreground) with the KPGO 9-m radio telescope in the background.

IVS 2014 Annual Report
74 Curtis

Table 1 Technical parameters of the radio telescope at KPGO.

Parameter Kokee Park

owner and operating agency USNO-NASA

year of construction 1993

radio telescope system Az-El

receiving feed primary focus

diameter of main reflector d 20m

focal length f 8.58m

f /d 0.43

surface contour of reflector 0.020inchesrms

azimuth range 0...540◦

azimuth velocity 2

◦/s

azimuth acceleration 1

◦/s2

elevation range 0...90◦

elevation velocity 2

◦/s

elevation acceleration 1

◦/s2

X-band

(reference ν = 8.4GHz,λ = 0.0357m)

8.1−8.9GHz

Tsys 40K

SSEFD(CASA) 900Jy

G/T 45.05dB/K

η 0.406

S-band

(reference ν = 2.3GHz,λ = 0.1304m)

2.2−2.4GHz

Tsys 40K

SSEFD(CASA) 665Jy

G/T 35.15dB/K

η 0.539

VLBI terminal type VLBA/VLBA4-Mark 5

Field System version 9.11.1

IVS 2014 Annual Report
Kashima and Koganei 11-m VLBI Stations

M. Sekido, E. Kawai

Abstract The Kashima and Koganei 11-m stations are

used for geodetic and astronomical monitoring observations and for an R&D test bed of VLBI technology.

1 General Information

A pair of 11-m diameter antennas are operated by the

VLBI group of the Space-Time Standard Laboratory

(STSL) of the National Institute of Information and

Communications Technology (NICT). The Kashima

11-m antenna is located in Kashima Space Technology Center (KSTC), on the east coast of the Japanese

main island. The Koganei 11-m antenna is located in

the headquarters of the NICT in Tokyo (Figure 1). The

11-m VLBI antennas at Kashima and Koganei (Figure 2) were established and have been operating for

the monitoring of crustal deformation of the Tokyo

metropolitan area (Key Stone Project) since 1995 [1].

After regular VLBI observations, the KSP VLBI Network terminated in 2001. Since then, the 11-m VLBI

stations at Kashima and Koganei have mainly been

used for research and technology developments. After

the “Tohoku earthquake” that occurred in March 2011,

the Kashima and Koganei 11-m stations participated in

IVS-R1, T2, and APSG sessions.

NICT Space-Time Standards Laboratory/Kashima Space Technology Center

NICT KSP Network Station

IVS 2014 Annual Report

Fig. 1 Location of NICT-Koganei Headquarters and Kashima.

2 Component Description

2.1 Antenna

The antenna parameters of Kashima-11 and Koganei11 are summarized in Table 1. The band-pass filters

for S-band (2212-2360 MHz) were installed in 2010

at both stations for mitigation of radio frequency interference from cell phone stations. The local oscillator frequency of XH-band at the Kashima 11-m station has been changed from 7600 MHz to 7680 Mhz

since 2008, and since then, the observation bands of

the Kashima and Koganei stations have been different

by 80 MHz.

75
76 Sekido and Kawai

Fig. 2 11-m VLBI antennas at Kashima (left panel) and Koganei (right panel).

Table 1 The antenna parameters of the 11-m antennas.

Kashima Koganei

Antenna Type Cassegrain type

Diameter 11-m

Mount Style Az El mount

Latitude N 35◦ 57’ 19.46” N 35◦ 42’ 37”.89

Longitude E 140◦ 39’ 26.86” E 139◦ 29’ 17”.06

Altitude 62.4 m 125.4 m

S band 2212 ∼ 2360 2212 ∼ 2360

Rx Freq. X Low band 7700 ∼ 8200 7700 ∼ 8200

[ MHz ] X High band 8180 ∼ 8680 8100 ∼ 8600

S band 3000 3000

Local Freq. X Low band 7200 7200

[ MHz ] X High band 7680 7600

SEFD [ Jy ] X-band 5700 9500

S-band 3300 5500

2.2 Data Acquisition Systems

Two kinds of samplers are available at both stations as

summarized in Table 2. The K5/VSSP32 [2] has four

channels of video band signal input per unit. Four units

of K5/VSSP32 constitute one geodetic VLBI terminal with 16 inputs. This system is constantly used for

geodetic VLBI observations including IVS sessions.

This sampler has digital filter functionality in it. The

input video signal is digitized with 8-bit quantization

with 64 MHz sampling. Then the frequency bandwidth

is shaped by digital filter and output by specified data

rate. The output data is written to a standard Linux file

system in K5/VSSP32 format1. Data format conversion

from K5/VSSP32 to Mark IV, VLBA, and Mark 5B are

available with conversion tools2.

Another sampler, ADS3000+ [3], has digital baseband conversion (DBBC) function. Several kinds of

data acquisition modes (personalities) are switched by

exchanging an FPGA program. The DBBC mode enables flexible selection of 16 video frequency channels with any of 4/8/16/32 MHz bandwidth. Therefore

this can be compatible with conventional 16 channels

of geodetic VLBI observations. Another data acquisition mode (8bit-128MHz-1ch) was used for astronomical observations requiring higher dynamic range

observations. Other modes (1bit-1024MHz-1ch, 2bit1024MHz-1ch, and 1bit-2048MHz-1ch) were used for

broadband VLBI observations for geodesy and time

and frequency transfer. Figure 3 shows the data acquisition terminal of K5/VSSP32 and K5/VSI.

2.3 Upgrading Network Speed

The local area network (LAN) connection speed connecting the Kashima 34-m antenna site, the Kashima

11-m, and the Koganei 11-m stations were upgraded

1 Please see http://ryuu.nict.go.jp/stmg/K5/

VSSP/vsspALL_header_format-e.pdf

2 Observation and data conversion software for K5/VSSP are

freely available from http://www2.nict.go.jp/aeri/

sts/stmg/K5/VSSP/index-e.html

IVS 2014 Annual Report
Kas11 & Kog11 VLBI Stations 77

Table 2 VLBI data sampler/DAS systems equipped at the

Kashima 11-m and Koganei 11-m stations.

System K5/VSSP32 ADS3000+(K5/VSI)

(4 units)

Video Converter K4/KSP 16ch not necessary

# of Input Channels 4 /unit x 4 units 1 or 2

# of Output Channels 16 1, 2, 16

Input Freq. Range 0 - 300 MHz 0 - 2 GHz

Sampling Rate 0.04,0.1,0.2,0.5,1, 128, 256, 1024,

[Msps] 2,4,8,16,32,64 2048,4096

Quantization bit 1,2,4,8 bit

Max. data rate [Mbps] 256 /unit x 4 4096

Output Interface USB 2.0 VSI-H

Fig. 3 Data acquisition terminal (K5/VSSP and K5/VSI) at the

Kashima 11-m station.

to 10 Gbps in 2014. The high speed network connection is provided by collaboration with the JGN-X (Next

generation Network Testbed). The 10G-LAN connection is used for sharing the data and correlation processing. In the case of IVS sessions, the VLBI data of

these stations are collected, format converted, and put

on external servers for e-transfer to correlators.

Not only the internal LAN, but also the outreach

network, were upgraded to 10 Gbps by the support

of JGN-X in this year. Then data transfers (e-transfer)

speed up to 10 Gbps became available through the

JGN-X and APAN network.

2.4 GNSS Site

Both Kashima 11 m and Koganei 11 m have GNSS

observation sites — named KSMV and KGNI, respectively. Their data is regularly uploaded to an International GNSS Service (IGS) Data Center. Figure 4

shows the KSMV station at the Kashima 11-m antenna

site. A local survey was performed in 2014 at Koganei.

The survey results may be used for a local tie at Koganei between VLBI and GPS.

Fig. 4 GNSS receiver pillar at the Kashima 11-m site registered

as KSMV of the IGS tracking station.

3 Staff

Kawai Eiji: In charge of station maintenance and

IVS observations.

Hasegawa Shingo: Supporting staff for IVS observation, operation of data conversion and maintenance

of file servers for e-transfer.

Ichikawa Ryuuchi: In charge of GNSS station care

and GNSS observations.

Sekido Mamoru: In charge of overall activities of the

Kashima and Koganei VLBI stations.

IVS 2014 Annual Report
78 Sekido and Kawai

4 Current Status

The Kashima and the Koganei 11-m stations are participating in geodetic VLBI sessions IVS-T2, APSG, and

JADE, 14 sessions a year in total. In addition, these two

stations are used as a test bed for R&D experiments including time and frequency transfer.

The problem of tearing of cables (coaxial cables

and status-control lines), which happened at the

Kashima 11-m antenna in October 2013, was fixed

in March 2014. Both stations have been normally

operating since April.

The Koganei 11-m antenna is jointly operated by

two groups in the NICT: the STSL and the Space

Weather and Environment Informatics Laboratory

(SWEIL). When the antenna is not used for VLBI

observations by STSL, down linked observations from

the STEREO satellite 3 have been provided by the

SWEIL until October 2014. This STEREO satellite

downlink has been suspended since October 10, 2014.

Pointing (antenna axis parameter) observation was

made in January 2015 in order to monitor the antenna

status. The last update of the axis parameters was made

in April 2014 for Kashima 11 m, and in April 2013 for

Koganei 11 m. The drift of the mean azimuth and elevation offsets were (0.004, 0.001) and (-0.006, -0.004)

in degrees for the Kashima 11-m and Koganei 11-m

antennas. The root mean square (RMS) scatter of the

deviation for the azimuth and elevation angles were

(0.006, 0.009) and (0.014, 0.011) for Kashima 11 m

and Koganei 11 m. The degradation of the parameters

was within the RMS deviation of the offset; thus the

parameters were retained.

3 http://www.nasa.gov/mission pages/stereo/main/index.html

Acknowledgements

We thank the research network JGN-X and the Information System Section of NICT for supporting the

high speed network environment.

References

1. Special issue for the Key Stone Project, J. Commun. Res.

Lab., Vol. 46, No. 1, pp.1-221, 1999.

2. Kondo,T., Y. Koyama, R. Ichikawa, M. Sekido, E. Kawai,

and M. Kimura, Development of the K5/VSSP System, J.

Geod, Soc. Japan, Vol. 54, No 4, pp. 233-248, 2008.

3. Takefuji, et al., “Next-generation A/D Sampler ADS3000+

for VLBI2010”, in VLBI2010: From Vision to Reality, Proceedings from the Sixth IVS General Meeting, edited by D.

Behrend and K.D. Baver. NASA/CP-2010-215864, p.378-

382, 2010.

IVS 2014 Annual Report
Matera CGS VLBI Station 2014 Annual Report

Giuseppe Bianco 1, Giuseppe Colucci 2, Francesco Schiavone 2

Abstract This report presents the status of the Matera

VLBI station. An overview of the station, some technical characteristics of the system, and staff addresses

are also given.

1 General Information

The Matera VLBI station is located at the Italian Space

Agency’s ‘Centro di Geodesia Spaziale G. Colombo’

(CGS) near Matera, a small town in the south of Italy.

The CGS came into operation in 1983 when the Satellite Laser Ranging SAO-1 System was installed. Fully

integrated into the worldwide network, SAO-1 was

in continuous operation from 1983 up to 2000, providing high precision ranging observations of several

satellites. The new Matera Laser Ranging Observatory

(MLRO), one of the most advanced Satellite and Lunar

Laser Ranging facilities in the world, was installed in

2002, replacing the old SLR system. CGS also hosted

mobile SLR systems MTLRS (Holland/Germany) and

TLRS-1 (NASA).

In May 1990, the CGS extended its capabilities to

Very Long Baseline Interferometry (VLBI), installing a

20-m radio telescope. Since then, Matera has observed

in 982 sessions up through December 2014.

In 1991 we started GPS activities, participating

in the GIG 91 experiment and installing at Matera

a permanent GPS Rogue receiver. In 1994, six TurboRogue SNR 8100 receivers were purchased in

1. Agenzia Spaziale Italiana

2. e-geos - an ASI/Telespazio company

Matera Network Station

IVS 2014 Annual Report

order to create the Italian Space Agency GPS fiducial

network (IGFN). At the moment 12 stations are

part of the IGFN, and all data from these stations,

together with 24 other stations in Italy, are archived

and made available by the CGS Web server GeoDAF

(http://geodaf.mt.asi.it).

In 2000, we started activities with an Absolute

Gravimeter (FG5 Micro-G Solutions). The gravimeter

operates routinely at CGS and is available for external

campaigns on request.

Thanks to the co-location of all precise positioning space-based techniques (VLBI, SLR, LLR, and

GPS) and the Absolute Gravimeter, CGS is one of the

few “fundamental” stations in the world. With the objective of exploiting the maximum integration in the

field of Earth observations, in the late 1980s, ASI extended CGS’ involvement to include remote sensing

activities for present and future missions (ERS-1, ERS2, X-SAR/SIR-C, SRTM, ENVISAT, and COSMOSkyMed).

The Matera VLBI antenna is a 20-meter dish with

a Cassegrain configuration and an AZ-EL mount. The

AZ axis has ±270 degrees of available motion. The

slewing velocity is 2 deg/sec for both the AZ and the

EL axes.

The technical parameters of the Matera VLBI antenna are summarized in Table 1.

The Matera time and frequency system consists of

three frequency sources (two Cesium beam and one Hmaser standard) and three independent clock chains.

The iMaser 3000 H-maser from Oscilloquartz is used

as a frequency source for VLBI.

79
80 Bianco et al.

Fig. 1 VLBI antenna.

Table 1 Matera antenna technical specification.

Parameter name Values (S/X)

Input frequencies 2210−2450 MHz / 8180−8980 MHz

Noise temperature <20 K

at dewar flange

IF output frequencies 190−430 MHz

100−900 MHz

IF Output Power

(300 K at inp. flange) 0.0 dBm to +8.0 dBm

Gain compression <1 dB at +8 dBm output level

Image rejection >45 dB within the IF passband

Inter modulation At least 30 dB below each of two carriers

products at an IF output level of 0 dBm per carrier

Tsys 55/65 K

SEFD 800/900 Jy

2 Activities during the Past Year

The VLBI frequency standard is a T4SCIENCE iMaser

3000 installed in 2013.

Specifications for this new maser can be found

here: http://www.t4science.com/product/imaser 3000.

3 Current Status

In 2014, 53 sessions were observed. Figure 2 shows a

summary of the total acquisitions per year, starting in

1990.

IVS 2014 Annual Report
CGS/Matera 2014 Report 81

Fig. 2 Observation time.

In 2004, in order to fix the existing rail problems,

a complete rail replacement was planned. In 2005, due

to financial difficulties, it was instead decided that only

the concrete pedestal under the existing rail would be

repaired. From then on, no rail movements have been

noted [1]-[3].

4 Future Plans

In order to plan the eventual building of a VLBI2010

system, the fund raising investigation process has begun. At this moment it is not clear when the budget for

starting the project will be ready.

References

1. M. Mannarella “Relazione sulle misure effettuate sulla

rotaia dell’antenna VLBI”, Telespazio doc. OT-SPASM REL 180010 1140 0222, 21/01/2004.

2. M. Mannarella “Misure sugli spostamenti indotti sulle piastre e sulla rotaia dell’antenna VLBI”, Telespazio doc. OTSPA-SM REL 180010 1320 0661, 06/04/2005.

3. M. Mannarella “Relazione sull’esito dei lavori di

ripristino delle parti ammalorate della fondazione

dell’antenna VLBI”, Telespazio Doc. OT-SPASM REL 180010 1320 0732, 27/06/2005.

IVS 2014 Annual Report
Medicina Station Status Report

Giuseppe Maccaferri, Andrea Orlati, Alessandro Orfei

Abstract General information about the Medicina

Radio Astronomy Station, the 32-m antenna status,

and the staff in charge of VLBI observations are

provided. Updates to the hardware were performed

and are briefly described.

1 The Medicina 32-m Antenna: General

Information

The Medicina 32-m antenna is located at the Medicina

Radio Astronomy Station. The station is run by the Istituto di Radioastronomia and is located approximately

33 km east of Bologna. The Consiglio Nazionale delle

Ricerche was the funding agency of the Istituto di

Radioastronomia until the end of 2004. Since January 1, 2005, the funding agency has been the Istituto

Nazionale di Astrofisica (INAF). The antenna, which

was inaugurated in 1983, has regularly taken part in

IVS observations since 1985 and is an element of the

European VLBI network.

A permanent GPS station (MEDI), which is a part

of the IGS network, is installed in the vicinity. Another

GPS system (MSEL) is installed near the VLBI telescope and is part of the EUREF network.

Istituto di Radioastronomia INAF, Medicina

Medicina Network Station

IVS 2014 Annual Report

2 Current Status and Activities

• Antenna - A long period of maintenance started on

April 2014 and was completed on January 2015.

One antenna wheel was repaired; the elevation rack

and gear was completely replaced; a new lift system for the antenna was installed; the subreflector

and the primary focus receiver box has now a new

driving system, and mechanical maintenance at the

primary focus equipment was completed.

• DBBC + FILA10G - Medicina has completed the

tests (including the Mark 5C, see below) to qualify this module for observing. The incoming astronomic VLBI session will be performed using it,

while we are on the way to verify the proper functioning of the acquisition system in the geodetic observations.

• Mark 5C - All the known problems at this date have

been fixed.

• Field System - Release 9.11.7 was installed and

tested.

3 Geodetic VLBI Observations

In 2014, due to the long period of maintenance, Medicina took part in five 24-hour routine geodetic sessions,

only (namely three IVS-R4 and two EUROPE experiments).

82
Metsahovi Radio Observatory Network Station 2014 Annual  ̈

Report

Minttu Uunila 1, Nataliya Zubko 2, Markku Poutanen 2, Juha Kallunki 1, Ulla Kallio 2

Abstract In 2014, Metsahovi Radio Observatory, to-  ̈

gether with the Finnish Geodetic Institute, have observed six IVS sessions: three T2 and three EUROPE

sessions.

1 General Information

Aalto University Metsahovi Radio Observatory and  ̈

Finnish Geodetic Institute (FGI) are two separate institutes which together form the Metsahovi IVS Net-  ̈

work Station. Metsahovi Radio Observatory operates  ̈

a 13.7-meter radio telescope on the premises of Aalto

University at Metsahovi, Kylm  ̈ al ̈ a, Finland about 35  ̈

km from the university campus. The Metsahovi Fun-  ̈

damental Geodetic Station of FGI is in the same area,

near Metsahovi Radio Observatory.  ̈

2 Component Description

The Metsahovi Radio Observatory has been opera-  ̈

tional since 1974. The telescope was upgraded in 1992-

1994. The radome was replaced with a new one, and

new surface panels were installed. Metsahovi, together  ̈

with FGI, began observing IVS T2 and EUROPE sessions in 2004. Approximately six to eight sessions are

observed per year. The surface accuracy of the present

1. Aalto University Metsahovi Radio Observatory  ̈

2. Finnish Geodetic Institute

Metsahovi Network Station  ̈

IVS 2014 Annual Report

telescope is 0.1 mm (rms). The speed of the Metsahovi  ̈

antenna is 1.2 degrees per second.

Metsahovi is known for its long-term quasar mon-  ̈

itoring. Astronomical VLBI observations are carried

out with the 22 and 43 GHz receivers. The geodetic

VLBI receiver of Metsahovi uses right circular polar-  ̈

ization and 8.15—8.65 and 2.21—2.35 GHz frequency

bands.

2.1 Metsahovi Fundamental Station  ̈

FGI is running the Metsahovi Fundamental Station.  ̈

It is a part of the IAG GGOS Core station network.

The instrumentation includes geodetic VLBI (in cooperation with Aalto University), Satellite Laser Ranging (SLR), DORIS, and GNSS equipment and absolute

and superconducting gravimeters.

Currently, instrumentation is being renewed based

on special funding from the Ministry of Agriculture

and Forestry. During this year, a new dome for SLR

was constructed. The installation of a new SLR telescope and other equipment is expected to be installed

within the next year.

At the start of 2015, the Finnish Geodetic Institute

will become a part of the National Land Survey of Finland (NLS) as the Finnish Geospatial Research Institute (the abbreviation remaining FGI). The construction of a new radio telescope for GeoVLBI observations will be realized, if the project is funded by NLS.

83
84 Uunila et al.

Fig. 1 Metsahovi Radio Observatory (photo by Merja Tornikoski).  ̈

Table 1 Staff at Metsahovi Radio Observatory and at FGI involved in geodetic observ  ̈ ations during 2014.

Staff at Metsahovi Radio Observatory  ̈

Name Title Responsibility

Ph.D., Lic.(tech.) Juha Kallunki Technical staff manager VLBI equipment

M.Sc.(tech.) Ari Mujunen Laboratory engineer VLBI equipment

D.Sc.(tech.) Minttu Uunila Post-doctoral researcher, IVS on-site technical contact VLBI observations, VLBI equipment

M.Sc.(tech.) Petri Kirves Operations engineer Receivers

Staff at Finnish Geodetic Institute

Name Title Responsibility

Prof. Markku Poutanen Head of the Department of Geodesy and Geodynamics Metsahovi research station  ̈

Ph.D. Nataliya Zubko Senior research scientist IVS observations, analysis

M.Sc. Veikko Saaranen Special research scientist IVS observations operations

M.Sc. Ulla Kallio Senior research scientist Local ties measurements

Ph.D. Diego Meschini Research scientist Correlation research

Ph.D. Jyri Nar ̈ anen  ̈ Special research scientist Metsahovi infrastructure  ̈

3 Staff

FGI is responsible for the geodetic VLBI observations

and is the owner of the S/X receiver. The radio telescope is owned and operated by the Aalto University,

and an annual agreement is made on its use for geodetic VLBI sessions. It is not possible to increase the

number of annual geodetic sessions (currently six to

eight) because the telescope is mainly used for astronomical observations. Operation during the geo-VLBI

sessions and technical questions are handled jointly;

all other technical work, telescope maintenance, and

maintenance of instrumentation are done by the personnel of the radio telescope.

Metsahovi Radio Observatory personnel working  ̈

with IVS observations are listed in Table 1. Dr. Uunila

is in charge of all (IVS, EVN, and GMVA) VLBI observations at Metsahovi. The preparation, operation of  ̈

IVS observations, and submission of data are provided

by staff from FGI. The personnel engaged in the work

are listed in Table 1.

IVS 2014 Annual Report
Metsahovi 2014 Report  ̈ 85

4 Current Status and Activities

4.1 IVS Sessions

Metsahovi, together with FGI, has observed six IVS  ̈

sessions (three T2 and three EUROPE sessions) in

2014. In EUR127 there was RFI on X-band channels.

This might have been caused by the fact that we had

to use a signal generator to produce the LO, which

was broken in the receiver. The Mark 5B also had to

be rebooted, and there were some non-detections. In

EUR128 there were no problems. In EUR130 there

were antenna slewing problems during the scan recording (see also the Technical Activities Section). The T2

sessions (T2097, T2098, and T2099) are not yet correlated, and there were no known problems.

4.2 Research Visits

Dr. Uunila visited the Goddard Space Flight Center

(GSFC) VLBI group in order to collaborate with local

group members on a comparison of the VieVS analysis

software package developed by the Vienna University

of Technology and the Solve package developed by the

GSFC VLBI group.

4.3 Technical Activities

DBBC boards were repaired in Bonn in January by

M. Wunderlich. The LO of the X-band receiver was

repaired in January at Metsahovi. A new 8 TB disk-  ̈

module was assembled and tested in October.

Throughout the year we experienced slewing problems with the antenna. These will be fixed in January

2015, when the old antenna control software version

will be replaced with a new one and the azimuth limits

will be changed from 0—360 to -90—450 degrees.

4.4 Data Analysis

Geodetic data analysis at Metsahovi is done by Dr. Uu-  ̈

nila. The analysis focuses on the IVS-INT01 sessions.

Data analysis at FGI is performed by Dr. Zubko.

The project of source structure study and its influence

on estimated geodetic VLBI parameters has been continued in cooperation with Dr. Rastorgueva-Foi from

University of Tasmania. The latest results on this research were presented at the EGU meeting this year.

Dr. Meschini is responsible for correlation.

Fig. 2 Metsahovi radio telescope (Photo by Merja Tornikoski).  ̈

4.5 Local Tie Measurements

The local tie measurements between the co-located instruments at Metsahovi are provided by Ulla Kallio.  ̈

A local tie between IGS station METS and the VLBI

antenna reference point was regularly performed with

kinematic GPS measurements during the geo-VLBI

campaigns beginning in 2008. Testing shows that a millimeter level accuracy can be achieved in local tie vector determination with the kinematic GPS method.

4.6 Laser Scanning of Telescope Dish

During the summer, the telescope dish was scanned

with a FARO Focus 3D terrestrial laser scanner established on the position of the secondary mirror to study

dish deformation (Figure 3). This experimental work

IVS 2014 Annual Report
86 Uunila et al.

Fig. 3 Laser scanning of antenna dish. The scanner is in place of

the secondary mirror.

was performed by Antero Kukko, Harri Kaartinen, Ulla

Kallio, and Henry Ronnberg. The preliminary results  ̈

show that the data is suitable for the focal length estimation, but not accurate enough for a detailed surface

deformation analysis. To get more precise results the

scanning will be repeated next year with another scanner.

5 Future Plans

In 2015 Metsahovi is scheduled to participate in seven  ̈

IVS sessions: three EUROPE sessions and four T2 sessions. The antenna control software will be updated in

January 2015.

IVS 2014 Annual Report
VERA 2014 Geodetic Activities

Takaaki Jike, Yoshiaki Tamura, Makoto Shizugami

Abstract The geodetic activities of VERA in the

year 2014 are briefly described. The regular geodetic

observations are carried out both in K- and S/X-bands.

The frequency of regular observations are three times

a month—twice for the VERA internal observations

in K-band. The networks of the S/X sessions are

JADE of GSI and IVS-T2. The raw data of the T2

and JADE sessions are electronically transferred to

the Bonn, Haystack, and GSI correlators via Internet.

Gravimetric observations are carried out at the VERA

stations. SGs are installed at Mizusawa and Ishigakijima in order to monitor precise gravity changes,

and the observations continued throughout this year.

The crustal movements generated by the 11-Mar-2011

earthquake off the Pacific coast of Tohoku continued

during 2014, and displacement of VERA-Mizusawa’s

position by post-seismic creeping continued.

1 General Information

VERA is a Japanese domestic VLBI network consisting of the Mizusawa, Iriki, Ogasawara, and Ishigakijima stations. Each station is equipped with a 20-

m radio telescope and a VLBI back-end. The VERA

Ishigakijima 20-m antenna is shown in Figure 1. The

VERA array is controlled from the Array Operation

Center (AOC) at Mizusawa via Internet.

The primary scientific goal of VERA is to reveal the

structure and the dynamics of our galaxy by determinMizusawa VLBI Observatory, National Astronomical Observatory of Japan

VERA Network Station

IVS 2014 Annual Report

Fig. 1 Complete view of the VERA Ishigakijima 20-m antenna.

ing three-dimensional force field and mass distribution.

Galactic maser sources are used as dynamical probes,

the positions and velocities of which can be precisely

determined by phase referenced VLBI relative to extragalactic radio sources. The distance is measured as a

classical annual trigonometric parallax. The observing

frequency bands of VERA are S and X, C (6.4 GHz),

K (22 GHz), and Q (43 GHz). Geodetic observations

are made in S/X- and K-bands. Q-band is currently not

used for geodesy. Only a single beam is used even in Kband in geodetic observations, although VERA can observe two closely separated (0.2

◦ < separation angle <

2.2

◦

) radio sources simultaneously by using the dual

beam platforms.

General information about the VERA stations is

summarized in Table 1, and the geographic locations

are shown in Figure 2. The lengths of the baselines

range from 1,000 km to 2,272 km. The skyline at Ogasawara station ranges from 7◦

to 18◦ because it is lo87
88 Jike et al.

cated at the bottom of an old volcanic crater. The northeast sky at Ishigakijima station is blocked by a nearby

high mountain. However, the majority of the skyline

is below 9◦. The skylines at Mizusawa and Iriki are

low enough to observe sources with low elevation. Because Ogasawara and Ishigakijima are small islands in

the open sea and their climate is subtropical, the humidity in the summer is very high. This brings about

high system temperatures in the summer, in particular

in K- and Q-bands. Iriki station as well as these stations

are frequently hit by strong typhoons. The wind speed

sometimes reaches up to 60–70 m/s.

Fig. 2 Distribution of the stations in the VERA Network.

Table 1 Location.

Site name Longitude Latitude Altitude

Mizusawa 141◦ 07’ 57”.199 E 39◦ 08’ 00”.726 N 75.7 m

Iriki 130◦ 26’ 23”.593 E 31◦ 44’ 52”.437 N 541.6 m

Ogasawara 142◦ 12’ 59”.809 E 27◦ 05’ 30”.487 N 223.0 m

Ishigakijima 124◦ 10’ 15”.578 E 24◦ 24’ 43”.834 N 38.5 m

2 Current Status

The parameters of the antennas and front- and backends are summarized in Tables 2 and 3, respectively.

Two observing modes are used for geodetic observations. One is the VERA internal observation in K-band

with the recording rate of 1 Gbps. The other is the conventional S/X-band observation with K5-VSSP. JADE,

which is GSI’s domestic observation project, and IVST2 sessions belong to this class. Only Mizusawa and

Ishigakijima participated in these sessions.

Table 2 Antenna parameters.

Diameter of main reflector 20m

Mount type AZ-EL

Surface accuracy 0.2mm (rms)

Pointing accuracy <12”(rms)

Azimuth Elevation

Slew range -90◦ – 450◦ 5

◦ – 85◦

Slew speed 2.1◦/sec 2.1◦/sec

Acceleration 2.1◦/sec2 2.1◦/sec2

S X K

HPBW 1550” 400” 150”

Aperture efficiency 0.25 0.4 0.47

Table 3 Front-end and back-end parameters.

Front-end parameters

Frequency band S X K

Frequency range (GHz) 2.18–2.36 8.18–8.60 21.5–24.5

Receiver temperature >100 ◦K 100 ◦K 39±8

◦K

Polarization RHC RHC LHC

Receiver type HEMT HEMT cooled HEMT

Feed type Helical array Horn

Back-end parameters

Observation type VERA T2 and JADE

channels 16 16

Bandwidth/channel 16 MHz 4 MHz

Filter Digital Analog video band

Recorder DIR2000 K5VSSP

Recording rate 1 Gbps 128 Mbps

Deployed station 4 VERA Mizusawa, Ishigakijima

3 Staff

Noriyuki Kawaguchi is director of Mizusawa VLBI

Observatory. The geodesy group consists of Yoshiaki Tamura (scientist), Takaaki Jike (scientist), and

Makoto Shizugami (engineer).

IVS 2014 Annual Report
VERA 2014 Report 89

4 Activities during the Past Year

VERA observes seven days a week, except for during

a maintenance period in June and July. The 24-hour

geodetic sessions are allocated two or three times in

a month. Among these geodetic sessions, VERA internal geodetic observations in K-band are performed

once or twice in a month, and Mizusawa and Ishigakijima participate in JADE by GSI or IVS-T2 sessions in

S/X-band on a once-a-month basis. The main purpose

of the VERA internal geodetic observations is to determine relative positions of the VERA antennas accurate

enough for astrometric requirements. The purpose of

the S/X sessions is to link the VERA coordinates into

the IVS reference frame.

In the VERA internal geodetic sessions, the

regularly-used frequency changed from S/X-band

to K-band in 2007. The reason for the shift of the

observing frequency band from S/X-band to K-band

is to avoid the strong radio interference by mobile

phones in S-band, particularly at Mizusawa. The

interfering signal which has line spectra is filtered

out. But this filtering considerably degrades the

system noise temperature. The interference zone is

increasing, so it is likely that S-band observing will

become impossible in the near future. On the other

hand, VERA has the highest sensitivity in K-band as

shown in Table 3. Thanks to the high sensitivity in

this band the maximum number of scans in K-band

is 800/station/24-hours while that in S/X-band is

500 at most. It has been confirmed that the K-band

observations are far more precise. In fact, standard

deviations of the individual determinations of the

antenna positions in K-band are less than half of those

in S/X-band.

In 2014, a long maintenance period from the beginning of June to the middle of August was allocated.

Except for this period, VERA carried out regular VLBI

observations. We participated in six T2 sessions and in

four JADE sessions. VERA internal geodetic observations were carried out 17 times. The final estimation of

the geodetic parameters are derived by using the software developed by the VERA team.

Continuous GPS observations were carried out at

each VERA station throughout the year. The superconducting gravimeter (SG) installed within the enclosure

of the Mizusawa VLBI observatory, in order to accurately monitor gravity change for the purpose of monitoring height change at the VERA Mizusawa station,

continued acquisition of gravity data. Four water level

gauges surrounding the SG were used for monitoring

the groundwater level. The preliminary results show

that gravity variation due to the variation of the water table can be corrected as accurately as the 1 micro

gal level. An SG was newly installed also at the VERA

Ishigakijima station, and observing started in January

2012. The observing continued also during 2014. The

observing aims at solving the cause of the slow slip

event which occurs frequently around the Ishigaki island.

5 State of the Crustal Movement after the

11-Mar-2011 Earthquake at Mizusawa

After the 2011 earthquake off the Pacific coast of

Tohoku (Mw=9.0) [Epoch=11 March 2011, 14:16:18

JST], VERA-Mizusawa was displaced by co-seismic

crustal movement and post-seismic creeping. Also

in 2014, the creeping continued, although the speed

declined. According to the newest analysis, the coseismic steps are X= -2.013 m, Y= -1.380 m, and Z=

-1.072 m, and the displacement by creeping during

2014 is X= -0.091 m, Y= -0.061 m, and Z= -0.031 m.

6 Future Plans

Now, the examination of increasing a recording rate to

4 Gbps from 1 Gbps with direct sampling (OCTAD)

is being carried out. The reconstruction accompanying this specification change is planned also for the

S/X system. The received frequency of X-band will be

widened to 8-9 GHz. Furthermore, the examination for

changing the recording system from tape recorder to

HDD (OCTADISK) is also under enforcement. With

these changes, the operation of a new software correlation system (OCTACOR2) is due to become regular. The participation of the Ishigakijima station in

IVS sessions will stop after the T2 session in February,

2015. The VERA Network operation office and correlation office will be merged, and the headquarters of the

VERA operation team will be assigned to Mizusawa in

the 2015 fiscal year.

IVS 2014 Annual Report
Noto Station Status Report

Gino Tuccari

Abstract The Noto VLBI station was fully operational

in 2014. A great effort was made to install the frequency agility mechanics and to develop a new SXLP

receiver and the VGOS compatible front- and back-end

systems.

1 Antenna and Receivers

Frequency agility installation in the antenna has been

done after summer with the help of a specialized company. The modification of the single receiver to be

adapted to the new environment will be progressively

realized, in order to avoid stopping any observational

run. A new SXLP receiver has been completed and is

under test. Both polarizations for each band are available and X band is expanded up to 1 GHz.

Development of the new VGOS broadband DBBR

receiver operating in the range of 1-16 GHz continued.

The feed and cryogenic sections were completed. Two

new front-end LNAs from Caltech were purchased.

This receiver has been developed to operate on a

typical 12-m VGOS antenna and will be adapted

to the Noto 32-m radio telescope, making use of a

tertiary mirror operating in the vertex room. Initially,

the DBBC3-L system will be used as a backend,

capable of covering the entire range up to 16 GHz

with the new developed GCoMo units. A Faraday

cage was developed and placed in the vertex room.

Its mechanical behavior allows the maintenance of

Istituto di Radioastronomia INAF, Noto

Noto Network Station

IVS 2014 Annual Report

the DBBC3-L system orientation always independent

of the antenna elevation position, to eliminate any

possible mechanical stress to the internal contacts and

electronic parts.

2 H-maser

Whereas the old EFOS-5 has been modified to be kept

still active in parallel with the new one, two masers are

now available. Additional pieces of equipment were installed in order to have a continuous comparison between the two atomic clocks and to optimize the clock

and timing distribution.

3 e-VLBI

The connection at 10 Gbps was activated in October

2013. Nowadays at the station, e-VLBI observations at

1 Gbps are routine operations.

4 DBBC

The DBBC3 project, a collaboration between IRA

(Italy) — MPI (Germany) — (OSO) Sweden, is

progressing as expected in the scheduled time. First

observations are planned for March 2015 for the

Event Horizon Telescope. Two double polarization

back-ends are going to be completed, including the

FILA40G unit. Its functionality is to receive multiple

10 G connections coming from the output of the

90
Noto 2014 Report 91

CORE3 boards and handling the data Ethernet packets

for different functionality. One of them is the recording

capability at 32 Gbps. Two pictures of the DBBC3

with the internal and external views are shown.

Fig. 1 DBBC3-L: internal view

Fig. 2 DBBC3-L: external view

5 Observations

During 2014, seven geodetic experiments were observed: EUR127, T2096, CRF83, EUR129, T2100,

EUR132, and CRF85.

IVS 2014 Annual Report
Ny-Alesund Geodetic Observatory 2014 Annual Report  ̊

Moritz Sieber

Abstract In 2014, the 20-m telescope at Ny-Alesund,  ̊

Svalbard, operated by the Norwegian Mapping Authority (NMA), took part in 136 out of the 138 IVS 24-hour

sessions for which Ny-Alesund was scheduled, includ-  ̊

ing the 15 sessions of CONT14.

1 General Information

The Geodetic Observatory of the Norwegian Mapping

Authority (NMA) is situated at 78.9◦ N and 11.9◦ E in

Ny-Alesund, in Kings Bay, at the west side of the is-  ̊

land of Spitsbergen. This is the biggest island in the

Svalbard archipelago. In 2014, Ny-Alesund was sched-  ̊

uled for 138 24-hour VLBI sessions, including R1, R4,

EURO, RD, T2, and RDV sessions and CONT14, and

47 one-hour sessions within the Intensives program.

In addition to the 20-meter VLBI antenna, the

Geodetic Observatory has two GNSS antennas in the

IGS system and a Super Conducting Gravimeter in the

Global Geodynamics Project (GGP) installed at the

site.

The French-German AWIPEV research base in NyAlesund operates a DORIS station. In October 2004, a  ̊

GISTM (GPS Ionospheric Scintillation and TEC Monitor) receiver was installed at the Mapping Authority’s

structure in the frame of ISACCO, an Italian research

project on ionospheric scintillation observations, led by

Giorgiana De Franceschi of the Italian Institute of Volcanology and Geophysics (INGV). Another Real-Time

Norwegian Mapping Authority, Geodetic Institute

NYALES20 Network Station

IVS 2014 Annual Report

Ionospheric Scintillation (RTIS) Monitor was set up by

the NMA in November 2012.

1.1 Component Description

The antenna with a 20-m diameter is intended for

geodetic use and receives in S- and X-band. Its design

and construction are similar to those at Green Bank

and Kokee Park. A rack with 14 video-converters, a

Mark IV decoder, and a Mark 5 sampler streams the

data to a Mark 5B+ recorder. Another Mark 5 unit is

used to transfer data via network to the correlators.

Timing and frequency is provided by a NASA NR

maser, which is monitored by a CNS system.

1.2 Staff

The staff at Ny-Alesund consists of four people em-  ̊

ployed at 75%, which means that three full-time positions are covered (see Table 1 for an overview). Each

position goes with a three-year contract that can be

extended up to 12 years, but people stay an average

of three to four years. The observatory is part of the

Geodetic Division of the Norwegian Mapping Authority with a main office at Hønefoss (near Oslo).

During 2014, Susana got the unique opportunity to

start working at the new observatory in the Azores —

together with her boyfriend, so there was no point in

even trying to convince her to stay. Geir took half a year

of leave to swap Svalbard for living on the small, remote island of Jan Mayen in the Arctic Ocean. To cover

the temporary low manning until his return in April

92
Ny-Alesund Geodetic Observatory  ̊ 93

Fig. 1 Station staff in October (image: Bjørn-Owe Holmberg).

2015 and until a new employee is found, Alex Burns

(MIT Haystack Observatory, Westford) and Anita Titmarsh (University of Tasmania, AuScope) agreed to

help out for some months, so our team became even

more international.

Table 1 Staff related to VLBI operations at Ny-Alesund.  ̊

Hønefoss Section Manager Reidun Kittelsrud

Assisting

Section Manager

Frode Koppang

Technical Manager Leif Morten Tangen

Ny-Alesund  ̊ Station Manager Moritz Sieber

Engineer Alex Burns (≥ Sept.)

Engineer Susana Garc ́ıa Espada

(≤ Sept.)

Engineer Geir Mathiassen (≤ Aug.)

Engineer Kent Roskifte

Engineer Anita Titmarsh (≥ Oct.)

2 Current Status and Activities

2.1 Maintenance

The antenna structure and gears show clear signs of

wear, so regular maintenance is becoming more crucial. In March, the receiver dewar had to be replaced,

one of the O-ring seals became defective, and the vacuum couldn’t be held. The work took longer than expected, and the maintenance period had to be extended

a bit. As a consequence, some Int3 and R1 sessions

could not be observed.

2.2 Monitoring

The monitoring system was extended and now checks

the main receiver parameters regularly, even when

there is no observation. Data is collected from several

logfiles throughout the last 24 hours and various plots

(see Figure 2) are generated and displayed online on

the station’s documentation-wiki. This way a good

overview over receiver- and recorder-performance,

and environment-parameters can be maintained.

Fig. 2 Monitor-plots: receiver parameters with phase-cal/Tsysdata, drive statistics, maser-timing, meteorological data, and

tide-water and gravity-measurements.

2.3 Session Performance

By end of 2013, Ny-Alesund was scheduled for 15  ̊

CONT14, 119 24-hour, and 44 one-hour sessions. At

the end of the year (2014), all of the CONT, 121 of

123 24-hour, and 45 one-hour sessions had been observed. One R1-session had to be cancelled due to extended maintenance work, and another session could

not be observed due to high windspeeds throughout the

scheduled period. Until mid-March there were several

shorter outages during observations, mainly due to a

poor receiver dewar that got replaced in the end. After

that there were only four sessions with a completion of

IVS 2014 Annual Report
94 Sieber

98% or less; a more extensive summary can be found

in Table 2.

Table 2 Sessions with trouble (recorded 98% or less).

Session Comments

R4621, R4623,

R1624, RV103,

R4624, R1625,

R1626, R4627,

R4628

Receiver dewar pressure increased, interrupted the schedule, and evacuated the dewar

to prevent further warmup; lost roughly one

hour of observations each time.

R1628 Decoder timeout caused delays in schedule.

R1630 Not observed due to extended maintenance

(replacing receiver dewar).

R1631 Decoder timeout caused delays in schedule.

R4631 Azimuth motor outage.

R1637 Tested emergency power supply during session (bad idea; lost half an hour).

R1662 Late start due to pointing problems.

R1664 Not observed due to high windspeed during

the entire schedule.

2.4 New Observatory

The road construction to the new observatory site was

completed during summer 2014, and the work on the

foundations began with an official inauguration in October. During winter and most of the next year, the station building and all infrastructure will be established.

MT Mechatronics is the contractor for the two new

telescopes. They will be pre-assembled and tested during 2015 and arrive in Ny-Alesund the year after.  ̊

Fig. 3 Sketch of the new observatory site (image: LPO arkitekter)

2.5 New Instrumentation

The station is in the transition towards a DBBC digital backend. To be able to perform parallel observations with the existing Mark IV rack, the second

Mark 5 recorder had to be upgraded from Mark 5A

to Mark 5B+. Thanks go to David Hall and WACO,

who provided us with some of the necessary parts.

The DBBC itself proved to be not really plug-and-play,

but with help from Gino Tuccari, Michael Wunderlich, Jamie McCallum, Ed Himwich, and others, we

managed to record some data by November. There is

still some calibration and tuning missing, so we looked

through AuScope’s wiki and all other documentation

we could find and hope to be operative by mid-2015.

The demand for storage capacity during CONT14 enabled us to justify a purchase of ten 8-TB modules.

All of Ny-Alesund’s data is transferred via network,  ̊

and with this extended buffer we are able to keep all

data until it is correlated (in case of bad transfers).

We still have a little backup in case of bad connectivity. The last hundred-or-so miles between Ny-Alesund  ̊

and Longyearbyen were connected by fiber cable in

September. But the line will not be operational before

April 2015.

3 Future Plans

Getting the DBBC operational is just a first step to try

out and get training for the new equipment. There is

no intention to increase the manning even during the

period of parallel observations (estimated to be 2018–

2020), so good routines need to be developed.

Fig. 4 20 years of the Geodetic Observatory in Ny-Alesund!  ̊

IVS 2014 Annual Report
German Antarctic Receiving Station (GARS) O’Higgins

Alexander Neidhardt 1, Christian Plotz  ̈

2

, Thomas Klugel  ̈

2

, Torben Schuler  ̈

2

Abstract In 2014, the German Antarctic Receiving

Station (GARS) O’Higgins did not contribute to the

IVS observing program, due to extended maintenance

work on the receiver front-end. The receiver with the

dewar was dismounted and updated at the IVS Centro

de Desarrollos Tecnologicos de Yebes in Spain. It will  ́

be installed in the coming 2015 campaign.

1 General Information

The German Antarctic Receiving Station (GARS) is

jointly operated by the German Aerospace Center

(DLR) and the Federal Agency for Cartography

and Geodesy (BKG, belonging to the duties of the

Geodetic Observatory Wettzell (GOW)). The Institute

for Antarctic Research Chile (INACH) coordinates

the logistics. The 9-m radio telescope at O’Higgins is

mainly used for downloading remote sensing data from

satellites such as TanDEM-X and for the commanding

and monitoring of spacecraft telemetry. It is also

used for geodetic VLBI during dedicated campaigns

in the Antarctic summer. In 2014, the station was

again manned by DLR staff and by a team for the

maintenance of the infrastructure (e.g. the power and

freshwater generation), lasting an entire year. BKG

staff was on site from January to the beginning of

March. No IVS sessions were run during this time

period. The transport of the new maser EFOS-50 from

1. Forschungseinrichtung Satellitengeodasie (FESG), Technis-  ̈

che Universitat M ̈ unchen  ̈

2. Bundesamt fur Kartographie und Geod  ̈ asie (BKG)  ̈

GARS O’Higgins Network Station

IVS 2014 Annual Report

Concepcion, Chile to Punta Arenas and on board the  ́

“Aquiles” to O’Higgins was one of the main tasks.

The installation of the maser was done on location

by T4Science. The complete replacement of both tide

gauges was also one of the tasks during this campaign

besides the installation of a new operator desk and

the setup of the network infrastructure. There was no

campaign between November—December 2014.

Over the last few years, special flights using “Hercules C-130” aircrafts and small “Twin Otter DHC6” aircrafts, as well as transportation by ship, were

organized by INACH in close collaboration with the

Chilean Army, Navy, and Airforce, and with the Brazilian and Uruguayan Airforce in order to transport staff,

technical material, and food for the entire stay from

Punta Arenas via Base Frei on King George Island

to O’Higgins on the Antarctic Peninsula. The conditions for landing on the glacier are strongly weather

dependent and involve an increasing risk; in general,

transport of personnel and cargo is always a challenging task. Arrival and departure times strongly depend

on the climate conditions and on the logistic circumstances.

After each Antarctic winter, the VLBI equipment at

the station must be initialized again. Damages resulting from the winter conditions or strong storms have

to be identified and repaired. Shipment of each kind of

material, such as spare parts or upgrade kits, has to be

carefully prepared in advance.

Besides the 9-m VLBI antenna, which is used for

the dual purposes of receiving data from and sending

commands to remote sensing satellites and performing geodetic VLBI, the following are other geodeticrelevant instruments also operated on site:

• currently two H-masers (EFOS-10 and EFOS-50),

an atomic Cs-clock, a GPS time receiver, and a To95
96 Neidhardt et al.

Fig. 1 The Webcam image of the VLBI antenna.

tal Accurate Clock (TAC), offering time and frequency.

• two GNSS receivers (OHI2 and OHI3), operating

in the framework of the IGS network while both

are Galileo enabled. The receivers worked without

failure.

• a meteorological station providing pressure, temperature, humidity, and wind information, as long

as the temporarily extreme conditions did not disturb the sensors.

• a radar tide gauge, which was established in 2012

and reinstalled in 2014. The radar sensor itself is

space referenced by a GPS-antenna mounted on top

and Earth referenced via the local survey network.

The radar gauge is operated only during the Antarctic summer.

• an underwater sea level gauge for permanent monitoring of water pressure, temperature, and salinity

(also updated in 2014).

• two SAR corner reflectors, which were installed in

March 2013 as part of a network to evaluate the localization of the accuracy of the TerraSAR-X mission.

2 Staff

The members of staff for operation, maintenance, and

upgrade of the VLBI system and other geodetic devices

are summarized in Table 1.

Table 1 Staff members.

Name Affiliation Function Mainly

working for

Torben Schuler  ̈ BKG head of the GOW GOW

Christian Plotz  ̈ BKG electronic engineer O’Higgins,

(chief engineer RTW) RTW, TTW

Christian Schade BKG geodesist O’Higgins

operator, SLR

Reiner Wojdziak BKG software engineer O’Higgins,

IVS Data Center

Leipzig

Andreas Reinhold BKG geodesist O’Higgins

operator

Thomas Klugel  ̈ BKG geologist administration

laser gyro/

local systems

Wettzell

Rudolf Stoeger BKG geodesist logistics for

O’Higgins,

GNSS

Alexander Neidhardt FESG head of the VLBI group RTW, TTW

and VLBI station chief

Gerhard Kronschnabl BKG electronic engineer TTW, RTW,

(chief engineer TTW) TIGO

3 Observations in 2014

GARS did not participate in any IVS sessions in 2014

due to extended maintenance work on the receiver

front-end.

4 Technical Improvements and

Maintenance

The extreme environment conditions in the Antarctic

require special attention to the GARS telescope and the

infrastructure. Corrosion frequently results in problems

with connectors and capacitors. Defective equipment

needs to be detected and replaced. The antenna, the

S/X-band receiver, the cooling system, and the data acquisition system have to be activated properly. A problem is the low transfer rates on the communication

line, which reduces Internet and phone access. Also,

the Web cams are regularly maintained.

An extended maintenance was performed on the

dismounted receiver front-end. The maintenance included a complete redesign and rearrangement of the

receiver hardware at the IVS Centro de Desarrollos

Tecnologicos de Yebes in Spain. The down converter  ́

unit and the receiver monitoring were replaced by a

completely newly developed 19” mountable system,

which was installed in the original frame structure. It

IVS 2014 Annual Report
GARS O’Higgins 97

is connected to a modular power supply. New local oscillators, a new noise calibration unit, and new front

and back plates were also part of the redesign of the receiver front-end. The dewar, which was revised in the

labs at Yebes in 2013, is also installed now into the

existing frame structure. The dewar should fulfill the

specification to hold 20 K in a vacuum of 5∗10−7 mbar

for more than one year without maintenance. For the

new hardware, new monitoring software is also available and must be integrated into the NASA Field System setup for O’Higgins. The new hardware will be

installed during the first campaign of 2015. The goal is

the realization of an almost remotely controllable, autonomous, stable, and service-reduced system for the

future challenges.

Fig. 2 The new receiver front-end at O’Higgins, which was

maintained at the IVS Centro de Desarrollos Tecnologicos de  ́

Yebes, Spain.

Additionally, the new maser EFOS-50 from

T4Science was shipped from TIGO Concepcion to  ́

O’Higgins, where it has been running parallel to

the old EFOS-10 since February 2014. All existing

GNSS receivers were upgraded with a Galileo-enabled

system. The tide gauges were completely reinstalled

during the 2014 campaign. A new control room with a

new operator desk was also installed and built-up during this campaign so that additional equipment, such

as a digital baseband converter and a new Mark 5B+,

can be installed before the first campaign of 2015.

The operator room is jointly used by DLR and BKG.

The goal is to extend the autonomous and remote

operability of the site to enable the requirements for

more observation sessions over the whole year. It is a

key feature to extend the operation periods in GARS

O’Higgins without increasing the presence of staff on

site.

Fig. 3 The new control room with the operator desk for VLBI

work of the BKG and satellite tracking of the DLR.

It is further planned to use the gaps between

the satellite downlinks and commanding periods for

geodetic VLBI. This requires a suitable communication with the scheduling and control software of the

DLR, which still has to be done.

In 2014, a common paper with the title “Earth and

space observation at the German Antarctic Receiving

Station O’Higgins” was published in Polar Record.

5 Future Plans

The plan is to install a new Field System PC, a new

Mark 5B+, and a new digital baseband converter

ADS3000+ in the first campaign of 2015. After the

installation of the receiver, the system must be brought

back into operation again. A dedicated plan should

offer a shared and interleaved observation of satellites

(DLR) and VLBI sources (BKG) during the whole

year.

IVS 2014 Annual Report
Onsala Space Observatory – IVS Network Station Activities

during 2014

Rudiger Haas, Gunnar Elgered, Johan L  ̈ ofgren, Tong Ning, Hans-Georg Scherneck, Thomas Hobiger  ̈

Abstract We participated in 39 IVS sessions, including CONT14. Eleven out of the initially planned sessions could not be observed due to the installation of

a new radome for the 20-m radio telescope. As in the

previous six years, we used several of the sessions that

involved both Onsala and Tsukuba to perform ultrarapid UT1-UTC sessions together with our colleagues

in Tsukuba. This included the complete CONT14 campaign where near real-time UT1-UTC on the baseline

Onsala—Tsukuba could be determined. The procurement of the telescopes for the Onsala Twin Telescopes

was started in the summer of 2014. The contract to buy

two VGOS radio telescopes was signed at the end of

the year.

1 General Information

The Onsala Space Observatory is the national facility for radio astronomy in Sweden with the mission to

support high-quality research in radio astronomy and

geosciences. The geoscience instrumentation at Onsala

includes equipment for geodetic VLBI, GNSS, a superconducting gravimeter with a platform for visiting

absolute gravimeters, several microwave radiometers

for atmospheric measurements, both GNSS based and

pressure based tide gauges, and a seismometer. The

Onsala Space Observatory can thus be regarded as a

fundamental geodetic station. Figure 1 shows an aerial

photo taken during the replacement of the radome enChalmers University of Technology, Department of Earth and

Space Sciences, Onsala Space Observatory

Onsala IVS Network Station

IVS 2014 Annual Report

Fig. 1 The replacement of the upper part of the radome enclosing

the 20-m radio telescope on 15 September 2014.

closing the 20-m radio telescope that is currently the

instrument that is used for geodetic VLBI observations. In the next two years the Onsala Twin Telescopes

(OTT) will be installed at the observatory, consisting of

a pair of two new antennas following VLBI2010 recommendations.

The staff members associated with the IVS Network Station at Onsala are listed in Table 1.

2 Geodetic VLBI Observations

In total, 50 IVS sessions including Onsala were

planned for 2014, including the CONT14 campaign.

But because the radome of the 20-m radio telescope

had to be replaced and the telescope could not be used

during this time, we could not participate in 11 of the

planned sessions. For the majority of the 39 sessions

that we observed, including the complete CONT14

campaign, we performed parallel recordings with the

old Mark IV/Mark 5A and the new DBBC/Mark 5B+

98
OSO – IVS Network Station 99

Table 1 Staff members associated with the IVS Network Station at Onsala. All e-mail addresses have

the ending @chalmers.se, and the complete telephone numbers start with the prefix +46-31-772.

Function Name e-mail telephone

Responsible P.I.s for geodetic Rudiger Haas rudiger.haas 5530  ̈

VLBI observations Thomas Hobiger (2014.08.01–) thomas.hobiger 5549

Observatory director John Conway john.conway 5503

Head of department Gunnar Elgered gunnar.elgered 5565

Ph.D. students and postdocs Niko Kareinen niko.kareinen 5566

involved in geodetic VLBI Johan Lofgren (–2014.06.30) johan.lofgren 5566  ̈

Tong Ning (–2014.06.30) tong.ning 5578

Responsible for the Michael Lindqvist michael.lindqvist 5508

VLBI Field System Rudiger Haas rudiger.haas 5530  ̈

Responsible for the Karl-Ake Johansson karl-ake.johansson 5571  ̊

VLBI equipment Leif Helldner leif.helldner 5576

Responsible for the Roger Hammargren roger.hammargren 5551

VLBI operators

Telescope scientist Henrik Olofsson henrik.olofsson 5564

Software engineer Mikael Lerner mikael.lerner 5581

Responsible for gravimetry Hans-Georg Scherneck hans-georg.scherneck 5556

data acquisition systems, see Table 2. Zero-baseline

tests with the two types of recording systems were

done both at Onsala and the Bonn correlator. The

Bonn correlator also produced several databases with

two Onsala stations, using both recording types. These

databases were systematically analyzed, and no significant differences in the derived geodetic results were

found. Finally, in the summer of 2014, the old Mark IV

rack was removed and placed in the observatories’

museum. Since then, the DBBC/Mark 5B+ system has

been the primary data acquisition system.

In the fall of 2014 a second data acquisition system

was installed, including a second DBBC and a Mark 5C

recorder. Several tests with parallel recordings of the

two systems were performed and are still under investigation. Also tests with a Fila10G/FlexBuff system were

done and are under investigation.

Three observing sessions failed, see Table 2,

because the wrong polarization for X-band was

connected.

In addition to the IVS sessions, we observed test

experiments together with Wettzell to observe signals

from several GLONASS satellites.

3 Monitoring Activities

We continued with the monitoring activities as described in previous annual reports:

Local tie vector at Onsala.

During CONT14 an automated classical geodetic

survey of the reference point of the 20-m radio telescope was performed. Together with additional measurements in the local network, thus the local tie vector

between the VLBI and GNSS reference points could

be determined in a local system. This was followed by

a several week long GNSS campaign in the local network. Finally, the combination of the classical survey

results and the results from the analysis of the GNSS

campaign gave a new realization of the local tie vector

which will be used for ITRF2014.

Additionally, data observed with two gimbalmounted GNSS antennas on the dish of the 20-m radio

telescope were used to determine a purely GPS-based

local tie vector. A manuscript on this topic has been

submitted and is under revision.

Vertical height changes of the telescope tower.

We continued to monitor the vertical height

changes of the telescope tower using the invar rod system at the 20-m telescope. The measurements are available at http://wx.oso.chalmers.se/pisa/.

Calibration of pressure sensor.

IVS 2014 Annual Report
100 Haas et al.

Time, Year

2004 2006 2008 2010 2012 2014

Difference in Pressure, hPa

-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1

Setra - SMHI

Vaisala - SMHI

Fig. 2 Time series of pressure differences between the VLBI

pressure sensors and the calibrated pressure sensor from SMHI.

We continued to calibrate the Onsala pressure

sensor using a Vaisala barometer borrowed from the

Swedish Meteorological and Hydrological Institute

(SMHI). This instrument was installed at Onsala in

late 2002. It has been calibrated regularly at the SMHI

main facility in Norrkoping since then. The latest cali-  ̈

bration was on October 11, 2011.

Since the installation of a new VLBI pressure sensor in 2008, the agreement between the Onsala VLBI

pressure and the pressure read by the calibrated sensor

is on the level of ±0.1 hPa. Unfortunately, this VLBI

pressure sensor failed on Christmas evening 2014 and

needs to be replaced by a new sensor.

Microwave radiometry.

The water vapor radiometer Astrid was operating

continuously during the year, although it was suffering

from a failure of the 31 GHz channel until September

2014. Hence, its data until then are only useful during

atmospheric conditions with no significant amount of

liquid water. Konrad was operating continuously during the first six months of 2014. During the second

half of the year Konrad had a failure of the mechanical waveguide switch used for calibrations.

Sea-level monitoring.

The GNSS-R based tide gauge was operated continuously. Additionally, a tide gauge based on pressure

sensors was operated next to it throughout the year.

The construction of the new tide gauge, a collaboration project with SMHI, was completed (see Figure 3).

It is equipped with a radar sensor and a bubbler sensor inside the tide gauge well, and another bubble sensor outside nearby. The first test measurements were

started in the autumn of 2014.

Superconducting gravimetry.

The superconducting gravimeter operated continuously and produced a highly precise record of gravity variations. The data loss in 2014 was 0.52% in the

Fig. 3 The new tide gauge station at the Onsala Space Observatory, operated together with SMHI.

one-second record, confined to one single event at the

end of February, a failing Flash Card memory in the

data buffer of the ADC converter. Since September

2014, tide solutions have been prepared on a weekly

basis and results made available on the SCG homepage

(http://holt.oso.chalmers.se/hgs/SCG/toe/toe.html).

Absolute gravimetry.

We supported a visiting absolute gravity measurement campaign with two gravimeters operating in parallel, one from Lantmateriet, the Swedish mapping,  ̈

cadastral and land registration authority, and one from

Leibniz University, Hannover, Germany.

Seismological observations.

The seismometer owned by Uppsala University and

the Swedish National Seismic Network (SNSN) was

operated throughout the year.

4 Future Plans

• For 2015 we plan to observe a total of 44 IVS

sessions. Additionally, we plan for further sessions

during EVN observing campaigns.

• We strive to restart operating ultra-rapid UT1-UTC

sessions with our colleagues at GSI in Japan.

• In parallel to the regular DBBC/Mark 5B+

operations, we will do tests with the

DBBC/Fila10G/FlexBuff system.

• We will continue the usual monitoring activities at

the observatory.

IVS 2014 Annual Report
OSO – IVS Network Station 101

Table 2 Geodetic VLBI observations at Onsala during 2014. Information is given on which VLBI backend was used, whether data

were e-transferred in real-time (RT) and/or off-line (OL) and to which correlator, whether modules were shipped to a correlator,

and whether Ultra-rapid UT1-UTC results were produced. The last column gives some general remarks and information on the

percentage of the scheduled Onsala (On) observations that were used in the analysis (as reported on the Web pages for the IVS

session analyses), compared to the station average (StAv) percentage per experiment. Three sessions were unsuccessful (R1-642,

R1-657, and RV-107) because unfortunately, the wrong polarization for X-band was connected. The Mark 5B+ module for C14-02

failed at the correlator, so the production had to be done with the Mark 5A data. During C14-03 the FS terminated during the night,

and this was not discovered in time because no operator was at the site, so two hours of data were lost.

Exper. Date VLBI-backend E-transfer Module Ultra-rapid General remarks and % of scheduled observations used in the

Mark IV DBBC RT OL shipment UT1-UTC analysis as reported in the IVS Web pages’ analysis reports.

R1-619 01.06 yes yes – Bonn – – Mark IV/Mark 5A in production, On: 93.3% (StAv: 89.9%)

R1-621 02.21 yes yes – Bonn – – Mark IV/Mark 5A in production, On: 94.6% (StAv: 89.2%)

R1-624 02.10 yes yes Tsuk Bonn – yes Mark IV/Mark 5A in production, On: 85.7% (StAv: 81.9%)

RV-103 02.12 yes – – Socc yes – Mark IV/Mark 5A in production, On: 84.8% (StAv: 88.3%)

RD-14-02 03.26 yes yes Tsuk Hays – yes Mark IV/Mark 5A in production, not correlated / analyzed yet

R1-631 03.31 yes yes Tsuk Bonn – yes Mark IV/Mark 5A in production, On: 85.4% (StAv: 77.0%)

RV-104 04.01 yes yes – Socc yes – Mark IV/Mark 5A in production, On: 38.2% (StAv: 48.9%)

R1-632 04.07 yes yes – Bonn – – Mark IV/Mark 5A in production, On: 83.0% (StAv: 71.5%)

RD-14-03 04.23 yes yes – Hays – – Mark IV/Mark 5A in production, not correlated / analyzed yet

C14-01 05.06 yes yes Tsuk Bonn yes yes DBBC/Mark 5B+ in production, On: 86.7% (StAv: 83.7%)

C14-02 05.07 yes yes Tsuk Bonn yes yes Mark IV/Mark 5A in production, On: 76.7% (StAv: 83.4%)

C14-03 05.08 yes yes Tsuk Bonn yes yes DBBC/Mark 5B+ in prod., 2 h lost, On: 82.5% (StAv: 86.9%)

C14-04 05.09 yes yes Tsuk Bonn yes yes DBBC/Mark 5B+ in production, On: 88.8% (StAv: 85.3%)

C14-05 05.10 yes yes Tsuk Bonn yes yes DBBC/Mark 5B+ in production, On: 90.8% (StAv: 86.2%)

C14-06 05.11 yes yes Tsuk Bonn yes yes DBBC/Mark 5B+ in production, On: 80.7% (StAv: 74.5%)

C14-07 05.12 yes yes Tsuk Bonn yes yes DBBC/Mark 5B+ in production, On: 86.2% (StAv: 83.3%)

C14-08 05.13 yes yes Tsuk Bonn yes yes DBBC/Mark 5B+ in production, On: 91.7% (StAv: 87.5%)

C14-09 05.14 yes yes Tsuk Bonn yes yes DBBC/Mark 5B+ in production, On: 91.7% (StAv: 87.2%)

C14-10 05.15 yes yes Tsuk Bonn yes yes DBBC/Mark 5B+ in production, On: 91.9% (StAv: 91.1%)

C14-11 05.16 yes yes Tsuk Bonn yes yes DBBC/Mark 5B+ in production, On: 90.3% (StAv: 84.9%)

C14-12 05.17 yes yes Tsuk Bonn yes yes DBBC/Mark 5B+ in production, On: 89.0% (StAv: 83.5%)

C14-13 05.18 yes yes Tsuk Bonn yes yes DBBC/Mark 5B+ in production, On: 88.9% (StAv: 85.3%)

C14-14 05.19 yes yes Tsuk Bonn yes yes DBBC/Mark 5B+ in production, On: 87.1% (StAv: 80.8%)

C14-15 05.20 yes yes Tsuk Bonn yes yes DBBC/Mark 5B+ in production, On: 88.1% (StAv: 82.3%)

RV-105 06.25 yes yes – Socc – – DBBC/Mark 5B+ in production, On: 86.2% (StAv: 78.1%)

R1-642 06.30 yes yes – Bonn – – failed, X-band wrong polarization

R1-643 07.07 yes yes – Bonn – – DBBC/Mark 5B+ in production, On: 91.9% (StAv: 90.1%)

RD-1405 07.08 yes yes – Hays – – DBBC/Mark 5B+ in production, not correlated / analyzed yet

R1-656 10.06 – yes – Bonn – – DBBC/Mark 5B+ in production, On: 75.8% (StAv: 64.9%)

R1-657 10.13 – yes – Bonn – – failed, X-band wrong polarization

RV-107 10.14 – yes – Socc – – failed, X-band wrong polarization

R1-661 11.10 – yes – Bonn – – DBBC/Mark 5B+ in production, On: 84.8% (StAv: 73.6%)

R1-663 11.24 – yes – Bonn – – DBBC/Mark 5B+ in production, On: 77.0% (StAv: 64.5%)

RV-108 12.03 – yes – Socc – – DBBC/Mark 5B+ in production, On: 95.5% (StAv: 91.2%)

R1-665 12.09 – yes – Bonn – – DBBC/Mark 5B+ in production, On: 82.3% (StAv: 72.9%)

R1-666 12.15 – yes – Bonn – – DBBC/Mark 5B+ in production, On: 82.3% (StAv: 73.9%)

T2-101 12.16 – yes – Hays – – DBBC/Mark 5B+ in production, not correlated / analyzed yet

RD-14-12 12.17 – yes – Hays – – DBBC/Mark 5B+ in production, not correlated / analyzed yet

R1-667 12.22 – yes – Bonn – – DBBC/Mark 5B+ in production, On: 92.4% (StAv: 87.3%)

• The new tide gauge station in collaboration with

SMHI will be inaugurated.

• We will begin construction work for the Onsala

Twin Telescopes.

IVS 2014 Annual Report
Parkes 2014 IVS Report

John Reynolds

Abstract This report presents the status of the Parkes

station in 2014.

1 Status

Parkes did not participate in any IVS experiments during 2014. Recent budgetary constraints and operational

changes within CSIRO/CASS have resulted in stringent self-imposed limits on the interchange of receiver

packages on the Parkes 64-meter antenna. As a consequence, it proved impossible to schedule the S/X receiver required for these experiments.

We are working with our colleagues at the University of Tasmania to redress this unfortunate state of affairs and to facilitate at least one installation of the S/X

receiver on the Parkes 64 m during 2015, with the aim

of participating in several back-to-back 24-hour sessions.

CSIRO

Parkes Network Station

IVS 2014 Annual Report

102
Korea Geodetic VLBI Station, Sejong

Yunmo Sung, Kiduk Ahn, Sangoh Yi, Hongjong Oh, Sangcheol Han, Eunjin Kim

Abstract This report briefly introduces the activities

carried out at the Sejong VLBI station during 2014.

The Sejong antenna can only perform S/X VLBI observing in Korea. Sejong station began to participate in

IVS VLBI IVS-R1 sessions in the latter half of 2014.

The geodesy division in NGII (National Geographic

Information Institute) manages the Sejong station, and

NGII has a plan to use the K- and Q-bands for geodetic

VLBI observations with the KVN (Korean VLBI Network of KASI) in the future.

1 General Information

The Sejong station is the first geodetic VLBI station in

the Republic of Korea which is dedicated to geodetic

purposes. The station is located about 120 km south of

Seoul at longitude 127◦18′12′′E, latitude 36◦31′12′′N,

and 153 meters in height in the middle of Sejong city,

which serves as a new administrative capital. The Sejong antenna is 22 meters in diameter, and multi frequency bands (S, X, K, and Q) are available at the same

time.

The staff at Sejong station consists of six people

including a new site director, Ahn Ki Duk, who began work in December 2014. Mr. Yi Sang Oh is responsible for planning of annual VLBI observing, both

international and domestic. Mr. Oh Hong Jong is responsible for RFI monitoring and co-location for space

geodetic techniques. Mr. Han Sang Cheol is responsiNational Geographic Information Institute

Sejong Network Station

IVS 2014 Annual Report

Fig. 1 Layout of Sejong station: 1. VLBI antenna 2. pillar for

co-location 3. UTP(Unified control Point) 4. IGS station (SEJN)

5. (Under construction) SLR site of KASI 6. (Under installation)

MR(Microwave Radiometer) of KASI.

ble for antenna maintenance. The Sejong station has a

VLBI antenna, an IGS station (SEJN), four pillars for

co-location, and a mobile SLR system (40 cm in diameter) which is already developed by KASI and will be

relocated. Three space techniques (VLBI, GNSS, and

SLR) are directly measurable by electric survey instrument. And an MR (Microwave Radiometer) will be installed on the roof of the main observation building. Dr.

Jung Ho Cho of KASI is the person in charge of the

MR, and NGII and KASI are expecting to use it to calibrate for the water vapor effect on VLBI and GNSS.

103
104 Sung et al.

Table 1 Staff members of the Sejong station.

Name Responsibility e-mail

Ki Duk Ahn Site Director akd8@korea.kr

Sangoh Yi Analysis sangoh.yi@korea.kr

Hongjong Oh Analysis stockoh11@korea.kr

Sangcheol Han VLBI maintenance hsc4907@korea.kr

Eunjin Kim Operator vikisio1015@gmail.com

Sangwon Lee Operator lsw860210@gmail.com

2 Sejong VLBI System

The Sejong VLBI configuration is listed in Table 2.

The S and X SEFDs were about 2,000 — 3,000 Jy.

The reason why they have high SEFDs is that we used

coaxial cable (length is about 30 cm) to connect from

the feed to the cryogenic chamber. We have a plan to

improve it in the future. The K- and Q-band receiver

systems are still not ready to be operated. Because Sejong antenna was designed to use the multi-frequency

receiving system, in order to work it properly, the lower

frequency system (that is S/X) must be completed in

the first place. S/X system was completed in the middle of 2014. We expect that the K and Q systems will be

completed within 2015. The Sejong site uses the Field

system (FS 9.10.4) and the K5 data recorder. To send

VLBI data to a correlator, we use data format converter

(k5tom5b) software developed by NICT.

Table 2 Sejong Antenna parameters.

Parameters Sejong VLBI

IVS letter codes Sejong (Kv)

CDP number 7368

DOMES number 23907S001

Location Lat.: 36◦31′N, Long.: 127◦18′E

Elevation 177m

Diameter of main reflector 22m

Antenna type Shaped Cassegrain

Aperture efficiency about 60%

Pointing accuracy 0.0131◦

Reflector surface accuracy 100 μm

Operation range AZ: ±270◦ EL: 0 ∼ 90◦

Slew speed 5

◦

/sec (AZ and EL)

FS Version 9.10.4

Data acquisition Recorder K5

Table 3 Receiving system of the Sejong VLBI system.

Bands S X K Q

Freq. [GHz] 2.1–2.6 8.0–9.0 21–23 42–44

Receiver noise temp. < 20K < 30K < 50K < 80K

Polarization R,L R,L R,L R,L

SEFD 3,000 3,000 – –

Aperture efficiency 0.6 0.6 0.6 0.6

3 Activities in 2014

3.1 VLBI Observations

In early 2014, we prepared to join IVS regular sessions

by doing several fringe tests with the Tsukuba (GSI)

and Kashima (NICT) antennas. We appreciate their

help. In August, the IVS managed the fringe test for

the Sejong antenna to verify its performance. Thankfully, three antennas (Sejong, Shanghai, and Hobart)

were involved in the fringe tests. Finally, the IVS finally accepted Sejong to join the IVS regular sessions.

Beginning with session IVS-R1655, we are consistently participating in IVS-R1 observations. In December, we successfully obtained the first light at Q-band.

The Sejong staff and the KVN members managed this

fringe test together. We used single dish observations

and used auto correlation modules to find fringes.

Fig. 2 Facilities for local-ties in the Sejong station.

IVS 2014 Annual Report
Sejong Station 105

Table 4 Activities for VLBI observations. [NGII: National Geographic Information Institute, KVN: Korean VLBI Network,

KJCC: Korea-Japan Correlation Center, GSI: Geospatial Information Authority of Japan, NICT: National Institute of Information and Communications Technology.]

No. session SKED Corr. Freq. Remarks

1 t2095 GSI NGII S/X ant. performance test

2 f14071 KVN KJCC X ant. performance test

3 s14073 GSI NGII S/X ant. performance test

4 r1633 GSI NGII S/X ant. performance test

5 s14108 GSI NGII S/X ant. performance test

6 c1415 NICT NGII S/X ant. performance test

7 f14141 NICT NGII S/X ant. performance test

8 jd1405 GSI NGII S/X ant. performance test

9 a14147a KVN KJCC X ant. performance test

10 kvnfrg IVS HAYSTACK S/X ant. performance test

11 kvwfrg IVS HAYSTACK S/X ant. performance test

12 r1655 IVS NGII-KASI X regular observing

13 f14293a KVN NGII-KASI X fringe test

14 r1658 IVS NGII-KASI X regular observing

15 – KVN KJCC Q fringe test

16 r1666 IVS KJCC S/X regular observing

17 f4c18a CVN CVN X fringe test

18 f14352a KVN KJCC X fringe test

19 r1667 IVS KJCC S/X regular observing

20 f14358a KVN KJCC X fringe test

21 r1668 IVS KJCC S/X regular observing

3.2 S/X Receiving System Improvement

Work

In early 2013, the S/X SEFDs showed ranges between

30,000 Jy and 80,000 Jy which is higher than we expected. The main problem was an S/X dual feed. We

separated the two feeds to improve the SEFDs to 1,500

— 2,000 Jy. We obtained these SEFD results by using

standard sources such as Cas A, Taurus A, and Cygnus

A. We will keep working on the improvement of the

antenna performances.

3.3 Joining the AOV (Asia-Oceania VLBI

Group)

The Sejong station joined the AOV group that was

discussed at the IVS 8th GM in Shanghai, China. In

2015, Sejong will participate in AOV VLBI observations about less than ten times due to the installation of

the K- and Q-band system. But we will actively work

with them as far as possible.

3.4 SLR Site Construction

KASI began constructing the mobile SLR site in October. The diameter of the SLR is 40 cm, and the construction will be completed in the middle of 2015. The

Sejong station is providing support for construction.

Fig. 3 Mobile SLR system developed by KASI.

4 Future Plans

We will take on the following activities in 2015: 1) participating in IVS-R1 sessions and the AOV, 2) improvement of S/X performance, 3) Korean VLBI observations (X, K, and Q) with KVN, 4) completion of SLR

site and installation of Microwave Radiometer, 5) five

local tie surveys, and 6) maintenance of VLBI system.

IVS 2014 Annual Report
Shanghai Station Report for 2014

Bo Xia, Zhiqiang Shen, Qinghui Liu

Abstract This report summarizes the observing

activities at the Sheshan station (SESHAN25) and

the Tianma station (TIANMA65) in 2014. It includes

the international VLBI observations for astrometry,

geodesy, and astrophysics and domestic observations

for satellite tracking. We will also report on the

updates and the development of the facilities at the two

stations.

1 General Information

The Sheshan station (SESHAN25) is located at Sheshan, 30 km west of Shanghai. It is hosted by Shanghai

Astronomical Observatory (SHAO), Chinese Academy

of Sciences (CAS). A 25-meter radio telescope is in operation at 1.3, 3.6/13, 5, 6, and 18 cm wavelengths. The

Sheshan station is a member of the IVS and EVN.

The Tianma station (TIANMA65) is located in the

western suburbs of Shanghai, Sheshan town, Songjiang

district. It is jointly funded by the Chinese Academy of

Sciences (CAS), Shanghai Municipality, and the Chinese Lunar Exploration Program. The telescope construction started in the early 2009, and the majority

of the mechanical system was completed in October

2012. On December 2, 2013, the Tianma 65-m telescope passed the acceptance evaluation. The Tianma

65-m radio telescope, one of the largest steerable radio telescopes in the world, is a multifunction facility for astrophysics, geodesy, and astrometry as well

Shanghai Astronomical Observatory, CAS

Shanghai Network Station

IVS 2014 Annual Report

as space science. By the end of 2014, TIANMA65 was

equipped with four cryogenic receiver systems (L, C,

S/X, and Ku). It is expected that another three highfrequency cryogenic receiver systems (K, X/Ka, and

Q) will be finished in 2015. A CDAS and DBBC2 were

installed at the Tianma telescope for VLBI data acquisition.

Fig. 1 Tianma 65-m radio telescope.

The SESHAN25 and TIANMA65 telescopes take

part in international VLBI experiments for astrometry, geodesy, and astrophysics researches including

RadioAstron Space VLBI observations. Apart from

its international VLBI activities, the telescope spent a

large amount of time on the Chinese Lunar Exploration

Project, including the testing before the launch of the

Chang’E-5T1 satellite and the tracking campaign after

the launch.

106
Report of Shanghai Station 107

2 VLBI Observations in 2014

In 2014, the SESHAN25 telescope participated in 16

IVS regular sessions and 11 INT3 Intensive sessions.

In addition, there were two Chinese domestic geodetic

sessions. SESHAN25 also participated in the three

regular EVN sessions in February, June, and October.

We did not participate in the session R1645 due to

the analog VLBI terminal VSI-C card problem. We

missed the session R1657 due to the antenna motor

problem. In 2014, TIANMA65 participated in two

IVS sessions. The low amplitude in SR6U, XR7U

and XR8U/L occasionally happened. In order to track

the Chinese Chang’E-5T1 satellite, SESHAN25 or

TIANMA65 have observed the Chang’E-5T1 satellite

for two days per week.

3 Development and Maintenance of the

Sheshan Telescope in 2014

We have upgraded the FS version from 10.04 to 11.10.

We have also upgraded the antenna control software to

measure the antenna pointing errors with the Gaussian

fitting method.

4 The Staff of the Shanghai VLBI Station

Table 1 lists the group members of the Sheshan VLBI

station. The staff are involved in the VLBI program at

the station with various responsibilities.

5 Outlook

In 2015, the Sheshan radio telescope will take part

in thirty-five IVS sessions and three EVN sessions.

The Tianma radio telescope will take part in six IVS

sessions. The telescopes will also regularly track the

Chang’E-5T1 satellite in its lunar orbit.

IVS 2014 Annual Report
108 Xia et al.

Table 1 The staff of the Sheshan VLBI station.

Name Background Position and Duty Contact

Xiaoyu Hong Astrophysics Director xhong@shao.ac.cn

Zhiqiang Shen Astrophysics Vice Director zshen@shao.ac.cn

Qinghui Liu Radio technique Chief Engineer liuqh@shao.ac.cn

Qingyuan Fan Ant. control Professor, Antenna qyfan@shao.ac.cn

Zhuhe Xue Software Professor, FS zhxue@shao.ac.cn

Quanbao Ling Electronics Professor, Hardware qling@shao.ac.cn

Bin Li Microwave Technical friend, Receiver bing@shao.ac.cn

Tao An Astrophysics Astrophysics antao@shao.ac.cn

Bo Xia Electronics VLBI friend,VLBI terminal bxia@shao.ac.cn

Shiguang Liang Microwave Professor, Receiver sgliang@shao.ac.cn

Li Fu Ant. mechanics Engineer, Antenna fuli@shao.ac.cn

Jinqing Wang Electronics Engineer, Antenna jqwang@shao.ac.cn

Lingling Wang Software Engineer, Timing system llwang@shao.ac.cn

Rongbing Zhao Software Engineer, Antenna software rbzhao@shao.ac.cn

Weiye Zhong Microwave Engineer, Receiver wyzhong@shao.ac.cn

Wei Gou Electronics Engineer gouwei@shao.ac.cn

Linfeng Yu Electronics Engineer lfyu@shao.ac.cn

Yongbin Jiang Electronics Engineer jyb@shao.ac.cn

Yunxia Sun HVAC Engineer, Refrigeration sunyunxia@shao.ac.cn

Xiaocong Wu Electronics Engineer wuxc@shao.ac.cn

Wen Guo Electronics Engineer gw@shao.ac.cn

Jian Dong Ant. Control Engineer dongjian@shao.ac.cn

Xiuting Zuo Software Engineer, Antenna zxt@shao.ac.cn

Yongchen Jiang Electronics Engineer, Disk Shipping yongchen@shao.ac.cn

Ying Chen Microwave Engineer, Receiver cying@shao.ac.cn

IVS 2014 Annual Report
Simeiz 22-m Radio Telescope as an IVS Network Station

A. E. Volvach, G. S. Kurbasova, L. N. Volvach

Abstract We briefly summarize the status of the 22-

m radio telescope as an IVS Network Station. We also

summarize the analysis of the ground and satellite measurements of local insolation in Crimea using NASA

SSE observations.

1 General Information

The 22-m radio telescope RT-22 of the Radio Astronomy Laboratory is located at the foot of mount Koshka

(“The Cat”) at the shore of the Black Sea, 25 kilometers west from the city of Yalta (Figure 1). RT-22, the

22-meter radio telescope, which was set in operation in

1966, is among the five most efficient telescopes in the

world.

The Simeiz geodynamics area consists of the radio

telescope RT-22, two satellite laser ranging stations, a

permanent GPS receiver, and a sea level gauge. The radio astronomical station Simeiz was founded in 1965.

The first single dish observation was made in 1966. The

first VLBI observation was made in 1969. The radioastronomical station Simeiz was included in international

VLBI networks in 1980.

The parameters of the 22-meter radio telescope are

presented in Table 1.

Radio Astronomy Lab of Crimean Astrophysical Observatory

Simeiz Network Station

IVS 2014 Annual Report

2 Activities during the Past Year and

Current Status

During 2014, the Space Geodesy and Geodynamics

stations regularly participated in the International Network programs — IVS, the International GPS Service (IGS), and the International Laser Ranging Service (ILRS).

During the period 2014 January 1 through 2014

December 31, the Simeiz VLBI station participated

in ten 24-hour geodetic sessions. Simeiz regularly

participated in the EUROPE and T2 series of geodetic

sessions.

2.1 Solar Energy in the Crimea on the SSE

Observations.

NASA’s Earth science research program has supported

satellite systems and research providing data important to the study of climate and climate processes.

These data include long-term estimates of meteorological quantities and surface solar energy fluxes [1].

These satellite and model-based products have been

shown to be accurate enough to provide reliable solar

and meteorological resource data over regions where

surface measurements are sparse or nonexistent, and

they offer two unique features — the data is global and,

in general, contiguous in time.

Crimea is located near the Euroasian tectonic zone

of high seismic activity. This results in special local climatic and geophysical conditions [2, 3]. Base ground

measurements needed to learn the features of local cli109
110 Volvach et al.

Fig. 1 The Simeiz VLBI station.

Table 1 The antenna parameters of the Simeiz station.

Diameter D, m 22

Surface tolerance, mm (root mean square) 0.25

Wavelength limit, mm 2

Feed System Cassegrain system or primary focus

Focal length F, m 9.525

Focal ratio F/D 0.43

Effective focal length for Cassegrain system, m 134.5

Mounting Azimuth-Elevation

Pointing accuracy, arc sec. 10

Maximum rotation rate, degree/sec 1.5

Maximum tracking rate, arcsec/sec 150

Working range  ̄in Azimuth, degrees (0 to South) -270 ± 270

in Elevation, degrees 0 - 85

matic and geophysical parameters are insufficient. We

use SSE-parameters for analysis of the distribution of

the energy (solar radiation) incident on the surface of

the Earth in Crimea in 2014. A summary of the estimated uncertainty associated with the basic solar and

meteorological data (i.e. solar radiation, temperature,

surface pressure, relative humidity, and wind speed)

underlying the parameters available through SSE 6.0

is given in [1]. The uncertainty estimates were derived through comparisons with ground measurements.

Quality ground-measured data are generally considered more accurate than satellite-derived values. But

measurement uncertainties from calibration drift, operational uncertainties, or data gaps are often unknown

or unreported for many ground site data sets [4].

The average insolation (kWh/m

2/day) is the

amount of electromagnetic energy (solar radiation)

incident on the surface of the Earth. The fraction

of insolation at the top of the atmosphere which

reaches the surface of the Earth depends on the local

conditions.

The insolation clearness index (dimensionless) is

a quantitative characteristic — the fraction of insolation of electromagnetic energy (solar radiation) at the

top of the atmosphere that is incident at the surface of

the Earth. The parameters of SSE for Sizing and Pointing of Solar Panels and for Solar Thermal Applications

contain information about the insolation clearness index for any region of the Earth’s surface. The distribution of the insolation clearness index over the surface

of the Earth in Crimea is shown in Figure 2.

The graph in Figure 2 shows that the fraction of insolation at the top of the atmosphere which reaches the

IVS 2014 Annual Report
Simeiz VLBI Station 111

Fig. 2 The 2014 Annual Monthly Averaged Insolation Clearness Index (0 to 1.0) in Crimea.

surface of the Earth in Crimea increases in the southeast.

The incoming solar radiation raises the temperature of the Earth’s surface. Analysis of variations of

the Earth’s surface temperature is useful for the study

of local meteorological, geographical, and geophysical

conditions.

Figure 3 is a graph of the 2014 Annual Monthly

Averaged Earth Skin Temperature (◦ C) in Crimea. The

Maximum Monthly Averaged Earth Skin Temperature

is shown in Figure 3.

3 Future Plans

Our plans for the coming year are the following: to

put into operation the VLBI Data Acquisition System

DBBC, to upgrade the laser of SLR Simeiz-1873 station, and to set up a new GPS station near the Simeiz

VLBI station.

IVS 2014 Annual Report
112 Volvach et al.

34

36

43

44

45

46

47

11

12

13

14

15

X: 37

Y: 43

Z: 15.74

East longitude ( o North latitude ( ) o ) Temperature ( 

oC )

12

13

14

15

Fig. 3 The 2014 Annual Monthly Averaged Earth Skin Temperature (◦ C) in Crimea.

References

1. NASA Surface meteorology and Solar Energy. URL:

https://eosweb.larc.nasa.gov/

2. Kurbasova G.S., Volvach A.E. Space Science and Technology, 20, pp.42-49, 2014.

3. Kurbasova G.S., Volvach A.E. CriMiCo2014 - 2014 24rd

International Crimean Conference Microwave and Telecommunication Technology, Conference Proceedings Weber

Publishing, 2014. Vol.2. P.1085-1086.

4. Volvach A.E., Kurbasova G.S. International VLBI Service

for Geodesy and Astrometry, edited by K. D. Baver, D.

Behrend, and K. L. Armstrong, NASA/TP-2014-217522,

2014. p.160-163.

IVS 2014 Annual Report
Svetloe Radio Astronomical Observatory 2014 IVS Annual Report

Sergey Smolentsev, Ismail Rahimov, Dmitry Ivanov

Abstract This report provides information about the

Svetloe Radio Astronomical Observatory during 2014.

The report also provides an overview of current geodetic VLBI activities and gives an outlook for the next

year.

1 General Information

Svetloe Radio Astronomical Observatory (Figure 1)

was founded by the Institute of Applied Astronomy

(IAA) as the first station of the Russian VLBI network

QUASAR. The sponsoring organization of the project

is the Russian Academy of Sciences (RAS). Svetloe

Radio Astronomical Observatory is located near SvetFig. 1 Svetloe observatory.

Institute of Applied Astronomy of RAS

Network Station Svetloe

IVS 2014 Annual Report

loe village in the Priozersky district of the Leningrad

region http://www.ipa.nw.ru/PAGE/rusipa.htm. The

basic instrument of the observatory is a 32-m

radio telescope equipped with special technical

systems for VLBI observations co-located with

GPS/GLONASS/Galileo receivers and an SLR system.

A Water Vapor Radiometer (WVR) has operated since

2013.

2 Technical Staff

Table 1 Staff related to VLBI operations at Svetloe.

Prof. Ismail Rahimov observatory chief

Vladimir Tarasov chief engineer

Tatiana Andreeva engineer

Alexander Isaenko engineer

Andrey Mikhailov FS, pointing system control

3 Component Description

3.1 Technical and Scientific Information

The main instrument at Svetloe observatory is a 32-

m radio telescope (RT-32), equipped with L, C, S/X,

and K cryogenic receivers with circular polarization, a

Mark 5B+ recorder, and a DAS P1002M. Main technical characteristics of the radio telescope are presented

in Table 2. Observations can be carried out both in radiometric mode and in radio interferometric mode.

113
114 Smolentsev et al.

All IAA observatories are equipped with the identical time standards and meteorological stations which

are used when carrying out all types of observations.

Automatic digital Weather Transmitter “Vaisala” is

used to obtain meteorological data in real time. A

Water Vapor Radiometer designed at the Institute of

Applied Astronomy is currently working at the Svetloe

observatory on a regular basis.

Table 2 Technical parameters of the radio telescope.

Year of construction 2000

Mount AZEL

Azimuth range ±270◦(from south)

Elevation range from −5

◦

to 95◦

Maximum azimuth

- velocity 0.83 ◦/s

- tracking velocity 2.5

′

/s

- acceleration 12.0

′

/s

2

Maximum elevation

- velocity 0.5

◦

/s

- tracking velocity 0.8

′

/s

- acceleration 12.0

′

/s

2

Pointing accuracy better than 10′′

Configuration Cassegrain (with

asymmetrical subreflector)

Main reflector diameter 32 m

Subreflector diameter 4 m

Focal length 11.4 m

Main reflector shape quasi-paraboloid

Subreflector shape quasi-hyperboloid

Main reflector surface accuracy ± 0.5 mm

Frequency range 1.4–22 GHz

Axis offset 3.7±2.0 mm

3.2 Co-location of VLBI, GPS/GLONASS,

and SLR System

The Topcon GPS/GLONASS/Galileo receiver with

meteo station WXT-510 is in operation (Figure 2).

The SLR system “Sazhen-TM” (Figure 3) at Svetloe observatory observed 3,089 passes of LAGEOS,

GLONASS, and other satellites and obtained 3,959

normal points during 2014.

Fig. 2 Topcon GPS/GLONASS/Galileo receiver at the Svetloe

observatory.

Fig. 3 “Sazhen-TM” SLR system at Svetloe observatory.

Fig. 4 WVR and RT-32 at Svetloe observatory.

IVS 2014 Annual Report
Svetloe IVS Annual Report 115

4 Current Status and Activities during

2014

Svetloe actively participates in both international (IVS

and EVN) and domestic (Ru) observation programs.

During 2014, Svetloe station participated in 29 24-hour

IVS sessions — 24 IVS-R4 sessions, three IVS-T2 sessions, and two EUROPE sessions – and in 21 IVSIntensive sessions.

Svetloe participated in 48 24-hour sessions in the

framework of the domestic Ru-E program for determination of all Earth orientation parameters and in 13

one-hour Ru-U sessions for obtaining Universal Time

using e-VLBI data transfer.

During 2014 a WVR was installed and successfully

worked (Figure 5).

Fig. 5 WVR at Svetloe observatory.

5 Future Plans

Our plans for the coming year are the following:

• To participate in IVS sessions,

• To carry out domestic observational programs for

obtaining Universal Time daily and for obtaining

Earth orientation parameters weekly with e-VLBI

data transfer,

• To carry out SLR observations of geodetic and navigation satellites,

• To participate in EVN and RADIOASTRON observational sessions,

• To continue geodetic monitoring of the RT-32 parameters,

• To continue WVR observations on a regular basis.

IVS 2014 Annual Report
JARE Syowa Station 11–m Antenna, Antarctica

Yuichi Aoyama, Koichiro Doi

Abstract In 2014, the 54th and the 55th Japanese

Antarctic Research Expeditions (hereinafter, referred

to as JARE–54 and JARE–55, respectively) participated in six OHIG sessions — OHIG88, 89, 90, 91,

92, and 93. These data were recorded on hard disks

through the K5 terminal. The hard disks storing the

OHIG83–87 sessions’ data were brought back from

Syowa Station to Japan in April 2014 by the icebreaker

Shirase, while those storing the OHIG88–93 sessions

data are scheduled to arrive in April 2015. The data

obtained from the five sessions — OHIG83–87 — by

JARE–54 were transferred to the Bonn Correlator via

the servers of National Institute of Information and

Communications Technology (NICT). At Syowa Station, JARE–56 will participate in six OHIG sessions

and in one Asia-Oceania VLBI (AOV) session in 2015.

1 General Information

To investigate polar science, the National Institute of

Polar Research (NIPR) is managing Japanese Antarctic Research Expeditions (JAREs). The 26 members of

JARE–55 overwintered at Syowa Station, East Ongul

Island, East Antarctica in 2014.

Syowa Station has become one of the key observation sites in the Southern Hemisphere’s geodetic and

geophysical networks (as shown in Figure 1, see [1]

for details). As a part of these geodetic measurements,

the JAREs have been operating the 11-m S/X–band anNational Institute of Polar Research

JARE Syowa Station 11–m antenna

IVS 2014 Annual Report

tenna at Syowa Station (69.0◦S, 39.6◦E) for geodetic

VLBI experiments since February 1998. A cumulative

total of 114 quasi-regular geodetic VLBI experiments

were performed by the end of 2014.

2 Component Description

For VLBI, the Syowa Station 11–m antenna is registered as IERS Domes Number 66006S004 and as CDP

Number 7342. The basic configuration of the Syowa

Station VLBI frontend system has not changed from

the description in [2].

The Syowa Station’s K4 recording terminal was

fully replaced by K5 simultaneously with the termination of the SYW session at the end of 2004. Syowa StaFig. 1 Syowa VLBI antenna.

116
JARE Syowa Station 117

Table 1 Staff members. JARE–54: February 2013 – January 2014 JARE–55: February 2014 – January 2015.

Name Affiliation Function

Koichiro DOI NIPR Project coordinator

Yuichi AOYAMA NIPR Liaison officer

Noriaki OBARA NIPR Chief operator of JARE–54

Hiroshi TANAKA NEC Antenna engineer for JARE–54

Takuya MASUNAGA NIPR Chief operator of JARE–55

Yasufumi YOSHIKAWA NIPR Operator of JARE–55

Hirofumi MIZUTA NEC Antenna engineer for JARE–55

tion has participated in the OHIG sessions in the austral

summer season since 1999. Data transfer through an

Intelsat satellite link from Syowa Station to NIPR has

been available since 2004. But its recent bandwidth is

about 3 Mbps and its effective speed of FTP transfer is

100–250 kB/sec, which is too slow to practically transfer the huge VLBI data.

3 Staff of the JARE Syowa Station 11–m

Antenna

The Syowa Station 11–m antenna is operated and

maintained by JARE and NIPR. The staff members

are listed in Table 1. OHIG sessions in 2014 were

performed primarily by the staff of JARE–55 as shown

in Figure 2. The first session of 2014, OHIG88, was

scheduled to be observed after the icebreaker Shirase

left Syowa Station on February 8, and so the staff of

JARE–54 could not use OHIG88 to instruct the staff

of JARE–55 in the operation and maintenance of the

11-m antenna. Instead, the staff of JARE-54 used a

simulation of a VLBI experiment to instruct the staff

of JARE-55 by the end of January 2014.

4 Current Status and Activities

4.1 Notes on System Maintenance

There had been two hydrogen masers, Anritsu

RH401A HM–1001C and HM–1002C, at Syowa

Station until HM–1002C was brought back to Japan in

January 2011 for an overhaul. Because the icebreaker

Shirase could not approach Syowa Station in the

2011/2012 and 2012/2013 austral summer seasons

Fig. 2 Syowa Station VLBI staff of JARE–55, Y. Yoshikara

(left), T. Masunaga (center) and H. Mizuta (right).

due to dense and thick sea ice, we could not return

HM–1002C to Syowa Station. During this period, the

unfavorable situation in which there was only one

hydrogen maser at Syowa Station lasted.

In addition, the ion pump of this hydrogen maser,

HM–1001C, began to abnormally stop on occasion after instability of the generator for power supplies occurred on March 11, 2011. Such trouble became sometimes an obstacle to VLBI observation. For example,

the ion pump of HM–1001C stopped suddenly at 00:00

UTC, November 21, 2013 just before the 36th scan of

the OHIG87 session. This abnormal stop caused about

two hours of unavailable data for the OHIG87 session.

To avoid such critical situations, we purchased a

new hydrogen maser, SD1T03B, in 2013. SD1T03B

was miniaturized in order to load it into a helicopter.

Therefore we succeeded in transporting it to Syowa

Station on December 16, 2013. SD1T03B was connected to the UPS for HM–1002C, and its startup was

accomplished on December 20, 2013. Since SD1T03B

has been used as the primary hydrogen maser from the

OHIG88 session, there was no clock trouble in 2014. In

IVS 2014 Annual Report
118 Aoyama and Doi

Table 2 Status of the OHIG sessions as of December 2014.

Code Date Station Hour Correlation Solution Notes

OHIG82 2013/Feb/11 Sy, Hh, Kk, Oh, Tc 24 h Yes Yes J54

OHIG83 2013/Feb/13 Sy, Hh, Kk, Oh, Tc 24 h Yes Yes

OHIG84 2013/Feb/20 Sy, Ft, Kk, Oh, Tc 24 h Yes Yes

OHIG85 2013/Nov/11 Sy, Ft, Hb, Ke, Kk, Tc, Ww, Yg 24 h Yes Yes

OHIG86 2013/Nov/13 Sy, Ft, Hb, Ke, Kk, Tc, Ww, Yg 24 h Yes Yes

OHIG87 2013/Nov/20 Sy, Ft, Hb, Hh, Ke, Kk, Tc, Ww, Yg 24 h Yes Yes †1, †2

OHIG88 2014/Feb/19 Sy, Ft, Ht, Ke, Kk, Tc, Ww, Yg -Hb, Oh 24 h – – J55

OHIG89 2014/Feb/25 Sy, Ft, Hb, Ht, Ke, Kk, Tc, Ww, Yg -Oh 24 h – –

OHIG90 2014/Feb/26 Sy, Ft, Hb, Ht, Ke, Kk, Tc, Ww, Yg -Oh 24 h – –

OHIG91 2014/Nov/12 Sy, Ft, Hb, Hh, Ke, Kk, Ww, Yg -Oh 24 h – –

OHIG92 2014/Nov/18 Sy, Ft, Hb, Ht, Ke, Kk, Ww, Yg -Oh 24 h – –

OHIG93 2014/Nov/19 Sy, Ft, Hb, Hh, Ke, Kk, Ww, Yg -Oh 24 h – –

J54: JARE–54, op. N. Obara, eng. H. Tanaka J55: JARE–55, op. T. Masunaga and Y. Yoshikawa, eng. H. Mizuta

†1 : No fringes occurred during 0000–0055UT because the ion pump of HM–1001C stopped.

†2 : T. Masunaga joined the JARE–54 team.

January 2015, HM–1001C, which was operated as the

secondary hydrogen maser in 2014, was replaced with

HM–1002C and brought back to Japan for an overhaul.

During the OHIG88 session, failures occurred in

the tracking system of the Syowa Station 11–m antenna. Consequently the 50th – 61st scans were missed.

4.2 Session Status

Table 2 summarizes the status of processing as of

December 2014 for the sessions starting in 2013. The

OHIG sessions involved Fortaleza (Ft), O’Higgins

(Oh), Kokee Park (Kk), TIGO Concepcion (Tc),  ́

Hobart 12-m antenna (Hb), HartRAO 26-m antenna

(Hh), HartRAO 15-m antenna (Ht), Warkworth (Ww),

Katherine (Ke), Yarragadee (Yg), and Syowa Station

(Sy). In 2005, Syowa Station joined the CRD sessions,

but after 2006, Syowa Station participated only in

OHIG sessions. Syowa Station took part in six OHIG

sessions in 2014.

K5 hard disks storing the OHIG 83–87 sessions’

data were sent from Syowa Station to Shirase in early

February, 2014. Shirase ran aground at 700 meters

from the shore at the Molodezhnaya base in the return

journey on February 16. Although Shirase was able to

leave the sunken rock after a few days, it bilged and

was flooded. But Shirase was able to return to Japan

somehow, and we obtained the K5 hard disks in April,

2014.

The OHIG83–87 sessions’ data were transferred to

NICT servers immediately and converted to the Mark

5 format data there. The converted data were transferred from the NICT servers to the Bonn Correlator

by FTP by the end of April. The OHIG 83–86 sessions’

data have been correlated without any problem. In the

OHIG87 session data, there appears to be a clock jump

of about 22 μs due to the abnormal stop of the HM–

1001C ion pump.

4.3 Analysis Results

As of December 2014, Syowa Station had contributed

114 sessions from May 1999. According to the results

analyzed by the BKG IVS Analysis Center, the accuracy of the position and the velocity of the Syowa Station 11–m antenna are 1 mm and 0.2 mm/yr, respectively. In addition, the length of the Syowa Station–

Hobart 12-m antenna baseline is increasing with a rate

of 66.8 ± 7.0 mm/yr. The Syowa Station–HartRAO

baseline shows a slight increase in its length with a rate

of 12.2 ± 0.8 mm/yr. The Syowa Station–O’Higgins

baseline also shows a slight increase, although its rate

is only 1.2 ± 0.8 mm/yr.

Detailed results from the data until the end of 2003

as well as comparisons with those from other space

geodetic techniques were reported in [3].

IVS 2014 Annual Report
JARE Syowa Station 119

5 Future Plans

Dismantling of the current Syowa Station antenna was

scheduled for the 2015/2016 austral summer season.

For this schedule, we presented a budget proposal for

replacing the current antenna with either a VGOS antenna or a small geodetic VLBI antenna. In parallel, the project to develop the small geodetic VLBI

antenna and its cryogenic system for feed and LNA

was advanced in collaboration with Tsukuba University, NICT and Geospatial Information Authority of

Japan. The project team concluded that the small antenna without the broadband receiving system could

hardly realize precise VLBI observations, even if the

cryogenic system would be installed. Although there

was possibility that the budget for the small antenna

might be approved in 2015, we gave up installing the

small antenna.

Instead, we tried to prolong the available period of

the current VLBI antenna. As a consequence, the importance of VLBI international observing was accepted

within NIPR, and NIPR decided to postpone the dismantling schedule until the 2019/2020 austral summer

season. We continue to present the budget proposal for

construction of the VGOS antenna after 2021 and to

make every effort until this proposal is approved.

Acknowledgements

This work is a part of the Science Program of JARE

supported by NIPR under the Ministry of Education,

Culture, Sports, Science, and Technology. Part of this

work was also supported by the NIPR through General

Collaboration Projects no. 25—20.

References

1. Shibuya, K., Doi, K., and Aoki, S. (2003): Ten years’

progress of Syowa Station, Antarctica, as a global geodesy

network site. Polar Geoscience, 16, 29-52.

2. Shibuya, K., Doi, K., and Aoki, S. (2003): JARE Syowa Station 11-m Antenna, Antarctica, in International VLBI Service for Geodesy and Astrometry 2002 Annual Report, 149-

152, NASA/TP-2003-211619, ed. by N. R. Vandenberg and

K. D. Baver.

3. Fukuzaki, Y., Shibuya, K. Doi, K., Ozawa, T., Nothnagel,

A., Jike, T., Iwano, S., Jauncey, D. L., Nicolson, G. D.,

and McCulloch, P. M. (2005): Results of the VLBI experiments conducted with Syowa Station, Antarctica. J. Geod.,

79, 379-388.

IVS 2014 Annual Report
Last Year of Operation of the TIGO VLBI Station in Concepcion ́

Hayo Hase 1, Cristian Herrera 2, Felipe Pedreros 2, Luis Feres 2, Sabina Rayo 2, Pablo Figueroa 2

Abstract After more than 12 years of continuous

operation, the TIGO VLBI station at Concepcion,  ́

Chile came to an end due to the termination of the

scientific-technical cooperation in the TIGO-project

between Germany and Chile. 36 scheduled VLBI

sessions were successfully recorded during the first

semester. In parallel the preparation of the disassembling of the observatory for its transportation to La

Plata in Argentina determined the main activities.

During the second semester the entire observatory was

packed to be moved. Besides that, the reflector was

surveyed, future Argentinean colleagues were trained

in TIGO by the Chilean staff, an inventory software

for an observatory was developed, and a study on

VGOS/GGOS network expansion was published.

1 General Information

The TIGO-project is based on a bilateral agreement between the Federal Republic of Germany and the Republic of Chile. Since 2002, TIGO has been located

in the terrain of the Universidad de Concepcion (long.  ́

73.025 degrees West, lat. 36.843 degrees South), in

Concepcion Chile, and has served the IVS, ILRS, IGS,  ́

IGFS, BIPM, and IERS with observational data. Between the main project partners BKG and Universidad

de Concepcion the cooperation was officially closed by  ́

the end of 2014. The reason to do so was the lack of interest to support a non-profit geodetic observatory by

1. Bundesamt fur Kartographie und Geod  ̈ asie (BKG)  ̈

2. Universidad de Concepcion (UdeC)  ́

TIGOCONC Network Station

IVS 2014 Annual Report

the Chilean government after the earthquake on February 27, 2010. The German government looked for other

partners and made an agreement with the Argentinean

National Research Council (CONICET) about the creation of an Argentinean-German Geodetic Observatory

(AGGO) in 2012. 2014, the last year of the TIGOproject, was full of activities to prepare the instruments

for the transport to the new AGGO site near La Plata,

Argentina. The acronym TIGO will stay in Chile, while

the new station will be called AGGO.

For more than ten years, TIGOCONC was among

the three most productive IVS-sites (Figure 1).

Fig. 1 TIGOCONC as the ‘center’ of the VLBI world. The baselines measured with Concepcion are projected to the Earth’s sur-  ́

face. The line width indicates the number of repetitions of baseline determinations during 2002—2014, demonstrating a solid

Southern hemisphere reference point which is very well connected to six continents by its continuous measurements.

TIGOCONC has been the VLBI reference point in

South America with most observations during 2003—

2013. It participated in total in 1,269 IVS sessions with

a total of 247,723 successful quasar observations. In

120
TIGO Concepcion ́ 121

Table 1 TIGO VLBI support staff in 2014.

Staff Function Email Remark

Hayo Hase Head hayo.hase@tigo.cl

Cristian Herrera Informatic Engineer cristian.herrera@tigo.cl

Felipe Pedreros Telecommunications Engineer felipe.pedreros@tigo.cl

Sabina Rayo student of mechanical engineering sabina.rayo@tigo.cl until May 2014

Pablo Figueroa student of telecommunications pablo.figueroa@tigo.cl until May 2014

Luis Feres student of aerospace engineering luis.fuentes@tigo.cl until May 2014

all VLBI operators vlbistaff@tigo.cl

addition, a few astronomical sessions were conducted

for the TANAMI project.

2 Component Description

The IVS network station TIGOCONC constitutes the

VLBI-part of the Geodetic Observatory TIGO, which

was designed to be a fundamental station for geodesy.

Hence, the VLBI radio telescope is co-located to an

SLR telescope (ILRS site), a GPS/Glonass permanent

receiver (IGS site), and other instruments such as a

seismometer and a superconducting and an absolute

gravity meter.

The atomic clock ensemble of TIGO consists of

two hydrogen masers, three cesium clocks, and four

GPS time receivers realizing the Chilean contribution

to the Universal Time scale (Circular T, BIPM).

The technical parameters of the TIGO radio telescope as published in [1] have not been changed.

3 Staff

The 2014 VLBI staff consisted of six persons, as listed

in Table 1. The team (Figure 2) was complemented by

students Luis Feres, Pablo Figueroa, and Dr. Sabina

Rayo performing night shifts until the closure of operations by the end of May 2014.

Fig. 2 The TIGO VLBI staff on top of the geodetic platform, and

the 6-meter telescope ready for shipment in the background. The

remaining geodetic reference marker is still visible at the bottom

edge (student operators absent).

4 Current Status and Activities

4.1 IVS Operation

During 2014 TIGO was scheduled to participate in 36

regular IVS experiments. Table 2 gives an overview

about the participation of TIGOCONC in 2014. Out

of 36 requested observation days, 33 could be observed successfully, reaching an efficiency of 91.6%.

The main reason for data loss have been related to technical problems in the refrigerating system of the receiver, recording problems on bad data carriers, and unexpected delays in the customs liberation procedure of

data carriers. According to previous schedules of moving TIGO to Argentina, the CONT14 scheduling was

made without TIGO. Due to delays in the execution of

the move, the possibility of including TIGO again in

IVS 2014 Annual Report
122 Hase et al.

Fig. 3 (Left) The VLBI telescope primary mirror covered with reflecting targets for photogrammetry measurements. (Right) Pictures

taken at different angles with the telescope pointing at 110 degrees of elevation. Credits: Rolando Dunner/AIUC.  ̈

CONT14 was not considered, as the preparations were

at an advanced stage.

Table 2 TIGO’s IVS observation statistics for 2014. The operation was closed on May 31, 2014.

Name R1xxx R4xxx OHIGxx Total IVS

# of Exp. 16 17 3 36

Correlated 13 17 3 33

No result 3 0 0 3

4.2 Reflector Surface Survey

A photogrammetry measurements campaign was performed on January 25 and 26, 2014, in order to measure the primary mirror surface accuracy. This work

was requested to the Centro de Astro-Ingenier ́ıa of the

Pontificia Universidad Catolica de Chile (AIUC) [2].  ́

The surface of the primary mirror was covered with

112 reflecting targets, and measurements were done by

using a VSTARS camera and software from Geodetic

Systems Inc.. Measurements were performed with the

telescope pointing at 2 degrees, 38 degrees, and 110

degrees of elevation to estimate gravity deformations

on the reflector’s surface. Subsequent analysis of the

pictures taken at different locations and angles around

the telescope allowed estimation of the mirror surface

RMS error of 0.25 [mm] at an elevation of 2 degrees,

0.26 [mm] at 38 degrees, and 0.28 [mm] at 110 degrees.

Results showed a surface RMS error 70 μm greater

than the design goal of 200 μm, meaning a 35% degradation for the last 12 years of operation. However, this

implies a loss of antenna gain less than 1% at 10 GHz.

Figure 3 shows the telescope primary mirror with the

reflecting targets attached to its surface, as well as the

photogrammetry measurements being performed.

4.3 Training of AGGO Staff

Federico Salguero, Jose Vera, and Augusto Cassino  ́

from CONICET, Argentina, visited TIGO in order to

gain a first introduction into the operation of VLBI and

later of the disassembling of the radio telescope.

4.4 Telescope Decommissioning

After 12 years of continuous operations and the preparations for the upcoming move to the new site in La

Plata (Argentina), an overhaul of the telescope was required. This major task was assigned to the company

MT-Mecatronica, who performed tests, parts replace-  ́

ment, lubrication, repainting, and the disassembly of

the telescope. Once in La Plata, MT-Mecatronica will  ́

be responsible for the re-commissioning of the telescope.

IVS 2014 Annual Report
TIGO Concepcion ́ 123

In addition, the cryogenic dewar was shipped to

the laboratories at the Wettzell Observatory for major

maintenance due to previous leakage problems.

Fig. 4 The staff of the TIGO, Wettzell, and AGGO observatories and the contracted MT-Mecatronica company preparing the  ́

transport to Argentina in front of the disassembled radio telescope, before storing it in its 40 ft. shipping container.

4.5 Observatory Inventory System

For the purpose of crossing the border between Chile

and Argentina, an inventory list of the Observatory had

to be made. Cristian Herrera developed a tailor made

software solution for the data acquisition by tablets,

storage in a database and creation of reports with filters. In order to not confuse already inventoried parts,

a barcode label was introduced for any registered part.

Each part of the observatory is registered in a database

with the following fields: name, part no., serial no.,

provenience, value, currency, manufacture date, place,

responsibility, auxiliary information, and photo. The

text information is barcoded and the photo, making the

identification easy, is also part of the database. It is not

made for VLBI only but for any part used in an observatory.

This system contains all the information for custom

purposes and can be used later on as the inventory system for AGGO.

Finally, the more than 2,000 items of TIGO were

registered with this system during February and December 2014.

4.6 Study of the VGOS/GGOS Network

Felipe Pedreros and Hayo Hase finished a study of densifying the global VGOS network with additional new

radio telescope sites to create a homogeneous site distribution of VGOS sites. As backbone for GGOS the

obtained configuration was extended with co-located

SLR sites in order to obtain an optimal GGOS network site distribution under the constraints of continental surface. This study was published in the Journal of

Geodesy [3].

5 Future Plans

The VLBI activities in 2015 will be focused on:

• Transporting TIGO to La Plata in Argentina.

• Setting up the new site in La Plata, Argentina.

• Educating new operators in VLBI operations.

• Resuming the execution of the 2015 IVS observation program.

References

1. Vandenberg, N. R. (editor): International VLBI Service for

Geodesy and Astrometry 1999 Annual Report, NASA/TP–

1999-209243, 1999.

2. R. Dunner,  ̈ Photogrammetry Measurements of TIGO, Internal Report, Centro de Astro-Ingenier ́ıa UC, Santiago, April

2014.

3. H. Hase, F. Pedreros, The most remote point method for the

site selection of the future GGOS network, J Geod (2014)

88:989—1006, DOI 10.1007/s00190-014-0731-y.

IVS 2014 Annual Report
Tsukuba 32-m VLBI Station

Takahiro Wakasugi1, Ryoji Kawabata1, Shinobu Kurihara1, Yoshihiro Fukuzaki1, Jiro Kuroda1, Kojin Wada1,

Syota Mizuno1,2, Takafumi Ishida1,2

Abstract The Tsukuba 32-m VLBI station is operated by the Geospatial Information Authority of Japan.

This report summarizes activities of the Tsukuba 32-

m VLBI station and other stations operated by GSI in

2014. 75 24-hour sessions including CONT14 and 148

Intensive sessions were observed using Tsukuba 32-

m and other GSI antennas in accordance with the IVS

Master Schedule of 2014. We have been constructing a

new observing facility that will be fully compliant with

the VGOS concept for the first time in Japan. The construction of the antenna was completed in March, and

the inauguration of the new Ishioka VGOS antenna was

held in October.

Fig. 1 The Tsukuba 32-m VLBI station.

1. Geospatial Information Authority of Japan

2. Advanced Engineering Service Co., Ltd.

Tsukuba Network Station

IVS 2014 Annual Report

1 General Information

The Tsukuba 32-m VLBI station (Figure 1) is located

at the Geospatial Information Authority of Japan (hereafter GSI) in Tsukuba science city, which is about 50

km to the northeast of Tokyo. GSI has two regional

stations besides Tsukuba: Chichijima and Aira, which

form a geodetic VLBI network in Japan (Figure 2).

GSI has observed the domestic VLBI session series

called JADE (JApanese Dynamic Earth observation by

VLBI) since 1996. The main purposes of the JADE series are to maintain the reference frame of Japan and to

monitor plate motions for the advanced study of crustal

deformations around Japan. Additionally, most JADE

Fig. 2 Geodetic VLBI network in Japan.

124
Tsukuba 32-m VLBI Station 125

sessions include Mizusawa and Ishigakijima, which are

part of the VERA network of the National Astronomical Observatory of Japan (NAOJ), the two antennas

in Kashima (11-m and 34-m), and the Koganei 11-m

station, which belong to the National Institute of Information and Communications Technology (NICT).

2 Component Description

The specifications of the Tsukuba 32-m antenna are

summarized in Table 1.

Table 1 Tsukuba 32-m antenna specifications.

Owner and operating agency Geospatial Information

Authority of Japan

Year of construction 1998

Radio telescope mount type Az-El

Antenna optics Cassegrain

Diameter of main reflector 32 m

Azimuth range 10 – 710◦

Elevation range 5 – 88◦

Az/El drive velocity 3

◦

/sec

Tsys at zenith (X/S) 50 K / 65 K

SEFD (X/S) 320 Jy / 360 Jy

RF range (X1) 7780 – 8280 MHz

RF range (X2) 8180 – 8680 MHz

RF range (X3) 8580 – 8980 MHz

RF range (S with BPF) 2215 – 2369 MHz

Recording terminal K5/VSSP32

ADS3000+ with DDC

3 Staff

Table 2 lists the regular members belonging to the GSI

VLBI observation group. Kojin Wada replaced Tadashi

Tanabe from April as the supervisor. There is no major

change in other aspects. Routine operations were primarily performed under contract with Advanced Engineering Service Co., Ltd. (AES).

Table 2 Member list of the GSI VLBI group.

Name Main Function

Kojin WADA Supervisor

Jiro KURODA Management, Co-location

Yoshihiro FUKUZAKI Installation of VGOS

Shinobu KURIHARA Correlation, Analysis,

IVS Directing Board member

Ryoji KAWABATA Operation, Co-location

The secretary of AOV

Takahiro WAKASUGI Operation

Syota MIZUNO Operation (AES, Co., Ltd)

Takafumi ISHIDA Operation (AES, Co., Ltd)

Toshio NAKAJIMA System engineer (NTT-ATC)

4 Current Status

4.1 Geodetic VLBI Observations

The regular sessions in the IVS Master Schedule that

were conducted by using the GSI’s antennas are shown

in Table 3. Tsukuba 32 m participated in 75 international and domestic 24-hour VLBI sessions, and in 148

Intensive one-hour sessions for dUT1 measurement in

2014. The other GSI antennas, Chichijima and Aira,

participated in not only domestic but also some international sessions such as IVS-T2 and APSG.

We observed the CONT14 campaign, which lasted

fifteen days from 6 to 20 May, by using Tsukuba 32

m. Although we faced a small problem concerning a

data recording server, most scans were recorded successfully. During the campaign, Tsukuba also observed

regular Intensive sessions four times. Switching between CONT and Intensive sessions was done fully automatically. The obtained data were transferred via the

Internet to the Bonn correlator.

Table 3 The number of regular sessions observed by using the

GSI’s antennas in 2014.

Sessions Tsukuba Aira Chichijima

IVS-R1 44 10 –

IVS-T2 7 7 7

APSG 2 2 2

IVS-R&D 1 – –

CONT14 15 – –

JADE 5 5 5

JAXA 1 1 1

IVS-INT2 101 – –

IVS-INT3 47 – –

Total 223 25 15

IVS 2014 Annual Report
126 Wakasugi et al.

4.2 VGOS Project by GSI

In 2012, we started a new project for constructing a

VGOS station in Japan. The construction of the antenna has been completed (Figure 3) and the necessary

equipment (Front-end, Back-end, H-maser, and so on)

has also been delivered. In order to achieve broadband

receiving, Eleven feed and Quadruple Ridged Flared

Horn (QRFH) systems have been purchased. In addition, a tri-band feed system developed by Spanish IGN

(Yebes observatory) has also been purchased for compatibility with the legacy S/X band receiving. After installing the Eleven feed and tri-band feed systems on

the antenna, the performance of the new antenna was

measured. As a preliminary result, we obtained SEFD

1250 Jy and 1700 Jy for X-band and S-band, respectively.

We held the inauguration ceremony of the new antenna in October (Figure 4). The Ishioka VGOS station will start to observe in regular IVS sessions in the

legacy S/X mode for two years as a first step in order

to establish a strong tie relation with Tsukuba and other

legacy antennas. The full VGOS mode of observation

will start after this S/X mode session series. The technical development for broadband receiving will also be

performed during this period.

4.3 Influence of the Repair on the

Tsukuba 32-m Antenna

As reported in the previous IVS Annual Report [1], the

Tsukuba 32-m antenna was forced to suspend all IVS

sessions from May to November in 2013 due to damage to the antenna basement [2], and R1 sessions in

the last quarter were observed by using AIRA instead

of Tsukuba. In the first quarter in 2014, AIRA continued to participate in R1 sessions after Tsukuba rejoined

them [3]. Tsukuba showed a satisfactory performance

as before the repair. Furthermore, the result of the local

tie survey conducted after the repair was very close to

that before the repair. In conclusion, the repair finished

well, and the Tsukuba 32 m is still in good condition.

Additionally, we showed the usefulness of a high speed

A/D sampler ADS3000+ with a K5/VSI data recording

and transferring system for regular VLBI experiments

by the result of AIRA’s performance in many R1 sessions.

5 Future Plans

The Asia-Oceania VLBI Group for Geodesy and Astrometry (AOV) was newly established in 2014 as a

subgroup of IVS in cooperation with twelve organizations in the Asia and Oceania region. Ryoji Kawabata was appointed secretary and will engage himself in processing and managing the AOV project with

the chair, Jim Lovell (University of Tasmania). GSI

will also make a substantial contribution to developing new technologies, obtaining new scientific knowledge that will lead to the decrease of damage caused

by natural disasters, and establishing a regional reference frame by using the Tsukuba and Ishioka antennas.

On the other hand, we will terminate the operation of

the other regional antennas, Aira and Chichijima, by

March 2015, because it has been a long time since they

Fig. 3 The Ishioka 13.2-m antenna.

IVS 2014 Annual Report
Tsukuba 32-m VLBI Station 127

Fig. 4 Inauguration ceremony in October.

were constructed, and GNSS has become able to play

the role that had been implemented by the domestic

VLBI network. Consequently, the year 2015 will be

a major milestone for us. We will concentrate on the

new VGOS project and AOV sessions with Tsukuba

and Ishioka instead of the domestic JADE sessions including Chichijima and Aira so far.

References

1. Wakasugi, T., R. Kawabata, S. Kurihara, Y. Fukuzaki, J.

Kuroda, T. Tanabe, S. Mizuno, T. Ishida, Tsukuba 32-m

VLBI Station, in International VLBI Service for Geodesy

and Astrometry 2013 Annual Report, edited by K. D. Baver,

D. Behrend, and K. L. Armstrong, NASA/TP-2014-217522,

pages 173-176, 2014.

2. Wakasugi, T., Status report of the Tsukuba VLBI Station -

damage of the antenna basement due to over loading -, TDC

News, IVS NICT-TDC News, No.33, pp.8-10, 2013.

3. Wakasugi, T., R. Kawabata, Regular Geodetic VLBI Observation with a Wide-band Recording System, TDC News,

IVS NICT-TDC News, No.34, pp.11-13, 2014.

IVS 2014 Annual Report
Nanshan VLBI Station Report 2014

Ming Zhang

Abstract The Nanshan VLBI station was upgraded

significantly during 2014. A lot of technical work still

needs to be done in 2015, although it is already back

online for IVS observations.

1 General Information

Fig. 1 The dismantling of the 25-m dish in April.

Built in 1997, the Nanshan 25-m telescope has reached

its design life. It has been under reconstruction since

20 March 2014. The climate-restricted construction period on the mountain plateau of Tianshan is only about

a half year, so the reconstruction comes in two stages.

At stage I, all parts above the elevation wheel will be

Xinjiang Astronomical Observatory, Chinese Academy of Sciences

XAO-CAS Urumqi Network Station

IVS 2014 Annual Report

Fig. 2 The aura of the rebuilt 26-m dish in November.

rebuilt this year; at stage II, the lower parts will be refurbished, including adjustment of the azimuthal track

next year. The alidade and all the receivers and terminals remain the same. We expect a significant improvement of the reflector’s surface accuracy after the reconstruction, so in the feed cabin we have reserved a room

for a future 7-mm receiver. The second focal room is

designed to be fitted with fixed multi-band feeds and

a movable sub-reflector. To fully utilize the height of

the elevation bearing, as well as to compensate for the

new big feed hole, we will increase the antenna diameter to 26 m. Stage I is planned to be finished before this

October in order to serve the coming lunar exploration

mission.

2 Activities during the Past Year

Because the major restoration work is being carried

out this year, many VLBI observations are being hindered. We joined few EAVN and EVN observations be128
Nanshan VLBI Station 129

fore the dismantling of the old 25-m telescope. We also

joined IVS observing soon after the restoration of the

new 26-m telescope. But because many antenna parameters need to be re-measured, we haven’t started VLBI

observations for astrophysical purposes as EVN and

EAVN have required. But we have managed to observe

ten scheduled IVS sessions outside the reconstruction

time range in 2014.

Table 1 The observed IVS sessions.

Session Date Remarks

R4618 JAN 02 Normal

R1621 JAN 21 Normal

T2095 FEB 18 Normal

RD1407 SEP 10 Normal

RD1409 OCT 07 Normal

RD1411 NOV 04 Normal

R1661 NOV 10 Normal

APSG35 DEC 08 Normal

R4665 DEC 11 Normal

R4668 DEC 30 Normal

3 Current Status

3.1 Antenna Restoration

The newly built 26-m dish has made its debut in IVS

observing, but time is still needed to completely restore this antenna and to make known its capabilities to

the astronomical community. Currently only S/X and L

bands are restored at a workable level. The new station

center needs to be calculated from recent IVS observations. The antenna parameters such as pointing, gain

curve, and beam map also need to be re-measured.

3.2 Backend and Recording System

Bundled with antenna upgrading, an RDBE is planned

to be purchased this year. A DBBC and Mark 5b+ and

Mark 6 will be purchased later on. The restored system

with the new antenna will have separate VLBI terminals for EVN besides the CVN one which allows more

remote accessibility. The Streamstor SDK for Mark 5

will be upgraded to version 9.2, and the FS will be upgraded to version 9.11.4 before joining the next EVN

session.

4 Future Plans

There is a program in progress to build a fully steerable

110-m radio telescope (QTT) in Qitai county which is

about 200 km east to Urumqi. Being less heavily engaged with astrophysical observations, Nanshan 26-m

antenna could be a specialized VLBI telescope in the

future. But the 26-m telescope will be a preliminary

experiment platform for new techniques such as ultrawideband digital receivers, which will be incorporated

in accordance with the new VGOS goals. There are

also plans to build dedicated VGOS antennas nearby.

IVS 2014 Annual Report
New Zealand VLBI Station, Warkworth

Stuart Weston, Tim Natusch, Lewis Woodburn, Ben Hart, Sergei Gulyaev

Abstract The Warkworth Radio Astronomical Observatory is operated by the Institute for Radio Astronomy

and Space Research (IRASR), AUT University, Auckland, New Zealand. Here we review the characteristics

of the VLBI station facilities and report on a number of

activities and technical developments in 2014.

1 General Information

The Warkworth Radio Astronomical Observatory for

which a panorama photo is shown in Figure 1 is located

some 60 km north of the city of Auckland, near the

township of Warkworth. Specifications of the Warkworth 12-m and 30-m antennas are provided in Table

1. The 12-m radio telescope is equipped with an S/X

dual-band dual-circular polarization feed at the secondary focus and an L-band feed at the prime focus.

Backend data digitizing is handled by a digital base

band converter (DBBC) manufactured by the HATLab, Catania, Italy. The 30-m radio telescope is currently equipped with an uncooled C-band dual-circular

polarization receiver. The station frequency standard is

a Symmetricom Active Hydrogen Maser MHM-2010

(75001-114). Mark 5B+ and Mark 5C data recorders

are used for data storage and streaming of recorded

data off site. The observatory network is directly connected to the national network provided by Research

and Education Advanced Network New Zealand Ltd

(REANNZ) via a 10 Gbps fiber link to the site [1].

Institute for Radio Astronomy and Space Research, AUT University

Warkworth Network Station

IVS 2014 Annual Report

2 Component Description

2.1 The 12-m Antenna: Progress and

Issues

In the beginning of 2014, a problem with slippage of

the elevation axis encoder occurred. Initially, this issue

could be dealt with by regenerating a pointing model

on a fortnightly basis, but eventually it progressed to

the point where a new model was required on an almost

daily basis. It was determined that, as been the case at

several other Patriot/Cobham 12-m antennas, the problem was caused by rotational slippage of the elevation

axis pin connected to the encoder in the housing. As

supplied by the manufacturer, this pin was intended to

be locked to the main structure of the dish by an interface fit and to convey rotational motion to the elevation

encoder. A permanent solution that locks the pin to the

structure of the dish through bolts drilled into the axis

bearing pin appears to have been successful; we have

not experienced any more drift, and the elevation encoder offset has since been stable.

A new DBBC was received in April 2014 and was

used to replace the original one purchased for the 12

m. This allowed the original DBBC to be returned to

Bonn for repair and upgrade. Following its return, it

has been installed as the digitizer for the 30-m antenna.

Since the installation of the new DBBC on the 12 m

we have seen a significant improvement in our SEFD

figures. Previously they were of the order of 6000 Jy;

now they are regularly ∼ 3800 Jy, comparable with the

AuScope 12-m antennas.

Having upgraded the Streamstor SDK for CONT14

and being able to address more than 1,024 scans and

130
Warkworth Observatory 131

Fig. 1 Photo of the two radio antennas at Warkworth on a frosty winter’s morning: on the left the 30 m and on the right the 12 m.

In the background on the left hand side are the antennas belonging to Spark (formerly Telecom New Zealand). (Image courtesy of

Stuart Weston)

Table 1 Specifications of the Warkworth 12-m and 30-m antennas.

12-m 30-m

Antenna type Dual-shaped Cassegrain wheel-and-track, Cassegrain

beam-waveguide

Manufacturer Cobham/Patriot, USA NEC, Japan

Main dish Diam. 12.1 m 30.48 m

Secondary refl. Diam. 1.8 m 2.715 m

Focal length 4.538 m

Surface accuracy 0.35 mm 1.2 mm

Mount alt-azimuth alt-azimuth

Azimuth axis range 90◦ ±270◦ −179◦to +354◦

Elevation axis range 7.2

◦

to 88◦ 6.0

◦

to 90.1

◦

Azimuth axis max speed 5◦/s 0.37◦/s

Elevation axis max speed 1◦/s 0.36◦/s

greater than 16 TB, we are in the process of upgrading

our station diskpacks to 32 TB.

2.2 The 30-m Antenna: Progress and

Issues

By mid 2014, the conversion of the 30-m antenna had

progressed to a stage where it was fully steerable and

equipped with an uncooled 6 GHz receiver (donated by

Jodrell Bank Observatory), and a First Light ceremony

was held where a 6.7 GHz Methanol maser spectral line

was received and displayed on a spectrum analyzer as

shown in Figure 2. More details of the conversion can

be found in [2].

With the return of the observatory’s original DBBC,

installation of the Mark 5B recorder and of a Symmetricom Universal Time and Frequency Distribution System to distribute signals from the observatory maser

to the 30-m site, the antenna became capable of interferometry. The first VLBI fringe was detected on the

baseline to the 26-m antenna at Hobart (Figure 3). We

gratefully acknowledge the generous assistance of the

University of Tasmania observatory in this accomplishment.

2.3 Warkworth Network

In April 2014, the network link between Warkworth

and the New Zealand research network (REANNZ)

was upgraded to 10 Gbps. The international circuits

from New Zealand provided by REANNZ are now

42 Gbps bi-directional to LA and 40 Gbps along SXTransport ScienceWave (which REANNZ shares with

AARNet) that handles all the research and education

IVS 2014 Annual Report
132 Weston et al.

Fig. 2 First light methanol maser spectral line at 6.7 GHz.

Credit: Tim Natusch

Fig. 3 The first VLBI fringe between Warkworth 30 m and Hobart 26 m at C-Band 6.7 GHz. Credit: Leonid Petrov

routes. In October 2014 we installed 10 Gbps fiber network interface cards in our e-transfer Mark 5. The bottle neck for us is now the receiving site. For example,

we can sustain 800 Mbps to the new data store in Perth

run by iVEC; speeds to Bonn and USNO are of the order of 100–200 Mbps.

3 Current Status and Activities

2014 has seen a significant increase in the number of

IVS sessions in which the 12 m has participated, due in

large part to the extra AUST sessions in which we are

now able to participate. A break down of session types

(i.e. OHIG, CRDS, APSG, R, and AUST) observed in

2014 is presented in Table 2, showing our much higher

utilization/participation in IVS this year versus 2013.

Table 2 The 12 m IVS 2014 Session Participation.

Experiment Number of sessions

2013 2014

APSG 2 2

OHIG 3 6

R1 8 0

R4 8 11

CRDS 6 6

CONT 0 14

AUSTRAL 6 57

AUST 15 15

The first geodetic observing with the Warkworth 30

m in C-Band with the Ceduna 30 m and Hobart26 (University of Tasmania) was conducted in December 2014.

The schedule and analysis was undertaken by Leonid

Petrov (NASA Goddard Space Flight Center), providing a preliminary solution for the 30-m antenna presented in Table 3 (Petrov et al, 2015, in preparation).

Table 3 The 30 m preliminary solution components, Credit:

Leonid Petrov.

Epoch X, mm Y, mm Z, mm

2000.01.01-12:00:00 -5115425635.06 477880304.86 -3767042837.73

2014.12.11-12:59:43 -5115425608.47 477880352.69 -3767042708.48

This observing will be repeated in 2015, it is hoped

with additional stations in Japan (Tsukuba and

Kashima) and South Africa (Hartebeesthoek) able to

participate.

Foundations have been laid for the future hosting

of a gravimeter when in transit here in New Zealand

from Antarctica. The site is just outside the 12 m antenna control facility so as to easily access utilities,

and it is also close to one of the LINZ (Land Information New Zealand) GNSS stations hosted at the Warkworth Observatory. In March 2015, a site survey of the

observatory will be undertaken with the assistance of

LINZ. This will provide a useful check of the initial

local tie survey of the 12-m antenna and GNSS station

conducted at the end of 2012 [3] and also provide a tie

to the 30-m radio telescope for the first time.

IVS 2014 Annual Report
Warkworth Observatory 133

References

1. Weston, S., Natusch, T., Gulyaev, S., Radio Astronomy and e-VLBI using KAREN. In Proceedings of the

17th Electronics New Zealand Conference, 2010. Preprint

arXiv:1011.0227.

2. Woodburn, L., Natusch, T., Weston, S., Thomasson, P., Godwin, M., Granet, C., Gulyaev, S., Conversion of a New

Zealand 30 metre Telecommunications antenna into a Radio Telescope, Publications of the Astronomical Society of

Australia, Accepted, 2015.

3. Gentle, P., Dawson, J., & Woods, A., The 2012 Warkworth

Observatory Local Tie Survey, 2013, Tie Survey, Land Information New Zealand.

IVS 2014 Annual Report
Westford Antenna 2014 Annual Report

Mike Poirier

Abstract Technical information is provided about the

antenna and VLBI equipment at the Westford site of

the Haystack Observatory, and about changes to the

systems since the IVS 2013 Annual Report.

1 Westford Antenna at Haystack

Observatory

Since 1981, the Westford antenna has been one of the

primary geodetic VLBI sites in the world. Located ∼70

km northwest of Boston, Massachusetts, the antenna is

part of the MIT Haystack Observatory complex.

The Westford antenna was constructed in 1961 as

part of the Lincoln Laboratory Project WestFord that

demonstrated the feasibility of long-distance communication by bouncing radio signals off a spacecraftdeployed belt of copper dipoles at an altitude of 3,600

km. In 1981, the antenna was converted to geodetic use

as one of the first two VLBI stations of the National

Geodetic Survey Project POLARIS. Westford has continued to perform geodetic VLBI observations on a regular basis since 1981. Westford has also served as a

testbed in the development of new equipment and techniques now employed in geodetic VLBI worldwide.

MIT Haystack Observatory

Westford Antenna

IVS 2014 Annual Report

Fig. 1 Aerial view of the radome and facilities of the Westford

antenna. (For scale the diameter of the radome is 28 m.)

Table 1 Location and addresses of the Westford antenna.

Longitude 71.49◦ W

Latitude 42.61◦ N

Height above m.s.l. 116 m

MIT Haystack Observatory

Off Route 40

Westford, MA 01886-1299 U.S.A.

http://www.haystack.mit.edu

2 Technical Parameters of the Westford

Antenna and Equipment

The antenna is enclosed in a 28-meter diameter airinflated radome made of 1.2 mm thick Teflon-coated

fiberglass (see Figure 1). System temperatures are 10—

20 degrees higher at X-band when the radome is wet

than when it is dry. The effect is smaller at S-band. The

major components of the VLBI data acquisition system

134
Westford Antenna 135

Fig. 2 Wide-angle view of the Westford antenna inside the

radome. The VLBI S/X receiver is located at the prime focus.

The subreflector in front of the receiver is installed when observing with the TAL receiver (see Section 4), which is located at the

Cassegrain focus.

Table 2 Technical parameters of the Westford antenna for

geodetic VLBI.

Parameter Westford

primary reflector shape symmetric paraboloid

primary reflector diameter 18.3 meters

primary reflector material aluminum honeycomb

S/X feed location primary focus

focal length 5.5 meters

antenna mount elevation over azimuth

antenna drives electric (DC) motors

azimuth range 90◦ −470◦

elevation range 4

◦ −87◦

azimuth slew speed 3

◦

s

−1

elevation slew speed 2

◦

s

−1

X-band system S-band system

frequency range 8180-8980 MHz 2210-2450 MHz

Tsys at zenith 50–55 K 70–75 K

aperture efficiency 0.40 0.55

SEFD at zenith 1400 Jy 1400 Jy

are a Mark IV electronics rack, a Mark 5B recording

system, and a Pentium-class PC running PC Field System version 9.10.2. The primary frequency and time

standard is the NR-4 hydrogen maser. A CNS Clock

GPS receiver system provides a 1 pps reference clock

to which the maser 1 pps is compared.

Westford also hosts the WES2 GPS site of the IGS

network. A Dorne-Margolin chokering antenna is located on top of a tower at about 60 meters from the

VLBI antenna. A LEICA GRX1200 Reference Station

receiver completes the WES2 GPS site.

3 Westford Staff

The personnel associated with the geodetic VLBI program at Westford, and their primary responsibilities,

are:

• Chris Beaudoin: broadband development

• Alex Burns: technician, observer

• Joe Carter: antenna servo support

• Brian Corey: VLBI technical support

• Kevin Dudevoir: pointing system software

• Dave Fields: technician, observer

• Colin Lonsdale: site director

• Glenn Millson: observer

• Arthur Niell: principal investigator

• Michael Poirier: site manager

4 Standard Operations

From January 1, 2014 through December 31, 2014,

Westford participated in 24 standard 24-hour sessions

along with a 15-day continuous CONT14 session.

Westford reduced its regularly scheduled 54 sessions to support developmental and operational testing

of the VGOS system.

Use of the Westford antenna is shared with the Terrestrial Air Link (TAL) Program operated by the MIT

Lincoln Laboratory. In this project, Westford serves as

the receiving end on a 42-km long terrestrial air link

designed to study atmospheric effects on the propagation of wideband communication signals at 20 GHz.

IVS 2014 Annual Report
136 Poirier

5 Research and Development

The Westford antenna, in its role as a testbed for VLBI

development, has been fitted with the VGOS broadband frontend and backend, MCI, and Mark 6 recorder

systems. Presently, we are running bi-weekly 1-hour

operational tests between Westford and the GGAO 12-

m antenna, exercising the equipment and test procedures while providing quality VLBI geodetic observations.

6 Outlook

Westford is expected to participate in 54 24-hour sessions starting in March 2015. These sessions will include R1, R&D, and several VGOS sessions, along

with the occasional fringe test and support of special

VGOS broadband development testing.

Westford has purchased a replacement PC Field

System (PCFS), and it is presently being configured by

NVI, Inc. The pointing system upgrade will be implemented early in 2015 with the new PCFS, which will

improve the compatibility with the new VGOS system

and more easily support the Lincoln Laboratory (LL)

program at Westford.

The Westford broadband system continues to be

operated successfully at Westford. Operational testing

continues, and we expect to become fully operational

supporting all of our NASA sessions during 2015.

Acknowledgements

I would like to thank Arthur Niell, Christopher Beaudoin, and Chester Ruszczyk for their contributions to

this report.

Funding for geodetic VLBI at Westford is provided

by the NASA Space Geodesy Program.

IVS 2014 Annual Report
Geodetic Observatory Wettzell - 20-m Radio Telescope and Twin

Telescopes

Alexander Neidhardt 1, Christian Plotz  ̈

2

, Gerhard Kronschnabl 2, Torben Schuler  ̈

2

Abstract In 2014, the 20-m radio telescope at

the Geodetic Observatory Wettzell in Germany,

contributed again very successfully to the IVS observing program. Technical changes, developments,

improvements, and upgrades were made to increase

the reliability of the entire VLBI observing system. A

new controller for the reflector heating was installed,

and updates were made in some gears to avoid an oil

leakage. In parallel, the new Twin radio Telescope

Wettzell (TTW) was brought to operation so that it

could observe the INT3 sessions as a tagged-along

site. Local analysis shows a very good performance in

X-band and a very good repeatability.

1 General Information

The 20-m Radio Telescope in Wettzell (RTW) is an

essential component of the Geodetic Observatory

Wettzell (GOW) and is jointly operated by Bundesamt fur Kartographie und Geod  ̈ asie (BKG) and  ̈

Forschungseinrichtung Satellitengeodasie (FESG)  ̈

of the Technische Universitat M  ̈ unchen (Technical  ̈

University Munich). In addition to the RTW, an ILRS

laser ranging system, several IGS GPS permanent

stations, a large laser gyroscope G (ringlaser), and

the corresponding local techniques (e.g. time and

frequency, meteorology and super conducting gravity

meters, etc.) are also operated. Currently, the first

1. Forschungseinrichtung Satellitengeodasie (FESG), Technis-  ̈

che Universitat M ̈ unchen  ̈

2. Bundesamt fur Kartographie und Geod  ̈ asie (BKG)  ̈

RTW/TWIN Wettzell Network Station

IVS 2014 Annual Report

antenna of the fully VGOS-compliant Twin radio

Telescope is in an operational test phase.

Within the responsibility of the GOW are the TIGO

system in Concepcion, Chile, operated mainly together  ́

with the Universidad de Concepcion (see separate re-  ́

port about TIGO), and the German Antarctic Receiving Station (GARS) O’Higgins on the Antarctic peninsula, operated together with the German Space Center

(DLR) and the Institute for Antarctic Research Chile

(INACH) (see separate report about O’Higgins).

2 Staff

The staff of the GOW consists in total of 31 members (plus 14 student operators) for operations, maintenance, and repair issues and for improvement and development of the systems. The staff operating VLBI is

summarized in Table 1.

3 Observations in 2014

The 20-m RTW has been supporting the geodetic VLBI

activities of the IVS and partly other partners, such as

the EVN, for over 30 years now. All successfully observed sessions in the year 2014 are summarized in

Figure 1. The telescope is in a very good and stable

state. The main priority in operations was the participation in all daily one-hour INTENSIVE-sessions (INT)

in order to determine UT1-UTC. Using the Field System extension for remote control, weekend INTENSIVEs were partly done in the new observation modes

by remote attendance. According to new safety regula137
138 Neidhardt et al.

Fig. 1 Observation statistics of the last years and observations in the year 2015.

Table 1 Staff - members of RTW.

Name Affiliation Function Mainly

working for

Torben Schuler  ̈ BKG head of the GOW GOW

Alexander Neidhardt FESG head of the VLBI group RTW, TTW

and VLBI station chief

Erhard Bauernfeind FESG mechanical engineer RTW

Ewald Bielmeier FESG technician RTW

Gerhard Kronschnabl BKG electronic engineer TTW, RTW,

(chief engineer TTW) TIGO

Christian Plotz  ̈ BKG electronic engineer O’Higgins,

(chief engineer RTW) RTW, TTW

Raimund Schatz FESG software engineer RTW

Walter Schwarz BKG electronic engineer RTW,

WVR

Reinhard Zeitlhofler  ̈ FESG electronic engineer RTW

Armin Boer  ̈ BKG electronic engineer Infrastruct.,

RTW

Jan Kodet FESG appl. phys. engineer DFG FOR1503

GNSS, time ref.

Katharina Kirschbauer FESG student Development

monitoring

Gordon Klingl FESG/ student Operator

BKG RTW/SLR

Yvonne Klingl FESG/ student Operator

BKG RTW/SLR

Matthias Kronschnabl FESG student Development

TWIN

Julia Weber FESG/ student Operator

BKG RTW/SLR

tions, unattended observations are not done until additional safety equipment is installed, such as wind sensors to move the antenna automatically into its stow position. Meanwhile, all data are transferred with e-VLBI

techniques (except VLBA-sessions together with Soccorro, New Mexico, USA). RTW now routinely uses

the Internet connection capacities of 1 Gbit/sec for the

e-Transfers with the Tsunami protocol to the correlators in Bonn, Tsukuba, Haystack, and Washington.

In addition to the standard sessions, RTW was active for other special observations such as the tracking of the ESA Venus Express (VEX) spacecraft, the

Mars Express (MEX) spacecraft, and the RadioAstron

satellite for the EVN. More progress was possible for

the tracking of Glonass and GPS satellites. Additional

developments of an L-band receiver and a permanent

satellite tracking mechanism enabled observations of

these GNSS satellites. GNSS observations could be

scheduled, commonly observed, correlated, and analyzed in cooperation with the Technical University in

Vienna, Austria and the observatory in Onsala, Sweden.

4 Technical Improvements and

Maintenance

Regularly, one maintenance day (obtaining replacements for the hardware, eight-pack repair, gear and

bearing maintenance, NASA Field System updates,

cryo-system maintenance, and repairs of the Mark IV

rack) was scheduled for the usual maintenance work

per month.

A new controller for the reflector heating was installed to enable the cleaning of the reflector from snow

and ice during the winter month (de-icing). The heating

rods had already been installed during the maintenance

IVS 2014 Annual Report
Wettzell - 20-m and Twin Radio Telescopes 139

Fig. 2 A panorama view of the observatory with the 20-m RTW on the right and the two TWIN telescopes in the back.

of the servo system in 2013. Additionally, one azimuth

and one elevation gear required a maintenance update

within the warranty period, because of an oil leakage

problem.

The existing dewar was replaced by a new one

to increase the maintenance intervals of the cryo system. The new dewar is an upgraded version of the replaced dewar. The upgrades were done at the IVS Centro de Desarrollos Tecnologicos de Yebes, Spain. The  ́

software for the dewar monitoring is also updated to

an Ethernet-based realization. The last month of 2014

showed that the pressure stability of the dewar is quite

good and keeps a pressure of lower than 10−8mbar,

which kept the temperature stable around 20K.

The NASA Field System is updated to the latest

available version, 9.11.6, to enable the DBBC connectivity. The upgrade of the station specific software

is still under progress. The goal is the homogenization with the TWIN control software. Additionally, the

Mark 5 systems were tested with the new “jive5ab”

from JIVE in Dwingeloo, The Netherlands. The software should become the basis for transfering the data

to the new TWIN control room in real-time while the

scans are recorded.

The usage of the new Digital Baseband Converters

(DBBC) was forced, so that the 20-m RTW is in principle DBBC-ready. Additionally a preferred solution

with the ADS3000+ from Japan was established and

tested (also in preparation for the O’Higgins upgrades).

Several test data were correlated at the Bonn Correlator to check functionality and quality (especially in

combination with the Twin operation tests). An additional correlator class was held in Wettzell by Alessandra Bertarini from the Bonn Correlator, to enable quality checks and analysis of local baselines with its own

correlator-PC (with four (plus four virtual) CPU-cores)

with a DiFX installation.

The remote control software “e-RemoteCtrl” was

also extended, mainly by the TUM. New features were

established in close cooperation with the developers

of the NASA Field System and with other test sites

at Australia (e.g. Hobart, Katherine, and Yarragadee).

The AuScope network and the Wettzell site already use

the software routinely. Therefore, a development and

research stay was paid by AuScope to extend the software with required utilities in November 2014.

Another new field is the preparation for tracking of

global navigation satellites. Therefore, new amplifier

and receiver boards were permanently installed. These

can be used after the waveguides for S-band to receive

the L-band of the satellite. Test experiments were operated together with the TU Vienna, Austria and the

Onsala Observatory, Sweden.

Because of new safety regulations, maintenance

manuals were established, and risk assessments were

started. A main focus is the reestablishment of the

unattended observations, which were limited. Therefore Vertex realized additional safety features, such as

oscillation detection and a minimum safety elevation.

Additionally, the system monitoring software SysMon

IVS 2014 Annual Report
140 Neidhardt et al.

was extended with additional features to support the

monitoring tool Zabbix. This should enable a realization of a general system status display during unattended observations.

According to the experiences from the AuScope

network, the saving of all documents, introductions,

and manuals in a central, digital document archive has

now begun.

5 The TWIN Radio Telescope Wettzell

(TTW)

The Twin Telescope Wettzell project is Wettzell’s realization of a complete VGOS conformity. The mechanical system is completely functional on both antennas. The controlling system was updated with the same

safety features as the 20-m RTW. The receiving and

the data acquisition systems for the northern antenna

(TTW1) is finished for first VGOS tests with S-/X-/Ka

setups. (There is only a cooling problem of one S-band

LNA in the receiver chain of the left-hand-circularpolarized signal; it will be exchanged after TTW2 is

operative.) The dewar and the cooler have been operating for over nine months now. The new control room is

completely set up to control both the Twin telescopes

and the old 20-m antenna.

The Twin telescope TTW1 (northern antenna, Wn)

started its operational test phase with regular Monday

INTENSIVE observations. These operational test sessions were performed together with the 20-m antenna,

using DBBCs and also a Japanese ADS3000+ system.

Approximately 190 observation hours were recorded

in 2014. The scans were correlated in Bonn and analyzed by the analysis group in Bonn and with separate

software in Wettzell. The X-band performance is excellent with an efficiency of over 80 percent at a system temperature of 30 K over the bandwidth of 6.4 to

9.6 GHz. The position repeatability after the analysis is

also quite good for X-band. S-band suffers from RFI,

so that it is not ideal for usage in the analysis. Filters

should reduce this problem. The Ka-band performance

was tested with a spectrum analyzer and a calibration

source and shows suitable results, which need to be

verified again after the new tri-band-receiver and updown converter hardware have been installed in 2015.

The broadband feed horn (Eleven feed) for the

second telescope TTW2 (south tower, Ws) arrived

in Wettzell and was tested here. The feed is built by

Omnisys in Goteborg, Sweden. It was finished in  ̈

August 2014 after some updates of the gold coating,

which originally led to worse system temperatures in

higher frequencies. In September 2014, the factory

approval in Sweden showed that the results of the test

measurements completely meet the specifications now.

After the feed was delivered to Wettzell, the system

temperatures could be verified, so that the shipment to

Mirad in Switzerland could be arranged. There it will

be tested again and mounted into the feed cone. The

already available feed patterns look quite promising.

But a mismatch in the conversion of the digital 3Ddrawings caused a mechanical misalignment between

feed mounting and cone. This error shifts the final

delivery in the timeline to a later date. It should then

be used with another broadband up-down-converter

rack in combination with a DBBC3 and a FILA10G

connection to a Mark 6 or a FlexBuf-system.

In the meantime the permanent survey of the reference point of the TTW2 was continued using total stations on different pillars and 20 to 30 reflectors in the

back structure of the antenna. The goal is a continuous

monitoring of the reference point over one year.

6 Future Plans

Dedicated plans for 2015 are:

• Update of the safety conformity papers for the 20-

m RTW,

• Complete change to the new digital baseband converters for the 20-m RTW,

• Establishment of first real broadband experiments

with S/X/Ka with TTW1,

• Development of a new receiver and system monitoring software for TTW2, and

• Installation of the Elevenfeed at TTW2 and first test

observations.

IVS 2014 Annual Report
Instituto Geografico Nacional of Spain  ́

Jesus G  ́ omez-Gonz  ́ alez  ́

1

, Francisco Colomer 1, Jose Antonio L  ́ opez-Fern  ́ andez  ́

2

, Luis Santos 3, Pablo de

Vicente 2

Abstract The National Geographic Institute (IGN) of

Spain has been involved in space geodesy activities

since 1995. The 40-m radio telescope at Yebes Observatory has been a network station for IVS since 2008

and participates regularly in IVS campaigns. IGN is

developing an Atlantic Network of Geodynamical and

Space Stations (project RAEGE). The first antenna saw

its first light in 2014 at Yebes Observatory. The construction of a second antenna of RAEGE (in Santa

Maria, Azores islands, Portugal) is complete, and commissioning is ongoing. Since March 2014, IGN Yebes

Observatory has been a Technology Development Center for IVS; therefore many such developments are being described in the appropriate report in this Annual

Report.

1 General Information

The National Geographic Institute of Spain (Instituto

Geografico Nacional, Ministerio de Fomento), has run  ́

geodetic VLBI programs at Yebes Observatory since

1995 and nowadays operates a 40-m radio telescope

which is a network station for IVS. Yebes Observatory

is also the reference station for the Spanish GNSS network and holds permanent facilities for gravimetry. A

new VGOS-type antenna has been built at Yebes as part

of the RAEGE project (the acronym RAEGE stands

1. Instituto Geografico Nacional (IGN)  ́

2. IGN Yebes Observatory

3. Secretaria Regional da Ciencia, Tecnologia e Equipamentos ˆ

(Azores, Portugal)

IGN-Yebes Network Station

IVS 2014 Annual Report

for “Red Atlantica hispano-portuguesa de Estaciones  ́

Geodinamicas y Espaciales”).  ́

Since 2014, IGN Yebes Observatory has been a

Technology Development Center for IVS. Activities

are described in the corresponding report in this Annual Report.

2 Current Status and Activities

In 2014, the 40-m radio telescope has participated in 53

sessions (17 R1, 15 R4, two T2, and two EUROPE, two

RD, and 15 in CONT14). All the data is being routinely

transferred by Internet to the IVS correlators.

2.1 RAEGE

IGN, together with Portuguese colleagues in DSCIG

(Azores Islands), continues the construction of a

network of four new Fundamental Geodynamical and

Space Stations. The RAEGE project was described in

previous IVS Annual Reports. The Spanish-Portuguese

VGOS network RAEGE will cover three continental

plates, with sites in Spain at Yebes (Eurasian Plate)

and Tenerife (African Plate), and in Portugal on the

Azorean islands of Santa Maria (Eurasian Plate) and

Flores (North American Plate).

First interferometric fringes of the RAEGE “Jorge

Juan” radio telescope were obtained on November 26,

2014, in an observation together with the 40-m radio

telescope at Yebes at X–band (see Figure 1).

The construction of a second antenna, in Santa

Mar ́ıa (Azores), is complete, and commissioning is

141
142 Gomez-Gonz  ́ alez et al.  ́

Fig. 1 First fringes of the RAEGE “Jorge Juan” radio telescope, obtained with the 40-m telescope also at Yebes Observatory.

ongoing. Also the construction of a control building is very advanced (see Figure 2). The officialinauguration is scheduled on May 20, 2015, as a

follow up of the 22nd meeting of the European VLBI

IVS 2014 Annual Report
IGN - Yebes Station Report 143

Table 1 Staff in the IGN VLBI group (e-mail: vlbitech@oan.es).

Name Background Role Address∗

Francisco Colomer Astronomer VLBI Project coordinator IGN, Yebes

Jesus G  ́ omez–Gonz  ́ alez  ́ Astronomer Deputy Director for IGN

Astronomy, Geophysics, and Space Applications

Jose Antonio L  ́ opez–Fdez  ́ Engineer RAEGE Director Yebes

Pablo de Vicente Astronomer VLBI technical coordinator Yebes

Jose Antonio L  ́ opez–P  ́ erez  ́ Engineer Receivers Yebes

Felix Tercero  ́ Engineer Antennas Yebes

Susana Garc ́ıa–Espada* Engineer geoVLBI expert Yebes

Javier Lopez–Ramasco  ́ Geodesist Geodesist Yebes

* At Azores since November 2014.

Group for Astrometry and Geodesy (EVGA, see

http://evga2015.raege.net/).

Detailed information on RAEGE is available on the

Web at http://www.raege.net/

2.2 Local Tie

A network of 24 monuments (concrete pillars) have

been built in 2014 in the area of Yebes Observatory

in order to relate the measurements taken by our two

VLBI radio telescopes (40-m and 13-m) and two

GNSS antennas (IGS code “YEBE”, on the roof of

the office building, and “YEB1”, on the roof of the

gravimeter building).

We have also investigated the possibility to measure the invariant reference point (IRP) of the 13-m radio telescope with a robotic total station, installed on

the central pillar of the concrete tower. A tripod with

an optical plummet is placed on the marked centered

screw of the pillar. Then it is possible to measure the

position of a corner cube reflector with a manufacturing precision of 0.0001 mm, which is attached magnetically to the inner sides of both antenna counterweights

(see Figure 3). Measures of the reflector (CCR) can

be taken every 30 seconds for both counterweights by

moving the antenna around the elevation and azimuth

axis. This operation can be done even when a regular

VLBI session is occurring.

A detailed description, measured values, and modeling results are shown in the proceedings of the 8th

IVS General Meeting (Gomez–Gonz  ́ alez et al., Shang-  ́

hai 2014).

3 IGN Staff Working on VLBI Projects

Table 1 lists the IGN staff who are involved in space

geodesy studies and operations. The VLBI activities

are also supported by other staff members such as receiver engineers, computer managers, telescope operators, secretaries, and students.

4 Future Plans

In order to comply with the VGOS specifications, a

new broadband receiver is being developed at Yebes

and should be available for observations in 2015. See

the report of the IGN Yebes Observatory Technology

Development Center for details. We look forward to

participating in the early VGOS tests starting in 2015

with the new RAEGE 13.2-m “Jorge Juan” antenna.

The infrastructure works for the RAEGE station

near the city of Tegueste (Tenerife, Canary Islands) will

be deployed in 2015, followed by the erection of the

antenna, built by MT Mechatronics GmbH.

Regarding the RAEGE station in Santa Mar ́ıa, the

official inauguration is scheduled on May 20, 2015 during the events of the EVGA meeting. Commissioning

will be performed for an expected start of observations

in 2016.

Preliminary work in Flores is being conducted to

characterize the presence of radio frequency interference at the selected site for the RAEGE station there.

IVS 2014 Annual Report
144 Gomez-Gonz  ́ alez et al.  ́

Fig. 2 Status of construction of the control building at the RAEGE station in Santa Mar ́ıa (Azores).

Fig. 3 Left: Vertex monument in Yebes. Middle: Reflector RRR attached magnetically to the inner side of one counterweight. Right:

Robotic Total Station Leica TS-30 set up above the central pillar.

IVS 2014 Annual Report
Zelenchukskaya Radio Astronomical Observatory 2014 IVS

Annual Report

Sergey Smolentsev, Andrei Dyakov, Dmitry Ivanov

Abstract This report summarizes information on activities at the Zelenchukskaya Radio Astronomical Observatory in 2014. The report provides an overview of

current geodetic VLBI activities and gives an outlook

for the next year.

1 General Information

Zelenchukskaya Radio Astronomical Observatory

(Figure 1) was founded by the Institute of Applied

Astronomy (IAA) as one of three stations of the

Russian VLBI network QUASAR. The sponsoring

organization of the project is the Russian Academy

of Sciences (RAS). The Zelenchukskaya Radio

Astronomical Observatory is situated in KarachaevoCherkesskaya Republic (the North Caucasus) about

70 km south of Cherkessk, near Zelenchukskaya

village (Table 1). The geographic location of the

observatory is shown on the IAA RAS Web site:

http://www.ipa.nw.ru/PAGE/rusipa.htm. The basic

instruments of the observatory are a 32-m radio

telescope equipped with special technical systems

for VLBI observations and a 13.2-m VGOS antenna.

The observatory is also equipped with co-location

instruments such as GPS/GLONASS/Galileo receivers

and an SLR system. In 2014 a WVR was installed.

Institute of Applied Astronomy of RAS

Network Station Zelenchukskaya

IVS 2014 Annual Report

Table 1 Zelenchukskaya Observatory location and address.

Longitude 41◦34′

Latitude 43◦47′

Karachaevo-Cherkesskaya Republic

369140, Russia

ipazel@mail.svkchr.ru

2 Technical Staff

Table 2 Staff related to VLBI operations at Zelenchukskaya.

Andrei Dyakov observatory chief

Dmitry Dzuba FS, pointing system control

Anatoly Mishurinsky front end and receiver support

Andrey Mikhailov FS, pointing system control

3 Component Description

3.1 Technical and Scientific Information

Characteristics of RT-32 are presented in Table 3.

3.2 Co-location of VLBI, GPS/GLONASS

and SLR System

The Javad GPS/GLONASS/Galileo receiver with

meteo station WXT-510 is in operation (Figure 2).

During 2014 “Sazhen-TM” SLR system at Zelenchukskaya observatory observed 1,767 passes of LAGEOS,

145
146 Smolentsev et al.

Fig. 1 Zelenchukskaya observatory.

Table 3 Technical parameters of the radio telescope.

Year of construction 2005

Mount AZEL

Azimuth range ±270◦(from south)

Elevation range from −5

◦

to 95◦

Maximum azimuth

- velocity 0.83 ◦/s

- tracking velocity 2.5

′

/s

- acceleration 12.0

′

/s

2

Maximum elevation

- velocity 0.5

◦

/s

- tracking velocity 0.8

′

/s

- acceleration 12.0

′

/s

2

Pointing accuracy better than 10′′

Configuration Cassegrain (with

asymmetrical subreflector)

Main reflector diameter 32 m

Subreflector diameter 4 m

Focal length 11.4 m

Main reflector shape quasi-paraboloid

Subreflector shape quasi-hyperboloid

Main reflector surface accuracy ± 0.5 mm

Frequency range 1.4–22 GHz

Axis offset 3.7±2.0 mm

GLONASS, and other satellites and obtained 8,768

normal points. The technical parameters of the system

are presented in Table 3.

Fig. 2 Javad GPS/GLONASS/Galileo receiver at the Zelenchukskaya observatory.

In 2014 a WVR was installed at Zelenchukskaya,

and it successfully works.

IVS 2014 Annual Report
Zelenchukskaya IVS Annual Report 147

Fig. 3 “Sazhen-TM” SLR system at Zelenchukskaya observatory.

4 Current Status and Activities during

2014

Zelenchukskaya observatory participates in IVS and

domestic VLBI observational programs. During 2014

Zelenchukskaya station participated in 50 24-hour IVS

sessions — 25 IVS-R4 sessions, three IVS-T2 sessions,

two EUROPE, five R&D, and 15 IVS-CONT sessions.

Zelenchukskaya participated in 48 24-hour sessions

in the framework of the domestic Ru-E program for

determination of all Earth orientation parameters and

in 364 one-hour Ru-U sessions for obtaining Universal Time using e-VLBI real time data transfer. e-VLBI

data transfer is used for Zelenchukskaya observational

data for the Ru-E 24-hour sessions, too.

Mounting of the 13.2-m antenna on its pedestal

(Figure 4) is finished.

In 2014 a WVR was installed and successfully

worked (Figure 5).

5 Future Plans

Our plans for the coming year are the following:

• To participate in IVS sessions,

• To carry out domestic observational programs for

obtaining Universal Time daily and for obtaining

Earth orientation parameters weekly with e-VLBI

data transfer,

Fig. 4 13.2 m at Zelenchukskaya observatory.

Fig. 5 WVR at Zelenchukskaya observatory.

• To carry out SLR observations of geodetic and navigation satellites,

• To participate in EVN and RADIOASTRON observational sessions,

• To continue geodetic monitoring of the RT-32 parameters,

• To perform regular WVR observations,

• To install receiver and other equipment of RT-13

and commission RT-13 in 2015.

References

1. Finkelstein A., Ipatov A., Smolentsev S. The Network

“Quasar”: 2008-2011 // “Measuring the future”, Proc. of the

Fifth IVS General Meeting, A. Finkelstein, D. Behrend (eds.),

St. Petersburg, “Nauka”, 2008. pp. 39–46.

IVS 2014 Annual Report

Operation Centers

Bonn Geodetic VLBI Operation Center

A. Muskens, A. Nothnagel  ̈

Abstract The IGGB Operation Center has continued to

carry out its tasks of organizing and scheduling various

observing sessions of the IVS-T2, IVS-OHIG, IVSINT3, and EUROPE series.

1 Center Activities

The IGGB VLBI Operation Center is part of the Institute of Geodesy and Geoinformation of the University

of Bonn, Nußallee 17, D-53115 Bonn, Germany. It has

been organizing and scheduling VLBI observing sessions for more than thirty years. The work of the Operation Center is closely related to the Bonn Correlator. For this reason, distribution of media (Mark 5 disk

units) to the stations after correlation is still the most

costly part of the operations since network capacity has

remained constant at 1 Gb/s for financial reasons.

• IVS-T2 Series

This series has been observed roughly every second

month (seven sessions in 2014) primarily for maintenance and stabilization of the VLBI terrestrial reference frame as well as for Earth rotation monitoring as a by-product. Each station of the global

geodetic VLBI network is planned to participate in

the T2 sessions at least once per year. In view of

the limitations in station days, priority was given

to strong and robust networks with many sites over

more observing sessions. Therefore, generally 15 to

Institut fur Geod  ̈ asie und Geoinformation der Universit  ̈ at Bonn  ̈

Bonn Operation Center

IVS 2014 Annual Report

21 stations have been scheduled in each session in

2014.

By the way, on November 11, 2014, the 100th T2

was scheduled and observed. Figure 1 shows the

increase in number of participating telescopes over

the years. The scheduling of these sessions has to

take into account that a sufficient number of observations is planned for each baseline of these

global networks. The recording frequency setup is

16 channels and 4 MHz channel bandwidth.

Fig. 1 Number of stations in T2 sessions since 2002.

• Measurement of Vertical Crustal Motion in

Europe by VLBI (EUROPE)

Since the late 1980s, a series of special sessions

has been regularly scheduled in Europe for precise

determination of station coordinates and for long

term stability monitoring. This year, six network

observing sessions with Ny-Alesund (six sessions),  ̊

Metsahovi (three), DSS65a (four), Svetloe (two),  ̈

151
152 Muskens and Nothnagel  ̈

Zelenchukskaya (two), Badary (two), Effelsberg

(one), Wettzell (six), Simeiz (three), Medicina

(two), Matera (one), Noto (three), and Yebes

(YEBES40M) (two) were scheduled employing

the frequency setup of 16 channels and 4 MHz

bandwidth (identical to the setup of the IVS-T2

sessions).

• Southern Hemisphere and Antarctica Series

(OHIG):

In February 2014, three sessions of the Southern Hemisphere and Antarctica Series with the

Antarctic stations Syowa (Japanese), Katherine

(North Australia), Yarragadee (West Australia),

TIGO (Concepcion), Warkworth (New Zealand),  ́

Hobart12 (Tasmania), HartRAO12 (South Africa),

Kokee, and Fortaleza have been organized.

O’Higgins (Germany) was omitted due to special

technical receiver and dewar upgrades. The (southern) winter O’Higgins burst (OHIG91-93) was

scheduled with all of the stations named above,

but it had to be observed without O’Higgins for

the same reason. The purpose of these sessions is

the maintenance of the VLBI terrestrial reference

frame (TRF) and monitoring of Earth rotation

as a by-product. The recording frequency setup

is 16 channels and 4 MHz channel bandwidth.

Due to the fact that Syowa is not able to deliver

the recorded data for nearly one year after the

observations, the correlation and the generation of

the databases is always delayed considerably.

• UT1 determination with near-real-time e-VLBI

(INT3):

The so-called INT3 sessions were originally set up

for the telescopes of Ny-Alesund, Tsukuba, and  ̊

Wettzell for weekly UT1 determinations aiming at

very quick delivery of results. The sessions are always scheduled to start on Monday morning at

7:00 a.m. UT. From the beginning of 2014 Seshan

has taken part in the INT3 sessions on a monthly

basis. The operations part of the INT3 sessions

also includes rapid data transmission and correlation. The raw VLBI observation data of four sites

is transferred to the Bonn Correlator by Internet

connections directly after the session is completed

to speed up delivery of the results. The transmission rate is about 400-600 Mb/s from Tsukuba and

Wettzell, 300 Mb/s from Seshan, and 100 Mb/s for

Ny-Alesund. For the latter, the data rate is limited  ̊

due to the use of a radio link for the first part of

the distance. All transmissions share the “last mile”

which is limited to 1 Gb/s due to financial limitations.

Altogether, 47 INT3 sessions were observed and

transmitted successfully in 2014. 96% of the sessions were correlated and the databases delivered

within the first four hours after the end of the observations. A further 2% were completed within the

next 48 hours due to difficulties with networking

hardware and/or station and processor problems.

2 Staff

Table 1 Personnel at IGGB Operation Center.

Arno Muskens  ̈ +49-228-525264 mueskens@mpifr.de

Axel Nothnagel +49-228-733574 nothnagel@uni-bonn.de

IVS 2014 Annual Report
CORE Operation Center 2014 Annual Report

Cynthia C. Thomas, Daniel S. MacMillan

Abstract This report gives a synopsis of the activities

of the CORE Operation Center from January 2014 to

December 2014. The report forecasts activities planned

for the year 2015.

1 Changes to the CORE Operation

Center’s Program

The Earth orientation parameter goal of the IVS program is to attain precision at least as good as 3.5 μs for

UT1 and 100 μas for pole position.

The IVS program, which started in 2002, used the

Mark IV recording mode for each session. The IVS

program began using the Mark 5 recording mode in

mid-2003. By the end of 2007, all stations were upgraded to Mark 5. Due to the efficient Mark 5 correlator, the program continues to be dependent on station

time and media. The following are the network configurations for the sessions for which the CORE Operation Center was responsible in 2014:

• IVS-R1: 49 sessions, scheduled weekly and mainly

on Mondays, six to 13 station networks

• RDV: Six sessions, scheduled evenly throughout

the year, 14 to 16 station networks

• IVS-R&D: 12 sessions, scheduled monthly, six to

14 station networks

• CONT14: 15 sessions, scheduled continuously during a two week period, 17 station networks

NVI, Inc.

CORE Operation Center

IVS 2014 Annual Report

2 IVS Sessions from January 2014 to

December 2014

This section describes the purpose of the IVS sessions

for which the CORE Operation Center is responsible.

• IVS-R1: In 2014, the IVS-R1s were scheduled

weekly with six to 13 station networks. During

the year, 20 different stations participated in

the IVS-R1 network, but there were only eight

stations that participated in at least half of the

scheduled sessions—Wettzell (49), Tsukuba (44),

Ny-Alesund (43), Fortaleza (37), Hart15m (36),  ̊

Hobart12 (31), Yarragadee (30), and Katherine

(29). Sejong and Tianma65 participated in the

IVS-R1 sessions for the first time during 2014.

The purpose of the IVS-R1 sessions is to provide

weekly EOP results on a timely basis. These sessions provide continuity with the previous CORE

series. The “R” stands for rapid turnaround because

the stations, correlators, and analysts have a commitment to make the time delay from the end of

data recording to the analysis results as short as

possible. The time delay goal is a maximum of 15

days from the end of data recording to the end of

correlation. Sixty-two percent of the IVS-R1 sessions were completed in 15 or fewer days. The remaining 38% were completed in 16 to 42 days [16

days (five), 17 days (four), 22 days (two), 23 days

(one), 26 days (one), 27 days (three), 28 days (one),

and 42 days (one)]. Participating stations are requested to ship disks to the correlator as rapidly as

possible or to transfer the data electronically to the

correlator using e-VLBI. The “1” indicates that the

sessions are mainly on Mondays.

153
154 Thomas and MacMillan

• RDV: There are six bi-monthly coordinated astrometric/geodetic experiments each year that use the

full ten-station VLBA plus up to six geodetic stations.

These sessions are being coordinated by the geodetic VLBI programs of three agencies: 1. USNO performs repeated imaging and correction for source

structure; 2. NASA analyzes this data to determine

a high accuracy terrestrial reference frame, and 3.

NRAO uses these sessions to provide a service to

users who require high quality positions for a small

number of sources. NASA (the CORE Operation

Center) prepares the schedules for the RDV sessions.

• R&D: The purpose of the twelve R&D sessions in

2014, as decided by the IVS Observing Program

Committee, was to test the 512 Mbps recording mode for the CONT14 Campaign (RD1401

and RD1402); vet sources for GAIA proposal

(RD1403, RD1404, RD1406, RD1408, RD1410,

and RD1412), and observe the Chang’E-3 Lander

with VLBI (RD1405, RD1407, RD1409, and

RD1411). Two extra R&Ds were added during

2014 to support the four requested Chang’E-3

Lander sessions.

3 Current Analysis of the CORE Operation

Center’s IVS Sessions

Table 1 provides the average formal errors for the R1,

R4, RDV, and CONT14 sessions from 2014. The R1

session formal uncertainties are not significantly different from the 2012-2013 errors. The R1 and R4 polar

motion and nutation uncertainties for 2014 sessions are

10-20% better than for 2012-2013. R1 and R4 UT1 uncertainties were comparable to those in 2012-2013. R1

uncertainties could be further reduced if we used a GPS

a priori model to obtain the post-earthquake behavior

at Tsukuba or if we estimated global spline parameters

for the post-seismic displacement at Tsukuba instead

of estimating the TSUKUB32 position for each session

after the earthquake, thereby weakening its contribution to EOP.

It is not clear why RDV polar motion uncertainties

are about 10% larger for 2014 than 2013. The RDV

formal errors are not significantly different than for R1

and R4 experiments. This is due to the increasing number of stations in R1 and R4 sessions as well as better

global geometry. For comparison, we also included the

formal uncertainties for the CONT11 and CONT14,

which are much better than for any of the networks discussed above that observed in 2014.

Table 2 shows EOP differences with respect to

the IGS series for the R1, R4, RDV, CONT11, and

CONT14 series. The WRMS differences were computed after removing a bias, but estimating rates does

not affect the residual WRMS significantly. Both the

R1 and R4 series for 2014 have better WRMS agreement in X-pole, Y-pole, and LOD for 2014 than for the

corresponding full series from 2000 to 2014. Adopting

the improved GPS a priori model strategy mentioned

above improves the R1 agreement with IGS by 20%.

The X-pole and Y-pole biases of the R1 and R4 sessions relative to IGS are significant and are likely due

to reference frame bias. In 2014, there appear to be

some performance issues regarding the RDV sessions

given that the WRMS agreement for polar motion and

LOD are significantly worse than for the full period

of observing since 2000. Over that full period 2000-

2014, the RDVs have the best agreement with IGS of

all the series. For comparison with the 2014 operational

sessions discussed here, we included the statistics for

both the CONT11 and CONT14 sessions, which have

the best WRMS agreement with IGS most likely because the CONT networks were unchanged over the respective periods of continuous observing. The X-Pole

agreement with IGS for CONT14 is significantly better than for CONT11. This is expected because the

CONT14 network has better geometry than CONT11.

4 The CORE Operations Staff

Table 3 lists the key technical personnel and their responsibilities so that everyone reading this report will

know whom to contact about their particular question.

5 Planned Activities during 2015

The CORE Operation Center will continue to be responsible for the following IVS sessions during 2015:

• The IVS-R1 sessions will be observed weekly and

recorded in Mark 5 mode.

IVS 2014 Annual Report
CORE Operation Center Report 155

• The IVS-R&D sessions will be observed ten times

during the year.

• The RDV sessions will be observed six times during the year.

IVS 2014 Annual Report
156 Thomas and MacMillan

Table 1 Average EOP Formal Uncertainties for 2014.

Session Num X-pole Y-pole UT1 DPSI DEPS

Type (μas) (μas) (μs) (μas) (μas)

R1 49 60(67,73) 55(66,63) 3.2(3.1,3.4) 86(105,110) 33(42,44)

R4 51 59(68,70) 57(66,67) 2.7(2.9,2.8) 112(120,124) 45(49,49)

RDV 6 59(54,48) 57(54,48) 2.7(2.8,2.5) 82(82,68) 34(33,28)

CONT11 15 38 37 1.7 42 17

CONT14 15 40 41 1.8 41 14

Values in parentheses are for 2013 and then 2012.

Table 2 Offset and WRMS Differences (2014) Relative to the IGS Combined Series.

X-pole Y-pole LOD

Session Type Num Offset WRMS Offset WRMS Offset WRMS

(μas) (μas) (μas) (μas) (μs/d) (μs/d)

R1 49(664) -45(15) 84(93) 55(47) 86(87) 3.4(1.3) 15(17)

R4 51(656) 7(-7) 73(106) 63(50) 82(108) 2.9(1.9) 13(17)

RDV 6(90) 40(60) 91(83) 58(46) 78(69) 5.3(0.1) 19(14)

CONT11 15 43 35 27 30 6.5 6

CONT14 15 10 25 89 33 1.0 5

Values in parentheses are for the entire series (since 2000) for each session type.

Table 3 Key Technical Staff of the CORE Operations Center.

Name Responsibility Agency

Dirk Behrend Organizer of CORE program NVI, Inc./GSFC

Brian Corey Analysis Haystack

Ricky Figueroa Receiver maintenance ITT Exelis

John Gipson SKED program support and development NVI, Inc./GSFC

Frank Gomez Software engineer for the Web site Raytheon/GSFC

David Gordon Analysis NVI, Inc./GSFC

Ed Himwich Network Coordinator NVI, Inc./GSFC

Dan MacMillan Analysis NVI, Inc./GSFC

Katie Pazamickas Maser maintenance ITT Exelis

David Rubincam Procurement of materials necessary for CORE operations GSFC/NASA

Braulio Sanchez Procurement of materials necessary for CORE operations GSFC/NASA

Dan Smythe Tape recorder maintenance Haystack

Cynthia Thomas Coordination of master observing schedule and preparation of

observing schedules

NVI, Inc./GSFC

IVS 2014 Annual Report
NEOS Operation Center

David M. Hall, Merri Sue Carter

Abstract This report covers the activities of the NEOS

Operation Center at USNO for 2014. The Operation

Center schedules IVS-R4 and the INT1 Intensive experiments.

1 VLBI Operations

NEOS operations in the period covered consisted,

each week, of one 24-hour duration IVS-R4 observing

session, on Thursday-Friday, for Earth Orientation,

together with five daily one-hour duration “Intensives”

for UT1 determination, Monday through Friday.

In 2014, the operational IVS-R4 network included

VLBI stations at Kokee Park (Hawaii), Wettzell

(Germany), Ny-Alesund (Norway), TIGO (Chile),  ̊

Fortaleza (Brazil), Tsukuba (Japan), Svetloe, Badary

and Zelenchukskaya (Russia), Hobart, Katherine and

Yarragadee (Australia), Yebes (Spain), and Matera and

Medicina (Italy). A typical R4 consisted of eight to 12

stations.

The regular stations for the weekday IVS Intensives were Kokee Park and Wettzell. Intensives including Kokee Park, Wettzell, and Svetloe were occasionally scheduled in order to characterize the Kokee Park

— Svetloe baseline so that Svetloe can be used as an

alternate for Wettzell should it be needed. Odd-day Intensives were scheduled with the scheduling technique

used since 2000; even-day Intensives were scheduled

with a newer, experimental scheduling technique.

U.S. Naval Observatory

NEOS Operation Center at USNO

IVS 2014 Annual Report

The Operation Center updated the version of sked

as updates became available.

All sessions are correlated at the Washington Correlator, which is located at USNO and is run by NEOS.

Table 1 Experiments scheduled during 2014.

52 IVS-R4 experiments

222 Intensives

2 Staff

D. M. Hall and M. S. Carter are the only staff members of the NEOS Operation Center. Mr. Hall is responsible for the overall management, and Carter makes

the schedules. M. S. Carter is located at the USNO

Flagstaff Station (NOFS).

157

Correlators

The Bonn Astro/Geo Correlator

Simone Bernhart 1, Walter Alef 2, Alessandra Bertarini 1,2, Gabriele Bruni 2, Laura La Porta 1, Arno Muskens  ̈

1

,

Helge Rottmann 2, Alan Roy 2, Gino Tuccari 2,3

Abstract The Bonn Distributed FX (DiFX) correlator

is a software correlator operated jointly by the MaxPlanck-Institut fur Radioastronomie (MPIfR), the In-  ̈

stitut fur Geod  ̈ asie und Geoinformation der Universit  ̈ at ̈

Bonn (IGG), and the Bundesamt fur Kartographie und  ̈

Geodasie (BKG) in Frankfurt, Germany.  ̈

1 Introduction

The Bonn correlator is hosted at the MPIfR1 VLBI correlator center in Bonn, Germany. It is operated jointly

by the MPIfR and the BKG2in cooperation with the

IGG3. It is a major correlator for geodetic observations

and astronomical projects such as VLBI at millimeter

wavelengths, astrometry, RadioAstron4 VLBI observations, and pulsar VLBI.

1. Institut fur Geod  ̈ asie und Geoinformation der Universit  ̈ at ̈

Bonn

2. Max-Planck-Institut fur Radioastronomie  ̈

3. Istituto di Radioastronomia - INAF

Bonn Correlator

IVS 2014 Annual Report

1 http://www.mpifr-bonn.mpg.de/

2 http://www.bkg.bund.de/

3 http://www.gib.uni-bonn.de/

4 http://www.asc.rssi.ru/radioastron/

2 Present Correlator Capabilities

The DiFX correlator5 was developed at Swinburne

University in Melbourne by Adam Deller and other

collaborators. It was adapted to the VLBA operational

environment by Walter Brisken and the NRAO staff,

and it is constantly updated by the worldwide DiFX

developer group. In Bonn, the DiFX is running on a

High Performance Compute Cluster (HPC cluster).

Its technical specifications can be gathered from last

year’s annual report.

In preparation for the CONT14 correlation in

spring/summer 2014, the Software Development

Kit (SDK) of all 14 Mark 5 units was upgraded to

version 9.3a.

Furthermore, in autumn the storage capacity was

enlarged by an additional geodetc RAID to a total of

about 610 TiB.

3 Staff

The people in the Geodesy VLBI group at the Bonn

correlator are:

Arno Muskens  ̈ - group leader and scheduler of T2,

OHIG, EURO, and INT3 sessions.

Simone Bernhart - support scientist, e-transfer supervision and operations, experiment setup and evaluation

of correlated data for geodesy, media shipping, and

Web site maintenance.

Alessandra Bertarini - Friend of the correlator,

experiment setup and evaluation of correlated data for

5 DiFX: A Software Correlator for Very Long Baseline Interferometry using Multiprocessor Computing Environments, 2007,

PASP, 119, 318

161
162 Bernhart et al.

both astronomy (e.g. APEX) and geodesy, and digital

baseband converter (DBBC) testing.

Laura La Porta - support scientist, e-transfer supervision and operations, geodetic experiment setup and

evaluation of correlated data, and DBBC testing.

The people in the astronomical group at the Bonn

correlator are:

Walter Alef - head of the VLBI technical department,

computer systems, and cluster administration.

Alan Roy - deputy group leader, support scientist

(water vapor radiometer, technical assistance, development of linear to circular polarization conversion

software for phased ALMA, and project manager for

equipping APEX for millimeter VLBI).

Gabriele Bruni - support scientist for RadioAstron,

experiment setup and evaluation of correlated data,

and e-transfer supervision and operations.

Armin Felke - FPGA programming for DBBC.

Heinz Fuchs - correlator operator, responsible for the

correlator operator schedule, daily operations, and

media shipping.

David Graham - consultant (technical development,

DBBC development, and testing).

Rolf Martens  ̈ - technician maintaining cluster hardware and Mark 5 playbacks.

Helge Rottmann - software engineer for correlator

development and operation, cluster administration,

developer for the ALMA Phasing Project, and Field

System.

Hermann Sturm - correlator operator, correlator

support software, media shipping, and Web page

development.

Gino Tuccari - guest scientist from INAF, DBBC

development, and DBBC project leader.

Michael Wunderlich - engineer, development and

testing of DBBC components.

4 Status

Experiments: In 2014 the Bonn group correlated 42

R1, six EURO, three T2, five OHIG, 47 INT3 experiments, and astronomical sessions (including 1 mm,

3 mm, RadioAstron and astrometric projects).

Moreover, the correlation of the 15 CONT14 observations was carried out in Bonn. The routine activities

of the Bonn correlator were suspended for about two

months to process the CONT14. All other data transfers to Bonn had been suspended during the CONT

campaign to allow the nine e-VLBI stations to transfer their data without interruption. A total of 192.5 TB

of data have been e-transferred to Bonn. Thanks to the

cooperation of the astronomy cluster users and in collaboration with the institute’s computer division, it was

possible to obtain a temporary buffer of 230 TB additional storage space for emergency cases (e.g., playback problems with disk packs) for the duration of the

processing.

e-VLBI: The total disk space available for geodetic etransfer data storage at the correlator is about 170 TB.

On average ≥ 90 % of the stations do e-transfer.

The average amount of e-transferred data per week

is about 10 TB, considering only the regular INT3

and R1 experiments. Most transfers are done using

the UDP-based Tsunami protocol, and the achieved

data rates range from 100 Mb/s to 800 Mb/s. The

upgrade of the 1 Gbps Internet connection to meet the

requirements of VLBI2010 Global Observing System

(VGOS) has not been realized yet — still due to

funding issues and apparently buereaucratic obstacles.

DiFX software correlator: The DiFX software

correlator has been operated in Bonn since 2009 and

is updated regularly. The stable DiFX release 2.3 was

installed in 2014. The Mark 5A/B/C control software

“jive5ab”, which was developed at the Joint Institute

for VLBI in Europe (JIVE), was installed on the

cluster and the Mark 5 units in preparation for future

more automated e-transfers. Jive5ab can be used as a

full replacement of MIT Haystack’s control programs

Mark 5A, DiMino, and drs. The installation on the

Mark 5 units was tested initially by copying data from

RAID onto modules in order to free up storage space

in preparation for the CONT14.

Two other branch versions of the DiFX software

correlator are available in Bonn: a DiFX version for

RFI mitigation, developed by J. Wagner, now at KASI,

and a DiFX version dedicated to RadioAstron, developed by J. Anderson, now at GFZ Potsdam.

DBBC: The Bonn group is involved in the development and testing of the DBBC VLBI backends and

ancillary parts (ex. FILA10G) for the European VLBI

Network (EVN) and geodesy. The DBBC2 is designed

as a full replacement for the existing VLBI terminals and includes additional features. Stations such as

for instance APEX, Pico Veleta, AuScope (Australia),

IVS 2014 Annual Report
The Bonn Correlator 163

HartRAO (Africa), and a large part of EVN have ordered one or more DBBC2s. The FILA10G, VLBI to

10GE interfaces have also been exported to Haystack

and Korean stations.

The next generation DBBC (DBBC3-L) is being

developed, and two prototypes are being integrated and

tested. The BBC3-L can handle a larger bandwidth of

4 GHz for each IF/polarization. A maximum of eight

IFs can be processed by a single DBBC3-L, so a dedicated variant of the modular system can also be used as

a complete VGOS backend at 32 or 64 Gbps, covering

the full RF range up to 16 GHz.

APEX: The Bonn VLBI group has equipped the APEX

telescope for VLBI observations at 1 mm. In 2013,

APEX conducted its first scientific observations by taking part in the Event Horizon Telescope (EHT) campaign. Observations were carried out at 4 Gbps, lasted

about 50 hours, and provided good detections for several sources including Sgr A* and M87.

In late 2014, upgrades were prepared and were

installed in January 2015: two Mark 6 recorders, a

temporary R2DBE on loan (2 GHz sampled bandwidth, 8 Gbps output), and a DBBC firmware upgrade for sampling 2x 1 GHz bandwidth (8 Gbps output) with 62.5 MHz-wide polyphase filter channels to

match ALMA. APEX was the partner station for firstfringe tests with the phased ALMA and the South Pole

Telescope in January 2015.

RadioAstron: Data from 13 global+RadioAstron experiments were transferred to Bonn until July 2014, the

end of the AO-1 observing period. Since January 2015,

two other experiments are being e-transferred to Bonn

for the AO-2 observations. The correlation of the three

key science projects based in Bonn is on-going, and six

experiments were finalized in 2014. Raw data are routinely transferred to ASC (Moscow) via the Internet or

HDD for backup purposes.

5 Outlook for 2015

DiFX Correlator: The present cluster used for correlation is now about seven years old. A proposal to the

Max Planck Society for a new cluster was awarded for

about 500 kAC and a new cluster with more than 1000

compute cores will be installed in the second quarter of

2015. Six full Mark 6 units (32 Gbps) have been procured for the correlator and will be mounted in racks

after refurbishment of the present location of the Mark

5 units.

DiFX for RadioAstron: Merging of the RadioAstron

DiFX branch version with the current trunk version of

the DiFX is ongoing.

e-VLBI: Another 80 TB RAID will be purchased for

geodetic e-transfers.

The jive5ab software will be tested for e-transfers,

as we are planning to cooperate with JIVE in developing an automatic e-VLBI data transfer controlled by

software at the correlator. In addition to enhanced computer security this will allow us to optimize the usage

of our Internet connection. This is absolutely essential

in cases where more than ten e-transfer stations take

part in the weekly R1 experiments and when observations will be performed with higher data rates in the

future.

DBBC: We will continue our support for the DBBC2 in

the field. New wide bandwidth modes for the DBBC2

are under test. The development work on the DBBC3

will continue, and new wideband modes will be implemented.

Phasing up ALMA: The group is involved in an international project to add array phasing capability to

ALMA. ALMA will record with a data rate of up to

64 Gbps, thus being an extremely sensitive station for

participation in VLBI experiments at the 3 mm and

1 mm wavelengths. The correlation of 3 mm data will

be done in Bonn. Correlation of 1 mm experiments will

be handled in a shared effort between Bonn and the

Haystack group.

The group made contributions in the phasing algorithm and in linear-to-circular polarization conversion.

The first VLBI fringe test experiment was observed

January 2015 on the baseline APEX-ALMA with up

to 40 antennas phased.

IVS 2014 Annual Report
Haystack Observatory VLBI Correlator

Mike Titus, Roger Cappallo, Brian Corey, Kevin Dudevoir, Arthur Niell, Jason SooHoo, Alan Whitney

Abstract This report summarizes the activities at the

Haystack Correlator during 2014. Highlights include

significant improvements in smoothing of operations

through testing for best performance, fixing of operational bugs or problems, and the addition of new machines. Many broadband tests were also conducted, and

the processing of the EHT March 2013 run continued,

along with testing to prepare for new EHT observations in March 2015. Non-real-time e-VLBI transfers

and DiFX and HOPS software support for other correlators continued.

1 Introduction

The DiFX VLBI correlator of the MIT Haystack Observatory, located in Westford, Massachusetts, is supported by the NASA Space Geodesy Program and the

National Science Foundation. It is dedicated mainly

to the pursuits of the IVS, with a smaller fraction of

time allocated to processing radio astronomy observations for the Event Horizon Telescope (EHT) project.

The Haystack correlator serves as a development system for testing new correlation modes, such as those

needed for the VGOS observations, and for recorder

developments, such as the Mark 6 system. Some software support is provided to similar DiFX installations

at the U.S. Naval Observatory, to the Max Planck Institute for Radioastronomy in Bonn, Germany, and to the

MIT Haystack Observatory

Haystack Correlator

IVS 2014 Annual Report

general IVS community for DiFX processing of IVS

experiments.

2 Summary of Activities

2.1 DiFX Cluster Developments

Another data server with 60 TB of storage space was

added to the available pool for storing incoming eVLBI-transferred data, raising the total to ∼200 TB.

Another compute server was added as well with the intention for it to become the master node. Over the last

year, equipment that was used exclusively by the Mark

IV was removed. Consolidation of Mark 5B Playback

units (PBUs) and re-arrangement of equipment in racks

has been an ongoing effort.

2.2 DiFX Production Improvements and

Fixes

Efficiency has greatly improved over the last year

through the smoothing of operations. This can be

attributed to software development, such as modifying

DiFX programs, e.g. ‘startdifx’, for more effective use

with Haystack’s particular installation, and studying

and optimizing maximum throughput methods given

our cluster setup. One example is distributing station

file data to separate file servers and playing back

some stations from modules in order to spread the I/O

load. As a result, the correlator runs with virtually no

backlog attributable to throughput limitations. Also,

some seriously debilitating bugs were identified and

164
Haystack Correlator 165

either fixed or patched around. Examples include

problems processing Mark 5B data from modules

(mark5bfix -1 problem discovered in DiFX version 2.3

and the trunk) and a problem with difx2fits handling

polarization data coming from the EHT processing.

2.3 Broadband Delay

Numerous tests have been performed. In April the first

test using RDBE firmware version 3.0 and complex

format data was conducted. It was a success. Following that were two GGAO phase calibration tests, then a

hiatus until October when an explosion of GGAO—

Westford broadband tests began. Tests in October—

November, which were designed to study different aspects of the broadband system, included setting all four

UDCs at both stations to the same frequency to see

how well the VLBI results compared between systems;

stepping the UDCs in frequency to measure fringe amplitudes over 2.2—11.5 GHz; varying the power level

into the RDBEs to test for level sensitivity in the VLBI

results; and observing 4C39.25 using the channel select

mode with minimum redundancy spacing and bands

spanning 3.0—10.7 GHz. Then finally, two one-hour

geodetic mode schedules were run using the setup described in the previous test. Mixed mode development

for experiment RD1301 also continued.

2.4 DBE Testing

Testing of RDBE firmware version 3.0 and complex/VDIF format occurred as mentioned above. This

configuration is now used in all broadband sessions. A

newly designed ROACH-2 digital back end (R2DBE)

and ancillary equipment, developed at the HarvardSmithsonian Center for Astrophysics for the EHT

project, were tested on the GGAO—Westford baseline

in September. These equipment tests produced good

fringes between the RDBE system recording 512

MHz of bandwidth vs. the R2DBE recording 2 GHz

bandwidth. The recordings were cross-correlated using

zoom mode in DiFX.

2.5 Mark 6

Another Mark 6 playback unit was added to the cluster, and use of Mark 6 has begun in the VGOS and

EHT projects. In particular, all VGOS tests since January 2014 have used the Mark 6 recording system, as

did the R2DBE tests described above.

2.6 Galactic Center Observations

Re-processing of the March 2013 EHT campaign on

DiFX continues in order to compare it with the Mark

IV correlator and to add the APEX station for which

fringes were found much later. Also 3 mm tests of

the LMT antenna and lab tests of R2DBEs and other

South Pole telescope equipment were conducted as

mentioned above.

2.7 Sejong Fringe Test

A fringe test was conducted using Hobart, Sheshan,

and Sejong in order to commission the new antenna at

Sejong, Korea, for routine IVS use. Results were good,

and Sejong now participates in regular IVS sessions.

2.8 DSS-13 DVP Data Decoding

JPL designed and observed with a new digital back

end, called the DVP, which recorded data in a different format than other DBE systems. DSS-13 used this

system in the T2 experiments. Extensive effort was put

into deciphering the setup of the station, which had

configuration problems, and as a result good fringes

were obtained.

2.9 DiFX Software Support

Support for the community continues for difx2mark4,

fourfit, and HOPS. This support includes addition of

features requested by users, other enhancements, and

bug fixes.

IVS 2014 Annual Report
166 Titus et al.

2.10 e-VLBI

Non-real-time transfers have continued. Data from

twenty sessions were transferred to Haystack this year

from twenty-six stations: eight in Japan (Kashima34,

Kashima11, Koganei, Tsukuba, Chichijima, Ishigaki,

Aira, and Mizusawa), one in central Asia (Badary),

eight in Europe (Simeiz, Svetloe, Zelenchukskaya,

Onsala, Ny-Alesund, Yebes, Wettzell, and Noto), three  ̊

in Australia (Hobart, Yarragadee, and Katherine), one

in New Zealand (Warkworth) two in South America

(Fortaleza and Concepcion (via Bonn)), two in South  ́

Africa (Hart15M and HartRAO) and one in Korea

(Sejong). The number of e-VLBI transfer stations

increased by six this year due to the addition of Yebes,

Sejong, Simeiz, Badary, Svetloe, and Zelenchukskaya.

3 Experiments Correlated

In 2014, thirty-seven geodetic VLBI sessions were

processed, at least in part, consisting of fourteen

R&Ds, six T2s, and seventeen tests of various types.

The test sessions included the broadband sessions

and fringe tests and an assortment of other projects,

some of which were touched on in the summary

above. As usual, smaller tests were not included in the

above count because they were too small to warrant

individual experiment numbers. All production and

test experiments were done on the DiFX cluster.

4 Current/Future Hardware and

Capabilities

The DiFX cluster currently consists of six PCs, each

with dual hex core 2.66 GHz Intel Xeon processors.

Three file storage servers, which can also act as DiFX

compute nodes, provide 200 TB of file storage. These

are all connected through a 40 Gb/sec infiniband network fabric using a Qlogic switch. Currently six Mark

5B and two Mark 6 playback units with DiFX fully installed are connected to the infiniband fabric. We have

processed up to 18 stations in one pass with this setup

through a combination of playback units and files.

A large expansion of hardware capability is imminent. The addition of 16 computer servers, 40GigE ethernet fabric and more Mark 6 PBUs is planned, with all

mentioned equipment either already in-house or their

purchases pending.

5 Staff

Staff who participated in aspects of Mark IV, DiFX,

Mark 5/6, and e-VLBI development and operations include:

5.1 Software Development Team

• Roger Cappallo - post processing; Mark 5B and 6;

correlator software integration and troubleshooting;

DiFX correlator development

• Geoff Crew - DiFX correlator development, post

processing software; Mark 6

• Kevin Dudevoir - correlation; maintenance/support; Mark 5A/5B/5C; e-VLBI; computer

system support/development; DiFX correlator development

• Jason SooHoo - e-VLBI; Mark 5A/5B/5C/6; computer system support

• Chester Ruszczyk - e-VLBI; Mark 5A/5B/5C/6

• Alan Whitney - system architecture; Mark

5A/5B/5C/6; e-VLBI

5.2 Operations Team

• Peter Bolis - correlator maintenance

• Alex Burns - playback drive maintenance; Mark

5/6 installation and maintenance; general technical

support

• Brian Corey - experiment correlation oversight; station evaluation; technique development

• Dave Fields - filling in for Alex Burns while he

takes a leave of absence at Ny-Alesund (previously  ̊

retired)

• Glenn Millson - correlator operator

• Arthur Niell - technique development

• Don Sousa - correlator operator; experiment setup;

tape library and shipping

IVS 2014 Annual Report
Haystack Correlator 167

• Mike Titus - correlator operations oversight; experiment setup; computer services; software and hardware testing

• Ken Wilson - correlator maintenance; playback

drive maintenance; general technical support

6 Conclusion/Outlook

A large expansion in compute servers and Mark 6

recorders is already underway. Broadband geodetic

sessions at more regular intervals will be scheduled

and processed in the near future and beyond that will

include the addition of the new Kokee 12-m antenna

with a new broadband system. EHT observations

in March 2015 will also be a large processing load.

Routine geodetic processing will continue as well.

IVS 2014 Annual Report
IAA Correlator Center 2014 Annual Report

Igor Surkis, Voytsekh Ken, Yana Kurdubova, Alexey Melnikov, Vladimir Mishin, Nadezda Mishina, Violet Shantyr,

Vladimir Zimovsky

Abstract The activities of the six-station IAA RAS

correlator include the regular processing of national

geodetic VLBI programs Ru-E, Ru-U (R-I), and RuF. The Ru-U (R-I) sessions have been transferred to the

IAA Correlator Center automatically in e-VLBI mode

and correlated there since 2011. The new six-station

FX correlator’s HPC was developed and mounted at

IAA.

1 Introduction

The IAA Correlator Center is situated at St.-

Petersburg, Russia and maintained by the Institute of

Applied Astronomy in Russia.

The main goal of the IAA Correlator Center is processing geodetic, astrometric, and astrophysical observations made with the Russian national VLBI network

Quasar.

2 Component Description

The ARC (Astrometric Radiointerferometric Correlator) (Figure 1) was the main data processing instrument

at the IAA Correlator Center in 2014. The ARC was

designed and built at the IAA RAS in 2007 - 2009. The

correlator is XF-type and is based on FPGA technology.

Institute of Applied Astronomy RAS

Institute of Applied Astronomy Correlator

IVS 2014 Annual Report

The ARC is a six-station 15-baseline correlator. It

is able to process up to 16 frequency channels on each

baseline for a total of 240 channels. The correlator is

able to handle two-bit VLBI signals with 32 MHz maximum clock frequency. The maximum data rate from

each station is 1 Gbit per second. The correlator uses

VSI-H input signals, and it is equipped with Mark 5B

playback systems.

Since 2011, the DiFX software correlator has been

used in some astrophysical experiments. DiFX is installed at the IAA on a Sun Fire X4450 Server as a

virtual machine under the VMware.

Since 2012 the six-station software FX VGOS

GPU-based near-real time correlator has been under

design. First fringes were obtained.

Fig. 1 View of the six-station ARC correlator, showing four

racks containing (left to right) signal distribution and synchronization system (SDSS) and three Mark 5B playback units, two

correlator crates and a KVM, three correlator crates, and one

more cabinet with an SDSS and three Mark 5B playback units.

168
IAA 2014 Report 169

3 Current Status and Activities

The ARC correlator was used for processing of all the

national geodetic VLBI observations at the IAA Correlator Center in 2014. The RUE and RUU (R-I) geodetic

VLBI sessions were observed at IAA RAS.

The three-station 24-hour RUE sessions for EOP

determination were observed one time per week, as in

2013.

The two-station one-hour sessions for UT1-UTC

determination in e-VLBI mode were observed once a

day. The RUU (R-I) sessions setup was the following:

frequency channel bandwidth of 8 MHz and total bitrate of 256 Mbps. The data transfer rate from stations

to correlator was increased in 2012, and near-realtime

correlation processing with a data bitrate of 256 Mbps

was achieved.

The DiFX software correlator continued to be

the main tool for processing spectral line sources

for VLBI in 2014. Several 2-Gbps tests with new

broadband acquisition system BRAS were done,

and data were processed with DiFX. Twenty-seven

Ru-P low data rate experiments were scheduled,

observed, and processed with high spectral resolution.

The HartRao station joined the Ru-P Orion KL

observations, and data were transferred from South

Africa to Saint-Petersburg using the Tsunami protocol.

During 2014, several wideband test experiments

were carried out. DiFX was used to get first fringes

in these experiments. DiXF copies are installed on

three GNU/Linux VMware virtual machines at a Sun

Fire X4450 Server and at a new hybrid-blade cluster.

Wideband experiments were processed using cluster

DiFX installation. Running at 60 cluster cores, DiFX

is more than 50 times faster than DiFX on a four-core

virtual machine.

4 FX Correlator Design

The design of a new FX software correlator intended

for the new small antenna VLBI network was started

in 2012. The correlator design is supposed to process a

data stream of up to 16 Gbps from each observatory.

VLBI data are recorded from four frequency bands

with bandwidths of up to 1024 MHz in one circular polarization or up to 512 MHz in two linear polarizations

using 2-bit sampling. The input data format is VDIF.

The correlator computes cross-spectra with a resolution of up to 4,096 spectral channels and extracts up to

32 phase calibration tones in each frequency band of

each station in near-real time.

We have developed six-station correlator software in 2014. In cooperation with the company

“T-Platforms”, the high-performance computing

cluster (Figure 2) was mounted at IAA.

Fig. 2 View of the high-perfomance computing cluster based on

the hybrid blade servers.

The correlator’s hardware is based on hybrid blade

server technology. Each blade server contains two Intel CPU and two Nvidia Tesla K20 GPUs and 64 GB

RAM. The present hardware contains 32 blade servers,

which are mounted into seven chassis. These servers

are used for FX data processing algorithms (doppler

tracking, FFT, and spectra multiplication) computing.

Also the HPC contains eight 19-inch servers; each of

them provides data receiving operation, pcal extraction, delay tracking, and bit repacking. These servers

are equipped with two GPUs, 256 GB RAM and 2x10

Gb fiber optic input. Data storage is based on Panasas

with 80 TB capacity. The interblock data communication is provided by infiniband network. Cluster components are mounted on four racks.

In the end of 2014, the two-station Ru0108 series

was processed. All fringes were obtained.

The six-station benchmark tests with a 96 Gbps input data stream were performed. The 16 Gbps data

stream from each station consisted of four bands and

two polarizations. 312 spectra total (78 spectra in each

band) with 4,096 frequency points each were calculated in near to real time. The results showed that our

algorithms require 80 Tesla K20 GPUs for near-real

time processing.

IVS 2014 Annual Report
170 Surkis et al.

The next year will be devoted to upgrading our

GPU software according to new CUDA specifications,

developing post-processing software, and developing

GUI software.

5 Staff

• Igor Surkis — leading investigator, software developer;

• Voytsekh Ken — GPU software developer;

• Alexey Melnikov — DiFX processing, scheduler of

the Ru-sessions;

• Vladimir Mishin — software developer, data processing;

• Nadezhda Mishina — software developer;

• Yana Kurdubova — software developer;

• Dmitry Pavlov — software developer;

• Violet Shantyr — software developer, post processing;

• Vladimir Zimovsky — leading data processing;

• Ekaterina Medvedeva — data processing;

• Alexander Salnikov — leading e-VLBI data transfering; and

• Ilya Bezrukov — e-VLBI data transfering.

IVS 2014 Annual Report
Shanghai VLBI Correlator

Fengchun Shu, Weimin Zheng, Wu Jiang, Zhong Chen, Renjie Zhu

Abstract This report summarizes the activities of the

Shanghai VLBI Correlator during 2014. Highlights include the commissioning of DiFX correlation, fringe

tests for Tianma65, e-VLBI connection with international stations, and validation of 512 MHz bandwidth

observations.

1 Introduction

The Shanghai VLBI Correlator is hosted and operated

by the Shanghai Astronomical Observatory (SHAO),

Chinese Academy of Sciences. It is located on the Sheshan campus, about 40 kilometers from the Xujiahui

headquarters of SHAO. The Shanghai correlator plays

a leading role in the data processing of the Chinese

domestic VLBI observing programs, inclusive of the

CMONOC project for monitoring the Chinese regional

crustal movement, and the Chinese deep space exploration project for spacecraft tracking.

As shown in Figure 1, Shanghai (including Seshan25 and Tianma65), Kunming, and Urumqi participate in some domestic geodetic and astronomical

sessions, while the Beijing station is mainly used for

spacecraft data downlink and VLBI tracking. A few

joint observations with the Chinese deep space stations

Kashi and Jiamus were also performed.

In order to contribute more to the international

VLBI community and to meet the requirements of

more domestic astronomical VLBI experiments, we

Shanghai Astronomical Observatory

Shanghai Correlator

IVS 2014 Annual Report

imported the DiFX correlator in recent years. The

Shanghai correlator was accepted as an IVS correlator

in March 2012. It will become operational for IVS

data correlation in 2015.

 75oE 90oE 105oE 120oE 135oE 

 16oN 

 24oN 

 32oN 

 40oN 

 48oN 

 56oN 

SHANGHAI

KUNMING

URUMQI

KASHI

BEIJING

JIAMUS

Fig. 1 Distribution of the VLBI stations in China.

2 Component Description

We are operating two types of correlators. The correlator developed by our own staff has been operational

since 2006. It is mainly used for spacecraft VLBI tracking in the Chang’E lunar exploration project by producing differential VLBI observables. The data latency is

less than one minute in real time mode, and the typical

accuracy is better than 1 ns. It is also used to correlate a

few tens of CMONOC geodetic sessions by producing

NGS card files which will be made public very soon.

The other correlator is the DiFX correlator, which is

171
172 Shu et al.

dedicated to astrophysical and geodetic data correlation.

By the end of 2014, the former 60 core DiFX platform was expanded to a 420 core cluster system (Figure 2). The storage space was also increased to 430 TB.

The new platform is very important for IVS data correlation. In the routine operations, half of the computing and the storage sources are assigned to the geodetic

correlation tasks. Features of the DiFX cluster system

are listed as follows:

• DiFX 2.2/2.3/trunk, HOPS 3.9/3.10

• Head nodes: DELL R820 (E5-4610 CPU, 2.4 GHz,

2*6 cores), 64 GB Memory, DELL R730 (E5-2623

CPU, 3.0 GHz, 2*4 cores), 64 GB Memory.

• Computing nodes: 20 DELL R630 nodes, two

socket Intel E5-2660 CPU (2.6 GHz, ten cores),

64 GB Memory, 400 cores in total

• I/O nodes: RAID6, 432 TB raw storage capacity

• Mark 5 units: three Mark 5A and three Mark 5B.

• 56 G Infiniband for internal computing network

connection

• 1/10 G Ethernet for internal and external network

connection

Fig. 2 DiFX cluster system and Mark 5A/B units.

3 Staff

The people involved in the development and operation

of the Shanghai Correlator are listed below.

• Weimin Zheng: group head, software correlator

development

• Xiuzhong Zhang: CDAS and other technique development

• Fengchun Shu: scheduler, experiment oversight,

CDAS evaluation

• Zhong Chen: e-VLBI, cluster administration

• Wu Jiang: DiFX operation, experiment support

• Tianyu Jiang: DiFX operation, experiment support

• Weihua Wang: lead correlator operator, automatic

correlation process development

• Wenbin Wang: operator, experiment support

• Zhaobao Jiang: media library, computer services

• Renjie Zhu: CDAS development

• Zhijun Xu: FPGA programming, hardware correlator development

• Yajun Wu: FPGA programming

• Juan Zhang: correlator software development and

maintenance

• Li Tong: correlator software development and

maintenance

• Lei Liu: post-doctoral fellow, correlator software

development

4 Summary of Activities

4.1 DiFX Correlation

With the help of the Bonn Correlator and the GSFC

group, we have obtained some experience in using

DiFX, HOPS, and Dbedit to generate Mark IV

database files. As mentioned above, a new DiFX

cluster system was installed and tested in December

2014 in preparation for IVS data correlation.

In order to make the correlation results reliable, we

also made a comparison with Bonn on the four-station

(NyShTsWz) INT3 session K14349. Although the two

correlators used different parameter configurations, the

total delay observables can be used for comparisons.

The database generated by the Shanghai Correlator

has been analyzed with nuSolve by Minghui Xu. Some

data solution statistics for comparison against the IVS

result1can be found in Table 1. Our results have an

additional bad point 2014-12-15 UT 7h12m49s on

1 Please see http://lupus.gsfc.nasa.gov/data10/

sessions/2014/k14349/k14349-analyst.txt

IVS 2014 Annual Report
Shanghai Correlator 173

NYALES20-SESHAN25. We suspect we lost a little

data from Seshan25 when copying from the original

Mark 5 module. We compared 141 common points

used in the solutions. The mean value of the X-band

group delay differences is 0.9 ps, and the RMS is

9 ps, while the mean value of the S-band group delay

differences is 10.7 ps, and the RMS is 58 ps. The

comparsion shows that there are two points with group

delay differences greater than 20 ps at X-band and five

points with differences greater than 100 ps at S-band.

As shown in Figure 3, we plotted the histogram after

the removal of the seven points with big differences

mentioned above.

Table 1 Statistics on UT1 solutions with data from the Bonn and

the Shanghai correlators.

Bonn Shanghai

Number of observations scheduled 180 180

Number of observations correlated 169 169

Number of observations used 142 141

WRMS delay residual (ps) 42.7 41.6

UT1 formal error (μs) 8.87 8.99

−20 −15 −10 −5 0 5 10 15 20

0

5

10

15

20

25

X−band group delay differences (ps)

Number of observations

−100 −80 −60 −40 −20 0 20 40 60 80 100

0

1

2

3

4

5

6

S−band group delay differences (ps)

Number of observations

Fig. 3 Histogram for group delay differences produced by the

Bonn and the Shanghai correlators.

4.2 Fringe Tests for Tianma65

In order to bring Tianma65 online for VLBI astrometry,

we have been conducting a series of fringe tests since

2013. We finally received good fringes for a standard

wideband S/X sequence on the Tianma65-Seshan25

baseline on March 24. As a result, Tianma65 participated in R1637 in May and in RD1404 in June. With

its high sensitivity, Tianma65 is able to improve the total observations of an array and the detection of weak

sources, which is important for radio-optical frame

connection and densification of the ICRF.

4.3 e-VLBI

The network link to Seshan25 and Tianma65 is

10 Gbps. The network link to the Urumqi, Kunming,

and Beijing stations is 155 Mbps for domestic e-VLBI

observations. In the Chang’E-5T1 lunar mission beginning in October 2014, the data transfer performed

well at 64 Mbps for each station.

In order to process IVS global sessions in 2015, we

established the network link to Kashima, Sejong, Hobart, Noto, HartRAO, Fortaleza, and the Bonn Correlator. The maximum data rate is 1 Gbps. More stations

involved in the CRF and APSG sessions will be connected to Shanghai.

4.4 Performance of CDAS

The Chinese VLBI Data Acquisition System (CDAS)

is a type of digital backend designed to replace the traditional analog BBCs. The new digital system has better bandpass and wider bandwidth. In 2014, we successfully upgraded the CDAS at Kunming, so it can

now observe standard wideband S/X sequences such

as in CRF and R&D sessions.

In addition to the DDC version currently being

used, we are also developing a PFB version of CDAS

with much more of a compact design. It contains two

Xilinx K7 FPGAs for data processing. The input signals are from two IFs with 512 MHz bandwidth each

or one IF with 1024 MHz bandwidth. Compared with

the previous platform, which consists of four Xilinx V4

FPGAs, the new one not only updated the key chips for

IVS 2014 Annual Report
174 Shu et al.

DSP but also added two TenGiga Ethernet SFP+ ports

for data transmission. For the application, the PFB version can be configured with 32 MHz bandwidth x 16

channels and 64 MHz bandwidth x 16 channels.

4.5 Development of Correlator Technique

Aimed at the parallel data processing of two spacecraft

in the Chang’E-5 mission, which was scheduled to be

launched in 2017, our own real time correlator systems

are undergoing a major upgrade.

4.6 VEPS

The VEPS (VLBI Ecliptic Plane Survey) project submitted to the NSFC (Natural Science Foundation of

China) has been funded with a four-year term from

2014 to 2017. In the first phase we planned to observe

approximately 2,000 radio sources along the ecliptic

with the total flux greater than 0.1 Jy by VLBI for the

first time. The 512 MHz bandwidth observing mode

with 32 MHz bandwidth x 16 channels at wide X-band

can be provided by CDAS and K5 backend. The fringes

have been obtained with Seshan25, Kunming, Urumqi,

Tianma65, and Sejong. The last two stations will be

backup stations for VEPS.

4.7 Experiments Correlated

In 2014, only two domestic geodetic VLBI experiments were carried out due to limited available time of

Urumqi and the launch of the Chang’E-5T1 mission.

After the Mark 5 modules were shipped to Shanghai,

the data correlations were done by both the domestic

correlator and the DiFX correlator. The output of the

DiFX correlator was further processed with HOPS.

The differential VLBI observations were conducted

frequently to support the navigation of the Chang’E5T1 spacecraft from October 24. The signals transmitted from the spacecraft were received by four Chinese

stations and then transferred to Shanghai in e-VLBI

mode for data correlation and the extraction of differential VLBI observables within one minute.

4.8 Phase-referencing of Spacecrafts

We have developed offline software to convert our

own correlator output into FITS-IDI format since 2013.

Based on this type of data, we try to do relative positioning between the rover and lander of Chang’E-3 on

the surface of the Moon by using the phase-referencing

method, and we get accuracy at the level of a meter.

Now, we are trying to do spacecraft positioning (CE5T1, MEX, et al.) with respect to the extragalactic radio

sources by using the phase-referencing method, and we

have gotten some preliminary results.

4.9 IVS GM2014

The eighth IVS General Meeting was held March 2-7,

2014 in Shanghai, China. The keynote of the eighth

General Meeting is the establishment of the VGOS

(VLBI Global Observing System) network under the

theme “VGOS: The New VLBI Network”. Fengchun

Shu served as a member of the program committee,

and Weimin Zheng served as the chair of the local organizing committee. During the meeting, an excursion

was arranged to visit the VLBI data processing center

equipped with the correlator, the Tianma Radio Telescope, the Sheshan 25-m antenna, and the Shanghai

Astronomical Museum. The local organizing work was

basically done by our group.

5 Future Plans

We will begin to correlate a few international VLBI

sessions coordinated by the IVS in 2015 and we will

ensure that the final results are reliable and convinced

by making comparisons with other IVS correlators. We

will continue to support the data correlation of the Chinese domestic VLBI observations. Considering that we

have already submitted a correlator upgrade proposal

for VGOS correlation, we are also interested in getting

some real VGOS data for trial correlation.

IVS 2014 Annual Report
Tsukuba VLBI Correlator

Shinobu Kurihara 1, Tetsuya Hara 1,2

Abstract This report summarizes the activities of the

Tsukuba VLBI Correlator during 2014. The weekend

IVS Intensive (INT2) and the Japanese domestic VLBI

observations (JADE) were regularly processed using

the K5/VSSP correlation software.

1 Introduction

The Tsukuba VLBI Correlator, located in Tsukuba,

Japan, is hosted and operated by the Geospatial Information Authority of Japan (GSI). It is fully devoted

to processing geodetic VLBI observations of the International VLBI Service for Geodesy and Astrometry (IVS). All of the weekend IVS Intensive (INT2) for

UT1-UTC (= dUT1) determination and the Japanese

domestic VLBI observations for geodesy called JADE

organized by GSI were processed at the Tsukuba VLBI

Correlator. The K5/VSSP correlation software developed by the National Institute of Information and Communications Technology (NICT) is used for all processing.

1. Geospatial Information Authority of Japan

2. Advanced Engineering Service Co., Ltd.

Tsukuba VLBI Correlator

IVS 2014 Annual Report

2 Component Description

2.1 e-VLBI

The Tsukuba VLBI Correlator has been connected

to a broadband network, and most of observed VLBI

data is delivered via the network. The Tsukuba VLBI

Correlator has a 10 Gbps dedicated link to the SINET4

operated by the National Institute of Informatics (NII),

which is connected to some research networks in

the world such as Internet2 in the U.S., GEANT2 in  ́

Europe, and TEIN4 at Singapore. It enabled us to

transfer massive amounts of data between the Tsukuba

VLBI Correlator and the overseas IVS Components. In

March, the Ishioka VGOS Station was also connected

to the Tsukuba VLBI Correlator and SINET4 with a

10 Gbps dedicated cable.

2.2 K5/VSSP Correlation Software

The K5/VSSP correlation software consists of several

programs for the calculation of a priori values of delay

and delay rate (apri calc), for the correlation processing for all observations (fx cor or cor), and for monitoring the results of the correlation processing by performing a so-called “coarse search” (sdelay), following

several utilities such as Komb for bandwidth synthesis

[1]. All of these programs were developed and have

been maintained by NICT. The K5/VSSP correlation

software can be used not only for K5 data processing

but also for the Mark 5 data processing by using the

data format conversion program (m5tok5).

175
176 Kurihara and Hara

Table 1 Correlator Hardware Capabilities.

Main system Second System

Number of servers 16 44

- 14 for correlation processing - 16 for correlation processing

- two for controlling correlation processing - two for controlling correlation processing

- 26 for data storage

Operating System Red Hat Enterprise Linux 6.3 CentOS version 5.5

CPU Intel Xeon X5687 @3.60GHz quad CPU x 2 Intel Xeon X3360 @2.83 GHz quad CPU

Intel Xeon 5160 @3.00 GHz dual CPU x 2

Intel Xeon X3480 @3.07 GHz quad CPU

Intel Xeon @3.80 GHz CPU x 2

Total storage capacity Data Direct Networks storage: 513 Tbytes Lustre File System: 30 Tbytes

Network 10 Gbps dedicated line connected to SINET4 by NII

The following are processes of the K5 correlation

and programs used in each process:

1. Transferring data from network stations to the correlator (tsunami and tsunamid).

2. Data format conversion from Mark 5 to K5 (m5tok5

or m5btok5).

3. Preparation of a priori parameter files (apri calc).

4. Fringe search to find a clock offset at each pair of

stations (fx cor or cor).

5. Running correlation processing for all observations

(fx cor or cor).

6. Coarse search for estimating residual delay and delay rate, and plotting them on a 3-D diagram (sdelay).

7. Bandwidth synthesis to derive a multi-band delay (komb), and making Mark III databases by

MK3TOOLS to be submitted to the IVS Data

Center.

The correlation and analysis management programs

developed by GSI can run the above processes consecutively and ultra-rapidly. The program for the management of data transfer rapid transfer accesses a data

server in an observing station, executes tsunamid there,

and then executes tsunami to transfer data automatically at the correlator side when an observation starts.

The data is converted from Mark 5 to K5 format by a

program rapid conv as necessary. Rapid cor is a program to search for a fringe for each baseline according

to the clock information of each station written in the

FS log. Once the fringe is detected, the main correlation processing is run sequentially with the clock offset

and rate found in the fringe search until the last observation. Rapid komb executes komb one after another

for bandwidth synthesis process. The fully automated

VLBI analysis software c5++ developed by NICT can

read the komb output files directly and derives a VLBI

solution [2]. Rapid c5pp, which gives a c5++ interface, makes a configuration file for c5++ automatically

and executes analysis.

2.3 Correlator Hardware Capabilities

The hardware supporting the activities of the Tsukuba

VLBI Correlator is summarized in Table 1. All of these

pieces of equipment are general purpose and commercially available products. It means that no dedicated

hardware is required in the K5 correlation processing.

In 2014, IBM System X3650 servers and a Data Direct

Networks storage system with a capacity of 513 TB

were incorporated into the main correlation processing

(Figure 1). It shortens correlation time by half. The existing system is also available as the second processing

system (Figure 2). There was no other hardware modification in this year.

3 Staff

The technical staff at the Tsukuba VLBI Correlator are:

• Shinobu Kurihara — correlator/analysis chief,

management.

• Tetsuya Hara (AES) — correlator/analysis operator, software development.

IVS 2014 Annual Report
Tsukuba Correlator 177

Fig. 1 View of the data processing servers and storage system at the Tsukuba VLBI Correlator.

4 Correlator Operations

4.1 IVS Intensives for UT1-UTC

In 2014, 106 Intensive sessions that were observed on

weekends in total were processed at the Tsukuba Correlator. The details are described in Table 2. The observed data at Wettzell is transferred to the Tsukuba

Correlator in near real-time with the Tsunami UDP

protocol and is converted to the K5 format immediately. The observed data at the Tsukuba station is also

transferred to the correlator at once. The whole process

from data transfer through analysis is implemented by

the rapid programs (see Section 2.2), and a dUT1 solution of the Tsukuba–Wettzell baseline can be derived

within a few minutes after the end of the last scan of

the session.

Table 2 Intensive sessions processed at the Tsukuba Correlator.

One session K14040 on February 9 was canceled and not processed due to heavy snow at the Tsukuba Station.

Baseline Period # of sessions

Intensive 2 TsWz Jan 04 – Dec 28 101

KkWz Jan 05 – Jan 19 3

KbWz Oct 25 – Oct 26 2

Total 106

4.2 JADE and JAXA

JADE is the domestic geodetic VLBI series involving

three GSI stations (Tsukuba, Aira, and Chichijima),

three NICT stations (Kashima 34-m, Kashima 11-m,

and Koganei 11-m), and two VERA stations of the National Astronomical Observatory of Japan (NAOJ) located in Mizusawa and Ishigakijima. Five JADE sessions were correlated in 2014. The JAXA session is

separately conducted from JADE including JAXA stations, such as Usuda, in order to determine the global

positions of the stations in the ITRF. One JAXA session was processed in this year.

IVS 2014 Annual Report
178 Kurihara and Hara

Fig. 2 View of the existing data processing servers.

4.3 Ultra-Rapid dUT1 Experiment

This experiment is the joint project with Sweden, Australia, and South Africa continued since 2007. During

five regular IVS 24-hour sessions and CONT14 sessions, the ultra-rapid dUT1 experiments were implemented and processed at Tsukuba Correlator. For details, refer to the report “Tsukuba VLBI Analysis Center” in this volume.

5 Outlook

We will continue to process the IVS Intensive sessions. For more stable operation, we will make further improvements to the rapid programs and maintain

hardware and network. When the Asia-Oceania VLBI

Group for the Geodesy and Astrometry (AOV) coordinates and conducts regional VLBI observations, we

will process the observed data and play a major role of

a correlator in the Asia-Oceania region.

References

1. Kondo, T., et al.: Development of the K5/VSSP System, Journal of the Geodetic Society of Japan, 54(4), 233-248, 2008.

2. Hobiger, T., et al.: Fully automated VLBI analysis with c5++

for ultra-rapid determination of UT1, Earth Planets Space,

62, 933-937, 2010.

IVS 2014 Annual Report
Washington Correlator

David M Hall, Daniel Veillette

Abstract This report summarizes the activities of the

Washington Correlator for the year 2014. The Washington Correlator provides up to 80 hours of attended

processing per week plus up to 40 hours of unattended

operation, primarily supporting Earth Orientation and

astrometric observations.

1 General Information

The Washington Correlator (WACO) is located at and

staffed by the U.S. Naval Observatory (USNO) in

Washington, DC, USA. The correlator is sponsored

and funded by the National Earth Orientation Service (NEOS), which is a joint effort of the USNO

and NASA. Dedicated to processing geodetic and

astrometric VLBI observations, the facility spent 100

percent of its time on these sessions. All of the weekly

IVS-R4 sessions, all of the IVS-INT01 Intensives, and

the APSG and CRF sessions were processed at WACO.

The facility houses the WACO DiFX correlator.

2 Activities during the Past Year

• The Washington Correlator made the transition

from the ageing Mark IV correlator to the new

DiFX software correlator. Work to achieve the final

configuration of the DiFX correlator, its associated

servers, and its network is ongoing.

U. S. Naval Observatory

WACO Correlator

IVS 2014 Annual Report

• The correlator staff continues the testing and repair

of Mark 5 modules.

• Intensive observations from Kokee Park and

Wettzell were routinely transferred via e-VLBI

during 2014. 24-hour sessions from both Hobart

antennas, Katherine, Yarragadee, Warkworth,

Ny-Alesund, Fortaleza, Yebes, Noto, HartRAO,  ̊

Wettzell, Tsukuba, Aira, Kashima, Chichijima,

and Sintotu were also transferred by high-speed

networks.

• Table 1 lists the experiments processed during

2014.

Table 1 Experiments processed during 2014.

57 IVS-R4 or R1 sessions

9 CRF (Celestial Reference Frame)

222 Intensives

3 Staff

The Washington Correlator is under the management

and scientific direction of the Earth Orientation Department of the U.S. Naval Observatory. Table 2 lists staff

and their duties.

4 Future Plans

Transition to the DiFX Software correlator took place

in October of 2014. Additional work to achieve the fi179
180 Hall and Veillette

Table 2 Staff.

Staff Duties

David Hall Chief VLBI Operations Division

Daniel Veillette VLBI Correlator Project Manager

Bruce Thornton Lead Physical Science Technician

Roxanne Inniss Media Librarian

Maria Davis Physical Science Technician

nal planned configuration of the DiFX correlator and

its associated servers and network is ongoing.

IVS 2014 Annual Report
Data Centers

BKG Data Center

Volkmar Thorandt, Reiner Wojdziak

Abstract This report summarizes the activities and

background information of the IVS Data Center for the

year 2014. Included are information about functions,

structure, technical equipment, and staff members of

the BKG Data Center.

1 BKG Data Center Functions

The BKG (Federal Agency for Cartography and

Geodesy) Data Center is one of the three IVS Primary

Data Centers. It archives all VLBI related data of

IVS components and provides public access for the

community. The BKG Data Center is connected to the

OPAR and GSFC CDDIS Data Centers by mirroring

the OPAR and the CDDIS file stocks several times

per day. The sketch in Figure 1 shows the principle of

mirroring.

IVS components can choose one of these Data Centers to put their data into the IVS archives by using its

incoming area, which each Data Center has at its disposal. The BKG incoming area is protected, and users

need to obtain a username and password to get access.

An incoming script watches the incoming area and

checks the syntax of the files sent by IVS components.

If it is okay, the script moves the files into the Data Center directories. Otherwise the files will be sent to a badfile area. Furthermore, the incoming script informs the

responsible staff at the Data Center by sending e-mails

about its activities. The incoming script is part of the

BKG

BKG Data Center

IVS 2014 Annual Report

Fig. 1 Principle of mirroring.

technological unit which is responsible for managing

the IVS and the Operational Data Center and for carrying out the first analysis steps in an automatic manner.

All activities are monitored to guarantee data consistency and to control all analysis steps from data arrival

to delivery of analysis products to IVS.

Public access to the BKG Data Center is available

through FTP and HTTP:

ftp://ivs.bkg.bund.de/pub/vlbi/

http://ivs.bkg.bund.de/vlbi/

183
184 Thorandt and Wojdziak

Structure of BKG IVS Data Center:

vlbi/ : root directory

ITRF2013/ : VLBI solutions for ITRF2013

ivscontrol/ : controlfiles for the data center

ivsdata/ : VLBI observation files

ivsdocuments/ : IVS documents

ivsproducts/ : analysis products

crf/ : celestial frames

trf/ : terrestrial frames

eops/ : earth orientation (24h sessions)

eopi/ : earth orientation (Intensive sessions)

daily_sinex/ : daily sinex files (24h sessions)

int_sinex/ : daily sinex files (Intensive sessions)

trop/ : troposphere

2 Technical Equipment

The BKG IVS Data Center is based on a DELL Server

(SUSE Linux operating system), disk space of 500

GBytes (Raid system), and a backup system operated

by an automatic tape library.

3 Staff Members

• Volkmar Thorandt (coordination, data analysis,

data center, volkmar.thorandt@bkg.bund.de)

• Reiner Wojdziak (data center, Web design,

reiner.wojdziak@bkg.bund.de)

• Dieter Ullrich (data analysis, data center, dieter.ullrich@bkg.bund.de)

• Gerald Engelhardt (data analysis, gerald.engelhardt@ bkg.bund.de)

IVS 2014 Annual Report
CDDIS Data Center Summary for the IVS 2014 Annual Report

Carey Noll

Abstract This report summarizes activities during the

year 2014 and the future plans of the Crustal Dynamics Data Information System (CDDIS) with respect to

the International VLBI Service for Geodesy and Astrometry (IVS). Included in this report are background

information about the CDDIS, the computer architecture, archive contents, and future plans for the CDDIS

within the IVS.

1 General Information

The Crustal Dynamics Data Information System (CDDIS) has supported the archiving and distribution of

Very Long Baseline Interferometry (VLBI) data since

its inception in 1982. The CDDIS is a central facility

that provides users access to data and derived products to facilitate scientific investigation. The CDDIS

archive of GNSS (GPS, GLONASS, etc.), laser ranging, VLBI, and DORIS data is stored online for remote

access. Information about the system is available via

the Web at the URL http://cddis.gsfc.nasa.gov. In addition to the IVS, the CDDIS actively supports other

IAG services including the International GNSS Service

(IGS), the International Laser Ranging Service (ILRS),

and the International DORIS Service (IDS), as well

as the International Earth Rotation and Reference Systems Service (IERS), and the IAG’s observing system,

the Global Geodetic Observing System (GGOS). The

NASA Goddard Space Flight Center

CDDIS Data Center

IVS 2014 Annual Report

current and future plans for the system’s support of the

IVS are discussed below.

2 System Description

The CDDIS archive of VLBI data and products is accessible to the public through anonymous ftp (ftp://cddis.gsfc.nasa.gov) and the Web

(http://cddis.gsfc.nasa.gov/archive).

2.1 Computer Architecture

The CDDIS is operational on a dedicated server, cddis.gsfc.nasa.gov. The system has over 32 Tbytes of

online disk storage; at this time, over 200 Gbytes are

devoted to VLBI activities. The CDDIS is located at

NASA GSFC and is accessible to users 24 hours per

day, seven days per week.

3 Archive Content

The CDDIS has supported GSFC VLBI and IVS

archiving requirements since 1979 and 1999, respectively.

The IVS Data Center content and structure is

shown in Table 1 (a figure illustrating the flow of information, data, and products between the various IVS

components was presented in the CDDIS submission

to the IVS 2000 Annual Report). In brief, dedicated

ftp-only accounts have been established on the CDDIS

185
186 Noll

Table 1 IVS data and product directory structure.

Directory Description

Data Directories

vlbi/ivsdata/db/yyyy VLBI database files for year yyyy

vlbi/ivsdata/ngs/yyyy VLBI data files in NGS card image format for year yyyy

vlbi/ivsdata/aux/yyyy/ssssss Auxiliary files for year yyyy and session ssssss;

these files include: log files, wx files, cable files, schedule files, correlator notes

Product Directories

vlbi/ivsproducts/crf CRF solutions

vlbi/ivsproducts/eopi EOP-I solutions

vlbi/ivsproducts/eops EOP-S solutions

vlbi/ivsproducts/daily sinex Daily SINEX solutions

vlbi/ivsproducts/int sinex Intensive SINEX solutions

vlbi/ivsproducts/trf TRF solutions

vlbi/ivsproducts/trop Troposphere solutions

Project Directories

vlbi/ivs-iers IVS contributions to the IERS

vlbi/ivs-pilotbl IVS Analysis Center pilot project (baseline)

Other Directories

vlbi/ivscontrol IVS control files (master schedule, etc.)

vlbi/ivsdocuments IVS document files (solution descriptions, etc.)

vlbi/raw Raw VLBI data

vlbi/dserver dserver software and incoming files

incoming computer, cddisin.gsfc.nasa.gov. Using

specified filenames, Operation and Analysis Centers

deposit data files and analyzed results to appropriate

directories within their ftp-only accounts. Automated

archiving routines, developed by GSFC VLBI staff,

peruse the directories and move any new data to the appropriate public disk area. These routines migrate the

data based on the filename to the appropriate directory

as described in Table 1. Index files in the main subdirectories under ftp://cddis.gsfc.nasa.gov/pub/vlbi

are updated to reflect data archived in the filesystem.

Furthermore, mirroring software was installed on the

CDDIS host computer, as well as all other IVS Data

Centers, to facilitate equalization of data and product

holdings among these Data Centers. At this time,

mirroring is performed between the IVS Data Centers

located at the CDDIS, the Bundesamt fur Kartographie  ̈

und Geodasie in Leipzig, and the Observatoire de  ̈

Paris.

The public file system in Table 1 on the CDDIS

computer, accessible via anonymous ftp, consists of

a data area, which includes auxiliary files (e.g., experiment schedule information, session logs, etc.) and

VLBI data (in both database and NGS card image formats). A products disk area was also established to

house analysis products from the individual IVS Analysis Centers as well as the official combined IVS products. A documents disk area contains format, software,

and other descriptive files.

4 Data Access

During 2014, an average of 250 distinct hosts accessed

the CDDIS on a monthly basis to retrieve VLBI related

files. These users, which include other IVS Data Centers, downloaded over 3.6 Tbytes (1.7 M files) of data

and products from the CDDIS VLBI archive last year.

Work on an update of the CDDIS website was completed in early 2014. In addition to a refresh of the appearance of the website, the content was reviewed and

updated.

5 Future Plans

The CDDIS staff will continue to work closely with the

IVS Coordinating Center staff to ensure that our system is an active and successful participant in the IVS

archiving effort.

IVS 2014 Annual Report
CDDIS 2014 Report 187

In 2013, the CDDIS systems engineer assessed the

requirements for the next generation computer system.

The new server, storage, and network hardware were

procured in 2014; staff members are installing the system in a new computer facility at GSFC to provide

more reliable power and network connectivity. CDDIS

operations will transition to the new system by mid2015. These system improvements are being made to

allow for growth, improved reliability, and disaster recovery.

IVS 2014 Annual Report
Italy INAF Data Center Report

Monia Negusini, Pierguido Sarti

Abstract This report summarizes the activities of the

Italian INAF VLBI Data Center. Our Data Center is located in Bologna, Italy, and it belongs to the Institute of

Radioastronomy, which is part of the National Institute

of Astrophysics.

1 Introduction

The main analysis activity and storage is concentrated in Bologna, where we store and analyze single

databases using CALC/SOLVE software.

The IRA began storing geodetic VLBI databases

in 1989, but the databases archived in Bologna mostly

contain data including European antennas from 1987

onward. In particular, most of the databases available

here have VLBI data with at least three European stations. But we also store all the databases with the NyAlesund antenna observations. In 2002, we decided to  ̊

store the complete set of databases available on the

IVS Data Centers, although we limited the time span

to the observations performed from 1999 onwards. All

the databases were processed and saved with the best

selection of parameters for the final arc solutions. In

order to perform global solutions, we have computed

and stored the superfiles for all the databases.

In some cases we have introduced GPS-derived wet

delays into the European databases (1998 and 1999

EUROPE experiments, for the time being), as if they

were produced by a WVR. These databases are availIstituto di Radioastronomia INAF, Bologna

INAF Data Center

IVS 2014 Annual Report

able and stored with a different code from the original

databases. In order to produce these databases, we have

modified DBCAL, and this new version is available to

external users.

2 Computer Availability and Routing

Access

To date, the main computer is a Linux workstation, on

which Mark 5 Calc/Solve version 11 was installed and

to which all VLBI data analysis was migrated. The Internet address of this computer is sarip.ira.inaf.it. Since

2011, a new server with a storage capacity of 5 TB

has been available, and therefore all experiments performed in the previous years were downloaded and

archived, thus completing the catalog. The older experiments will be analyzed in order to perform global

long term analysis. At present, the databases are stored

in the following directories:

1 = /data2/dbase2

2 = /geo1/dbase1

3 = /geo1/dbase

4 = /geo1/dbase3

The superfiles are stored in:

/data1/super1

The list of superfiles is stored in the file

/data2/mk5/save files/SUPCAT. The username for

accessing the databases is geo. The password

may be requested by sending an e-mail to negusini@ira.inaf.it.

188
Data Center at NICT

Ryuichi Ichikawa 1, Mamoru Sekido 2

Abstract The Data Center at the National Institute of

Information and Communications Technology (NICT)

archives and releases the databases and analysis results

processed at the correlator and the Analysis Center at

NICT. Regular VLBI sessions of the Key Stone Project

VLBI Network were the primary objective of the Data

Center. These regular sessions continued until the end

of November 2001. In addition to the Key Stone Project

VLBI sessions, NICT has been conducting geodetic

VLBI sessions for various purposes, and these data are

also archived and released by the Data Center.

1 General Information

The IVS Data Center at National Institute of Information and Communications Technology (NICT) archives

and releases the databases and analysis results processed by the correlator and the Analysis Center at

NICT. Major parts of the data are from the Key Stone

Project (KSP) VLBI sessions [1], but other regional

and international VLBI sessions conducted by NICT

are also archived and released. Because routine observations of the KSP network terminated at the end of

November 2001, there have been no additional data

from the KSP regular sessions since 2002.

On March 11, 2011 the devastating megaquake

(Mw 9.0) hit our antennas. The azimuth track and one

azimuth wheel of the Kashima 34 m were damaged as

1. National Institute of Information and Communications Technology (NICT)

2. Kashima Space Research Center, NICT

NICT Data Center

IVS 2014 Annual Report

a consequence of the megaquake. The antenna repair

had already been finished in March 2013. On the other

hand, the 11-m antennas at Kashima and Koganei were

not damaged by the earthquake. We have observed 20

VLBI experiments using the 11-m antennas including

time and frequency transfer experiments, international

and domestic geodetic experiments, and astronomical

experiments during the repair of the 34-m antenna.

The analysis results in SINEX (Solution INdependent EXchange) format as well as in other formats

are available on the WWW server. Database files of

non-KSP sessions, i.e. other domestic and international geodetic VLBI sessions, are also available on

the WWW server. Table 1 lists the WWW server

locations maintained by the NICT Data Center. In the

past, an FTP server was used to provide data files, but

it was decided to terminate the FTP service because of

the security risks of maintaining an anonymous FTP

server. Instead, the www3.nict.go.jp WWW server was

prepared to provide large size data files.

The responsibility for the maintenance of these

server machines was moved from the VLBI research

group in 2001 to a common division which handles all

institutional network service of the laboratory in order

to improve the network security of these systems.

2 Activities during the Past Year

2.1 KSP VLBI Sessions

The KSP VLBI sessions were performed with four

KSP IVS Network Stations at Kashima, Koganei,

Miura, and Tateyama on a daily or bi-daily basis

until May 1999. The high-speed ATM (Asynchronous

189
190 Ichikawa and Sekido

Table 1 URL of the WWW server systems.

Service URL

KSP WWW pages http://ksp.nict.go.jp/

IVS WWW mirror pages http://ivs.nict.go.jp/mirror/

Database files http://www3.nict.go.jp/aeri/sts/stmg/database/

e-VLBI Sessions http://www2.nict.go.jp/aeri/sts/stmg/research/e-VLBI/UT1/

Transfer Mode) network line to the Miura station

became unavailable in May 1999, and real-time

VLBI observations with the Miura station became

impossible. Thereafter, the real-time VLBI sessions

were performed with the three other stations. Once

every six days (every third session), the observed

data were recorded to the K4 data recorders at three

stations, and the Miura station participated in the

sessions with the tape-based VLBI technique. In this

case, the observed data at the three stations other than

the Miura station were processed in real-time, and

the analysis results were released promptly after the

observations completed. A day later, the observed

tapes were transported from the Kashima, Miura, and

Tateyama stations to the Koganei station for tape-based

correlation processing with all six baselines. After

the tape-based correlation processing was completed,

the data set produced with the real-time VLBI data

processing was replaced by the new data set.

In July 2000, unusual site motion of the Tateyama

station was detected from the KSP VLBI data series,

and the frequency of the sessions was increased from

bi-daily to daily on July 22, 2000. The daily sessions

were continued until November 11, 2000, and the site

motions of the Tateyama and Miura stations were monitored in detail. During the period, it was found that

the Tateyama station moved approximately 5 cm to the

northeast direction. The Miura station also moved approximately 3 cm to the north. The unusual site motions of these two stations gradually settled, and the

current site velocities seem to be almost the same as

the site velocities before June 2000. According to the

investigations of the time series of the site positions,

the unusual site motion started sometime between the

end of June 2000 and the beginning of July 2000. At

the same time, volcanic and seismic activities near the

Miyakejima and Kozushima Islands began. These activities are believed to have caused the regional crustal

deformation in the area, explaining the unusual site

motions at Tateyama and Miura.

2.2 Other VLBI Sessions

In recent years, we have carried out time and frequency

transfer experiments using VLBI. In addition, domestic

and international geodetic and astronomical VLBI sessions were conducted by NICT in cooperation with the

Geospatial Information Authority of Japan (GSI), the

National Astronomical Observatory (NAO), and other

organizations. These sessions are listed in Table 2. The

recent observed data of these sessions were mainly processed by the K5 software correlator at NICT either at

Koganei or at Kashima or by using a real-time hardware correlator developed by NAO.

3 Current Status

The repair of the Kashima 34-m antenna was finished

in March 2013. In 2014, the Kashima 34-m and 11-

m antennas participated in various experiments. Especially, we have concentrated our effort on testing for

developments of broadband receiving systems.

4 Future Plans

The IVS Data Center at NICT will continue its service

and will archive and release the analysis results accumulated by the correlator and the Analysis Center at

NICT. In addition, a number of VLBI sessions will be

conducted for the purposes of various technology developments.

References

1. Special issue for the Key Stone Project, J. Commun. Res.

Lab., Vol. 46, No. 1, March 1999.

IVS 2014 Annual Report
Data Center at NICT 191

Table 2 VLBI sessions conducted by NICT (since 2005). In 2012, all experiments were observed using 11-m antennas at Kashima

and Koganei because the 34-m antenna was under repair to recover from the earthquake damage. At the end of March 2013, the

repair of the 34-m antenna was finished.

Year exp. names sessions

2005 Geodetic c0505 (CONT05, partial participation), GEX13

Hayabusa 14 sessions

2006 Geodetic GEX14, viepr2, CARAVAN (three sessions)

Spacecraft Geotail: one session

Pulsar one session

2007 Ultra Rapid e-VLBI 15 times, 29 sessions

Time Transfer four sessions, 12 days in total

Cs-Gas-Cell one session

Spacecraft Hayabusa: one session

2008 Ultra Rapid e-VLBI eight times, 33 sessions

Time Transfer 26 sessions

Variable Star e-VLBI 31 sessions

2009 e-VLBI 15 sessions, 90.5 hours in total

IVS 12 sessions, 332 hours in total

Time Transfer nine sessions, 72 hours in total

VERA 16 sessions, 149 hours in total

Survey 26 sessions, 276 hours in total

2010 IVS 38 sessions, 442 hours in total

Radio astronomy 34 sessions, 324 hours in total

Spacecraft (IKAROS, UNITEC-1, QZSS) 33 sessions, 259 hours in total

Domestic geodetic 13 sessions, 94 hours in total

Time Transfer nine sessions, 86 hours in total

e-VLBI nine sessions, 27 hours in total

2011 IVS two sessions, 48 hours in total

Radio astronomy 100 hours in total

earthquake damage investigation 216 hours in total

2012 IVS nine sessions, 216 hours in total

Radio astronomy (Sgr-A⋆) 13 sessions, 28 hours in total

Domestic geodetic three sessions, 72 hours in total

International fringe test (New Zealand and Korea) two sessions, 16 hours in total

International geodetic (New Zealand) one session, 24 hours in total

Time transfer 11 sessions, 264 hours in total

2013 IVS five sessions, 120 hours in total

Radio astronomy (including Sgr-A⋆ obs.) 71 sessions, 266 hours in total

Domestic geodetic 14 sessions, 213 hours in total

Time transfer two sessions, 46 hours in total

International fringe test (New Zealand and Korea) two sessions, 16 hours in total

Pulsar 39 sessions, 274 hours in total

2014 IVS 13 sessions, 332 hours in total

Radio astronomy (including Sgr-A⋆ obs.) 95 sessions, 632 hours in total

Domestic geodetic five sessions, 130 hours in total

Time transfer five sessions, 288 hours in total

Pulsar three sessions, 24.5 hours in total

IVS 2014 Annual Report
Paris Observatory (OPAR) Data Center

Christophe Barache, Sebastien Lambert, Teddy Carlucci

Abstract This report summarizes the OPAR Data Center activities in 2014. Included is information about

functions, architecture, status, future plans, and staff

members of the OPAR Data Center.

1 General Information

The Paris Observatory (OPAR) has provided a Data

Center for the International VLBI Service for Geodesy

and Astrometry (IVS) since 1999. The OPAR, as well

as CDDIS and BKG, is one of the three IVS primary

Data Centers. Their activities are done in close collaboration for collecting files (data and analysis files)

and making them available to the community as soon

as they are submitted. The three Data Centers have a

common protocol and each of them:

• has the same directory structure (with the same control file),

• has the same script,

• is able to receive all IVS files (auxiliary, database,

products, and documents),

• mirrors the other ones every three hours, and

• gives free FTP access to the files.

This protocol gives the IVS community a transparent access to a Data Center through the same directory,

and a permanent access to files in case of a Data Center

breakdown.

Observatoire de Paris/SYRTE – CNRS – UMPC – GRGS

OPAR Data Center

IVS 2014 Annual Report

2 Architecture

To be able to put a file in a Data Center, Operational

and Analysis Centers have to be registered by the IVS

Coordinating Center. The file names have to conform

to the name conventions. A script checks the file and

puts it in the right directory. The script undergoes permanent improvement and takes into account the IVS

components’ requests. The structure of the IVS Data

Centers is detailed in Table 1.

3 Current Status

The OPAR Data Center is operated on a PC server

(PowerEdge 2800 - Xeron 3.0 GHz) located at the Paris

Observatory and running the Fedora Linux operating

system. To make all IVS products available online, the

disk storage capacity was significantly increased, and

the server is equipped now with a RAID 3 TB disk extensible up to 4.7 TB.

The OPAR server is accessible 24 hours a day,

seven days per week through Internet connection with

2 Mbit/s rate. Users can get the IVS products by using

the FTP protocol. Access to this server is free for users.

FTP access: ftp ivsopar.obspm.fr

username : anonymous

password : your e-mail

cd vlbi (IVS directory)

The OPAR Web statistics increased in 2014 —

more than 5,000 different visitors reached the server.

192
OPAR Data Center 193

Table 1 Directories of the IVS Data Center.

RECENT used for the new mirroring method

ivscontrol control files needed by the Data Center (session code, station code, solution code...)

ivsdocuments documents about IVS products

ivsdata files related to the observations

aux auxiliary files (schedule, log...)

db observation files in database CALC format

ngs observation files in NGS format

sinex observation files in SINEX format

ivsproducts results from Analysis Centers

eopi Earth orientation parameters, Intensive sessions

eops Earth orientation parameters, 24-h sessions

crf celestial reference frames

trf terrestrial reference frames

daily sinex 24-hour time series solutions of Earth orientation and site positions in SINEX FORMAT

int sinex daily Intensive solution in SINEX format, mainly designed for combination

trop tropospheric time series (starting July 2003)

They viewed approximately 50,000 pages and downloaded five Go. The OPAR staff will continue to work

with the IVS community and in close collaboration

with the two other primary Data Centers in order to

provide public access to all VLBI related data. To obtain information about the OPAR Data Center please

e-mail ivs.opa@obspm.fr.

IVS 2014 Annual Report

Analysis Centers

Analysis Center of Saint Petersburg University

Dmitriy Trofimov, Veniamin Vityazev

Abstract This report briefly summarizes the activities

of the Analysis Center of Saint Petersburg University

during 2014. The current status, as well as our future

plans, are described.

1 General Information

The Analysis Center of Saint Petersburg University

(SPU AC) was established at the Sobolev Astronomical Institute of the SPb University in 1998. The main

activity of the SPU AC for the International VLBI Service before 2007 consisted of routine processing of 24-

hour and one-hour observational sessions for obtaining

Earth Orientation Parameters (EOP) and rapid UT1-

UTC values, respectively. In 2008 we began submitting

the results of 24-hour session processing.

2 Activities during the Past Year

• In 2014, the routine estimation of the five Earth Orientation Parameters was performed. The OCCAM

software package (version 6 2) was used for current processing of VLBI data [1]. The time series

is named spu00004.eops. It includes data obtained

by the IRIS-A, NEOS-A, R1, R4, RDV, and R&D

observing programs, and it covers 26 years of observations (from January 2, 1989 until the end of

2014). The total number of experiments processed

Sobolev Astronomical Institute of Saint Petersburg University

AI SPbU Analysis Center

IVS 2014 Annual Report

at the SPU AC is about 2,070, of which about 110

VLBI sessions were processed in 2014. Our experience and the equipment of the Analysis Center

was used for giving lectures and practical work on

the basics of radio interferometry to university students. We use our original manual on the training

in modern astrometry and in particular VLBI [2].

In 2014, the work of the SPU AC was performed

within the project “Acquisition and analysis of

time-series in astronomy and study of astronomical

catalogs” (SPU grant for fundamental research

6.0.161.2010).

• All parameters were adjusted using the Kalman filter technique. For all stations (except the reference

station), the wet delay, clock offsets, clock rates,

and troposphere gradients were estimated. Troposphere wet delay and clock offsets were modeled

as a stochastic process such as a random walk. The

clock rates and the troposphere gradients were considered to be the constant parameters.

• The main details of the preparation of the EOP time

series spu00004.eops are summarized below:

– Data span: 1989.01–2014.12

– CRF: fixed to ICRF-Ext.2

– TRF: VTRF2005 was used as an a priori TRF

– Estimated parameters:

1. EOP: x, y,UT1−UTC,dψ,dε;

2. Troposphere: troposphere gradients were estimated as constant parameters, and wet troposphere delays were modeled as a random

walk process;

3. Station clocks were treated as follows: offset

as a random walk process, rate as a constant.

– nutation model: IAU 1980

– mapping function: VMF1

197
198 Trofimov and Vityazev

– technique: Kalman filter

– software: OCCAM v.6 2

3 Current Status

The assistant professor of Saint Petersburg University,

Dmitriy Trofimov, was in charge of the routine processing of the VLBI observations. General coordination and support for the activities of the SPU AC at

the Astronomical Institute were performed by Professor Veniamin Vityazev.

4 Future Plans

In 2015, we are going to continue our regular processing of the VLBI sessions as well as giving lectures and

practical training for students in a special course on radio astrometry. This course is a part of the systematic

curriculum of astronomical education at SPb University.

References

1. O. Titov, V. Tesmer, J. Boehm. OCCAM v. 6. 0 Software

for VLBI Data Analysis, In International VLBI Service for

Geodesy and Astrometry 2004 General Meeting Proceedings, N. R. Vandenberg and K. D. Baver (eds.), NASA/CP2004-212255, pp. 267-271, 2004.

2. V. Vityazev, I. Guseva, V. Kiyaev, M. Mishchenko, O. Titov,

A. Tsvetkov. Celestial and Terrestrial Coordinates (In Russian), Manual on Astrometry, p. 301, SPb University, 2011.

IVS 2014 Annual Report
Geoscience Australia Analysis Center 2014 Annual Report

Oleg Titov

Abstract This report gives an overview of the activities of the Geoscience Australia IVS Analysis Center

during 2014.

1 General Information

The Geoscience Australia (GA) IVS Analysis Center

is located in Canberra within the Geodesy Section,

Geodesy and Seismic Monitoring Group, Community

Safety and Earth Monitoring Division (CSEMD).

2 Activities during the Past Year

Several celestial reference frame (CRF) solutions have

been prepared using the OCCAM 6.3 software. The latest solution was uploaded in March 2014. VLBI data

comprising 3,325 daily sessions from January 1991 to

March 2014 were used to compute several global solutions with different sets of reference radio sources. This

includes 5,567,029 observational delays from 2,949 radio sources having three or more observations.

Station coordinates were also estimated using NoNet-Rotation (NNR) and No-Net-Translation (NNT)

constraints. The long-term time series of the station coordinates have been used to estimate the corresponding velocities for each station. The tectonic motion for

the Gilcreek VLBI site after the Denali earthquake was

Geoscience Australia

GA Analysis Center

IVS 2014 Annual Report

modeled using an exponential function typical of postseismic deformation.

The adjustment was made by least squares collocation, which considers the clock offsets, wet troposphere

delays, and tropospheric gradients as stochastic parameters with a priori covariance functions. The gradient

covariance functions were estimated from GPS hourly

values.

The solution, aus2014a.crf, was imposed by the

NNR constraints, and it is consistent with the CRF solutions submitted by other Analysis Centers.

The GA Analysis Center has submitted SINEX files

for ITRF2013 and ITRF2014 solutions covering the

time period from 1979 to the end of 2014.

In 2014, all three new AuScope 12-meter radio

telescopes were actively working in different IVS

geodetic and astrometric programs. Another radio

telescope, Hobart26, operated by the University of

Tasmania (UTAS), participated in the geodetic VLBI

programs occasionally.

A program for optical identification and spectroscopy of the reference radio sources continued in

collaboration with the Australian Telescope National

Facility, University of Sydney, and Nordic Optical

Telescope. More observing runs at Gemini North and

Gemini South (service mode) were done in 2014.

A new paper on the reference radio source redshift

determination is under preparation.

Acknowledgements

This report has been published with the permission of

the CEO, Geoscience Australia. 
c Commonwealth of

Australia (Geoscience Australia) 2015.

199
Report for 2014 from the Bordeaux IVS Analysis Center

Patrick Charlot, Antoine Bellanger, Romuald Bouffet, Geraldine Bourda, Arnaud Collioud, Alain Baudry  ́

Abstract This report summarizes the activities of the

Bordeaux IVS Analysis Center during the year 2014.

The work focused on (i) the regular analysis of the IVSR1 and IVS-R4 sessions with the GINS software package, also producing a 12-year long solution (2002—

2013); (ii) the systematic VLBI imaging of the RDV

sessions and calculation of the corresponding source

structure index and compactness values; (iii) the investigation of the correlation between astrometric position instabilities and source structure variations, and

(iv) the continuation of activities to identify and monitor optically-bright radio sources suitable as transfer

sources to align the International Celestial Reference

Frame (ICRF) and the future Gaia frame. Also to be

mentioned is the organization of a workshop on gravitation, reference systems, astronomy, and metrology,

and participation in the IAU Working Group Meeting

on the next ICRF realization.

1 General Information

The Laboratoire d’Astrophysique de Bordeaux (LAB),

formerly Bordeaux Observatory, is located in Floirac,

near Bordeaux, in the southwest of France. It is funded

by the University of Bordeaux and the Centre National

de la Recherche Scientifique (CNRS). VLBI activities

are primarily developed within the Metrologie de  ́

l’espace, Astrodynamique, Astrophysique (M2A) team.

Laboratoire d’Astrophysique de Bordeaux

Bordeaux Analysis Center

IVS 2014 Annual Report

The contribution of the Bordeaux group to the IVS

has been mostly concerned with the maintenance, extension, and improvement of the International Celestial

Reference Frame (ICRF). This includes regular imaging of the ICRF sources and evaluation of their astrometric suitability, as well as developing specific VLBI

observing programs for enhancing the celestial frame.

In addition, the group is in charge of the VLBI component in the multi-technique GINS software package [1] as part of a collaborative effort within the

French Groupe de Recherches de Geod  ́ esie Spatiale  ́

(GRGS) to combine VLBI and space geodetic data

(SLR, GPS, and DORIS) at the observation level. This

effort involves institutes in Toulouse, Nice, and Paris.

2 Description of Analysis Center

The Bordeaux IVS group routinely analyzes the

weekly IVS-R1 and IVS-R4 sessions with the GINS

software package. During the past year, weekly normal

equations for all such sessions in 2014 (with six-hour

EOP resolution) were produced and integrated in the

multi-technique solutions derived by the GRGS. In

addition, we produced a solution that includes all

IVS-R1 and IVS-R4 sessions from 2002 to 2013. The

motivation for setting up this 12-year long VLBI solution was to obtain multi-technique results derived from

combining all space geodetic data at the observation

level in the framework of the ITRF2013 preparation.

The group is also focused on imaging the ICRF

sources on a regular basis by systematic analysis of the

data from the RDV sessions which are conducted six

times a year. This analysis is carried out with the AIPS

and DIFMAP software packages. The aim of such reg200
Bordeaux AC Report for 2014 201

ular imaging is to characterize the astrometric suitability of the sources based on the so-called “structure index” and to compare source structural evolution and

positional instabilities. Such studies are essential for

identifying sources of high astrometric quality, which

is required, e.g., for the future Gaia link.

3 Scientific Staff

During the past year, there were no changes in the IVS

staff. In all, six individuals contributed to one or more

of our IVS analysis and research activities during 2014.

A description of what each person worked on, along

with the time spent on it, is given below.

• Patrick Charlot (20%): researcher with overall responsibility for Analysis Center work and data processing. His interests include the ICRF densification, extension, and link to the Gaia frame, studies of radio source structure effects in astrometric

VLBI data, and astrophysical interpretation.

• Antoine Bellanger (100%): engineer with a background in statistics and computer science. He is

tasked to process VLBI data with GINS and to develop procedures and analysis tools to automate

such processing. He is also the M2A Web master.

• Romuald Bouffet (30%): Ph. D. student from the

University of Bordeaux whose thesis is focused on

the study of the relationship between radio source

structure and position instabilities. He is using astrometric data and VLBI images from IVS sessions.

• Geraldine Bourda (50%): astronomer in charge of  ́

developing the VLBI part of GINS and responsible for the analysis results derived from GINS. She

is also leading a VLBI observational program for

linking the ICRF and the future Gaia optical frame.

• Arnaud Collioud (100%): engineer with a background in astronomy and interferometry. His tasks

are to image the sources in the RDV sessions using

AIPS and DIFMAP, to develop the Bordeaux VLBI

Image Database and IVS Live tool, and to conduct

simulations for the next generation VLBI system.

• Alain Baudry (10%): radioastronomy expert with

specific interest in radio source imaging and astrometric VLBI. He is a Professor Emeritus and is

working part time as a co-investigator for developing upgrades of the ALMA mm/submm array.

4 Analysis and Research Activities in 2014

As noted above, a major part of our activity consists

of imaging the sources observed during the RDV sessions on a systematic basis. During 2014, two such

sessions were processed (RDV92 and RDV94), resulting in 337 VLBI images at either X- or S-band for

150 different sources. The imaging work load has been

shared with USNO since 2007 (starting with RDV61);

the USNO group processes the odd-numbered RDV

sessions while the Bordeaux group processes the evennumbered ones. The VLBI images are used in a second

stage to derive structure correction maps and visibility maps along with values for structure indices and

source compactness (see [2, 3] for a definition of these

quantities) in order to assess astrometric source quality. All such information is made available through the

Bordeaux VLBI Image Database (BVID)1. At present,

the BVID comprises a total of 4,007 VLBI images

for 1,170 different sources (with links to an additional

6,775 VLBI images from the Radio Reference Frame

Image Database of USNO) along with 10,572 structure

correction maps and as many visibility maps.

In addition to such regular imaging, studies aimed

at characterizing correlations between astrometric position instabilities and source structural variations have

been pursued. As indicated in our 2013 IVS report, although a link between the two phenomena was found,

a fraction of the sources shows a negative correlation.

Investigating further such discrepancies, a number of

explanations have been put forward: (i) misidentification of the core component over the epochs in the successive VLBI maps, (ii) imprecision in the VLBI core

location (e.g. due to blended VLBI components in the

inner part of the jet), (iii) effects of the S-band data, not

considered in this study, (iv) inadequacy of the brightness centroid motion to match astrometric instabilities,

(v) opacity variations affecting the VLBI core position

along the jet, and (vi) precession effects (due to the rotation of the central black hole) or orbital motion (due

to the presence of a binary black hole system) causing true VLBI core displacement. Focusing on the latter and taking an additional step, we developed simulations of jets affected by such physical phenomena

(precession and the presence of a binary black hole).

Preliminary results indicate that the resulting trajecto1 The Bordeaux VLBI Image Database may be accessed at

http://www.obs.u-bordeaux1.fr/BVID.

IVS 2014 Annual Report
202 Charlot et al.

ries on the sky show oscillations whose amplitude and

time scale are in agreement with those observed in actual sources, hence giving credence to these considerations.

Another major activity of the group is the identification and characterization of appropriate radio

sources to align the ICRF and the future Gaia optical

frame. To this end, two complementary directions are

being followed: (i) the identification and monitoring

of such sources within ICRF2 and (ii) the search for

additional sources (outside of ICRF2) to increase the

pool of transfer sources. As noted in our 2012 IVS

report, the examination of ICRF2 led to the identification of 195 transfer sources. Following our proposal,

most of these sources were inserted into IVS programs

and are now observed on a regular basis. During the

past year, the work has consisted of assessing the

time coverage of these sources, in collaboration with

the IVS Coordinating Center, with the aim of getting

one epoch per month, similar to the overall Gaia time

coverage. Additionally, some of the transfer sources

from the other set (the non-ICRF2 sources) were

inserted into Deep Space Network sessions through

a collaboration with the Jet Propulsion Laboratory.

These sources are much weaker and require large

antennas for detection. Observations to characterize

potential transfer sources in the southern hemisphere

are also soon to be initiated following acceptance of a

proposal by the Australian Long Baseline Array.

Most of this work (source imaging, assessment

of structural effects, identification of Gaia transfer

sources, etc.) naturally fits within the tasks of the

IAU Working Group on the next ICRF realization

which was set up at the 2012 IAU General Assembly.

Both G. Bourda and P. Charlot are members of this

Working Group and as such contributed to the two

meetings of the Working Group held during the past

year (7 March 2014 in Shanghai and 14 October 2014

in Luxembourg).

5 Dissemination and Outreach

A workshop on gravitation, reference systems, astronomy, and metrology was hosted by the Bordeaux group

on 3-4 April 2014 as part of the five-year planning

exercise for French astronomy. During the workshop,

P. Charlot gave a talk on the next generation VLBI system, putting emphasis on the need to set up a VGOS antenna in Tahiti. The planning exercise concluded with

a one-week long meeting covering all fields of astronomy that took place in the fall of the 2014.

The IVS Live Web site [4], dedicated to monitoring IVS sessions and viewing VLBI images of the observed sources, was updated on a regular basis during

2014. It now includes 6,335 IVS sessions (with 71 stations participating) and 1,799 sources. Monitoring of

the connections indicates that there were 1,017 visits

from around the world (47 countries, 277 locations)

during 2014, with 70% originating from different individuals. On the other hand, the Bordeaux VLBI Image

Database was accessed from 77 different locations in

27 countries. In all, there were 629 connections, with

about one-third originating from different individuals.

6 Outlook

Our plans for the coming year are focused on moving

towards operational analysis of the IVS-R1 and IVSR4 sessions with the GINS software package. Imaging

of the RDV sessions and evaluation of the astrometric

suitability of the sources will continue along the lines

described in this report. Dissemination activities include upgrading the BVID by implementation of a new

user interface. Of the most importance are our observing programs in cooperation with IVS and other groups

to search and monitor Gaia transfer sources both in the

northern hemisphere and in the southern hemisphere.

The aim is to finalize the source list by 2016, in time for

the first release of the Gaia catalog. Finally, we expect

to contribute to the work towards the next realization

of the ICRF in accordance with the plans of the IAU

Working Group in charge of this task. This includes

participation in the upcoming meetings of the Working

Group, among which is the one to be held during the

IAU General Assembly this summer in Hawaii.

Acknowledgements

We would like to thank the Observatoire Aquitain des

Sciences de l’Univers (OASU) for supporting IVS activities in Bordeaux.

IVS 2014 Annual Report
Bordeaux AC Report for 2014 203

References

1. Bourda, G., Charlot, P., Biancale, R.: 2007, GINS: A New

Tool for VLBI Geodesy and Astrometry, 18th EVGA Working Meeting, Eds. J. Bohm, A. Pany, and H. Schuh, IGG  ̈

Vienna, p. 59–63.

2. Fey, A. L., Charlot, P.: 1997, VLBA Observations of Radio

Reference Frame Sources. II. Astrometric Suitability Based

on Observed Structure, ApJS, 111, 95–142.

3. Charlot, P.: 2008, Astrophysical Stability of Radio Sources

and Implication for the Realization of the Next ICRF, 5th

IVS General Meeting, St Petersburg, Eds. A. Finkelstein and

D. Behrend, p. 345–354.

4. Collioud, A.: 2011, IVS Live: All IVS on your deskstop,

Proceedings of the 20th Meeting of the European VLBI

Group for Geodesy and Astronomy, Eds. W. Alef, S. Bernhart, and A. Nothnagel, Universitat Bonn, Institut f  ̈ ur ̈

Geodasie und Geoinformation, Schriftenreihe 22, p. 14–18.  ̈

IVS 2014 Annual Report
BKG/DGFI Combination Center Annual Report 2014

Sabine Bachmann 1, Linda Messerschmitt 1, Ralf Schmid 2, Mathis Bloßfeld 2, Daniela Thaller 1

Abstract This report summarizes the activities of the

BKG/DGFI Combination Center in 2014 and outlines

the planned activities for 2015. The main focus in 2014

was on the generation of the IVS contribution to the

next ITRF, the inclusion of additional Analysis Centers

into the combined solution, and the design and set-up

of a new Combination Center website.

1 General Information

The BKG/DGFI Combination Center was established

in October 2008 as a joint effort of the Federal Agency

for Cartography and Geodesy (Bundesamt fur Kar-  ̈

tographie und Geodasie, or BKG) and the German  ̈

Geodetic Research Institute (Deutsches Geodatisches  ̈

Forschungsinstitut, or DGFI). The participating institutions, as well as the tasks and the structure of the

IVS Combination Center, are described in [1]. The

tasks comprise quality control and a timely combination of the session-based intermediate results of the

IVS Analysis Centers into a final combination product

(e.g., Earth orientation parameters, or EOP). In coordination with the IVS Analysis Coordinator, the combination results are released as official IVS products.

The Combination Center is also expected to contribute

to the generation of the official IVS input to any ITRF

activities.

1. Federal Agency for Cartography and Geodesy (BKG)

2. Technische Universitat M  ̈ unchen, Deutsches Geod  ̈ atisches  ̈

Forschungsinstitut (DGFI-TUM)

BKG/DGFI Combination Center

IVS 2014 Annual Report

The BKG/DGFI Combination Center performs a

combination of session-based results of the IVS Analysis Centers on an operational basis. The strategy for

the combination is based on the combination of normal

equations and was adopted from the combination process as developed and performed by the IVS Analysis

Coordinator (cf. [2], [3]). At BKG, the following tasks

are performed:

• Quality control of the Analysis Center results:

checking the format of the results and their

suitability for combination, identification and

reduction of outliers, comparison of the Analysis

Centers’ results with each other, and comparison

of the results with external time series provided by

the IERS or IGS.

• Feedback to the Analysis Centers: quality control

results are available at the BKG IVS Combination

Center web pages [5].

• Generation of high-quality combination products

and timely archiving and distribution: combination

products are created by using the combination part

DOGS-CS of DGFI’s software package DOGS

(DGFI orbit and geodetic parameter estimation

software) [4].

• Submission of official IVS combination products to

the IERS: the products are submitted to the responsible IERS components to be used for IERS product

generation (e.g., EOP rapid products and the EOP

series IERS C04).

• Generation of the official IVS input to the ITRF: the

combined session products (from 1984 to present)

are submitted for ITRF computation in the form of

normal equations in SINEX format. This work is

also supported by the staff of the IERS Central Bureau, hosted by BKG.

204
BKG/DGFI Report 2014 205

• Final results are archived in the BKG Data Center

and mirrored to the IVS Data Centers at Observatoire de Paris (OPAR) and Goddard Space Flight

Center (GSFC). This work is assisted by the staff

of the BKG Data Center in Leipzig.

DGFI is in charge of the following Combination

Center functions:

• DGFI is developing state-of-the-art combination

procedures. This work, as well as the following

item, is related to the ITRS Combination Center at

DGFI and DGFI’s efforts within the IERS WG on

Combination at the Observation Level (COL).

• The software DOGS-CS is updated by implementing and documenting the developed state-of-the-art

combination procedures.

• Adhering to IERS Conventions: the DGFI DOGS

software package is continuously updated to be in

accordance with the IERS Conventions.

2 Activities during the Past Year

At BKG, the following activities were performed in

2014:

• Generation of a combined solution of IVS 24-h

rapid sessions twice a week.

• Generation of a combined long-term solution of

IVS 24-h sessions every three months.

• Validation and inclusion of 11 contributions to the

IVS combined contribution to the ITRF.

• Ensuring that the combination process is in agreement with the IERS2010 Conventions.

• Generation of the IVS combined contribution to the

next ITRF for the IERS ITRS Center.

• Inclusion of new Analysis Centers (GFZ, Germany

and CGS, Italy) into the routine rapid combination.

• Design and set-up of the new IVS Combination

Center website [5].

• Refinements of the combination procedure and implementation of source parameter combination.

• Development of an alternative combination procedure using the Bernese GNSS Software; implementation of the basic VLBI combination functions and

preprocessing routines in cooperation with the University of Bonn.

• Participation in a pilot project on digital object

identifiers (DOI) for data in cooperation with

R. Heinkelmann (Deutsches GeoForschungsZentrum, Germany); feasibility investigation for

providing data and meta data.

An initial set of SINEX files for the ITRF generation was submitted to the IERS ITRS Center at the

beginning of December 2014. Ten institutions had submitted their SINEX files in order to contribute to the

combined solution. One of the main tasks in 2014 was

to gather the SINEX contributions and to make sure

that all contributions meet the IVS analysis specifications for ITRF contributions. In the course of the year,

it turned out that the ITRF could be extended by another year, including sessions until the end of 2014

(instead of 2013 as foreseen in the original ITRF call

for participation). With one year of additional data,

an eleventh institution announced its participation. The

challenge in 2014 was to ensure a consistent data quality, homogeneous data contributions, and the set-up of

a combination procedure meeting the IVS specifications, e.g. meeting the IERS2010 standards.

In Figure 1, the data contribution to the next ITRF

is shown. Comparing the institutions contributing to

the ITRF with those contributing to the routine combination listed in Section 4 illustrates the effort coming

along with the ITRF contribution compared to the routine rapid combination. The final deadline for all IERS

Technique Services for the (extended) ITRF contribution is now February 28, 2015.

0

1000

2000

3000

4000

5000

6000

Number of contributed SINEX files

Ins"tu"on

Fig. 1 AC SINEX files provided for the IVS combined solution

for the next ITRF.

Within the past year, the IVS Combination Center

website has been newly designed and set up [5]. The

IVS Combination Center manages a stand-alone website to inform IVS users about VLBI combination deIVS 2014 Annual Report
206 Bachmann et al.

tails such as structure, basics, organization, and the current combination results. The content of these pages is

regularly updated. To best use the technical progress

we did some scale and structure changes. The basis

is now a professional Content Management System

(CMS), which was developed for this purpose. Many

functions and extensions are already disposed in the

CMS and will simplify the future administration. Now,

users are able to fill in an evaluation form about the

Web page content, to search for keywords, to look at

glossary entries, or to print out all information. An

automatic view of the recent combination status and

many other tools were added. Due to these changes and

the new design we will increase the benefit of the IVS.

A screenshot of the newly designed Web site is shown

in Figure 2. The new Web site is planned to go online

within the first half of 2015.

expanded range of func!on 

Fig. 2 Screenshot of the newly designed BKG Combination

Center website.

At DGFI, the following activities were performed

in 2014:

• Update of similarity transformation program.

• Handling of radio source position parameters with

DOGS-CS.

• Validation of input files for ITRF contribution and

evaluation of the weighting procedure within the

combination in cooperation with BKG.

3 Staff

The list of the staff members of the BKG/DGFI Combination Center in 2014 is given in Table 1.

More details on the IVS Combination Center at

BKG can be found in an interview for the IVS Newsletter [6].

4 Current Status

In 2014, six IVS Analysis Centers (BKG, DGFI,

GSFC, IAA, OPA, and USNO) contributed to the IVS

combined rapid and quarterly product (see [5]). The

GFZ (German Research Center for Geosciences) and

CGS (Centro di Geodesia Spaziale, Italy) Analysis

Centers are currently under review and will become

IVS Operational ACs in the near future. The rapid

solutions contain only R1 and R4 sessions, and new

data points are added twice a week as soon as the

SINEX files of at least four IVS Analysis Centers are

available. Long-term series are generated quarterly

and include all 24-h sessions since 1984. The quarterly

series include long-term EOP, station positions, and

velocities. Furthermore, a VLBI TRF is generated and

published. The preprocessing to read and write source

positions was implemented, and the software was

extended to process source parameters. The results

of the combination process are archived by the BKG

Data Center in Leipzig. The combined rapid EOP

series, as well as the results of the quality control of

the Analysis Center results, are also available directly

at the BKG/DGFI Combination Center website [5] or

via the IVS Analysis Coordinator website.

5 Future Plans

In 2015, the work of the BKG/DGFI Combination Center will focus on the following aspects:

• Finishing the extended IVS contribution to the next

ITRF realization: inclusion of the IVS sessions of

one additional year (2014).

• Inclusion of new Analysis Centers (CGS and GFZ)

into the routine rapid and quarterly combination.

IVS 2014 Annual Report
BKG/DGFI Report 2014 207

Table 1 Staff members of the BKG/DGFI Combination Center.

Name Affiliation Function E-Mail

Sabine Bachmann BKG Combination procedure development sabine.bachmann@bkg.bund.de

Linda Messerschmitt BKG Operational combination /Web site maintenance linda.messerschmitt@bkg.bund.de

Mathis Bloßfeld DGFI Combination strategies mathis.blossfeld@tum.de

Michael Gerstl DGFI Software maintenance michael.gerstl@tum.de

Ralf Schmid DGFI Combination strategies schmid@tum.de

• Investigation of the combination of source coordinates for time series of source coordinates and

generation of a combined celestial reference frame

based on VLBI intra-technique combination.

• Establishing the digital object identifier (DOI) for

combined VLBI products in cooperation with GFZ.

References

1. Schwegmann, W., Gerstl, M., Heinkelmann, R., BKG/DGFI

Combination Center Annual Report 2008, in: International

VLBI Service for Geodesy and Astrometry 2008 Annual Report, NASA/TP-2009-214183, D. Behrend and K. D. Baver

(eds.), 250–252, 2009.

2. Nothnagel, A., Bockmann, S., Artz, T.,  ̈ Analysis Coordinator Report, in: International VLBI Service for Geodesy and

Astrometry 2007 Annual Report, NASA/TP-2008-214162,

D. Behrend and K. D. Baver (eds.), 16-17, 2008.

3. Nothnagel, A., Bockmann, S., Artz, T.,  ̈ Analysis Coordinator Report, in: International VLBI Service for Geodesy and

Astrometry 2009 Annual Report, NASA/TP-2010-215860,

D. Behrend and K. D. Baver (eds.), 45–47, 2010.

4. http://ilrs.dgfi.badw.de/fileadmin/dogs/cs manual.ps

DOGS-CS software manual (German version only).

5. http://ccivs.bkg.bund.de/ BKG Combination Center website.

6. Hase, H., BKG/DGFI Combination Center at Frankfurt, IVS

Newsletter 36, 2-3, 2013. http://ivscc.gsfc.nasa.gov/publications/newsletter/issue36.pdf.

IVS 2014 Annual Report
Matera CGS VLBI Analysis Center

Giuseppe Bianco 1, Roberto Lanotte 2

Abstract In this document G. Bianco as primary

contact and R. Lanotte as associate member, both for

the IVS Analysis Center at the Space Geodesy Center

(CGS) of the Italian Space Agency (ASI), report the

VLBI data analysis activities performed from January

2014 through December 2014 and the contributions

that the CGS intends to provide in the future as an IVS

Analysis Center.

1 General Information

The CGS VLBI Analysis Center is located at the Matera VLBI station close to the town of Matera in the

middle south of Italy. The Matera VLBI station became operational at the CGS/ASI in May 1990. Since

then, it has been active in the framework of the most

important international programs. The CGS, operated

by E-GEOS S.p.A. (an ASI/Telespazio company) under an ASI contract, provides full scientific and operational support using the main space geodetic techniques: VLBI, SLR, and GPS. The work presented in

this report is carried out by the E-GEOS staff consisting of Roberto Lanotte and Simona Di Tomaso.

1. Italian Space Agency, Centro di Geodesia Spaziale

2. E-GEOS S.p.A., Centro di Geodesia Spaziale

CGS Analysis Center

IVS 2014 Annual Report

2 Activities during the Past Year

During 2014, the following activities were performed

at CGS:

• Global VLBI Solution cgs2014a.

In the year 2014 we continued the annual realization of a global VLBI solution. This year’s

solution is named cgs2014a and was realized

using the CALC/SOLVE software developed at

NASA/GSFC. The main and final characteristics

of the cgs2014a solution are:

– Data span: 1984.01.04 — 2013.12.26 for a total

of 4,356 sessions

– Estimated Parameters:

· Celestial Frame: Right ascension and declination as global parameters for 969 sources,

· Terrestrial Frame: Coordinates and velocities for 99 stations as global parameters, and

· Earth Orientation: X pole, Y pole, UT1, Xp

rate, Yp rate, UT1 rate, dpsi, and deps.

• IVS Tropospheric Products.

Regular submission of tropospheric parameters

(wet and total zenith path delays, east and north

horizontal gradients) for all VLBI stations observing in the IVS R1 and R4 sessions continued

during 2014. Currently, 1,390 sessions have been

analyzed and submitted, covering the period from

2002 to 2014. The results are available at the IVS

products ftp site.

• Daily Solution Files (DSNX).

This year we started to provide daily sinex files for

the IVS project “Daily EOP + station-coordinates

solutions”. At the present about 5000 sessions have

been analyzed and submitted to IVS.

208
CGS Analysis Center 2014 Annual Report 209

• CGS contribution to IVS combination for

ITRF2013.

About 4,500 VLBI sessions from 1984 to the end

of 2013 have been analyzed following the instructions provided by the IVS Analysis Coordinator,

John Gipson. The produced sinex files have been

submitted to be included in the IVS contribution to

ITRF2013.

• CGS contribution to IERS EOP Operational Series.

Since 2008, CGS has been delivering IERS R1 and

R4 session EOP estimates as a regular contribution

to the IERS EOP operational series.

• Software development.

We started the realization of the software “resolve”.

The main goal of this software is the visual editing

of a VLBI database. One of the reasons that led us

to the development of this software was to have the

capability of work on the output obtained from a

run of SOLVE in BATCH mode. At the present we

have used resolve to edit approximately 5% of the

databases of the daily sinex production.

2.1 Staff at CGS Contributing to the IVS

Analysis Center

• Dr. Giuseppe Bianco, responsible for CGS/ASI

(primary scientific/technical contact).

• Dr. Rosa Pacione, responsible for scientific activities, E-GEOS.

• Dr. Roberto Lanotte, geodynamics data analyst, EGEOS.

• Dr. Simona Di Tomaso, geodynamics data analyst,

E-GEOS.

3 Future Plans

• Continue and improve the realization of our global

VLBI solution, providing its regular update on

time.

• Continue to participate in the IVS analysis projects.

IVS 2014 Annual Report
DGFI Analysis Center Annual Report 2014

Ralf Schmid, Michael Gerstl, Manuela Seitz, Detlef Angermann

Abstract This report presents the activities of the

DGFI Analysis Center during 2014. Besides the

regular IVS submissions, DGFI continued to reprocess

24-hour sessions including the estimation of source

positions. DOGS-RI, the new VLBI analysis software

to be used at DGFI, is near completion.

1 General Information and Component

Description

The DGFI Analysis Center (AC) is located at the German Geodetic Research Institute (Deutsches Geoda- ̈

tisches Forschungsinstitut, or DGFI) in the city center of Munich in Germany. In 2014, DGFI was still an

autonomous and independent research institution affiliated with the Bavarian Academy of Sciences and

Humanities (BAdW) and funded by the Free State of

Bavaria. In January 2015, DGFI became an institute of

the Technische Universitat M ̈ unchen (TUM), and it is  ̈

now called “DGFI-TUM”.

Research performed at DGFI covers many different

fields of geodesy (geometric techniques, gravity field,

Earth system modeling, etc.) and includes the contribution to national and international scientific services

and research projects as well as various functions in

scientific organizations (see http://www.dgfi.tum.de).

DGFI closely cooperates with other TUM institutions

(including personnel at the Geodetic Observatory

Deutsches Geodatisches Forschungsinstitut der Technischen  ̈

Universitat M ̈ unchen (DGFI-TUM)  ̈

DGFI Analysis Center

IVS 2014 Annual Report

Wettzell) and with BAdW within the framework of the

Center of Geodetic Earth System Research (CGE).

DGFI has been acting as an IVS AC since the establishment of the IVS in 1999. Since November 2008,

DGFI has been an operational AC regularly submitting

constraint-free normal equations for 24-hour sessions

in the SINEX format. Since 2008, DGFI has also been

involved in the BKG/DGFI Combination Center.

2 Staff

In 2014, the DGFI AC had to cope with a rather low

number of personnel again, as Manuela Seitz was still

on maternity leave.

Table 1 Staff members and their main areas of activity.

Dr. Detlef Angermann Group leader

Dr. Michael Gerstl Development of the analysis

software DOGS-RI

Dr. Ralf Schmid Routine data analysis, combination

of different space geodetic

techniques

Dr. Manuela Seitz CRF/TRF combination, ICRF3,

(currently on combination of different space

maternity leave) geodetic techniques

The activities of the DGFI AC were more or less

limited to the routine analysis of 24-hour sessions

which have been performed by Ralf Schmid since

the end of May 2013. In addition, Michael Gerstl is

engaged in the development of new VLBI analysis

software called DOGS-RI (DGFI Orbit and Geodetic

Parameter Estimation Software - Radio Interferom210
DGFI Analysis Center 211

etry). Table 1 lists the staff members and their main

areas of activity.

3 Current Status and Activities

Analysis Activities

In 2014, the DGFI AC continued to re-analyze 24-hour

sessions including the estimation of source positions.

Still using the analysis software OCCAM, the period

from April 2008 to June 2011 could be covered. This

means that, at the end of December 2014, consistent

DGFI SINEX files were available from April 2008 to

December 2014.

If operational and reprocessed solutions are

summed up, DGFI analyzed 576 sessions altogether

from seven consecutive years and submitted the

corresponding daily SINEX files to the IVS. Among

them were 212 IVS-R1, 210 IVS-R4, 29 VLBA,

26 EUROPE, 26 IVS-T2, 25 IVS-R&D, 15 CONT14,

13 IVS-OHIG, ten CONT08, seven APSG, and

three CRF sessions (see Table 2).

Table 2 Sessions analyzed in 2014.

Session type 2008 2009 2010 2011 2012 2013 2014 Total

APSG 2 2 2 1 – – – 7

CONT08 10 – – – – – – 10

CONT14 – – – – – – 15 15

CRF 2 1 – – – – – 3

EUROPE 4 6 6 4 – 1 5 26

IVS-OHIG 3 3 2 2 – 3 – 13

IVS-R1 33 51 52 26 – 4 46 212

IVS-R4 36 50 52 26 – 3 43 210

IVS-R&D 6 9 3 4 – 2 1 25

IVS-T2 5 7 7 3 – 4 – 26

VLBA 4 6 6 3 3 2 5 29

Total 105 135 130 69 3 19 115 576

When reprocessing VLBI sessions from former

years, it turned out that some of the databases available

at the IVS Data Centers were incomplete. Table 3

shows the stations whose data were missing. Usually, the absence of a station was connected to a

recorrelation of the session.

In the meantime, all databases were resubmitted by

the responsible agencies and, except for R4498, reanalyzed by the DGFI AC. All solutions could benefit significantly from the additional data.

Table 3 Missing stations in IVS databases prior to reprocessing.

Session Database Missing station(s)

R4498 11SEP01XE Zc

R1471 11FEB21XA Sh, Tc

R4454 10OCT28XE Ma

R4444 10AUG19XE Bd

R4428 10APR29XE Ma, Zc

R4407 09DEC03XE Bd, Zc

R4400 09OCT15XE Wz

R4395 09SEP10XE Tc

R4390 09AUG06XE Ma

R4380 09MAY28XE Bd

R4367 09FEB26XE Ny

R4337 08JUL17XE Zc

R4335 08JUL02XE Kk

R4331 08JUN05XE Ny

R4330 08MAY29XE Bd

R4327 08MAY07XE Sv

In addition, a newly combined multi-year solution

based on VLBI and GNSS observations was set up to

demonstrate the simultaneous realization of ICRS and

ITRS. While the standard deviations of all parameters improve, the combination of LOD seems to shift

the positions of certain VCS-only sources and some

sources observed in RDV sessions, which has to be further investigated.

Software Development

The development of DOGS-RI is still in progress. Detailed comparisons with OCCAM have helped to debug

the new software, and also to detect deficiencies in the

operational OCCAM processing (e.g., files with a priori information were not up-to-date, etc.).

With DOGS-RI, the DGFI AC will have a software

available that follows IERS 2010 Conventions and that

can provide the new nutation parameters (dX, dY). A

lot of time was spent on the proper relativistic calculation of the partial derivatives w.r.t. the parameters. In

many places, difference quotients could be replaced by

time derivatives.

The handling of station coordinates and discontinuities was facilitated, and DOGS-RI will allow a common adjustment of multiple sessions.

IVS 2014 Annual Report
212 Schmid et al.

4 Future Plans

In 2015, we would like to continue reprocessing 24-

hour sessions backward from April 2008. Further detailed comparisons between DOGS-RI and OCCAM

will be necessary before we can switch to the new software.

IVS 2014 Annual Report
GFZ Analysis Center 2014 Annual Report

Robert Heinkelmann 1, Tobias Nilsson 1, James M. Anderson 1, Kyriakos Balidakis 1, Susanne Glaser 2, Maria

Karbon 1, Li Liu 1,3, Cuixian Lu 1, Julian A. Mora-Diaz 1, Virginia Raposo-Pulido 1,4, Benedikt Soja 1, Minghui

Xu 1,3, Harald Schuh 1,2

Abstract This report briefly provides general information and the component description of the IVS Analysis

Center at GFZ. Recent results are mentioned, and the

planned future activities are outlined.

1 General Information

Helmholtz Centre Potsdam, GFZ German Research

Centre for Geosciences is the national research center

for Earth sciences in Germany. Main tasks of GFZ according to its website1

are:

System Earth — Research Focus of the GFZ German Research Center for Geosciences

The Earth is a dynamic planet. Under the influence of

external and internal forces, it is continuously changing.

The solid Earth, the atmosphere, the hydrosphere and the

things living within them are always interacting. In short,

the Earth is a complex system, with forces and interactions between many different partners. To understand the

world in which we live, from our regional environment

to the entire planet, it is necessary to understand how the

System Earth works in all details. In the analysis, we have

to include the activities of mankind and their influence on

the natural processes in this complex, nonlinear system,

which in turn affects the environment we live in.

1. Helmholtz Centre Potsdam, GFZ German Research Centre for

Geosciences, Germany

2. Technische Universitat Berlin, Institute of Geodesy and  ̈

Geoinformation Science, Chair of Satellite Geodesy, Germany

3. Shanghai Astronomical Observatory, Chinese Academy of

Sciences, China

4. Instituto Geografico Nacional, Madrid, Spain  ́

GFZ Analysis Center

IVS 2014 Annual Report

1 http://www.gfz-potsdam.de

The overarching research aim of the GFZ is one of developing strategies and demonstrating practical options,

e.g. to preserve natural resources and to exploit them in

an environmentally friendly way, to guard against natural catastrophes, to assess changes in the climate and the

environment and man’s impact on these, and to research

and utilise our world below ground, all based on a comprehensive understanding of systems and processes.

At this research facility within Department 1 ‘Geodesy

and Remote Sensing’ and Section 1.1 ‘GPS/GALILEO

Earth Observation’ a VLBI group that is an associate

Analysis Center (AC) of IVS has been estabilshed

since the end of 2012.

2 Component Description

GFZ is an associate AC of IVS. We are installing and

automatizing our VLBI analysis process in preparation

for becoming an operational AC. We analyze all incoming geodetic and astrometric types of sessions and

provide interim results in the SINEX format within 24

hours after the provision of database files of version 4

or higher at IVS Data Centers. In 2013 and 2014 we

re-processed all available IVS databases and submitted these for inclusion in the IVS contribution to the

ITRF2014 (formerly ITRF2013). We are also performing as an IVS Combination Center for tropospheric

products [6]2.

2 http://kg6-dmz.gfz-potsdam.de/ivs/php/tropospheric combinati

on.php

213
214 Heinkelmann et al.

3 Staff

The members of the VLBI group and their functions

are listed in Table 1, and a picture of us is displayed as

Figure 1. In 2014, Virginia Raposo-Pulido visited the

Observatoire de Paris, Paris, France, for several months

to cooperate with Nicole Capitaine and Sebastien Lam-  ́

bert on the determination of systematic effects of the

CRF. Julian Mora-Diaz visited the Max Planck Institute for Radio Astronomy, Bonn, Germany, for a few

weeks to determine radio source structure maps together with Alessandra Bertarini.

Since last year (Annual Report 2013) two more scientists and one PhD student joined our VLBI group (in

alphabetical order):

• James M. Anderson, PhD, is a radio astronomer,

who studied at NRAO, USA, and who has been in

the past working e.g. at JIVE, The Netherlands, and

at MPI Bonn, Germany,

• Kyriakos Balidakis, MSc, is a geodesist from Aristotle University in Thessaloniki, Greece, who will

be working on atmospheric modelling for space

geodetic techniques for his PhD, and

• Susanne Glaser, Dr.-Ing., a geodesist from Technische Universitat Dresden, Germany, focussed in the  ̈

past on ITRF computation and combination strategies.

Table 1 Members of the VLBI group at GFZ without MSc students.

Name Main activity

Harald Schuh Head of Department 1 at GFZ

Robert Heinkelmann Head of VLBI group

Tobias Nilsson Head of software development

James Anderson Satellite observations, D-VLBI

Kyriakos Balidakis Atmospheric effects

Susanne Glaser Simulations w.r.t. GGOS

Maria Karbon Kalman filtering, EOP

Li Liu Satellite observations

Cuixian Lu Atmospheric effects

Julian Mora-Diaz CRF, source structure

Virginia Raposo-Pulido CRF, systematic effects

Benedikt Soja Kalman filtering, atmosphere

Minghui Xu CRF

Fig. 1 The GFZ VLBI group and guests in September 2014

for the farewell of our guest Santiago Belda-Palazon (Univer-  ́

sity of Alicante, Spain) and the welcome of Dr. Alexei Lapshin (Moscow State University of Geodesy and Cartography)

at Wirtshaus Moorlake, Berlin-Wannsee. Missing colleagues:

Cuixian Lu and Virginia Raposo-Pulido.

4 Current Status and Activities

• IVS Operational Analysis Center at GFZ

At GFZ we are preparing to become an operational

AC of the IVS. Therefore, starting in mid 2014

we entered into the test phase. In accordance with

the test phase, we are now analyzing all new rapid

turnaround sessions, and we submit our SINEX

files within one day after the version 4 (or higher)

databases become available. Until the end of the

test phase the GFZ contribution is being used for

the official products but with a very small weight

compared to operational ACs. During 2014, routines have been established and have been continuously improved in order to run the complete analysis chain as smoothly as possible, and several steps

(such as downloading files necessary for analysis)

have been completely automated. Doing so, wherever possible we already consider the future VGOS

situation, where many routines applied today will

have to be revised or have to deal with significantly

more data and different data formats. In 2015 we

will continue optimizing these routines, as well as

improving our analysis setup including the valuable

feedback we get from the IVS Combination Center

at BKG. Hopefully we will be accepted as an operational AC in the near future.

• Contribution to ITRF2014

We made a complete reanalysis of all VLBI data

available from IVS servers from 1979 until now. A

part of the results of the reanalysis has been submitted for inclusion in the IVS contribution to the

IVS 2014 Annual Report
GFZ 2014 Report 215

ITRF2014. Statistics of the solution and first results

are presented in [3].

• VLBI Data Analysis using Kalman Filtering

At GFZ we are developing our own version of

the Vienna VLBI Software (VieVS, [1]), named

VieVS@GFZ. Currently, a main part of this work

is the implementation of a Kalman filter as an alternative to the single session least squares solver. The

developments are funded by the research project

VLBI analysis in real-time (VLBI-ART) (Austrian

Science Fund FWF, project no. 24187). In 2014 a

first version of the Kalman filter was completed that

— as we believe — provides results of the same

quality or better than those obtained with the least

squares [4].

• Space Applications

The main research topic of the VLBI group at GFZ

is the analysis of VLBI observations to spacecraft.

Here, in the project Ties between kinematic and

dynamic reference frames (D-VLBI) (Deutsche

Forschungsgemeinschaft DFG, project no. SCHU

1103/4-1) we have been extending our VLBI

analysis software VieVS@GFZ for group delay

and differential VLBI observations to spacecraft,

e.g. GNSS satellites [5], and to extragalactic radio

sources. In 2015, we plan to perform differential

VLBI observations towards various satellites and

interplanetary spacecraft, such as RadioAstron,

Gaia, and GNSS.

• Simulation of the Global Geodetic Observing

System

Within the project GGOS-SIM: Simulation of the

Global Geodetic Observing System 3(DFG, project

no. SCHU 1103/8-1), Dr.-Ing. Susanne Glaser, our

guest scientist from TU Berlin, will perform simulations of all four space geodetic techniques involved in ITRF computation: DORIS, GNSS, SLR,

and VLBI together with colleagues from GFZ at

Oberpfaffenhofen, Germany. The main goal of the

project is to assess to what extent the ITRF can

be improved by involving additional terrestrial colocation stations or by having several techniques

co-located in space, e.g. onboard GRASP (Geodetic Reference Antenna in Space), a planned NASA

mission.

• Twin Telescope Simulations

3 http://www.earth.tu-berlin.de/menue/forschung/projekte/ggossim

We have tested advanced analysis methods by performing simulations for the future VGOS network

in cases where stations operate more than one antenna, e.g. so-called twin telescopes. More specifically, we investigated to what extent it is possible

to combine the tropospheric parameters of these antennas in order to improve the data analysis. We

found that this approach improves the estimated

station coordinates as long as the separation between the antennas is smaller than about 1 km

[8, 9].

• Homogenization of Pressure Data

In 2014, we started a process of calibration and

homogenization of the long time series of pressure measurements (and other meteorological

parameters) recorded at the IVS stations. This will

be achieved involving pressure from numerical

weather prediction models as well as measurements from surrounding WMO meteorological

stations. At the end of the process we will have

identified and removed biases, jumps, and other

inhomogeneities in the long pressure time series,

and at the same time we will have calibrated the

mean value which will improve the accuracy. It is

very important to have high quality pressure measurements for the VLBI data analysis for obtaining

accurate zenith wet delay estimates because these

parameters correlate with other parameters such as

station coordinates [2].

• Celestial Reference Frame

Several studies related to improving the celestial

reference frame (CRF) were performed. For example, we have studied the apparent proper motion of

the ICRF2 special handling and other radio sources

[7] and obtained source structure maps. Other subjects in this context were considerations about the

datum definition [10, 11] and about the CRF systematics, such as the aberration caused by the acceleration of the ICRS origin [13]. Part of the work

done here was funded by the project ECORAS - extension of the coordinate parameterization of radio

sources observed by VLBI (DFG, project no. HE

5937/2-1).

• Solar Corona Modeling

In 2014 we continued studies related to measuring

the electron density of the solar corona by VLBI

observations angularly close to the Sun. The innovative approach and results are highlighted in [12].

IVS 2014 Annual Report
216 Heinkelmann et al.

5 Future Plans

The following activities are planned for 2015:

• Continuing our current investigations.

• Furthering the development of the software

VieVS@GFZ. In particular we want to implement the bandwidth synthesis ambiguities

and ionospheric delay determination as part of

our VieVS@GFZ version. Development is also

foreseen for preparing the software for VGOS.

Acknowledgements

We are grateful to the Austrian Science Fund (FWF)

and to the German Research Foundation (DFG) for

funding our projects, and we acknowledge the invaluable contributions of the other IVS components that enable our work.

References

1. J. Bohm, S. B  ̈ ohm, T. Nilsson, A. Pany, L. Plank,  ̈

H. Spicakova, K. Teke, and H. Schuh. The new Vienna VLBI software. In S. Kenyon, M. C. Pacino, and

U. Marti, editors, IAG Scientific Assembly 2009, number

136 in International Association of Geodesy Symposia,

pages 1007–1011, Buenos Aires, Argentina, 2012. Springer.

doi:10.1007/978-3-642-20338-1_126.

2. R. Heinkelmann, J. Bohm, H. Schuh, and V. Tesmer. The  ̈

effect of meteorological input data on the VLBI reference

frames. In H. Drewes, editor, Geodetic Reference Frames,

number 134 in International Association of Geodesy Symposia, pages 245–251, Munich, Germany, 2009. Springer.

doi:10.1007/978-3-642-00860-3_38.

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Mora-Diaz, E. Parselia, V. Raposo-Pulido, B. Soja, M. Xu,

and H. Schuh. The GFZ VLBI solution - characteristics and

first results. In D. Behrend, K. D. Baver, and K. Armstrong,

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H. Schuh. ERP estimation using a Kalman filter in VLBI.

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U. Schreiber, S. Pogrebenko, G. Kronschnabl, J.A. MoraDiaz, B. Soja, M. Karbon, C. Lu, V. Raposo-Pulido, and

H. Schuh. New progress in VLBI tracking of GNSS satellites at GFZ. In D. Behrend, K. D. Baver, and K. Armstrong,

editors, Proceedings of the Eighth IVS General Meeting:

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978-7-03-042974-2.

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and H. Schuh. IVS rapid tropospheric parameter recombination and comparison with GNSS products. In

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H. Schuh. Modeling special handling source positions in

the GFZ VLBI solution. In D. Behrend, K. D. Baver, and

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C. Lu, J. A. Mora-Diaz, V. Raposo-Pulido, M. Xu, and

H. Schuh. Atmospheric modeling in the data analysis of

twin telescope observations. In D. Behrend, K. D. Baver,

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39, 2014. ISBN 978-7-042974-2.

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and H. Schuh. Atmospheric modeling for co-located VLBI

antennas and twin telescope. J. Geodesy, 2014. submitted.

10. V. Raposo-Pulido, R. Heinkelmann, T. Nilsson, M. Karbon,

B. Soja, E. Tanır Kayıkc ̧ı, C. Lu, J. Mora-Diaz, H. Schuh,

and J. Gomez-Gonz  ́ alez. Effects of the datum configuration  ́

of radio sources on EOP determined by VLBI. In N. Capitaine, editor, Proceedings of the Journees 2013 ”Syst  ́ emes `

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M. Xu, T. Nilsson, M. Karbon, L. Liu, C. Lu, B. Soja, and

H. Schuh. Datum effects on the stability of the celestial

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IVS 2014 Annual Report
BKG/IGGB VLBI Analysis Center

Volkmar Thorandt 1, Thomas Artz 2, Gerald Engelhardt 1, Dieter Ullrich 1, Sebastian Halsig2, Christoph Holst2,

Andreas Iddink2, Judith Leek 2, Axel Nothnagel 2

Abstract In 2014, the activities of the BKG/IGGB

VLBI Analysis Center, as in previous years, consisted

of routine computations of Earth orientation parameter (EOP) time series and of a number of research topics in geodetic VLBI. The VLBI group at BKG continued its regular submissions of time series of tropospheric parameters and the generation of daily SINEX

(Solution INdependent EXchange format) files. Quarterly updated solutions were computed to produce terrestrial reference frame (TRF) and celestial reference

frame (CRF) realizations. The analysis of all Intensive

sessions for UT1–UTC estimation was continued. Additionally, the BKG Analysis Center has generated input in the form of daily SINEX files for the ITRF2014

VLBI combination solution. All solutions are based on

the new Calc/Solve software, release 2014.02.21 [1],

following the IERS2010 conventions. At IGGB, the

emphasis has been placed on individual research topics.

1 General Information

The BKG/IGGB VLBI Analysis Center was established jointly by the analysis groups of the Federal

Agency for Cartography and Geodesy (BKG), Leipzig,

and the Institute of Geodesy and Geoinformation of

the University of Bonn (IGGB). Both institutions cooperate intensely in the field of geodetic VLBI. The responsibilities include both data analysis for generating

1. BKG

2. IGGB

BKG/IGGB Analysis Center

IVS 2014 Annual Report

IVS products and special investigations with the goal

of increasing accuracy and reliability. BKG is responsible for the computation of time series of EOP and

tropospheric parameters, for the generation of SINEX

files for 24-hour VLBI sessions and one-hour Intensive

sessions, and for the generation of quarterly updated

global solutions for TRF and CRF realizations. Besides

data analysis, the BKG group is also responsible for

writing schedules for the Int2 UT1-UTC observing sessions. Details of the research topics of IGGB are listed

in Section 3.

2 Data Analysis at BKG

At BKG, the Mark 5 VLBI data analysis software system Calc/Solve, release 2014.02.21 [1], has been used

for VLBI data processing. It is running on a Linux

operating system. Calc/Solve allows generation of socalled TRP files derived from the Vienna Mapping

Function (VMF1) data. They contain external information about the troposphere on a scan-by-scan basis,

specifically the a priori delay, dry and wet mapping

functions, and gradient mapping functions. The BKG

VLBI group uses TRP files to input data related to

VMF1. The VMF1 data were downloaded daily from

the server of the Vienna University of Technology. Additionally, the technological software environment for

Calc/Solve was refined to link the Data Center management with the pre- and post-interactive parts of the

EOP series production and to monitor all Analysis and

Data Center activities.

• Processing of correlator output

The BKG group continued the generation of calibrated databases for the sessions correlated at the

217
218 Thorandt et al.

MPIfR/BKG Astro/Geo Correlator at Bonn (e.g.,

EURO, OHIG, and T2) and submitted them to the

IVS Data Centers.

• Scheduling

BKG continued scheduling the Int2 Intensive

sessions, which are observed on the TSUKUBAWETTZELL baseline. Altogether, 102 schedule

files for this baseline were created in 2014. Due to

maintenance of the TSUKUBA antenna, two schedule files for baseline KASHIM34-WETTZELL

were also made available.

• BKG EOP time series

The BKG EOP time series bkg00013 was replaced

by a new one, bkg00014. One main difference to

the former solution was the use of the IERS2010

conventions. Further, two new VLBI stations (SEJONG in Korea and TIANMA65 in China) could

be included successfully in data processing.

Each time after the preprocessing of any new

VLBI session (correlator output database version

1), a new global solution with 24-hour sessions

since 1984 was computed, and the EOP time

series bkg00014 was extracted. Altogether, 4,728

sessions were processed. The main parameter

types in this solution are globally estimated station

coordinates and velocities together with radio

source positions. The datum definition was realized

by applying no-net-rotation and no-net-translation

conditions for 25 selected station positions and

velocities with respect to VTRF2008a and a

no-net-rotation condition for 295 defining sources

with respect to ICRF2. The station coordinates of

the telescopes AIRA (Japan), CHICHI10 (Japan),

CTVASTJ (Canada), DSS13 (USA), HART15M

(South Africa), KASHIM11 (Japan), KASHIM34

(Japan), KOGANEI (Japan), KUNMING (China),

PT REYES (USA), SEJONG (Korea), SEST

(Chile), SINTOTU3 (Japan), TIANMA65 (China),

TIGOCONC (Chile), TSUKUB32 (Japan),

UCHINOUR (Japan), VERAISGK (Japan),

VERAMZSW (Japan), WIDE85 3 (USA), and

YEBES40M (Spain) were estimated as local

parameters in each session.

• BKG UT1 Intensive time series

The UT1-UTC Intensive time series bkgint09

was replaced by bkgint14 in consideration of the

IERS2010 conventions. The series bkgint14 was

generated with fixed TRF (VTRF2008a) and fixed

ICRF2. The a priori EOP were taken from final

USNO series [2]. The estimated parameter types

were only UT1-TAI, station clock, and zenith

troposphere.

The algorithms of the semi-automatic process for

handling the Intensive sessions Int2/3 with station

TSUKUBA after the Japan earthquake [3] were

further used; i.e. before the regular analysis can

be started, the most probable station positions of

TSUKUBA for the epochs of the Int2/3 sessions

have to be estimated.

A total of 4,963 UT1 Intensive sessions were analyzed for the period from 1999.01.01 to 2014.12.31.

• Quarterly updated solutions for submission to

IVS

In 2014, one quarterly updated solution was computed for the IVS products TRF and CRF. There

are no differences in the solution strategy compared to the continuously computed EOP time series bkg00014. The results of the radio source positions were submitted to IVS in IERS format. The

TRF solution is available in SINEX format, version

2.1, and includes station coordinates, station velocities, and radio source coordinates together with the

covariance matrix, information about constraints,

and the decomposed normal matrix and vector.

• Tropospheric parameters

The VLBI group of BKG continued regular submissions of long time series of tropospheric parameters to the IVS (wet and total zenith delays and

horizontal gradients) for all VLBI sessions since

1984. The tropospheric parameters were extracted

from the standard global solution bkg00014 and

transformed into SINEX format.

• Daily SINEX files

The VLBI group of BKG also continued regular

submissions of daily SINEX files for all available

24-hour sessions for the IVS combined products

and for the IVS time series of baseline lengths. In

addition to the global solutions, independent session solutions (bkg2014a) with the new models

mentioned above were computed for the station coordinates, radio source coordinates except for 295

defining sources of ICRF2, and EOP parameters including the X,Y-nutation parameters. The a priori

datum for TRF is defined by the VTRF2008a, and

ICRF2 is used for the a priori CRF information.

• SINEX files for Intensive sessions

By using IERS2010 conventions, a new set of

SINEX files for all Intensive sessions (bkg2014a)

IVS 2014 Annual Report
BKG/IGGB VLBI Analysis Center 219

was generated. The parameter types are station

coordinates, pole coordinates and their rates,

and UT1-TAI and its rate. But only the normal

equations stored in the SINEX files are important for further intra-technique combination or

combination with other space geodetic techniques.

• Contribution to ITRF2014

The BKG Analysis Center submitted 4,728 SINEX

files for 24-hour sessions (bkg2014a.snx itrf2013)

to IVS as input to a combined VLBI solution for

ITRF2014.

3 Research Topics at IGGB

• Development of automatic scheduling

In the last years, an automatic scheduling method

which is based on the so-called impact factors of

the observations was developed at IGGB. These

factors are closely related to the covariance matrix of the observations. Although 24-hour multibaseline sessions can be scheduled, the main focus of the investigations is given to Intensive sessions with two or three telescopes and observing

durations of only one hour. The procedure has been

optimized further, and first schedules have actually

been observed in 2014 showing promising results.

At first glance, all standard deviations of the UT1-

TAI estimates from observations scheduled with

impact factors are small with no outliers compared

to those from the standard approach. Further work

has to be done to successfully apply the procedure

to 24-hour sessions.

• Application of inequality constraints

When estimating zenith wet delays (ZWD) using

the zenith hydrostatic delays (ZHD) as a priori information in a VLBI estimation process, sometimes

negative values are present. But negative values

do not correspond to actual meteorological conditions and physical properties. An Inequality Constrained Least Squares adjustment from the field of

convex optimization has been applied to the VLBI

data analysis to constrain these parameters to be

non-negative. But deficiencies in the a priori ZHDs,

for example due to missing or incomplete pressure

data, are compensated by the ZWD estimates to

close to 100%. For this purpose, different strategies

to improve the a priori information have been investigated and adapted to the VLBI data analysis.

First results are shown in [4].

• Modifying the stochastic model

Routinely, the stochastic model in VLBI data analysis only includes uncertainties from the VLBI correlation process. But dynamic processes in the atmosphere also lead to elevation-dependent uncertainties and induce physical correlations between

the observations. Thus, the formal errors for the

derived VLBI parameters are too optimistic. For

this purpose, the standard stochastic information is

augmented by a variance-covariance matrix derived

from an atmospheric turbulence model [10], which

is based on the Kolmogorov turbulence theory. Several solution setups with regard to differnt turbulence parametrizations have been applied to the

CONT11 VLBI campaign. First results have shown

that the WRMS post-fit residuals decrease and the

baseline length repeatabilities improve slightly. But

only minor variations between the different solution setups could be observed [5].

• Determination of an ICRF combination approach including Ka-band catalogs

The ICRF1 and ICRF2 were computed as monolithic dual frequency S/X-band (2.3/8.4 GHz)

solutions from a single Analysis Center using a

single analysis software package. In addition to an

improved precision one of the main objectives for

the upcoming realization of the ICRF3 is enhanced

frequency coverage compared to the ICRF2. By

including solutions with full variance-covariance

information based on X/Ka-band (8.4/32 GHz)

observations in a rigorous VLBI intra-technique

combination, an improved frequency coverage can

be realized. A method to mix the combination on

the level of datum free normal equation systems

and on the solution level with full covariance

information has been developed and implemented

in the existing combination software BonnSolutionCombination (BoSC) developed at IGGB

[6]. Preliminary results of a combined S/X- and

X/Ka-band catalog verify the correct functionality.

• Studies on VLBI observations of satellites

Observing moving targets, such as e.g., Earth orbiting satellites, with radio telescopes is not new.

But for the future, important investigations have to

be done to observe artificial sources routinely. At

IGGB, the scheduling procedure described above

was extended to handle artificial sources. In this

IVS 2014 Annual Report
220 Thorandt et al.

way, schedules for geostationary satellites [7] as

well as global navigation satellite system (GNSS)

satellites were created. To assess the various schedules, observations were simulated based on clock

noise and atmospheric noise as well as baseline dependent noise terms. From these observations, orbit

shifts were estimated and compared.

• Improved deformation analysis of the Effelsberg

100-m radio telescope

In 2013, an improved measurement concept was

built up to scan the main reflector of the Effelsberg

100-m radio telescope in seven different elevation

angles between 90◦and 7.5◦[8]. During the scan

procedure, the scanner was mounted directly below

the subreflector. This position enabled sampling of

the main reflector in a single scan with almost no

shadowing effects. Based on these measurements,

an upgraded data processing containing object segmentation, point cloud reduction, and laser scanner self-calibration has been implemented. This improves the accuracy and the reliability of the derived estimates representing focal length variations

as well as local, area-based, and elevation dependent deformations on the main reflector’s surface.

As a result, the focal length of the 100-m radio telescope Effelsberg decreases by 22.7 mm when tilting the telescope from 90◦

to 7.5◦. Area-based deformations of ±2 mm have been detected as well

at certain areas. Furthermore, the misalignment of

several surface panels has been revealed.

• Delay corrections for deforming radio telescopes

Gravitational deformation of radio telescopes is another source of uncertainty of geodetic and astrometric VLBI. In a study, which also includes the

development of a ray tracing program, a complete

model of gravitationally induced path length deviations was developed. It includes delay correction

components for all deformable parts of a radio telescope. Using information of the improved deformation analysis reported above and other auxiliary

measurements, a complete delay model was published for the Effelsberg 100-m radio telescope [9].

4 Personnel

Table 1 Personnel at the BKG/IGGB Analysis Center

Thomas Artz IGGB +49-228-733563 artz@igg.uni-bonn.de

Gerald Engelhardt BKG +49-341-5634438 gerald.engelhardt@bkg.bund.de

Sebastian Halsig IGGB +49-228-732623 halsig@igg.uni-bonn.de

Christoph Holst IGGB +49-228-733570 holst@igg.uni-bonn.de

Andreas Iddink IGGB +49-228-732623 iddink@igg.uni-bonn.de

Judith Leek IGGB +49-228-733565 judith.leek@igg.uni-bonn.de

Axel Nothnagel IGGB +49-228-733574 nothnagel@uni-bonn.de

Volkmar Thorandt BKG +49-341-5634285 volkmar.thorandt@bkg.bund.de

Dieter Ullrich BKG +49-341-5634328 dieter.ullrich@bkg.bund.de

Reiner Wojdziak BKG +49-341-5634286 reiner.wojdziak@bkg.bund.de

References

1. GSFC, NASA (2014): Release of Mark 5 VLBI Analysis

Software Calc/Solve from February 21, 2014 (Web reference: http://gemini.gsfc.nasa.gov/solve).

2. USNO (2014): Earth orientation parameters series from finals USNO series 2014, (Web reference:

http://gemini.gsfc.nasa.gov/500/oper/solve apriori files/usno

finals.erp).

3. Engelhardt G, Thorandt V, Ullrich D (2013): Rapid UT1 Estimation Derived from Tsukuba VLBI Measurements after

2011 Earthquake. In: Proceedings of the 21st Meeting of the

European VLBI Group for Geodesy and Astronomy 2013,

edited by N Zubko and M Poutanen, pages 85-87, Kirkkonummi 2013, Finland

4. Halsig S, Artz T, Nothnagel A (2015): Improved Parameter

Estimation of Zenith Wet Delay Using an Inequality Constrained Least Squares Method. In: IAG Symposia Series,

vol. 43, in press

5. Halsig S, Artz T, Leek J, Nothnagel A (2014): VLBI analyses using covariance information from turbulence models.

In: Proceedings of the IVS General Meeting 2014, edited by

D Behrend, KD Baver, and KL Armstrong, pages 272-276,

Science Press 2014, China

6. Iddink A, Artz T, Nothnagel A (2015): Development of a

Combination Procedure for Celestial Reference Frame Determination. In: IAG Symposia Series, vol. 43, in press

7. Artz T, Leek J, La Porta L, Nothnagel A (2015): Scheduling Scenarios for VLBI Observations of Satellites. In: IAG

Symposia Series, vol. 43, in press

8. Holst Ch, Nothnagel A, Blome M, Becker P, Eichborn

M, Kuhlmann H (2015): Improved area-based deformation

analysis of a radio telescope’s main reflector based on terrestrial laser scanning. J. Appl. Geodesy, in press

9. Artz T, Springer A, Nothnagel A (2014) A complete VLBI

delay model for deforming radio telescopes: the Effelsberg

case. J Geod, 88(12):1145—1161, DOI 10.1007/s00190-

014-0749-1

10. Brunner FK, Schon S (2008): Atmospheric turbulence the-  ̈

ory applied to GPS carrier-phase data. J Geod, 82:47-57,

DOI: 10.1007/s00190-007-0156-y

IVS 2014 Annual Report
GSFC VLBI Analysis Center Report

David Gordon 2, Chopo Ma 1, Dan MacMillan 2, John Gipson 2, Sergei Bolotin 2, Karine Le Bail 2, Karen Baver 2

Abstract This report presents the activities of the

GSFC VLBI Analysis Center during 2014. The GSFC

VLBI Analysis Center analyzes all IVS sessions,

makes regular IVS submissions of data and analysis products, and performs research and software

development aimed at improving the VLBI technique.

1 Introduction

The GSFC VLBI Analysis Center is located at NASA’s

Goddard Space Flight Center in Greenbelt, Maryland.

It is part of a larger VLBI group which also includes

the IVS Coordinating Center, the CORE Operation

Center, a Technology Development Center, and a

VGOS Station. The Analysis Center participates in

all phases of geodetic and astrometric VLBI analysis,

software development, and research. We maintain a

Web site at http://lupus.gsfc.nasa.gov. We provide

a pressure loading service to the geodetic community, a ray tracing service, and additional services

for hydrology loading, nontidal ocean loading, and

meteorological data. These services can be found by

following the links on the GSFC VLBI group Web

site: http://lupus.gsfc.nasa.gov/dataresults main.htm.

1. NASA Goddard Space Flight Center

2. NVI, Inc./NASA Goddard Space Flight Center

GSFC Analysis Center

IVS 2014 Annual Report

2 Analysis Activities

The GSFC VLBI Analysis Center analyzes all IVS sessions using the Calc/Solve/νSolve systems, and performs the fourfit fringing and Calc/Solve analysis of

the VLBA-correlated RDV sessions. The group submitted the analyzed databases to IVS for all R1, RDV,

R&D, CONT14, AUST, INT01, and INT03 sessions.

During 2014, GSFC analyzed 198 24-hour sessions

(51 R1, 51 R4, seven RDV, three R&D, 15 CONT14,

48 AUST, six EURO, four T2, five OHIG, three CRF,

and five CRDS) and 376 one-hour UT1 sessions (229

INT01, 99 INT02, and 48 INT03), and we submitted

updated EOP and daily Sinex files to IVS immediately

following analysis. We also generated a solution for the

ITRF2013 IVS combination solution.

3 Research Activities

• Source Monitoring: We continued monitoring

sources observed in different categories: ICRF2,

geodetic, ICRF2 non-geodetic, special handling,

and Gaia link sources (categories 1 to 4). The

geodetic sources have a target of 12 sessions per

year, the ICRF2 sources five per year, the special

handling six per year, and the Gaia link sources 12

per year.

• Gaia Transfer Sources: In 2014, we continued to

monitor the 195 Gaia link sources proposed by Bordeaux Observatory, setting a target of 12 observations per year. Thirty-three of these can only be detected in R&D and RDV sessions because they are

weak sources. The Gaia link source position uncertainties were all improved, and most are now better

221
222 Gordon et al.

than 100 μas. But seven of the weakest category 4

sources still have large position uncertainties. We

also updated the sked flux catalog with more realistic values from recent observations.

• Source Name Translation Table: A source name

translation table was compiled from different files:

IERS TN35, the Calc/Solve blokq file, the latest

GSFC source catalog, the NRAO SCHED catalog, the RFC catalog, and the JPL X/Ka catalog.

This table specifies IVS, J2000 (long and short),

IERS/B1950, and JPL names, as well as coordinates in J2000 and first date of observation. More

information and access to the file can be found

following this link: http://lupus.gsfc.nasa.gov/IVSAC data information.htm, under the name “official

IVS source name and translation table”.

• Stability of ICRF2: In 2010, we presented a method

to analyze source position time series and evaluate

the statistical time stability of sources, and we generated stability index functions. At the IVS 2014

General Meeting, we presented a a re-evaluation of

this work, using the latest GSFC source time series, and compared it to the solution computed in

2009. We showed how five more years of data can

strengthen statistical studies. For 3C418, for example, the Allan variance showed a threshold of 50

μas for the noise level (flicker noise) for both coordinates in 2010. With five more years of data, the

threshold is passed, and the declination white noise

reaches a level of 10 μas. We also showed that the

ICRF2 defining sources realize a more stable frame,

suggesting that the solutions are getting more consistent, and the latest solution shows better statistical stability.

• Second Epoch VCS Observations: A proposal to reobserve up to 2,400 VCS (VLBA Calibrator Survey) sources on the VLBA was begun. The investigators are D. Gordon (PI), C. Ma, six other IVS

members, and two NRAO astronomers. Six of the

eight 24-hour sessions were run in 2014. Of 1,800

sources observed, 1,556 sources were re-observed,

and 231 new sources were detected. For the reobserved sources, position formal errors were reduced by a factor of ∼3.2 in both RA and Declination.

• Galactic aberration: The aberration acceleration

vector estimated from VLBI has a large component

in the direction of the Galactic center due to the

rotation of the Solar System barycenter around the

Galactic center. Our estimate of this component

is 5.3 ±0.3 μas/year, which is close to estimates

from parallax measurements (Reid et al., [Ap J,

783:130, 2014] estimated 4.9 ±0.4 μas/year.).

Our estimated aberration vector has a significant

component, 1.7 ±0.4 μas/year, perpendicular to

this direction, which at this point is unexplained.

• Intensive Scheduling: Since mid-2010, two alternating strategies have been used to schedule the

IVS-INT01 sessions: the original strategy (‘STN’)

and the Maximal Source Strategy or MSS. The

STN emphasizes source strength over sky coverage, using a catalog with a small number of strong

sources, while the MSS emphasizes sky coverage

over source strength, using a catalog of all the

geodetic sources. In 2014, we investigated the use

of catalogs with intermediate numbers of sources

and different balances of source strength and sky

coverage. We also used two different approaches to

generating source catalogs: using a certain number

of sources best for observing throughout the year

and a certain number of sources best for observing at specific times of the year. We conducted two

studies. The first one determined that smaller numbers of sources tend to be better in each approach,

and the second one indicated the best number of

sources in each approach. We plan to examine the

cases identified in the second study in more detail

during 2015.

• High Frequency EOP: We estimated an empirical

model of diurnal and semi-diurnal Earth Rotation

(‘HF-EOP’) derived from 35 years of VLBI data,

and we compared the results against other models derived from Space Geodesy (SG) using GPS

and/or VLBI, as well as results derived from various satellite altimetry tidal models (‘tidal models’).

Overall there was good agreement among the empirical SG HF-EOP models, as well as HF-EOP

models derived from altimetry data. A difference

between the two classes of models is that the SG

HF-EOP models are generally given in terms of the

amplitudes and phases of 71 terms in the tidal potential. In contrast the altimetry derived models are

given in terms of 12 ortho-tides. We directly estimated the ortho-tide coefficients from VLBI data.

Comparing a time series generated using these two

approaches, we found that the orthotide formalism

does not capture all of the signal. Increasing the

IVS 2014 Annual Report
GSFC Analysis Center 223

number of ortho-tide terms to 20 reduces but does

not eliminate the residual signal.

• Troposphere Raytracing: We investigated the

calculation of troposphere ray trace delays along

the signal path through the troposphere for each

VLBI observation and their application in VLBI

analysis. Tropospheric refractivity fields were

determined from the pressure, temperature, specific humidity, and geopotential height fields of

the NASA GSFC GEOS-5 numerical weather

model. Compared with VMF1, baseline length

and vertical site repeatabilities were improved

for 72% of baselines and 11 of 13 sites for the

CONT11 data set as well as for a larger data set

(2011-2013). A ray tracing service provides ray

trace delays for all VLBI sessions since 2000 at

http://lacerta.gsfc.nasa.gov/tropodelays.

• Hydrology Loading: We found that VLBI analysis results are improved if hydrology loading is

modeled. Hydrology loading series were calculated

from 1) the GSFC GLDAS hydrology model data

or 2) GRACE (Gravity Recovery and Climate Experiment) mascon data. Applying either series in

VLBI analysis yielded a reduction in 1) baseline

length repeatabilities for 80% of baselines, 2) site

vertical repeatabilities for 80% of sites, and 3) annual site vertical amplitudes for 90% of sites. The

GLDAS loading series for VLBI sites are available

at http://lacerta.gsfc.nasa.gov/hydlo.

• Update of Meteorological Data Web Service: We

continued updating the meteorological data Web

service (http://lacerta.gsfc.nasa.gov/met) with the

latest data from ECMWF. The last data processed

is December 31, 2014. This website contains time

series (1979 to end of 2014) of pressure and temperature for 171 VLBI stations.

• Network Connectivity: We investigated network

connectivity to see if this could provide us with

insight into past performance or future scheduling

of networks. We looked at several questions, such

as how the VLBI networks have evolved; what

stations observe most frequently with other stations; whether there are stations that are relatively

isolated from the rest of the VLBI networks and

what effect this has, and whether or not the relative

number of successful observations between two

sites can be computed. Although this work has not

yet led to any conclusions, a by-product has been

the development of tools to display networks and

to interactively rotate figures of them on the screen.

• SGP Future Network Simulations: We have continued collaborating with Erricos Pavlis and Magda

Kuzmicz-Cieslak (UMBC) to optimize the choice

of a global network of co-located technique sites

and specifically to decide where NASA should establish new sites. The VLBI observation and solution setup input was provided to the Geodyn software for SLR+VLBI+GPS combination solutions.

The simulation input is for a broadband-only network and several mixed broadband/legacy station

networks, which we consider a reasonable expectation of observing in five years. We are working on

the simulation input for the future network in ten

years, which is expected to have about 30 broadband antennas.

4 Software Development

The GSFC VLBI Analysis Center develops and

maintains the Calc/Solve analysis system, a package of

∼120 programs and 1.2 million lines of code. During

2014, we switched over to version 11 of Calc, which

complies with the IERS 2010 Conventions.

νSolve is a part of the next generation VLBI

data analysis software. It is being developed as a

replacement for interactive SOLVE. νSolve is now

the standard tool for initial processing of routine

VLBI sessions at GSFC, and it was used to analyze

the first experimental broadband (VGOS) VLBI

observations. Also, an automated processing mode

for Intensive sessions was developed and is being

tested. A User Guide was also written. The first public

release of νSolve was made in 2014. It is available at:

ftp://gemini.gsfc.nasa.gov/pub/misc/slb/.

5 Staff

During 2014, the Analysis Center staff consisted of one

GSFC civil servant, Dr. Chopo Ma, and six NVI, Inc.

employees who work under contract to GSFC. We also

had two temporary student interns from Chalmers University of Technology (Sweden). Dr. Ma oversees the

GSFC VLBI project for GSFC and is also the IVS

IVS 2014 Annual Report
224 Gordon et al.

co-representative to the IERS. Dr. John Gipson is the

GSFC VLBI Project Manager as well as the IVS Analysis Coordinator. Table 1 lists the staff members and

their main areas of activity.

Table 1 Staff members and their main areas of activity.

Ms. Karen Baver Intensive analysis, monitoring,

and improvement; software development; Web site development; quarterly Nuvel updates.

Dr. Sergei Bolotin Database analysis, νSolve development, vgosDB development,

ICRF3.

Dr. John Gipson High frequency EOP, parameter estimation, vgosDB development, station dependent noise.

Dr. David Gordon Database analysis, RDV analysis, ICRF3, astronomical source

catalogs, VCS-II observations,

calc/difxcalc development, quarterly ITRF updates.

Dr. Karine Le Bail Source monitoring, time series

statistical analysis (EOP, nutation, source positions), database

meteorological data analysis.

Dr. Chopo Ma ICRF3, CRF/TRF/EOP, VGOS

development.

Dr. Daniel MacMillan CRF/TRF/EOP, mass loading,

antenna deformation, aberration,

VGOS and SGP simulations,

VLBI/SLR/GPS combinations.

Ms. Linnea Hesslow (Intern)High frequency EOP, network

connectivity.

Ms. Emma Woxlin (Intern)Station stabilities, vgosDB development.

6 Future Plans

Plans for the next year include ICRF2 maintenance,

second epoch VCS observations and analysis, preparations for ICRF3, participation in VGOS development,

continued development of νSolve and the new vgosDB

data format, and further research aimed at improving

the VLBI technique.

7 Publications

‘Tropospheric Delay Raytracing Applied in VLBI

Analysis’, David Eriksson, D.S. MacMillan, John

M. Gipson, J. Geophys. Res. Solid Earth, 119,

doi:10.1002/2014JB011552, 2014.

‘Continental Hydrology Loading Observed

by VLBI Measurements’, David Eriksson

and D.S. MacMillan, J. Geod., 88:675-690,

doi:10.1007/s00190-014-0713-0, 2014.

‘IVS Working Group IV and the New Open Format Database’, John Gipson, IVS 2014 General Meeting Proceedings; D. Behrend, K. D. Baver, K. L. Armstrong (editors); p. 248-252, 2014.

‘The VLBI Analysis Software νSolve: Development Progress and Plans for the Future’, S. Bolotin,

K. Baver, J, Gipson, D. Gordon, D. MacMillan, IVS

2014 General Meeting Proceedings; D. Behrend, K. D.

Baver, K. L. Armstrong (editors); p. 253-257, 2014.

‘Balancing Sky Coverage and Source Strength in

the Improvement of the IVS-INT01 Sessions’, Karen

Baver, John Gipson, IVS 2014 General Meeting Proceedings; D. Behrend, K. D. Baver, K. L. Armstrong

(editors); p. 267-271, 2014.

‘Troposphere Delay Raytracing Applied in VLBI

Analysis’, David Eriksson, Daniel MacMillan, John

Gipson, IVS 2014 General Meeting Proceedings; D.

Behrend, K. D. Baver, K. L. Armstrong (editors); p.

279-282, 2014.

‘Revisiting the VLBA Calibrator Surveys for

ICRF3’, David Gordon, IVS 2014 General Meeting Proceedings; D. Behrend, K. D. Baver, K. L.

Armstrong (editors); p. 386-389, 2014.

‘The NASA Goddard Group’s Source Monitoring

Database and Program’, John Gipson, Karine Le Bail,

Chopo Ma, IVS 2014 General Meeting Proceedings;

D. Behrend, K. D. Baver, K. L. Armstrong (editors); p.

390-394, 2014.

‘Evaluation of the Stability of ICRF2 in the Past

Five Years Using the Allan Variance’, Karine Le Bail,

David Gordon, John Gipson, IVS 2014 General Meeting Proceedings; D. Behrend, K. D. Baver, K. L. Armstrong (editors); p. 395-398, 2014.

IVS 2014 Annual Report
Haystack Observatory Analysis Center

Arthur Niell, Roger Cappallo, Brian Corey, Mike Titus

Abstract Analysis activities at Haystack Observatory

are directed at improving the accuracy of geodetic measurements, whether these are from VLBI, GNSS, SLR,

or any other technique. Those analysis activities that

are related specifically to technology development are

reported elsewhere in this volume for the Haystack IVS

Technology Development Center, although sometimes

the distinction is not clear. In this article we describe

upgrades to the VGOS signal chain instrumentation at

GGAO12M and Westford, present a preliminary analysis of the one-hour VGOS session held in December

2014, and discuss the results and potential impact of

measurements of apparent cable delays for both the

GGAO12M and Westford broadband systems

1 Introduction

The broadband instrumentation for the next generation

geodetic VLBI system, previously called VLBI2010

but now referred to as VGOS (for VLBI2010 Global

Observing System), was implemented on a new

12-m antenna at Goddard Space Flight Center near

Washington, D.C. and on the Westford 18-m antenna

at Haystack Observatory near Boston, Massachusetts,

USA. In October 2012, the first geodetic observing

sessions were conducted using the broadband system,

and in May 2013 a 24-hour session yielded measurements of correlated flux densities as well as estimation

MIT Haystack Observatory

Haystack Analysis Center

IVS 2014 Annual Report

of geodetic parameters. Results from these sessions

were described in previous IVS publications [1] [2].

Most of 2014 was an upgrade period for the Westford 18-m antenna broadband system. The only session

with reportable geodetic VLBI results was observed on

December 19, 2014.

In the area of analysis of measurements related

to geodetic accuracy, several single-antenna sessions

were used to determine the instrumental effects which

might degrade the accuracy of the VLBI observations,

such as sensitivity of cable electrical length to antenna

position or motion.

In this report we highlight changes in the instrumentation that have been implemented since the previously reported results, summarize the geodetic analysis of the December session, and describe some results of the measurements made to determine the extent of uncalibrated orientation-dependent and motioninduced variations in cable electrical length.

While these activities are being reported as part of

the Analysis Center activity at Haystack, the division

between technology development and technique development is fuzzy. The activities that are reported here

are related to analysis of the VGOS observations and

validation of the technique.

The features of the VGOS system as implemented

on the GGAO12M and Westford antennas are repeated

here for reference:

• four bands of 512 MHz each, rather than the two (S

and X) for the Mark IV systems

• dual linear polarization in all bands

• multitone phase cal delay for every channel in both

polarizations

• group delay estimation from the full spanned bandwidth, which in recent sessions extends from 3.0

GHz to approximately 10.7 GHz

225
226 Niell et al.

• simultaneous estimation of the total electron

content difference (dTEC) between sites and the

ionosphere-free group delay, using the phases

across all four bands.

The features indicated in the last three bullets have

required changes in analysis of the geodetic delays, and

these have been implemented in the post-correlation

software difx2mark4 and fourfit.

2 Instrumentation Improvements and

Observing Parameters

Several improvements were made to the instrumentation after the May 2013 session. In the Westford

front end (Dewar and post-Dewar electronics), the

Monitor and Control Instrumentation was rebuilt to

provide more reliable and versatile functionality. But

the most significant changes were the upgrades of

the digital backends from RDBE-H (real samples,

Mark 5B format) to the RDBE-G (complex samples,

VDIF format). Internally the RDBEs were improved

by the replacement of both the NRAO synthesizer

and the attenuator assembly with, respectively, a

much simpler Haystack-designed synthesizer and

commercial attenuators. The RDBE-G also has a new

personality (fpga3.0) that incorporates noise diode

control; internal time-comparison of the GPS, maser

1pps, and RDBE pulse; and pulse cal extraction.

Equally significant, recording is now on a single

Mark 6 instead of four Mark 5Cs.

The frequencies of the four 512 MHz bands were

chosen to span the range 3 GHz to 10.7 GHz with lower

edges of approximately 3.0 GHz, 5.2 GHz, 6.4 GHz,

and 10.2 GHz. The lower limit was chosen to avoid

the effect of RFI at S-band for these initial VGOS sessions, and the high frequency limit was chosen to make

use of the upper end of the available frequency range of

the UpDown Converter, but to be below the frequency

where the sensitivity begins to decrease significantly.

The frequencies of the two intervening bands were proposed by Bill Petrachenko (private communication) to

provide the best delay precision when the TEC difference between antennas is also estimated.

The frequency sequence, or ‘frequence’, within a

band was changed to a minimum redundancy sequence,

thus improving the delay sensitivity and reducing the

sidelobes in the delay resolution function [3].

3 The Observing Session of December 19,

2014

This one-hour session, denoted X141219, was initially

planned to be the first of a series of sessions for which

the only objective was to develop observing procedures

for the two stations, but interest evolved, and the goal

was expanded to encompass all activities associated

with a VGOS observing session.

The schedule was generated using sked. As reported last year, because sked does not yet have the

capability to account for the antenna performance at

all four bands, the SEFDs at both S-band and X-band

as used in sked for the two antennas were adjusted

to allow use of the R1 session parameters. The 100

strongest sources were selected from the catalog of

good geodetic sources. The minimum elevation was

set to 5◦for both antennas (although it was subsequently discovered that the minimum usable elevation

for GGAO12M is 6.25◦). Furthermore, for GGAO a

cone with half-angle of about 20◦centered on the direction to the SLR site to the southwest was masked

out to avoid potential damage to the LNAs by the SLR

aircraft avoidance radar. A minimum scan length of 30

seconds was set, and the minimum SNR was set to

15 for both bands. As generated by sked the average

observed scan length was 31 seconds, and the average number of scans per hour was 48. The observed

SNRs for the coherent fit of all bands and both polarizations range from 38 to 375 with a median value

of 83. From these numbers it is clear that for future

sessions the minimum observation time can be significantly reduced if the goal is a minimum SNR of 20. Of

course weaker sources can also be introduced to improve the sky coverage.

The process for the geodetic analysis of the session is described in the Haystack Observatory Analysis Center Annual Report for 2013 [4]. Briefly summarized, the correlator output from each of the four

bands is processed with fourfit to determine that the

same clock offset model can be used and that the data

quality is acceptable; the four bands are combined in

one file using fourmer; the delay and phase offsets

between polarizations are obtained from one or more

IVS 2014 Annual Report
Haystack Analysis Center 227

strong sources using one polarization of GGAO12M

as the reference; fourfit is run on the combined data

from all four bands, including both polarizations, to

determine a single delay observable; the fourfit output

is converted to a database and meteorological data are

added, and parameter estimation is done using nuSolve.

For the nuSolve analysis, because this is only a onehour session, the model parameterization was relatively

simple. The estimated parameters were the clock behavior at GGAO, the position of GGAO, and the atmosphere zenith delays and gradients at both stations. The

clocks and atmospheres were modeled as piecewiselinear (PWL) functions using the default constraints

from nuSolve. The post-fit delay residuals are shown

in Figure 1. The WRMS is 5.6 psec.

Fig. 1 Group delay post-fit residuals for X141219 after reweighting. The weighted RMS value is 5.6 psec. The horizontal

axis is time, spanning the 72 minutes of the session. The vertical

axis is delay in nanoseconds, from -0.020 to +0.025.

The uncertainties for the position components of

GGAO are sensitive to the length of the segments of

the clocks, zenith wet delays, and gradients. The solution corresponding to Figure 1 used four segments for

each of clocks and ZWDs and two segments of gradients in the one hour session. The resulting uncertainties

for GGAO in Up, East, and North are 6.1, 2.5, and 1.6

mm.

4 Uncorrected Delays Due to Antenna

Motion

As mentioned in last year’s report, the two sites do not

yet have delay measurement instrumentation for the cable carrying the 5 MHz reference signal from the maser

to the phase calibration generator in the front end. Any

variation of delay in this cable would thus produce an

uncorrected variation in the observed delay. If this variation is correlated with antenna position, it may result

in an error in the estimated position. The most common

problem is for the delay to vary due to cable stretching with motion in elevation or in azimuth (or both),

although change related to thermal variation as solar

illumination varies might have a small effect.

Fig. 2 Azimuthal variation of Westford 5 MHz one-way cable

delay on June 20, 2014 measured with a Mark IV cable cal system. Each thin line represents the delays measured while the antenna slewed ∼345◦

in one direction, with dotted lines = CW

and solid lines = CCW; data have been smoothed with ∼20◦

boxcar averaging. Heavy solid curve and points are medians of

unsmoothed data in 15◦ bins, and heavy dotted line is a best-fit

sinusoid. Azimuth limits at Westford are 90◦and 470◦.

In 2014, the 5 MHz cables at both sites were

replaced because the old cables exhibited strong

azimuthal delay dependence of 20-30 ps. Significant

reduction in the azimuth variation was achieved at both

sites, as shown in Figures 2 and 3. At Westford the

azimuth dependence is well described by a sinusoid

of amplitude ∼3 ps. If VLBI data are left uncorrected

for this effect, a shift in the local E-W position of ∼1

mm will result. At GGAO the delay variation over

azimuth is ∼1 ps with the LMR-400UF cable and ∼8

ps with the RG-214 cable. Hysteresis effects of order

2-3 ps are present with the RG-214 cable, as seen in

the differences between the CW and CCW data; these

IVS 2014 Annual Report
228 Niell et al.

effects make it difficult to model the variations. A

further complication to modeling is the fact that the

GGAO delays are the sum of uplink and downlink

delays, whereas corrections should only be made for

the uplink delay. At present the LMR-400UF cable,

with its smaller azimuth dependence and hysteresis, is

used to carry the 5 MHz signal. The elevation delay

dependence (not shown) is <∼1 ps at both sites.

It is clear from cable delay measurements conducted over the last few years that the 5 MHz cables

can degrade over time scales of months to years, in

the sense of developing stronger azimuth variations and

hysteresis effects. Until permanent cable measurement

systems are installed at both sites, periodic monitoring of the cable delays will be carried out to check for

changes in the orientation dependence.

Fig. 3 Azimuthal variation of the GGAO 12-m round-trip cable

delay on December 5, 2014 for two different 5 MHz cables. Delay is the group delay of the phase cal phases over a 500 MHz

span and represents the sum of the delays in the uplink 5 MHz

coax cable and the downlink RF optical fiber. Data have been

smoothed with 20◦ boxcar averaging. Azimuth limits on the 12

m are -180◦and 360◦.

5 Outlook

Observations using the GGAO12M and Westford antennas are scheduled to become more frequent beginning in January 2015 with the initiation of the VGOS

Demonstration Series. This series will initially be a set

of six bi-weekly sessions of nominally one hour duration using the same observing configuration as was

used for the X141219 session. The goal for the observations is to develop and demonstrate the full data path

for a VGOS session, from schedule to analysis. Based

on the degree of success of those sessions, the duration

of a session and the frequency of further observations

may be increased. Other session parameters, such as

length of scan and the band frequencies, will also be

investigated. By mid-year, monthly twenty-four hour

sessions are expected to be conducted.

Acknowledgements

We thank the Broadband Development group for their

efforts in constructing, implementing, and operating

the systems at GGAO and at Westford and for assisting

in the testing and observations; John Gipson for guidance in getting sked to work; David Gordon for getting the broadband output into databases; and Sergei

Bolotin for developing nuSolve and getting it to work

with the new broadband observable.

References

1. Niell et al., First Broadband Results with a VLBI2010 System, IVS 2012 General Meeting Proceedings, NASA/CP2012-217504, D. Behrend and K. D. Baver (eds.), 13-17,

2012. http://ivscc.gsfc.nasa.gov/publications/gm2012.

2. Niell et al., VGOS Operations and Geodetic Results,

IVS 2014 General Meeting Proceedings “VGOS:

The New VLBI Network”, D. Behrend, Karen D.

Baver, and Kyla L. Armstrong (eds.), 97-101, Science Press (Beijing). ISBN 978-7-03-042974-2, 2014.

http://ivscc.gsfc.nasa.gov/publications/gm2014.

3. Rogers, A. E. E., Effective Bandwidth for Phase Delay Measurements, Radio Sci., 5, 1239-1247, 1970.

4. Niell et al., Haystack Observatory Analysis Center, in International VLBI Service for Geodesy and Astrometry 2013

Annual Report, edited by K. D. Baver, D. Behrend, and

K. L. Armstrong, NASA/TP-2014-217522, 276-279, 2014.

http://ivscc.gsfc.nasa.gov/publications/ar2013/index.html.

IVS 2014 Annual Report
IAA VLBI Analysis Center Report 2014

Elena Skurikhina, Sergey Kurdubov, Vadim Gubanov, Daniil Shigaev

Abstract This report presents an overview of the IAA

VLBI Analysis Center activities during 2014 and the

plans for the coming year.

1 General Information

The IAA IVS Analysis Center (IAA AC) is located

at the Institute of Applied Astronomy of the Russian

Academy of Sciences in St. Petersburg, Russia. The

IAA AC contributes to IVS products, such as daily

SINEX files, TRF, CRF, rapid and long-term series of

EOP, and tropospheric parameters. EOP, UT1, station

positions, and tropospheric parameters were estimated

from domestic observation programs Ru-E and Ru-U.

The IAA AC generates NGS files.

2 Activities during the Past Year

2.1 Routine Analysis

During 2014, the IAA AC continued to submit daily

SINEX files for the IVS-R1 and IVS-R4 sessions as

rapid solution (iaa2014a.snx) and SINEX files based

on all 24-hour experiments for the quarterly solution.

The routine data processing was performed with the

OCCAM/GROSS software using a Kalman filter. The

IAA AC operationally processed the 24-hour and InInstitute of Applied Astronomy of RAS

IAA Analysis Center

IVS 2014 Annual Report

tensive VLBI sessions and submitted the results to the

IERS and the IVS on a regular basis. Processing of the

Intensive sessions is fully automated. The EOP series

iaa2007a.eops and iaa2005a.eopi and troposphere parameters iaa2007a.trl were continued.

2.2 Global Solution

iaa2014a.crf and iaa2014a.trf were submitted to

IVS. A new global solution was calculated using all

available data from 1980 until June 2014. A total of

6,912,198 delays were processed. The CRF was fixed

by NNR constraints to 212 radio sources. The TRF

was fixed by NNR and NNT constraints to the station

positions and velocities of 15 stations: MATERA,

KOKEE, WETTZELL, FORTALEZA, WESTFORD,

ALGOPARK, NYALES20, ONSALA60, HARTRAO,

BR-VLBA, FD-VLBA, HN-VLBA, KP-VLBA,

LA-VLBA, and NL-VLBA. Stochastic signals were

estimated by means of the least-squares collocation

technique. The radio source coordinates, station

coordinates, and corresponding velocities were estimated as global parameters. EOP, WZD, troposphere

gradients, and station clocks were estimated as arc

parameters for each session. 6,732 global parameters

were estimated: 2,946 source positions, the positions

and the velocities of 117 VLBI stations, and 23

position and velocity discontinuities.

229
230 Skurikhina et al.

2.3 ITRF2014 Contribution

Daily SNX files for ITRF 2014 were calculated for the

data until the end of 2014.

2.4 EOP Parameter Calculation from

Domestic “Quasar” Network

Observations

VLBI observations using the “Quasar” network for

EOP monitoring are carried out in the framework of

two domestic programs: Ru-E and Ru-U.

The purpose of the Ru-E program is to provide EOP

results on a regular basis from 24-hour sessions using

a three-station network: “Svetloe” – “Zelenchukskaya”

– “Badary”.

The purpose of the Ru-U program is to provide

UT1-UTC results on a regular basis from Intensive sessions using one baseline “Badary” – “Zelenchukskaya”

(“Badary” – “Svetloe”).

Correlation is performed using the IAA ARC correlator.

Observational data from one-hour Ru-U (named

as Ru-I since August 2014) sessions are transmitted

to the correlator using e-VLBI data transfer. The calculation of UT1 time series is performed automatically. The result is a UT1-UTC time series available

at ftp://quasar.ipa.nw.ru/pub/EOS/IAA/eopi-ru.dat.

We use e-VLBI data transfer for the data of 24-

hour sessions from “Badary” and “Zelenchukskaya”.

The data of 24-hour sessions are shipped to the

IAA correlator on disk modules only from “Svetloe”

observatory. The EOP time series is available at

ftp://quasar.ipa.nw.ru/pub/EOS/IAA/eops-ru.dat.

During 2014, 48 Ru-E and 365 Ru-U sessions were

observed. IAA AC performed analysis of these observations. The accuracy obtained in 2014 for EOPs in

comparison to the IERS EOP 08 C04 series is presented in Table 1.

2.5 CONT14 Data Analysis

Processing of the CONT14 observations was carried

out using software package OCCAM/GROSS. In

Table 1 RMS differences with EOP IERS 08 C04.

EOP Nsess Bias RMS

Xp, mas 43 -0.59 0.73

Yp, mas 43 0.13 1.08

UT1-UTC,μs 43 6 32

Xc,mas 43 0.02 0.27

Yc, mas 43 0.04 0.38

UT1-UTC Int., μs 365 25 49

the calculation of diurnal EOP, 15 daily sessions

were combined into one 15-day session (consisting

of 16,430 scans and 145,214 delays), which was

processed using the forward run of the Kalman filter

to estimate the stochastic parameters. EOP (pole

coordinates and universal time), WZD, and clock

parameters are considered as stochastic.

Diurnal variations of Xp, Yp, and dUT1 were compared with the model of diurnal variations from the

EOP IERS Conventions (2003) model of subdaily EOP

variations (designated here as “model”). The results are

presented in Figure 1. RMS differences between EOP

and the “model” are presented in Table 2.

Table 2 CONT14: RMS differences between EOP and “model”.

EOP Npoint RMS

Xp, μas 22,792 188

Yp, μas 22,792 159

dUT1,μs 22,792 19

The values of Tropospheric Total Zenith Delay

(TZD) obtained during CONT14 from VLBI are

in good agreement with data obtained from GPS

observations. The results are presented in Figure 2.

2.6 Impact of Ocean Tides in the Diurnal

and Semi-diurnal Variation of the Earth

Rotation from VLBI Data Analysis

The aim of the study of V. Gubanov and S. Kurdubov

presented to Astronomical Letters is to determine the

parameters of the model of diurnal and semi-diurnal

variations of terrestrial pole coordinates and Universal Time arising from lunar-solar tides in the World

ocean. For this purpose, data processing of all availIVS 2014 Annual Report
IAA AC 2014 AR 231

-100

 0

 100

 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

dUT1, μs

CONT14 day number (MJD - 56783.0)

dUT1

model

-100

 0

 100

 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

CONT14 day number (MJD - 56783.0)

error

dUT1 - model

-1

 0

 1

Yp, mas

Yp

model

-1

 0

 1 error

Yp - model

-1

 0

 1

Xp, mas

Xp

model

-1

 0

 1 error

Xp - model

Fig. 1 EOP intra-day variations from CONT14.

able geodetic VLBI observations on a global network

of stations in the past 35 years were performed using

program package QUASAR IAA RAS. The complication of this problem is that the required corrections

of the model parameters are within 1 mm and thus

are at the limit of their detection using modern methods of ground positional measurements. This requires

the analysis of long series of VLBI observations with

high precision reduction and a developed control system for the processing of joint adjustments of observational data. The obtained results, in general, confirm

the high accuracy of the basic model of IERS Conventions (2010), but for some harmonic variations of terrestrial pole coordinates and Universal Time, it is possible to detect statistically significant corrections that

may be used to improve this model.

3 Current Status

The IAA AC performs data processing of all kinds

of VLBI observation sessions. For VLBI data analysis

we use the QUASAR and the OCCAM/GROSS software packages. All reductions are performed in agreement with IERS Conventions (2010). Both packages

use NGS files as input data.

The IAA AC submits to the IVS Data Center all

kinds of products: daily SINEX files for EOP and EOPrates and station position estimates, SINEX files for

ITRF2013, and also TRF, CRF, and tropospheric parameters.

The QUASAR and the OCCAM/GROSS software

packages are supported and are being developed.

4 Future Plans

• Continue to submit all types of IVS product contributions.

• Continue investigations of EOP, station coordinates, and tropospheric parameter time series.

• Improve algorithms and software for processing

VLBI observations.

• Contribute to ITRF2014.

• Contribute to ICRF3 Working Group study.

IVS 2014 Annual Report
232 Skurikhina et al.

 2400

 2500

Warkworth, TZD from VLBI, mm

 2400

 2500

 2600 Katherine, TZD from VLBI, mm

 2100

 2300 Zelenchukskaya, rms [TZD(VLBI-GPS)] = 6,3 mm, bias = -9,4 mm

 2100

 2200

Yebes, rms [TZD(VLBI-GPS)] = 6,8 mm, bias = -12,9 mm

 2200

 2400 Wettzell, rms [TZD(VLBI-GPS)] = 5,4 mm, bias = 1,2 mm

 2400

 2600 Westford, rms [TZD(VLBI-GPS)] = 6,8 mm, bias = -3,4 mm

 2300

 2500

Yarragadee, rms [TZD(VLBI-GPS)] = 7,5 mm, bias = -10,5 mm

 2400

 2600 Tsukuba, rms [TZD(VLBI-GPS)] = 7,2 mm, bias = -5,3 mm

 2300

 2500 Onsala, rms [TZD(VLBI-GPS)] = 5,6 mm, bias = -2,2 mm

 2300

 2400

Ny Alesund, rms [TZD(VLBI-GPS)] = 3,8 mm, bias = -2,7 mm

 2200

 2300

Matera, rms [TZD(VLBI-GPS)] = 6,2 mm, bias = -3,2 mm

 2100

 2200

Kokee, rms [TZD(VLBI-GPS)] = 6,9 mm, bias = 0,9 mm

 2350

 2450

Hobart12, rms [TZD(VLBI-GPS)] = 5,5 mm, bias = -0.5 mm

 2350

 2450

Hobart26, rms [TZD(VLBI-GPS)] = 5,5 mm, bias = -10,0 mm

 2000

 2200 Hartebeeshoek, rms [TZD(VLBI-GPS)] = 6,8 mm, bias = 5,1 mm

 2600

 2700

Forteleza, rms [TZD(VLBI-GPS)] = 8,5 mm, bias = 4,1 mm

 2150

 2250 Badary, rms [TZD(VLBI-GPS)] = 1,3 mm, bias = 0.1 mm

Fig. 2 TZD intra-day (VLBI compared with GPS) variations

from CONT14.

IVS 2014 Annual Report
Italy INAF Analysis Center

Monia Negusini, Pierguido Sarti

Abstract This report summarizes the activity of the

Italian INAF VLBI Analysis Center. Our Analysis

Center is located in Bologna, Italy and belongs to the

Institute of Radio Astronomy (IRA), which is part of

the National Institute of Astrophysics (INAF). The

IRA runs the observatories of Medicina and Noto,

where two 32-m twin VLBI AZ-EL telescopes are

located. This report contains the AC’s VLBI data

analysis activities and illustrates the local surveys

carried out in 2014 at IRA observatories.

1 Current Status and Activity

The activities related to local ties between different

geodetic systems located at the observatories were carried out in 2014. At the Medicina and Noto sites, the

local values of the Deflection of the Vertical (DoV)

were determined using two different methods: a combination of GPS and geometric leveling on one side

and gravity residuals on the other. The combination

of Global Navigation Satellite System (GNSS) techniques, mostly GPS, and geometric leveling can be

adopted for the computation and/or validation of geoid

undulation, models, and DoV values. Additional methods that can be successfully employed to determine local DoV values are e.g. astro-geodetic measurements

with total stations or zenith cameras.

During the surveys carried out in March 2014 at

Medicina and in July 2014 at Noto, we employed GPS

Istituto di Radioastronomia INAF, Bologna

INAF Analysis Center

IVS 2014 Annual Report

and high precision spirit (geometric) leveling to compute local geoid undulation over the areas surrounding

the radio astronomy observatories. At site Medicina,

two crews measured along the L ≈ 4.8 km loop in one

day, using one Trimble DiNi12 and one Leica DNA03

digital level (σ = 0.3 mm/km), and two pairs of 2-m

invar rods. In spite of the challenging road conditions,

the leveling survey was a real success, with leveling errors on every line well below the 2√

L tolerance and a

global misclosure of 0.9 mm over the L ≈ 4.8 km loop.

At Noto where only one measuring crew was available, two full working days were necessary to complete the back and forth observations along the lines,

using the Leica DNA03 digital level and the 2-m invar rods. Due to local specific limitations, no feasible

roads/paths were identified to connect the N and E endpoints of the lines, and no closed loop was realized. The

total length of the lines resulted in L ≈ 2.4 km, with a

maximum misclosure of 0.6 mm on a 600 m line, i.e.

≈ 1/3 of the 2√

L tolerance. The geometric leveling

data were analyzed with STAR*LEV.

Eight hour GPS observations were performed close

to the endpoints of the leveling lines, employing Trimble 5700 receivers and LEIAT 504 Choke Ring antennas. The GPS data analysis was performed with

Bernese V5.2 software, processing L1 carrier only

using CODE troposhere parameters and global ionospheric maps. All models were expressed in IGS08 and

the coordinates of MEDI (DOMES #12711M003), and

NOT1 (DOMES #12717M004) were kept fixed to the

ITRF2008 values at the relevant epochs: (2014 : 107)

and (2014:207), respectively.

In addition, the remove-restore technique used for

the computation of the gravimetric geoid undulation

could also be implemented to estimate the DoV and

to define its ξ and η DoV components.

233
234 Negusini and Sarti

Starting from the gravity residuals computed for

the estimate of the Italian quasi-geoid ITALGEO05, the

residual vertical deflection components were obtained

using the Fast Collocation approach. The restore phase

was performed adding the long-wavelength component

in the term of deflection of the vertical and the high frequency due to the topography to the residual values of

ξ and η.

The DoV results will be published in a paper currently under preparation.

2 Data Analysis and Results

The IRA began analyzing VLBI geodetic databases in

1989, using a CALC/SOLVE package on the HP1000

at the Medicina station. In subsequent years, the same

software was installed first on an HP360 workstation

and later on an HP715/50 workstation. In more recent

years, two HP785/B2600 workstations and an HP282

workstation were used. In 2007, a new Linux workstation was set up for the migration of all the VLBI data

analysis, and Mark 5 Calc/Solve was installed. During

2014, our Analysis Center had an internal problem, and

we did not participate regularly in IVS activities. But

we continued to update the catalog, and we installed

and tested the latest release of CALC/SOLVE and the

new geodetic software νSolve.

3 Outlook

In 2015, we will contribute again to IVS activities and

submit INAF tropospheric parameters regularly to the

IVS Data Center. We will also produce an updated long

term geodetic solution.

IVS 2014 Annual Report
JPL VLBI Analysis Center Report for 2014

Christopher S. Jacobs

Abstract This report describes the activities of the JPL

VLBI Analysis Center for the year 2014. Highlights

for the year include tracking the Maven Mars mission,

the commissioning of a new 34-m antenna in Australia, DSS 35, and continued operation for the combined NASA-ESA Ka-band network. In addition, our

DVP backend was successfully interfaced to the JIVE

and DiFX correlators. We continue to support VLBIbased navigation using our combined spacecraft, celestial reference frame, terrestrial reference frame, earth

orientation, and planetary ephemeris VLBI systems.

1 General Information

The Jet Propulsion Laboratory (JPL) Analysis Center is

in Pasadena, California. Like the rest of JPL, the center

is operated by the California Institute of Technology

under contract to NASA. JPL has done VLBI analysis

since about 1970. We focus on spacecraft navigation,

including:

1. The Celestial Reference Frame (CRF) and The Terrestrial Reference Frame (TRF) are efforts which

provide infrastructure to support spacecraft navigation and Earth orientation measurements.

2. The Time and Earth Motion Precision Observations

(TEMPO) measures Earth orientation parameters

based on single baseline semi-monthly measurements. These VLBI measurements are then combined with daily GPS measurements as well as

Jet Propulsion Laboratory, California Institute of Technology

JPL Analysis Center

IVS 2014 Annual Report

other sources of Earth orientation information. The

combined product provides Earth orientation for

spacecraft navigation.

3. Delta differenced one-way range (∆DOR) is a

differential VLBI technique which measures the

angle between a spacecraft and an angularly

nearby extragalactic radio source. This technique

thus complements the radial information from

spacecraft doppler and range measurements

by providing plane-of-sky information for the

spacecraft trajectory.

2 Technical Capabilities

The JPL Analysis Center acquires its own data and supplements it with data from other centers. The data we

acquire are taken using NASA’s Deep Space Network

(DSN).

1. Antennas: Most of our work uses 34-m antennas

located near Goldstone (California, USA), Madrid

(Spain), and Tidbinbilla (Australia). These include

the following Deep Space Stations (DSS): the

“High Efficiency” subnet comprised of DSS 15,

DSS 45, and DSS 65, which has been the most

often used set of JPL antennas for VLBI. More

recently, we have been using the DSN’s beam

waveguide (BWG) antennas: DSS 13, DSS 24,

DSS 25, DSS 26, DSS 34, DSS 35, DSS 54, and

DSS 55. Less frequent use is made of the DSN’s

70-m network (DSS 14, DSS 43, and DSS 63).

Typical X-band system temperatures are 35K on

the HEF antennas. The 70 m and BWGs are about

20K. Antenna efficiencies are typically well above

50% at X-band.

235
236 Jacobs

2. Data acquisition: We use ROACH-based Digital

Back Ends with Mark 5C VLBI recorders. These

units became fully operational in 2014. In addition, we have JPL-unique systems called the VLBI

Science Recorder (VSR) and the Wideband VSRs

(WVSR) which have digital baseband converters

and record directly to hard disk. The data are later

transferred via network to JPL for processing with

our software correlator.

3. Correlators: The JPL VLBI Correlator has been exclusively based on the SOFTC software which handles the ∆DOR, TEMPO, and CRF correlations as

well as tests of antenna arraying.

4. Solution types: We run several different types

of solutions. For ∆DOR spacecraft tracking we

make narrow field (≈ 10◦) differential solutions.

The TEMPO solutions typically have a highly

constrained terrestrial (TRF) and celestial frame

(CRF) as a foundation for estimating Earth orientation parameters. These reference frames are

produced from global solutions which then provide

the framework needed for use by TEMPO and

∆DOR.

3 Staff

Our staff are listed below along with areas of concentration. Note that not all of the staff listed work on

VLBI exclusively, as our group is involved in a number

of projects in addition to VLBI.

• Durgadas Bagri: TEMPO and Ka-band phase calibrators.

• Konstantin Belov: CRF global solutions.

• James Border: ∆DOR spacecraft tracking.

• Cristina Garc ́ıa-Miro: Madrid data acquisition,  ́

NASA-ESA southern declination collaboration,

and educational outreach.

• Shinji Horiuchi: Canberra data acquisition and

NASA-ESA southern declination collaboration.

• Chris Jacobs: NASA-ESA southern declination collaboration, X/Ka CRF, TRF, and S/X CRF.

• Peter Kroger: ∆DOR spacecraft tracking.

• Gabor Lanyi: MODEST, fringe fitting and correlation support, ∆DOR, and TRF.

• Steve Lowe: Software correlator, fringe fitting software, and ∆DOR.

• Walid Majid: pulsars, ∆DOR, and VLBA phase referencing.

• Chuck Naudet: NASA-ESA southern declination

collaboration and source stability studies.

• Andres Romero-Wolf: MODEST scripts.

• Lawrence Snedeker: Goldstone data acquisition

and NASA-ESA southern declination collaboration.

• Ojars Sovers: S/X and X/Ka, and CRFs and TRF.

• Alan Steppe: TEMPO and TRF.

4 Current Status and Activities

The TEMPO task’s EOP measurements continue.

Our S/X CRF work is being downsized in favor of

X/Ka-band (8.4/32 GHz) CRF which continues to

make major strides forward. In particular, in 2014

with ESA’s Malargue, Argentina antenna adding much  ̈

needed southern coverage and DSN operations at 2048

Mbps, our XKa median precision reached the level of

the ICRF2 for 525 common sources.

VLBI spacecraft tracking continues to provide

measurements of angular position in support of

mission navigation and planetary ephemeris development. 2014 was a busy year for VLBI spacecraft

tracking in the Deep Space Network. The ISRO Mars

Orbiter Mission and the NASA MAVEN mission were

supported by Delta-DOR for their cruise from Earth

to Mars, achieving highly accurate orbit insertions in

September. The ephemeris of Mars was maintained

by Delta-DOR measurements of the MRO and 2001

Odyssey orbiters. Delta-DOR support for Rosetta

was completed in June as the spacecraft started its

approach to Comet 67P/Churyumov-Gerasimenko. A

series of Delta-DOR measurements was completed

with New Horizons in June—August to support a

trajectory correction maneuver for targeting to Pluto.

Regular measurements began in December for Pluto

approach. Measurements continued in support of the

Dawn low thrust cruise from Vesta to Ceres. Ceres is

now in view, and the Delta-DOR support for Dawn is

nearing completion. Finally, in December, Delta-DOR

support began for the Hayabusa-2 (JAXA) mission.

Also, a number of “mixed-baseline” Delta-DOR

passes were completed between DSN antennas and

antennas belonging to ESA, JAXA, and ISRO. These

measurements are validating inter-agency operability

IVS 2014 Annual Report
JPL Analysis Report 237

for current and planned cross-support agreements.

Preparations are now underway to support future

measurements with Akatsuki (JAXA), Juno, InSight,

OSIRIS-REx, and Solar Probe Plus.

5 Future Plans

In 2015, we hope to deploy operational Ka-band phase

calibrators at our overseas sites. We expect the combined NASA-ESA deep space network to reach subnanoradian (200 μas) Ka-band CRF results over the

south polar cap (−90◦ < δ < −45◦

). Collaborative

work at K-band is expected to complete full sky coverage as well as improve spatial density through an approved VLBA proposal. At S/X-band the VCS-II collaboration should complete its re-survey of over 2,000

sources. On the spacecraft front, we plan to continue

supporting a number of operational missions while further improving techniques for using VLBI for spacecraft tracking.

Acknowledgements

Research described herein done in part at the Jet

Propulsion Laboratory, California Institute of Technology under contract with the National Aeronautics

and Space Administration. Government sponsorship acknowledged. Copyright 
c 2015. All Rights

Reserved.

References

1. C. S. Jacobs and ICRF-3 working group, ‘ICRF3: Roadmap

to the Next Generation ICRF,’ 223rd AAS, session 251.25,

National Harbor, MD, 5–9 Jan 2014.

http://extras.aas.org/meeting/aas223/251/251.25

2. C. S. Jacobs and ICRF-3 working group, ‘The ICRF-3: Status, Plans, and Progress on the next generation CRF.’ 8th

IVS General Meeting, Shanghai, China, 2–7 March 2014.

3. C. S. Jacobs, J. E. Clark, C. Garc ́ıa-Miro, C. E. Goodhart,  ́

S. Horiuchi, R. Madde, M. Mercolino, C. J. Naudet, L. G.

Snedeker, I. Sotuela, L. A. White, The X/Ka-band (8.4/32

GHz) CRF: Results from combined NASA-ESA baselines

including Malargue, Argentina 8th IVS General Meeting  ̈

Shanghai, China, 2–7 March 2014.

4. A. de Witt. A. Bertarini, C. Jacobs, J. McCallum, T. Jung,

J. Quick, S. Horiuchi, J. Lovell, C. Phillips, B. W. Sohn, R.

Ojha, ‘Completing K-band CRF in South Hemisphere,’ 8th

IVS General Meeting, Shanghai, China, 2–7 March 2014

5. J. Boehm and ICRF-3 working group, The ICRF-3: Status,

Plans, and Progress on the next generation CRF. EGU General Assembly, Vienna, Austria, 27 April 2014.

http://publik.tuwien.ac.at/files/PubDat 229493.pdf

6. S. Horiuchi, J. E. Clark, C. Garc ́ıa-Miro, C. S. Jacobs, R.  ́

Madde, M. Mercolino, L. G. Snedeker, I Sotuela, L. A.

White, ‘All Sky CRF at X/Ka-band (8.4/32 GHZ),’ XXXI

URSI General Assembly, Beijing, China, 16 Aug 2014.

7. Z. Malkin, C. S. Jacobs, and ICRF-3 working group,

‘ICRF-3: Status, Plans, Progress on Next Generation

ICRF,’ Journees 2014, Pulkovo Observatory, St. Petersburg,  ́

Russia, 22 Sep 2014.

http://www.gao.spb.ru/english/as/j2014/presentations/

malkin.pdf

8. C. S. Jacobs and ICRF-3 working group, ‘ICRF-3:

Roadmap to the next generation ICRF,’ poster, Astronomia Dinamica en Latino-America (ADeLA) 2014,

ADeLA, Universidad de Santiago, Chile, 29 Sept1 Oct 2014. adela2014.das.uchile.cl/talks/Posters/CJacobs

ADeLA2014@SCL.pdf

9. C. S. Jacobs, ‘Celestial Reference Frames,’ Astronomia

Dinamica en Latino-America (ADeLA) 2014, workshop

lectures, Universidad de Santiago, Chile, 2-3 Oct 2014.

adela2014.das.uchile.cl/talks/Workshop Classes/CJacobs

Santiago ADeLA2014@SCL.pdf

10. C. S. Jacobs and P. Charlot, ‘Radio Sources,’ Astronomia

Dinamica en Latino-America (ADeLA) 2014, workshop

lecture, Universidad de Santiago, Chile, 2-3 Oct 2014.

adela2014.das.uchile.cl/talks/Workshop Classes/CJacobs

PCharlot ADeLA2014@SCL.pdf.pdf

11. C. S. Jacobs, C. Garc ́ıa-Miro, S. Horiuchi, J. E. Clark, J. de  ́

Vicente, M. Dugast, R. Madde, M. Mercolino, D. Pazos, C.

J. Naudet, L. Snedeker, G. Bourda, P. Charlot, I. Sotuela, L.

A. White, ‘The X/Ka CRF with tie to GAIA’s optical frame,’

CNEA/ITeDA Seminar, Mendoza, Argentina, 8 Oct 2014.

12. C. S. Jacobs and B. Garcia, ‘El f ́ısico de la NASA: Christopher Jacobs dio una charla en la CNEA,’ Interview/news

piece by Pedro Fernandez of Noticias Acequia, Mendoza,

Argentina, regarding CONAE/ESA/NASA Collaboration,

https://www.youtube.com/watch?v=XWV9Mhu-TXQ

13. C. Garc ́ıa-Miro, C. S. Jacobs, S. Horiuchi, J. E. Clark, R.  ́

Madde, M. Mercolino, D. Pazos, C. J. Naudet, L. Snedeker,

G. Bourda, P. Charlot, I. Sotuela, L. A. White, ‘The X/Ka

CRF: towards a GAIA frame tie,’ 12th EVN Symposium,

Cagliari, Italy, 7–10 Oct 2014

http://evn2014.oa-cagliari.inaf.it/EVN2014/Talks/03/ Wed

Morning/GarciaMiro EVN2014.pptx

14. C. Garc ́ıa-Miro, J. E. Clark, C. S. Jacobs, R. M. Campbell,  ́

M. Kettenis, S. P. Rogstad, S. Horiuchi, L. Snedeker, ‘The

VLBI Digital Terminal at the NASA’s DSN: First Results

from non-JPL Correlators,’ poster 14, 12th EVN Symposium, Cagliari, Italy, 7-10 Oct 2014

15. C. S. Jacobs and ICRF-3 working group, ‘The

ICRF-3: Proposed Roadmap to the Next Generation ICRF,’ REFAG-2014, Luxembourg, 15 Oct 2014.

IVS 2014 Annual Report
238 Jacobs

http://geophy.uni.lu/users/tonie.vandam/REFAG2014/SESS

III CRF EOP/Jacobs a.pdf

16. C. S. Jacobs, J. E. Clark, C. Garc ́ıa-Miro, S. Horiuchi, R.  ́

Madde, M. Mercolino, C. J. Naudet, D. Pazos, P. Pope, L.

Snedeker, I. Sotuela, L. A. White, ‘The X/Ka CRF: Results

from combined NASA-ESA baselines including Malargue,  ̈

Argentina,’ REFAG-2014, Luxembourg, 15 October 2014.

http://geophy.uni.lu/users/tonie.vandam/REFAG2014/SESS

III CRF EOP/Jacobs b.pdf

17. A. Iddink, C. S. Jacobs, T. Artz, A. Nothnagel, ‘A Proposed

Combination Process for ICRF-3,’ REFAG-2014, Luxembourg, 15 Oct 2014.

http://geophy.uni.lu/users/tonie.vandam/REFAG2014/

SESS III CRF EOP/Nothnagel.pdf

18. C. S. Jacobs and ICRF-3 Working Group, ‘The ICRF-3: Proposed Roadmap to the next generation ICRF,’ Seminar, Max

Planck Institute for Radio Astronomy, Bonn, Germany, 20

Oct 2014.

19. C. S. Jacobs, C. Garc ́ıa-Miro, S. Horiuchi, J. E. Clark, R.  ́

Madde, M. Mercolino, D. Pazos, C. J. Naudet, L. Snedeker,

G. Bourda, P. Charlot, I. Sotuela, L. A. White, ‘The X/Ka

CRF: towards a GAIA frame tie,’ Seminar, Centro Astronomico de Yebes, Yebes, Spain, 23 Oct 2014  ́

20. C. S. Jacobs, C. Garc ́ıa-Miro, S. Horiuchi, L. Snedeker, D.  ́

Bagri, J. E. Clark, G. E. Lanyi, C. J. Naudet, L. A.White,

R. Madde, M. Mercolino, D. Pazos, G. Bourda, P. Charlot

‘VLBI in the DSN: Cat M&E, Clock Sync/TEMPO, DeltaDOR,’ MDSCC Seminar, Robledo de Chavela, Spain, 24

Oct 2014.

21. D. Shin, D. Bagri, J. Border, Advanced Calibration Technique for Accurate Three-Way Spacecraft Ranging Interplanetary Network Progress Report, vol. 42-199, p. 1-11

http://ipnpr.jpl.nasa.gov/progress report/42-199/199C.pdf

22. C. S. Jacobs and ICRF-3 working group, ‘ICRF-3: Multiwavelength progress,’ Extra-galactic Science with Gaia, Observatoire de Meudon, France, 10-12 Dec 2014

http://egsg2014.obspm.fr/cours/JACOBS.pdf

23. C. S. Jacobs, J. Souchay, R. Gaume, and ICRF-3 Working

Group, ICRF-3 status report, IERS Directing Board, AGU

splinter meeting, San Francisco, Dec 14 2014.

IVS 2014 Annual Report
KASI Combination Center 2014 Annual Report

Jungho Cho, Younghee Kwak

Abstract This report briefly summarizes the activities of the combination center of Korea Astronomy and

Space Science Institute (KASI) for the year 2014. The

current status and the future plans are also described.

1 General Information

The KASI IVS Combination Center is located in

Science Complex in Daejeon, South Korea. As a

government-funded research institute, KASI operates

the IVS Combination Center based on experiences

of GNSS data processing using Bernese software

(hereafter Bernese). Bernese with the subprogram

ADDNEQ2 has been used for normal equation stacking and estimation of VTRF and EOPs [1]. In addition

to playing the role of an IVS Combination Center,

the KASI Space Geodesy Group is also in charge

of geodetic applications of the KVN (Korean VLBI

Network).

2 Activities during the Past Year

KASI is facing the phase of geodetic applications using

the KVN. KVN Tamna among three KVN stations was

first surveyed in terms of Invariant Point (IVP). For the

task, a 3D Laser Scanner was introduced for visualizing the IVP variations. A GNSS survey was also carried

out for the coordinate transformation from topocentric

Korea Astronomy and Space Science Institute

KASI Combination Center

IVS 2014 Annual Report

to geocentric. As a result of the test surveys, it is recognized that more dense measurements for both, with

additional elevation and azimuth angles, are necessary.

3 Current Status

Dr. Younghee Kwak moved to the Advanced Geodesy

Group of the Vienna University of Technology in late

March and is working at the group as a project assistant. The Space Geodesy Group has been re-organized

since June, and Dr. Jungho Cho has been appointed as

head of the group. The Space Geodesy Group continuously handles IVS Combination Center tasks as well

as KVN geodetic applications.

4 Future Plans

In 2015, VTRF which was determined by the modified

Bernese in 2013 will be improved in terms of precision.

In a couple of years, the three IVPs of the KVN telescopes will be determined and will be on a periodical

survey schedule. In the next few years, KASI will contribute to the Asia-Oceania VLBI group for Geodesy

and Astrometry (AOV) as an Analysis Center.

References

1. Kwak. Y. and J. Cho, KASI Combination Center 2013 Annual Report, IVS 2013 Annual Report, 288-291, NASA/TP2014-217522, ed. by K. D. Baver, D. Behrend, and K. L.

Armstrong, 2014.

239
KTU-GEOD IVS Analysis Center Annual Report 2014

Emine Tanır Kayıkc ̧ı 1, Kamil Teke 2

Abstract This report summarizes the activities of the

KTU-GEOD IVS Analysis Center (AC) in 2014 and

outlines the planned activities for 2015. Determination

of optimal weights of constraints on VLBI auxiliary

parameters as well as estimation intervals is our specific interest in 2015.

1 General Information

KTU-GEOD IVS Analysis Center (AC) is located at

the Department of Geomatics Engineering, Karadeniz

Technical University, Trabzon, Turkey.

2 Staff at KTU-GEOD Contributing to the

IVS Analysis Center

The staff who contributed to the research at the KTUGEOD IVS Analysis Center (AC) in 2014 are listed in

Table 1 with their working location.

3 Current Status and Activities

During 2014, we focused on inter-technique comparisons of different parameters estimated from the

1. Karadeniz Technical University, Department of Geomatics

Engineering

2. Hacettepe University, Department of Geomatics Engineering

KTU-GEOD Analysis Center

IVS 2014 Annual Report

Table 1 Staff.

Name Working Location

Emine Tanır Karadeniz Technical University,

Kayıkc ̧ı Dept. of Geomatics Engineering,

Trabzon, Turkey.

Kamil Teke Hacettepe University,

Dept. of Geomatics Engineering,

Ankara, Turkey.

observations of the space/satellite geodetic techniques

i.e. VLBI (Very Long Baseline Interferometry), GNSS

(Global Navigation and Satellite Systems),and DORIS

(Doppler Orbitography and Radio Positioning Integrated by Satellite). The zenith tropospheric delays

(ZTD) and horizontal total gradients derived from IGS

[1] and IVS [2] of the co-located site Wettzell between

2002—2013 are shown in Figures 1 and 2 [3].

The GNSS-derived Zenith Tropospheric Delays

(ZTDs) play an important role in meteorological

studies by means of incorporating ZTDs at GNSS

sites into numerical weather prediction models. The

Trop-NET system (reference) developed at the Geodetic Observatory Pecny (GOP, RIGTC) in order to

facilitate near real-time troposphere monitoring using

ground-based GNSS data (based on the Bernese GNSS

Software, [4] was installed and has been routinely used

at the KTU-GEOD IVS AC since September 2014.

KTU-GEOD IVS AC established a cooperation with

GOP within the COSTES1206 Action (GNSS4SWEC,

WG1). Approximately 33 sites from IGS and EUREF

permanent networks in entire Europe were selected

for an initial setting and testing [5, 6]. These are

ANKR Ankara (Turkey), ARGI Thorshavn (Faroe

Islands), AUT1 Thessaloniki (Greece), BRST Brest

(France), BUCU Bucurest (Romania), GLSV Kiev

240
KTU-GEOD Annual Report 2014 241

2.452 2.4525 2.453 2.4535 2.454 2.4545 2.455 2.4555 2.456 2.4565 2.457

x 106

2100

2200

2300

2400

IVS−WZ

Julian Day

TROTOT(mm)

2.452 2.4525 2.453 2.4535 2.454 2.4545 2.455 2.4555 2.456 2.4565 2.457

x 106

2100

2200

2300

2400

2500

IGS−WTZR

Julian Day

TROTOT(mm)

2.452 2.4525 2.453 2.4535 2.454 2.4545 2.455 2.4555 2.456 2.4565 2.457

x 106

2100

2200

2300

2400

2500

IGS−WTZA

Julian Day

TROTOT(mm)

Fig. 1 Troposphere ZTD estimates derived from IVS and IGS intra-technique combined solutions at the co-located site Wettzell.

2.454 2.4545 2.455 2.4555 2.456 2.4565 2.457

x 106

2100

2200

2300

2400

2500

TROTOT

Julian Day

TROTOT(mm)

2.454 2.4545 2.455 2.4555 2.456 2.4565 2.457

x 106

−5

0

5

EAST GRADIENT

Julian Day

TROTOT(mm)

2.454 2.4545 2.455 2.4555 2.456 2.4565 2.457

x 106

−10

−5

0

5

NORTH GRADIENT

Julian Day

TROTOT(mm)

Fig. 2 Troposphere north and east gradients from IGS intra-technique combined solution at the co-located site Wettzell.

(Ukraine), GOPE Pecny (Czech Republic), HOFN

Hoefn (Iceland) , ISTA Istanbul (Turkey), JOZE

Jozefoslaw (Poland), KIRU Kiruna (Sweden), KTVL

Katzively (Ukraine), M0SE Roma (Italy), MAS1

Maspalomas (Spain), MATE Matera (Italy), MEDI

Medicina (Italy), METS Metsahovi (Finland), MORP  ̈

Morpeth (UK), NICO Nicosia (Cyprus), ONSA

Onsala (Sweden), ORID Ohrid (Macedonia), PDEL

IVS 2014 Annual Report
242 Tanır Kayıkc ̧ı and Teke

Ponta Delgada (Portugal), PENC Penc Budapest

(Hungary), POLV Poltava (Ukraine), POTS Potsdam

(Germany), PUYV Le Puy en Velay (France), RIGA

Riga (Latvia), SOFI Sofia (Bulgaria) VLNS Vilnius

(Lithuania), WTZR Wettzell (Germany), YEBE Yebes

(Spain), ZECK Zelenchukskaya (Russia), and ZIMM

Zimmerwald (Switzerland). Because some of the

GNSS core stations are selected as co-located with

VLBI antennas and the two techniques mostly share

similar models, inter-technique comparisons will be

performed between the common parameters of VLBI

and GNSS techniques that is one of the interests of the

meteorology community.

4 Future Plans

Together with Dr. Vincenza Tornatore as PMD (Politechnico di Milano) AC’s team coordinator, Dr. Tanır

Kayıkc ̧ı plans to perform an inter-technique comparison of certain common parameters and a combination

of TRF from the analyses of the DORIS and VLBI observations. The output of this study will be submitted

as a paper for the DORIS special issue of the Journal of

Advances in Space Research in 2015. One of the members, Kamil Teke, plans to investigate the possibility of

improving the accuracy of certain types of VLBI parameters using Vienna VLBI Software, VieVS [7].

Acknowledgements

We are thankful to all the governing board of IVS. We

are grateful to Karadeniz Technical University for their

financial support of KTU-GEOD IVS AC research activities. Emine Tanır Kayıkc ̧ı acknowledges Turkish

National Scientific and Research Council (TUBITAK)

for the financial support of her research stay at Politecnico di Milano during July and August 2014. Kamil

Teke is thankful to Hacettepe University for providing

financial support for his participation in IVS meetings

and the Vienna VLBI group for collaboration.

References

1. J.M. Dow, R.E. Neilan, C. Rizos, The International GNSS

Service in a changing landscape of Global Navigation Satellite Systems, J. Geod, 83, 3-4, 191-198, 2009.

2. H. Schuh, D. Behrend, VLBI: a fascinating technique for

geodesy and astrometry, J. Geodyn, 61, 68-80, 2012.

3. N. Mammadaliyev, Analysis of IVS and IGS Combined Tropospheric Time Series and Outlier Detection, Diploma Thesis, Karadeniz Technical University, Department of Geomatics Engineering, Supervisor: E. Tanır Kayıkc ̧ı, Trabzon,

Turkey, 2014 (in Turkish).

4. R. Dach, U. Hugentobler, P. Fridez, M. Meindl (eds),

Bernese GPS Software Version 5.0, Astronomical Institute,

University of Bern, 2007.

5. J. Dousa, Precise near real-time GNSS analyses at Geodetic  ̃

observatory Pecny - precise orbit determination and water  ́

vapour monitoring, Acta Geodyn Geomater, 7, 157, 1-11,

2010.

6. URL 1: GOP’s Trop-NET system for near real-time troposphere monitoring, http://www.pecny.cz/gop/index.php/

trop-net/trop-net-intro, Date of Access: December 2014.

7. J. Bohm, S. B  ̈ ohm, T. Nilsson, A. Pany, L. Plank, H. Spi-  ̈

cakova, K. Teke, H. Schuh, The new Vienna VLBI Software

VieVS, in Proceedings of IAG Scientific Assembly 2009,

International Association of Geodesy Symposia Series Vol.

136, edited by S. Kenyon, M. C. Pacino, and U. Marti, p.

1007-1011, 2012.

IVS 2014 Annual Report
Analysis Center at the National Institute of Information and

Communications Technology

Mamoru Sekido

Abstract This report summarizes the activities of

VLBI data analysis at the National Institute of Information and Communications Technology (NICT) in

2014.

1 General Information

The VLBI Analysis Center is operated by the spacetime standards group and is located at the Kashima

Space Technology Center and its headquarters of NICT

in Tokyo. This analysis report is focused on the processing of VLBI experiments related to NICT’s research goals on Geodesy and time and frequency transfer with a compact VLBI system. Development of original software package “C5++” [1], which is for the

analysis of Space Geodesy (SLR, VLBI, and GNSS),

has been continued under multi-organization collaborations.

2 Staff

Members who are contributing to the Analysis Center

at the NICT are listed below (in alphabetical order, with

working locations in parentheses):

• HOBIGER Thomas (Koganei, Tokyo): analysis

software development and atmospheric modeling.

NICT, Japan

NICT Analysis Center

IVS 2014 Annual Report

He moved to the Onsala Space Observatory in

August 2014.

• ICHIKAWA Ryuichi (Koganei, Tokyo): coordination of activities

• KONDO Tetsuro (Kashima): Maintenance of

correlation software K5VSSP and development of

broadband synthesis software.

• SEKIDO Mamoru (Kashima): development of

VLBI systems, coordination of activities

• TAKIGUCHI Hiroshi (Koganei, Tokyo): GPS analysis for time and frequency transfer.

3 Current Activities

3.1 Frequency Transfer by Means of VLBI

Space geodetic techniques such as GNSS have been

proven to be a useful tool for time and frequency transfer purposes. VLBI could be another space geodetic

technique that can be utilized for frequency transfer.

In contrast to GNSS, VLBI does not require any orbital information as it directly refers to an inertial reference frame defined by the location of the quasi-stellar

objects. Thus day boundary jumps, which are seen in

GNSS analysis and are caused by discontinuities of

satellite orbits, are avoidable. As summarized by [6],

current VLBI systems can provide a frequency link stability of about 2 x 10-15 @ 1d (ADEV). NICT’s SpaceTime Standards Laboratory is working on the realization of a frequency transfer system based on the principles of VLBI, whereas developments from the upcoming geodetic VLBI2010 system are expected to help to

reach these goals.

243
244 Sekido

Fig. 1 The concept of the distant frequency comparison system composed of a pair of small-diameter antennas and a largediameter antenna. Transportable small-diameter antennas are

placed in laboratories, where the atomic frequency standards to

be compared are being developed. The sensitivity of VLBI observation between a pair of small-diameter antennas is boosted

by using a large-diameter antenna.

An overview of the project (Gala-V) is indicated

in Figure 1. Transportable small-diameter antennas are

placed in laboratories, where atomic frequency standards to be compared are located. By joint observation with small- and large-diameter antennas, the delay observable between a small-antenna pair is derived.

Disadvantages of the small-diameter antennas (hereafter referred to as A and B) on sensitivity is compensated by joint observation with a large-diameter antenna (hereafter referred as O) and expanded observation frequency range. The delay observable (τAB) between the small diameter antenna pair (AB) is computed by linear combination of those (τOA, τOB) of the

small and large diameter baselines (OA,OB) as follows:

τAB(tprt)

= τOB(tprt −τOA(tprt))−τOA(tprt −τOA(tprt))

∼= τOB(tprt)−τOA(tprt)−

d

dt

τAB(tprt)×τOA(tprt),

(1)

where tprt is the reference epoch of the observation.

One of the small-diameter antennas equipped with

a broadband feed and high speed data acquisition system was moved to the National Meteorology Institute

of Japan (NMIJ) in Tsukuba by the end of March 2014.

Another small antenna was installed at NICT Headquarters in Koganei, Tokyo. Both NMIJ and NICT are

the national institutes engaged in the development of

Fig. 2 The clock difference between NICT and NMIJ compared

by VLBI(‘+’) and GPS(‘×’) observations. The difference between UTC[NMIJ] and UTC[NICT] reported by BIPM is superimposed with a solid line and ‘*’.

atomic frequency standards and are keeping the time

series of UTC[NMIJ] and UTC[NICT], respectively.

Therefore, the NMIJ and NICT baseline is a good test

bed for developing the frequency comparison system.

An example of the result of a clock comparison experiment conducted in August 2014 is displayed in

Figure 2. Observations were made 1-3 August 2014

with two small antennas at NMIJ and NICT and with

the Kashima 34-m antenna with X-band. Clock difference behaviors were estimated by GPS observation

and VLBI observations. Because the clock behaviors

of both institutes are regularly reported to the Bureau

International des Poids et Mesures (BIPM), the clock

difference deduced from BIPM publication is superimposed in the plot. All of these data are almost consistent.

Figure 3 shows the histogram of delay residual distribution of the VLBI analysis. Because the errors of

the OA and OB baselines are added in linear combination of equation (1), the delay residual distribution of

the AB baseline is increased by the root-sum-square of

the two observables.

3.2 Broadband System

A prototype of a broadband feed (6.5 - 15 GHz) was

originally developed by and at NICT and installed at

the Kashima 34-m antenna at the end of 2013. Its

first light observation was successful in January 2014.

This achievement demonstrated that a broadband anIVS 2014 Annual Report
Analysis Center at NICT 245

Fig. 3 Histograms of the VLBI analysis residual distribution of

the OA, OB, and AB baselines are indicated. The residual distribution of the AB baseline increased by the root-sum-squre of the

residuals of the OA and OB baselines.

tenna can be realized without building a new telescope, and an existing Cassegrain antenna can be updated for broadband observation. The system equivalent flux density (SEFD) of the current broadband

system is 1000 - 2000 Jy in a 6.5-15 GHz frequency

range. Improvement of the receiver is planned by upgrading the broadband feed, so that the observation frequency range will become fully compatible with the

VGOS system. VLBI experiments for fringe testing

and broadband bandwidth delay measurements were

conducted on the Kashima - Ishioka (GSI) baseline at

the end of 2014.

3.3 Development of a Multi-technique

Space-geodetic Analysis Software

Package

Driven by the need to update the existing space geodetic analysis software and motivated by the demanding

goals of GGOS, an analysis software package named

“c5++” was developed. The software was designed

to support the combination of space geodetic data of

SLR, VLBI, and GNSS on the observation level, but it

also enables processing of single-technique solutions.

VLBI, GNSS, and SLR modules (see Figure 4) share

the same library, which contains all geophysical models according to the latest IERS Conventions. In addition, local tie information can be included as virtual

observations which relate between technique-specific

reference points. The library also provides interfaces

to various space geodetic data formats, enables reading/writing of SINEX files, and supports all necessary

mathematical functions for the parameter adjustment

process. c5++ does not have a graphical user interface

(GUI) but is called directly from the command line and

controlled via a configuration file.

c5++ was compared against other software packages [2] and is currently being used by the Geospatial

Information Authority of Japan (GSI) for ultra-rapid

determination of UT1 [3] on a routine basis.

In contrast to a combination of space geodetic

results where parameters are derived individually

from each technique, the combination of all available

space geodetic observations on the observation level

is expected to obtain more robust parameters. Outliers

are less likely to bias the solution as data from other

techniques helps to identify such data artifacts. Moreover, weaknesses of one technique can be compensated

by adding a second technique, improving geometrical

coverage and stabilizing the estimation of parameters

which otherwise would depend on observations from

that single technique. In order to demonstrate the

capability of the software to combine data at the

observation level, SLR and VLBI observations were

processed together, with the goal of studying site

motions at TIGO and revealing the benefits of this

approach [4].

In addition to local tie information, site-wise common parameters, i.e. troposphere and clocks, can be

estimated when microwave-based techniques are combined on the observation level. Hobiger et al. [5] discusses how common parameters between GNSS and

VLBI have to be estimated and where biases/offsets

need to be taken into account. In order to test this concept, GPS and VLBI data from the CONT11 campaign



	
















Fig. 4 The basic concept of c5++ allows processing of singleand multi-technique space geodetic observations by taking advantage of the usage of identical geophysical models (from [5]).

IVS 2014 Annual Report
246 Sekido

were utilized. Obtained results show that the combination of space geodetic data on the observation level

leads to a consistent improvement of station position

repeatability and Earth orientation parameters as well

as nuisance parameters such as troposphere estimates.

Furthermore, estimation of common parameters (troposphere or clocks) at co-located sites helps to improve

the solution further and derive an utmost physically

consistent model of the concerned parameters (see details in [5]).

4 Future Plans

Plans and tasks in 2015 are (1) the development of

broadband phase synthesis technique, (2) conducting

frequency transfer experiments with the broadband

VLBI system, and (3) establishing its processing chain

to analysis.

Acknowledgements

We thank Dr. Kennichi Watabe, Dr. Tomonari

Suzuyama, and Dr. Masaki Amemiya of NMIJ for

their support in the installation of the small-diameter

antenna at NMIJ and the frequency transfer experiments of the Gala-V project.

References

1. Hobiger, T., et al., “c5++ - Multi-technique Analysis Software for Next Generation Geodetic Instruments”, IVS 2010

General Meeting Proceedings - VLBI2010: From Vision to

Reality, NASA/CP-2010-215864, pp. 212-216, 2010

2. L. Plank, J. Boehm, and H. Schuh (2011), DeDeCC - Comparison of VLBI data analysis software - results; 12th IVS

Analysis Workshop, March 31, 2011, Bonn, Germany, 2011.

3. T. Hobiger, T. Otsubo, M. Sekido, T. Gotoh, T. Kubooka,

and H. Takiguchi, Fully automated VLBI analysis with c5++

for ultra-rapid determination of UT1, Earth, Planets, Space,

45, 2, 75–79, 2010.

4. T. Hobiger, T. Otsubo, and M. Sekido, Combination of space

geodetic observations from SLR and VLBI on the observation level with c5++, Adv. in Space Research, 53(1), 119–

129, doi:10.1016/j.asr.2013.10.004, 2014.

5. T. Hobiger and T. Otsubo, Combination of GPS and VLBI

on the observation level during CONT11 - common parameters, ties and inter-technique biases, under review, 2014.

6. C. Rieck, R. Haas, R.T.K. Jaldehag, and J.M. Johansson,

VLBI and GPS-based Time-transfer Using CONT08 Data,

IVS 2010 General Meeting Proceedings, NASA/CP-2010-

215864, 365-369, 2010.

IVS 2014 Annual Report
NMA Analysis Center 2014 Annual Report

Ann-Silje Kirkvik

Abstract The Norwegian Mapping Authority (NMA)

has been an Associate Analysis Center within the IVS

since 2010. In 2014, NMA delivered its first official

product to IVS. This was the contribution to ITRF2014

with 22 years of 24-hour sessions processed. In the future, NMA will continue to work towards becoming a

fully Operational Analysis Center

1 General Information

NMA has been an Associate Analysis Center within

the IVS since 2010. The analysis center is operated

by the Geodetic Institute at NMA with main offices

in Hønefoss, Norway. NMA is a governmental agency

and the IVS activities at NMA are completely funded

by the Norwegian government.

NMA aims to become a fully Operational Analysis Center and to contribute with timely session-bysession unconstrained normal equations. NMA is using

the analysis software GEOSAT. GEOSAT was originally developed by Per Helge Andersen at the Norwegian Defense Research Establishment (NDRE). In the

recent years, a lot of effort has been put into training a team at NMA to continue the development of

GEOSAT.

Norwegian Mapping Authority (NMA)

NMA Analysis Center

IVS 2014 Annual Report

2 Component Description

GEOSAT was originally designed to combine information from VLBI, GNSS, and multi-satellite DORIS and

SLR, one epoch at a time with the use of a Kalman filter

and models that are common across the techniques. As

a result, the different data types can complement each

other at each epoch in the determination of all common parameters. To validate GEOSAT, a large number of VLBI sessions were processed and submitted to

the IVS Combination Center at BKG for review. The

main focus has been to process R1 and R4 sessions, but

several other 24-hour sessions have also been tested.

GEOSAT is not, in its current condition, able to process Intensive sessions.

3 Staff

The current team involved in the development, maintenance, and usage of GEOSAT is:

• Ann-Silje Kirkvik - VLBI

• Halfdan Pascal Kierulf - VLBI

• Asmund Skjæveland - VLBI  ̊

• Ingrid Fausk - SLR

• Geir Arne Hjelle - DORIS, miscellaneous

• Micheal Dahnn - GNSS  ̈

• Eirik Mysen - Combination technique

• Per Helge Andersen - GEOSAT founder

• Laila Løvhøiden - Project manager

The team was considerably strengthened in 2014.

Geir Arne Hjelle was employed in the beginning of

2014 and has been helping out in different parts of

the project. Micheal Dahnn and Eirik Mysen have also  ̈

247
248 Kirkvik

been assigned to the project, and the project has gotten

a new project manager. In addition, Asmund Skjæve-  ̊

land has been assigned to help with the routine processing of R1 and R4 sessions as NMA progresses towards becoming a fully Operational Analysis Center.

Per Helge Andersen was originally planning to retire

in June 2015 but has agreed to stay on until the end of

2015.

4 Current Status and Activities

At the General Meeting in Shanghai in March 2014, it

was shown that GEOSAT was able to produce EOP estimates comparable to the other Analysis Centers’. The

test data were the R1 and R4 sessions from 2006. The

results were promising and it was decided that NMA

should try to contribute to ITRF2013. Later tests on

11 years (2003-2013) of R1 and R4 sessions revealed

several problems that had to be fixed. In particular, the

station coordinates were bad.

With all the new antennas being built there are some

sites that now have two operational antennas observing in the same session. This situation had never been

tested in GEOSAT before, and it turned out that the

software was mixing the different monuments at the

same site. The station coordinate could be off by hundreds of meters. Hobart and Hartebeesthoek were the

sites that revealed this problem. Once this was fixed,

there were still problems with the solution.

The station coordinates were still off by half a meter

in some cases, but after some investigation it turned

out that the eccentricities were not applied at all due to

a software bug. This was easily fixed and the solution

started to look good from NMA’s point of view.

But a thorough review of the data set by Sabine

Bachmann at BKG revealed that the station coordinates

still were off by up to 1.5 cm for some stations. This

problem was a lot harder to solve. All the station displacement models were checked and updated, but nothing improved the result. Finally, it turned out that a preprocessing algorithm was throwing away almost all the

cable calibration data and the remaining cable calibration data was applied with the wrong sign. Fixing this

problem finally gave comparable station coordinates.

With these fixes, most 24-hour sessions from

1994 until 2013 were analyzed and submitted to the

ITRF2013 solution. Late in 2014 it was decided that

ITRF2013 should become ITRF2014, and processing

of sessions from 2014 was also started.

5 Future Plans

The main focus for the team members at NMA is still to

learn as much as possible from Per Helge Andersen in

order to have the necessary competence to sustain and

develop GEOSAT themselves after his retirement. This

includes both the software design and the theoretical

aspects of the models and estimation technique.

After finishing the work on ITRF2014 the next step

is to prepare the software and production chain in order

to try submitting timely unconstrained normal equations to the IVS Combination Center. In addition, the

software must be updated so that it can estimate earth

orientation parameters with higher frequency than one

day.

IVS 2014 Annual Report
Paris Observatory (OPAR) Analysis Center

Sebastien Lambert, C  ́ esar Gattano, Christophe Barache, Jean Souchay, Franc ̧ois Tar  ́ is, Christian Bizouard,

Olivier Becker

Abstract We report on the operational and research

activities at the Paris Observatory VLBI Analysis Center (OPAR) for 2014. Our achievements include the reanalysis of opa2014a and research related to celestial

reference frames.

1 Analysis Service

1.1 Operational Solutions

A reanalysis of the complete 24-hour session database

was done (identified as opa2014a), and the resulting

EOP series and radio source catalogs were sent to the

IVS. This solution estimated EOP and rates as session

parameters, most of the station coordinates and the velocities as global parameters, and most of the sources’

coordinates as global parameters. Stations undergoing strong nonlinear displacements were estimated

as session parameters (TIGOCONC, TSUKUB32,

KASHIM11, KASHIM34, VERAMZSW, KOGANEI,

and USUDA64). Troposphere and clock parameters

were estimated every 20 minutes and 60 minutes,

respectively, and gradients were estimated every

six hours (at all sites). Axis offsets were estimated as

global parameters for a list of 80 stations. We used

up-to-date geophysical and astronomical modeling to

compute the theoretical delay and partials, including

the IAU 2006 nutation and precession, the Vienna

mapping functions 1, the FES 2004 ocean loading

Observatoire de Paris/SYRTE – CNRS – UMPC – GRGS

OPAR Analysis Center

IVS 2014 Annual Report

model, and the antenna thermal deformations as

provided by A. Nothnagel (2009, J. Geod., 83, 787).

Constraints were applied to the 295 ICRF2 defining

sources (no-net rotation) and to 27 stations (no-net

rotation and no-net translation of positions and velocities). We used the latest version of the Calc/Solve

geodetic VLBI analysis software package.

24-hour sessions were analyzed routinely within 24

hours after version 4 of the observation database file

was submitted to the IVS. The operational solution is

aligned to the opa2014a global solution. Unconstrained

normal equations relevant to EOP, rates, and station

and source coordinates were sent to the IVS in SINEX

format for combination in the framework of the IVS

Analysis Coordinator’s task.

An operational solution analyzing Intensive sessions after 2002 was started (opa2014i). The solution

opa2014i included Intensive sessions in order to produce UT1 consistent with VTRF 2013D, ICRF2, and

the IERS EOP 08 C04 Earth orientation data. To account for the nonlinear displacement of TSUKUB32,

we modeled the antenna displacement by a transient

decay model fitted to the station coordinate time series

(see next section).

All the above products, except SINEX files, were

published on the OPAR Web site at

http://ivsopar.obspm.fr

together with exhaustive explanations and plots.

SINEX files were only sent to the Data Centers.

249
250 Lambert et al.

1.2 Other Contributions

Station and radio source coordinate time series are updated as new observations arrive. For each source, a

page displays the time series and provides links to

source information at various external databases (e.g.,

the French Virtual Observatory software package Aladin that permits a user to get the optical counterpart

of the VLBI quasars, or the Bordeaux VLBI Image

Database that gives the VLBI structure).

As for past years, the Earth’s free core nutation

(FCN) is regularly monitored at OPAR: we maintain

an FCN model directly fitted to routinely estimated

nutation offsets (Figure 1). It is worth noting that the

FCN amplitude seems to be approaching a maximum.

The follow-up of this variation in the next years

will certainly improve our knowledge of the FCN

phenomenon.

1980 1985 1990 1995 2000 2005 2010 2015

−0.5

0

0.5

dX (mas)

1980 1985 1990 1995 2000 2005 2010 2015

−0.5

0

0.5

dY (mas)

Fig. 1 The amplitude of the free core nutation.

OPAR also contributed to the ITRF 2013 (now

ITRF 2014) solution. Late in 2014, the Analysis Center

continued to submit SINEX files for sessions up to the

end of the year.

2 Research

2.1 VLBI Astrometry and Geodesy

In Lambert (2014, A&A 570, 108), astrometric catalogs obtained by several IVS Analysis Centers and submitted to the IVS in 2012 and 2013 were compared to

the ICRF2 in terms of radio source coordinates, global

second-degree deformations, and error distribution. All

catalogs were found to be consistent with the ICRF2

within 20 μas. But at high observational rates, the formal error is limited to the level of ∼10 μas likely by

correlated-noise errors. Comparison of differences to

ICRF2 against formal errors raised noise floors of the

differences between 50 μas and 100 μas, and hence no

improvement occurred with respect to the ICRF2. The

inconsistencies between catalogs result in differences

significantly larger than the accuracy expected for the

future ICRF realizations. These inconsistencies have to

be clarified in the near future in view of the ICRF3 and

accurate linking to reference frames at other frequencies.

In parallel, C. Gattano (PhD student at SYRTE under the supervision of C. Bizouard and S. Lambert) is

currently studying the link between precise VLBI astrometry and estimation of nutation, as well as the possibility of increasing the accuracy of both products for

benefits in astronomy and geophysics.

2.2 Optical Counterpart

The astrometry team of the SYRTE has also been contributing to improving the Large Quasar Astrometry

Catalog (LQAC; Souchay et al. 2009, A&A 494, 799),

which contains accurate positions and optical information of more than 300,000 extragalactic objects including geodetic VLBI sources.

F. Taris is the principal investigator of a quasar

monitoring program in the optical frequencies (Taris

et al. 2013, A&A 552, 98) using large telescopes (e.g.,

ESO) for monitoring of morphology and small robotic

telescopes for measuring magnitude variability. The

work aims at a better understanding of the link between radio and optical positions. Targets are both

ICRF sources and sources designed for the link with

Gaia.

The team will soon release a database gathering radio (VLBI) and optical (LQAC, morphology imaging

and magnitude records) information.

More recently, the team also worked on dynamical modeling of AGN core from VLBI observations

(Roland et al. 2014, A&A, accepted for publication).

This work, devoted to 1926+738, indicates the possiIVS 2014 Annual Report
OPAR Analysis Center 251

ble presence of systems of black holes separated by

more than 0.1 mas, and even multiple systems separated by more than 1 mas. Such configurations could

have strong implications in the radio-to-optical link,

depending on whether the various black holes are emitting in optical and/or radio frequencies.

IVS 2014 Annual Report
Onsala Space Observatory – IVS Analysis Center Activities

during 2014

Rudiger Haas, Thomas Hobiger, Hans-Georg Scherneck, Johan L  ̈ ofgren, Tong Ning, Niko Kareinen  ̈

Abstract This report briefly summarizes the activities

of the IVS Analysis Center at the Onsala Space Observatory during 2014 and gives examples of results of

ongoing work.

1 General Information

We concentrate on research topics that are relevant for

space geodesy and geosciences. These research topics

are related to data observed with geodetic VLBI and

complementing techniques.

2 Activities during the Past Year

We worked primarily on the following topics:

• Automated reference point determination

• A local tie vector based on classical survey and

GPS measurements

• A purely GPS-based local tie vector

• Evaluation of DBBC vs. Mark IV

• VLBI with GLONASS signals

• Coastal sea level observations with GNSS

• Ocean Tide Loading

• Gravimetry observations

Chalmers University of Technology, Department of Earth and

Space Sciences, Onsala Space Observatory

Onsala Analysis Center

IVS 2014 Annual Report

3 Automated Reference Point

Determination

The approach to determine the reference point of a radio telescope in an automated fashion during ongoing

VLBI observations [1] was applied to the CONT14

campaign. Several retro-reflectors were mounted on

the elevation cabin of the 20-m radio telescope and

then observed from various survey pillars with total

stations while the telescope was observing CONT14.

A manuscript describing the experiment and its results

is in preparation.

4 A Local Tie Vector Based on Classical

Survey and GPS Measurements

In connection to the above described automated determination of the reference point of the 20-m radio telescope, a classical survey of the complete local site network was also performed, including the reference point

of the IGS station ONSA. This allowed us to determine a new realization of the local tie vector between

the VLBI and GNSS reference points at the obseratory

in the local coordinate system. After the classical survey, a several week long GPS campaign was performed

in the local network. The corresponding data analysis

gave the coordinates of the markers of the local survey

network in a global cartesian coordinate system. Thus,

by combining the local survey results and the results

from the GPS campaign, a new realization of the local tie vector expressed in a global cartesian coordinate

system could be determined. The results were submitted to IERS to be used for the preparation of ITRF2014.

252
OSO – IVS Analysis Center 253

5 A Purely GPS-based Local Tie Vector

GPS data observed with the receivers connected to two

gimbal-mounted GPS antennas on the 20-m radio telescope were analyzed for several observing sessions,

both kinematic ones during real VLBI sessions, and

dedicated semi-kinematic stop-and-go sessions. The

data were analyzed together with the data from the IGS

station ONSA and successively the reference point of

the radio telescope, the axis offset, and the local tie vector between the VLBI and GNSS reference points were

determined. The analysis shows that both types of sessions, i.e. kinematic and semi-kinematic, give consistent results, for both the local tie vector and the telescope axis offset. The repeatability of the local tie vector from the different sessions is on the order of 1.5

to 3 mm for the different components. The agreement

with the ITRF2008 local tie vector is on the level of 1

to 5 mm in the different components. The study shows

that this approach is suitable to continually monitor the

local tie vector at co-location sites with accuracies on

the order of a few millimeters [2].

6 Evaluation of DBBC vs. Mark IV

During 2013 and 2014, a large number of geodetic

VLBI sessions performed at Onsala were observed

both with the old Mark IV/Mark 5A data acquisition

system and with the new DBBC/Mark 5B+ data acquisition system. Zero-baseline tests were performed

using the DiFX software correlator at Onsala and at

the Bonn correlator. The Bonn correlator also produced

several VLBI databases that include two Onsala stations, one with the Mark IV/Mark 5A data acquisition

system and one with the DBBC/Mark 5B+ data acquisition system. Several of these databases were analyzed

and investigated for systematic differences in both the

raw observations and also the geodetic parameters derived from the analysis [3]. No significant differences

were found, and as a result of this study we decided to

retire the old Mark IV rack in the summer of 2014 and

to completely switch over to an operational use of the

DBBC/Mark 5B+ data acquisition system.

7 VLBI with GLONASS Signals

We continued test experiments to perform VLBI observations with signals of GLONASS satellites. These

tests were done on the Onsala-Wettzell baseline, involving the L-band system on the Onsala 25-m telescope and the L-band receiver on the Wettzell 20-m

telescope. The data were successfully correlated with

the DiFX software correlator installed at Onsala [4].

Different a priori delay models were tested. The correlation results were post-processed with both AIPS and

Fourfit.

From the AIPS post-processing we could successfully determine group delays, integrated delay rates,

and phase delays. The RMS-scatter of the phase delays was on the level of 10 ps for solution intervals of

2 s, while group delays reached an RMS-scatter below

1.5 ns for solution intervals not shorter than 30 s. Total delay values, i.e. a priori delay models plus fringefitted delay residuals from AIPS, agreed on a level of

0.8–0.9 ns for group delays and 0.2–0.4 ns for phase

delays (approximated by integrated delay rates) [4].

Mk4/DiFX fourfit 3.9 rev 6188 132500.xwouaq, No0089a, XV

ONSALA85 - WETTZELL, fgroup L, pol RR

9

Error code H

127.0

2.991

214.803

119.7

0.0e+00

0.028742

-0.000391

-0.001119

 0.00

1596.8700

0.160

g130128

16383

2013:028

132501.92

132504.96

132502.00

2014:345:210353

2015:009:124920

2014:204:120420

02h13m52.8900s

+36 ̊42’52.910"

Fringe quality

SNR

Int time

Amp

Phase

PFD

Delays (us)

SBD

MBD

Fringe rate (Hz)

Ion TEC 

Ref freq (MHz)

AP (sec)

Exp.

Exper #

Yr:day

Start

Stop

FRT

Corr/FF/build

RA & Dec (J2000)

Amp. and Phase vs. time for each freq., 19 segs, 1 APs / seg (0.16 sec / seg.), time ticks 1 sec

U

Validity

L

X V

1596.87 Freq (MHz)

119.7 Phase

214.8 Ampl.

257.9 Sbd box

U/L 19/0 APs used

X 130 PC freqs

V 130 PC freqs

X:V -114:-81 PC phase

X:V 0:0 Manl PC

X 0 PC amp

V 12

L00UR Chan ids X

L00UR Chan ids V

Group delay (usec)(model)

Sband delay (usec)

Phase delay (usec)

Delay rate (us/s)

Total phase (deg)

-2.88141498483E+02

-2.88112365092E+02

-2.88140898806E+02

4.94282070579E-01

-200.5

Apriori delay (usec)

Apriori clock (usec)

Apriori clockrate (us/s)

Apriori rate (us/s)

Apriori accel (us/s/s)

-2.88141107092E+02

-1.1010000E+02

0.0000000E+00

4.93300185789E-01

1.57835841850E-05

Resid mbdelay (usec)

Resid sbdelay (usec)

Resid phdelay (usec)

Resid rate (us/s)

Resid phase (deg)

-3.91391E-04

2.87420E-02

2.08286E-04

9.81885E-04

119.7

+/-

+/-

+/-

+/-

+/-

5.4E-04

5.4E-04

1.6E-06

8.9E-07

0.9

RMS Theor. Amplitude 214.803 +/- 1.691 Pcal mode: NORMAL, NORMAL Pcal period (AP’s) 9999, 9999

ph/seg (deg) 1.7 2.0 Search (64X8) 214.778 Pcal rate: -9.818E-04, 8.155E-07 (us/s) sb window (us) -8.000 8.000

amp/seg (%) 2.5 3.4 Interp. 0.000 Bits/sample: 2 SampCntNorm: disabled mb window (us) -0.000 0.000

ph/frq (deg) 0.0 0.5 Inc. seg. avg. 214.745 Sample rate(MSamp/s): 16 dr window (ns/s) -1.957 1.957

amp/frq (%) 0.0 0.8 Inc. frq. avg. 214.775 Data rate(Mb/s): 32 nlags: 256 t_cohere infinite ion window (TEC) 0.00 0.00

X: az 0.0 el 0.0 pa -0.0 V: az 0.0 el 0.0 pa -0.0 u,v (fr/asec) 0.000 0.000 simultaneous interpolator

Control file: cf_1234 Input file: /common/expts/g130128_141210/1234/No0089a/XV..xwouaq Output file: Suppressed by test mode

Fig. 1 Fringe plot for one scan of the GLONASS-VLBI experiment G130128, observed on the baseline Onsala–Wettzell.

IVS 2014 Annual Report
254 Haas et al.

An example for post-correlation analysis with

Fourfit is presented in Figure 1, which depicts the

fringe plot for one scan of the experiment G130128. A

high quality fringe with SNR 127 and stable phase is

achieved from an integration time of just 3 s.

8 Coastal Sea Level Observations with

GNSS

We used the GNSS-R tide gauge at Onsala to study reflected signals from multiple GNSS, i.e. from GPS and

GLONASS. The recorded data were analyzed with two

different strategies, using only data from the upwardlooking antenna and applying the SNR analysis, and

using data from both antennas and applying geodetic

phase delay analysis. The analysis shows that multiGNSS signals give consistent results for sea level derived from reflectometry [5]. The agreement with respect to sea level observed by a co-located traditional

tide gauge is better for the phase-delay analysis than

for the SNR analysis. Figure 2 depicts results from the

analysis of multi-GNSS observations collected during

20 days in 2012. The root-mean-square (RMS) differences were on the level of 32 to 35 millimeters for GPS

and GLONASS phase-delay solutions, while the SNR

solutions gave RMS differences on the order of 40 to 90

millimeters. The worst RMS agreement was achieved

with SNR analysis on the L2 frequency.

The SNR approach was applied also to other

coastal stations worldwide that are only equipped with

one upward-looking GNSS antenna [6]. The chosen

stations were located in different regions around the

world, in both hemispheres and exposed to different

multi-path environments, as well as different tidal

ranges. All stations had co-located traditional tide

gauges that could be used for comparison to the

derived sea level results. The analysis shows that the

relative accuracy of the SNR technique, defined as the

ratio of RMS and tidal range, is between 2.4% and

10.0% for all stations.

A new reflectometry instrument that focuses specifically on GLONASS signals was compared to the Onsala GNSS-R tide gauge. The new system is based on

rather inexpensive commercially off-the-shelf equipment. It could be shown that the precision and accuracy of the GLONASS-R system is comparable to the

existing GNSS-R [7].

Fig. 2 Sea level derived from the GNSS tide gauge at the Onsala

site during 20 days in 2012 (October 9 to 29). From top to bottom the sea level times series are derived from: GPS phase (L1),

GLONASS phase (L1), GPS and GLONASS phase (L1), GPS

SNR (L1), GLONASS SNR (L1), GPS phase (L2), GLONASS

phase (L2), GPS and GLONASS phase (L2), GPS SNR (L2), and

GLONASS SNR (L2). Each time series is paired with the independent sea level observations from the co-located tide gauge

(black line). A mean is removed from each time series, and the

pairs are displayed with an offset of 40 cm to improve visibility.

9 Ocean Tide Loading

The Automatic Ocean Tide Loading service was operated throughout the year. It is heavily used by the international scientific community.

10 Gravimetry Observations

The superconducting gravimeter in the gravity laboratory was operated throughout the year. The data

loss in 2014 was 0.52% in the one-second record,

confined to one event at the end of February, a

failing Flash Card memory in the data buffer of

the ADCconverter. Since September 2014, tide

solutions have been prepared on a weekly basis

and results made available on the SCG homepage

(http://holt.oso.chalmers.se/hgs/SCG/toe/toe.html).

The analysis includes the sea-level sensors at the

Onsala Space Observatory as ancillary data in the

regression. The RMS of the residual is typically below

8 nm/s2.

IVS 2014 Annual Report
OSO – IVS Analysis Center 255

11 Future Plans

The IVS Analysis Center at the Onsala Space Observatory will continue its efforts to work on specific topics relevant to space geodesy and geosciences. For the

future we plan to intensify our activities, in particular concerning tropospheric parameters, e.g. horizontal gradients in the atmosphere using VLBI, GNSS and

radiometers. A special focus for the coming years will

be work related to the Onsala Twin Telescope project.

Furthermore, we will work on an automated near realtime analysis of the IVS INT-sessions. We will also

continue our efforts concerning VLBI observations of

GNSS signals.

References

1. Losler M, Haas R, Eschelbach C. Automated and contin-  ̈

ual determination of radio telescope reference points with

sub-mm accuracy: results from a campaign at the Onsala

Space Observatory. Journal of Geodesy, 87(8), 791–804,

doi: 10.1007/s00190-013-0647-y.

2. Ning T, Haas R, Elgered G (2014). Determination of the

Telescope Invariant Point and the local tie vector at Onsala using GPS measurements. In: IVS 2014 General Meeting Proceedings “VGOS: The New VLBI Network”, Edited

by Dirk Behrend, Karen D. Baver, and Kyla L. Armstrong,

Science Press (Beijing). 163–167. ISBN/ISSN: 978-7-03-

042974-2.

3. Kareinen N, Haas R, La Porta L, Bertarini A (2014). Going

digital – the transition from Mark IV to DBBC at Onsala. In:

IVS 2014 General Meeting Proceedings ”VGOS: The New

VLBI Network”, Edited by Dirk Behrend, Karen D. Baver,

and Kyla L. Armstrong, Science Press (Beijing). 178–182.

ISBN/ISSN: 978-7-03-042974-2.

4. Haas R, Neidhardt A, Kodet J, Plotz C, Schreiber U, Kro-  ̈

nschnabl G, Pogrebenko S, Duev D, Casey S, Marti-Vidal

I, Yang J, Plank L (2014). The Wettzell—Onsala G130128

Experiment — VLBI Observations of a GLONASS Satellite. In: IVS 2014 General Meeting Proceedings ”VGOS:

The New VLBI Network”, Edited by Dirk Behrend, Karen

D. Baver, and Kyla L. Armstrong, Science Press (Beijing).

451–455. ISBN/ISSN: 978-7-03-042974-2.

5. Lofgren J, Haas R (2014). Sea level measurements us-  ̈

ing multi-frequency GPS and GLONASS observations.

EURASIP Journal on Advances in Signal Processing.

2014(1), doi: 10.1186/1687-6180-2014-50.

6. Lofgren J, Haas R, Scherneck H-G (2014). Sea level time  ̈

series and ocean tide analysis from multipath signals at five

GPS sites in different parts of the world. Journal of Geodynamics, 80, 66–80, doi: 10.1016/j.jog.2014.02.012.

7. Hobiger T, Haas R, Lofgren J (2014). GLONASS-  ̈

R: GNSS reflectometry with an FDMA based satellite

navigation system. Radio Science, 49(4), 271–282, doi:

10.1002/2013RS005359.

IVS 2014 Annual Report
PMD Analysis Center 2014 Annual Report

Vincenza Tornatore

Abstract Research activities carried out at the (PMD)

IVS Analysis Center during 2014 are briefly highlighted, and future plans for 2015 projects are outlined in this report. The main topics tackled during

2014 concern so called space ties and consistency of

Celestial and Terrestrial Reference Systems materializations. Comparisons with other geodetic techniques

have been performed for parameter estimates related to

tropospheric and ionospheric effects.

1 General Information and Staff

Milan University of Technology (Politecnico di Milano), Department of Civil and Environmental Engineering (DICA) [1] hosts and supports activities of

the PMD (Politecnico di Milano DICA) Analysis Center. In particular the Geodesy and Geomatic research

area of DICA supplies hardware equipment, software

licenses and assistance, and the personnel necessary to

manage it.

The following collaborators gave their contribution

to the development of PMD activity during 2014:

• Vincenza Tornatore — team coordinator, responsible for AC projects and data analysis;

• Giovanna Venuti — GNSS troposphere parameter

estimation;

• Cinzia Vajani — software maintenance;

• Daniele Passoni — data processing.

Politecnico di Milano, Department of Civil and Environmental

Engineering (DICA), Geodesy and Geomatic area

PMD Analysis Center

IVS 2014 Annual Report

2 Current Status and Activities

Research topics investigated during 2014 mainly addressed problems related to reference frame stability

and inter-technique comparisons of different parameters estimated using data from geodetic space techniques such as GNSS (Global Navigation and Satellite Systems), VLBI (Very Long Baseline Interferometry), and Doppler Orbitography and Radio Positioning

Integrated by Satellite (DORIS). The activities can be

summed up in the following main research lines:

1. space ties: post-processing of VLBI correlated data

of GNSS observations

2. ICRF stability

3. estimate of atmospheric parameters using space

geodetic techniques.

2.1 Data Processing of VLBI Observations

of Satellites

A number of observing tests of GNSS satellites by

the VLBI technique were performed with some VLBI

stations able to receive GNSS frequencies during past

years [12]. The efforts were dedicated to a deeper analysis of the correlation output to investigate possible indications to improve observations or correlation of the

artificial satellite signals. For this analysis, software

that is widespread in the radio astronomy community

for processing natural radio source data was used. The

software is the Astronomical Image Processing System

(AIPS) developed and maintained by NRAO [2].

The data were stored in files of FITS-IDI (Flexible Image Transport System-Interferometry Data Inter256
PMD 2014 Annual Report 257

change) [8] format with 0.5 s integration time. To calculate the delays and rates necessary for geodetic parameter estimation, first fringe-fitting [5], had to be applied. Here, as an example, we report on the analysis of

one experiment which gave some useful information.

As the first step the amplitude and phases of the

visibility fringes were plotted as they were collected in

the FITS file (every 0.5 s) without any summation or

averaging. Some insights of plots at two epochs, differing by only 0.5 s, showed that the phase often changed

by about 160 deg. This big change of the phase during only 0.5 s, corresponding to a variation of about 10

cm in the correlator model, seems to be very high and

requires some improvements of the model.

Fringe fitting was attempted with different integration times, but solutions became worse with increasing of integration time. The best solution was that with

integration time equal to observation time, i.e. 0.5 s.

The fringe fitting was done on a full first scan average

of four minutes, beginning on channel BCHA 235 to

ECHA 275, selecting only the strongest peaks. Then

solutions were applied to all of the 512 channels. This

result, obtained by taking correlation integration time

equal to observing time interval, prevents the calculation of rates during the fringe fitting, because during

0.5 s integration time we have only one point in the plot

of the phase with time. To make possible a good estimate of rates (the slope of phases with time) we should

have in each integration time a good number of points

(e.g. 20 points, one every eight degrees). This corresponds to a request of correlation, for the data of this

example, not every 0.5 s but e.g. every 0.025 s (0.5/20).

In this experiment only delays and phases could be corrected during fringe fitting; in Figure 1 DELAYS of

antenna 2 with respect to antenna 1 are represented for

each of the observed four IFs, and in Figure 2 PHASES

are shown. Rates could be not determined on the basis

of a single integration.

During inspection of the correlated data it was also

noticed that the amplitude of the signals progressively

decreases as long as the scan proceeds. One possible

explanation could be that during the four minutes of

observations, the satellite travels out of the antenna primary beam. In fact, because of the lack of proper antenna software (continuous tracking) it was possible to

track the satellite only stepwise.

After this work, the following suggestions for satellite signal correlation and observation can be gathered

to obtain better results:

• recorrelate each scan of four minutes with an integration time of 0.025 sec;

• make a Doppler tracking as good as possible;

• check the correlator model (10 cm is really a large

number);

• use continuous tracking during observations.

2.2 ICRF Stability

Baselines, site coordinates, and CPO were estimated

in ICRF1 and ICRF2 [7], using the software VieVS

[4] and following the IERS (International Earth Rotation and Reference Systems Service) Recommendations [10] and the IVS (International VLBI Service for

Geodesy and Astrometry) Conventions on VLBI data

processing [9]. Time series of estimated parameters

have been deeply analyzed, using standard Allan deviation methods, in tight collaboration with the VIE IVS

Analysis Center (AC) and the PUL IVS AC. A thorough description of the analysis and discussion of the

results have been submitted for publication.

2.3 Estimation of Atmospheric Parameters

using VLBI and GNSS Data

The Geodesy and Geomatics area of the DICA (Department of Civil and Environmental Engineering) is

developing algorithms to process and analyze GNSS

and VLBI data, not only for positioning purposes but

also for estimation of tropospheric parameters, that today have an increasing interest for meteorological applications. More specifically these parameters are tropospheric and VTEC estimation parameters by GNSS

and VLBI techniques carried out during 2014 for intertechnique comparisons and for real time modelling of

troposphere parameters by national GNSS networks.

We dispose in Italy a national GNSS network: Rete

Dinamica Nazionale (RDN) and of several regional

real time GNSS networks [3]; then three sites are colocated with GNSS and VLBI equipment [11]. Some

tests have been performed in collaboration with the

IVS KTU AC for the use of the Scientific GNSS software Bernese version 5.2 [6], to estimate atmospheric

parameters.

IVS 2014 Annual Report
258 Tornatore

Delay vs UTC time for MULTI.UVDATA.1

SN 1 Rpol IF 1 - 4

Plot file version 4 created 20-FEB-2014 14:41:16

2R WZ

IF 1

400

300

200

100

0

-100

2R WZ

IF 2

400

300

200

100

0

-100

2R WZ

IF 3

Nano Seconds

400

300

200

100

0

-100

2R WZ

IF 4

Time (hours)

13 15 20 25 30 35 40 45 50 55 14 00

400

300

200

100

0

Fig. 1 Solutions from fringe fitting, delays of antenna 2 with respect to antenna 1.

Gain phs vs UTC time for MULTI.UVDATA.1

SN 1 Rpol IF 1 - 4

Plot file version 5 created 20-FEB-2014 14:44:02

2R WZ

300 IF 1

200

100

0

2R WZ

IF 2

200

100

0

-100

-200

2R WZ

IF 3

Degrees

300

200

100

0

2R WZ

IF 4

Time (hours)

13 15 20 25 30 35 40 45 50 55 14 00

300

200

100

0

Fig. 2 Solutions from fringe fitting, phases of antenna 2 with respect to antenna 1.

IVS 2014 Annual Report
PMD 2014 Annual Report 259

3 Future Plans

The PMD Analysis Center plans to tackle the following topics during 2015: co-location on Earth and

in Space for improved reference frames, investigation

into dedicated algorithms for improvement of tropospheric parameter estimation and comparisons among

atmospheric parameter estimates that come from the

space geodetic techniques of VLBI and GNSS and that

are particularly addressed to a not very broad region.

Then in collaboration with IVS KTU AC an intertechnique comparison between VLBI and DORIS for

a combination of TRF common parameters is being set

up.

References

1. http://www.dica.polimi.it/en/

Politecnico di Milano (DICA) website

2. http://www.aips.nrao.edu/cook.html

AIPS Cookbook

3. Benciolini, B., Biagi, L., Crespi, M., Manzino, A. and

Roggero, M., Reference frames for GNSS positioning services: some problems and proposals in Journal of Applied

Geodesy, 53-62, 2008.

4. Bohm J., B  ̈ ohm S., Nilsson T., Pany A., Plank L., Spi-  ̈

cakova H., Teke K., Schuh H, The new Vienna VLBI

Software VieVS in IAG Symposium 139, Kenyon S., Pacino M.C., Marti U. (eds), 1007-1012, 2012.

5. Cotton, W. D., Fringe fitting. ASP Conference Series, 82,

1995.

6. R. Dach, P. Walser (eds), Bernese GNSS Software Version

5.2, Astronomical Institute, University of Bern, 2013.

7. Fey A. L., Gordon D., Jacobs C. S. (eds), IERS technical

note 35, The second realization of the international celestial

reference frame by very long baseline interferometry, Verlag

des Bundesamt fur Kartographie und Geod  ̈ asie, Frankfurt  ̈

am Main, 2009 (http://www.iers.org/TN35).

8. Greisen, E., The FITS Interferometry Data Interchange

Convention. AIPS Memo114r, 2011.

9. Nothnagel A. Conventions on thermal expansion modeling

of radio telescopes for geodetic and astrometric VLBI, in

Journal of Geodesy, 83, 787—792, 2008.

10. Petit G., Luzum B. (eds.), IERS Conventions (2010), IERS

Technical Note 36, Frankfurt am Main: Verlag des Bundesamt fur Kartographie und Geod  ̈ asie, 2010.  ̈

11. Ray, J. and Z. Altamimi, Evaluation of co-location ties

relating the VLBI and GPS reference frames, in Journal

of Geodesy, 79(4-5), doi: 10.1007/s00190-005-0456-z 189-

195. 2005.

12. Tornatore, V., R. Haas, S. Casey, D. Duev, S. Pogrebenko, G.

Molera Calves,  ́ Direct VLBI Observations of Global Navigation Satellite System Signals, Earth on the Edge: Science for a Sustainable Planet, IAG Symposium 139, doi:

10.1007/978-3- 642-37222-3 32247-252, ISBN (online):

978-3-642-37221- 3, 2014.

IVS 2014 Annual Report
Pulkovo IVS Analysis Center (PUL) 2014 Annual Report

Zinovy Malkin, Yulia Lopez (nee Sokolova)  ́

Abstract This report briefly presents the PUL IVS

Analysis Center activities during 2014 and plans for

the coming year. The main topics of the investigations

of the PUL staff in that period were ICRF-related studies, computation and analysis of EOP series, celestial

pole offset (CPO) and free core nutation (FCN) modeling, and VLBI2010 related issues.

1 General Information

The PUL IVS Analysis Center was organized in

September 2006. It is located at and sponsored by

the Pulkovo Observatory of the Russian Academy

of Sciences. It is a part of the Pulkovo EOP and

Reference Systems Analysis Center (PERSAC) [1].

The main topics of our IVS related activity are:

• Improvement of the International Celestial Reference Frame (ICRF).

• Computation and analysis of the Earth orientation

parameters (EOP) from Intensives and 24-hour IVS

sessions.

• Analysis of EOP and source position time series.

• Modeling of the celestial pole offset (CPO) and free

core nutation (FCN).

• Comparison of VLBI products, primarily EOP,

with results of other space geodesy techniques.

• Computation and analysis of observation statistics.

The PUL Analysis Center Web page [2] is supported. It contains the following sections:

Pulkovo Observatory

Pulkovo Analysis Center (PUL)

IVS 2014 Annual Report

• General information about the PUL Analysis Center. Includes brief history, activity overview, and a

scientific staff list.

• VLBI data analysis. Includes results of VLBI data

analysis, such as UT1 Intensive series, CPO/FCN

series, and mean Pole coordinates. These data are

updated daily.

• OCARS catalog. Includes the latest version of the

catalog OCARS (Optical Characteristics of Astrometric Radio Sources) [3]. The catalog is regularly

updated as new information becomes available.

• Approaches and occultations. Includes tables for

forthcoming mutual events of planets and astrometric radio sources, such as close angular approaches

and occultations for the period until 2050 [4].

• PUL members’ publications and presentations.

• VLBI technology overview.

• Links to the VLBI World. Includes links to (primarily geodetic and astrometric) VLBI coordinating bodies, stations, analysis centers, software, etc.

• Contact information.

2 Staff

In 2014 the following persons contributed to the PUL

activity:

1. Zinovy Malkin (70%) — team coordinator, EOP

and CRF analyst;

2. Yulia Lopez (nee Sokolova) (100%) — CRF ana-  ́

lyst.

260
Pulkovo Analysis Center (PUL) 261

3 Activities and Results

The main activities and results of the PUL IVS Analysis Center during 2014 included:

• ICRF-related research. The main directions of this

activity were comparison and combination of radio

source position catalogs and investigation of their

stochastic and systematic errors. In 2014, the following results were obtained:

– A new method of investigation of the stochastic errors of external radio source position catalogs (RSPCs) has been tested [5]. Using this

method the stochastic errors of nine recently

published RSPCs were evaluated. It has been

shown that the result can be affected by the systematic differences between catalogs if the latter are not accounted for. It was also found that

the formal uncertainties of the source positions

in the RSPCs correlate with the external errors.

We also investigated several topics related to

the formal uncertainties and systematic errors

of RSPCs.

– We continued investigations of the impact of

the correlation information on the orientation

parameters between celestial reference frames

[6]. We compared results of determination

of the orientation angles between celestial

reference frames realized by radio source

position catalogs using three methods of

accounting for correlation information: using

the position errors only, using additionally the

correlations between the right ascension and

declination (RA/DE correlations) reported in

radio source position catalogs published in the

IERS format, and using the full covariance

matrix. The computations were performed

with nine catalogs computed at eight analysis

centers. Our analysis has shown that using the

RA/DE correlations only slightly influences

the computed rotational angles, whereas using

the full correlation matrices leads to substantial

change in the orientation parameters between

the compared catalogs.

– Studies related to modeling the Galactic aberration in source proper motions.

1. We analyzed all available determinations of

the Galactic rotation parameters R0 and Ω0

made during the last ten years to derive the

most probable value of the Galactic aberration constant A = R0Ω2

0

/c [7]. We used several statistical methods to obtain reliable estimates of R0 and Ω0 and their realistic errors. As a result, we obtained the value of

A = 5.0±0.3 μas/yr as the current best estimate of the GA constant. We suggest that

the proposed value of the GA constant can

be safely used in practice during coming

years.

2. During recent years, much attention has

been paid to the astrometric implications of

the galactic aberration in proper motions

(GA). This effect causes systematic errors

in astrometric measurements at the μas

level. Some authors consider it so serious

that it requires redefinition of the celestial

reference frame (CRF). We argue that

such attention to the GA is too much

exaggerated. It is just a small astrometric

correction that must be taken into account

during highly accurate astrometric and

geodetic data processing. The accuracy of

this correction depends on the accuracy

of the Galactic rotation parameters and,

for most applications, on the accuracy

of the rotation matrix between Galactic

and equatorial systems. Our analysis has

shown that our knowledge today of these

two factors is sufficient to compute the GA

correction with accuracy of better than 10%.

The remaining effect at a level of few tenths

μas/yr is negligible nowadays. Another

consequence of introducing the GA correction is the necessity to return to classical

astrometric modeling of the VLBI-derived

extragalactic radio source positions by the

linear trend model. Changing the current

paradigm of VLBI-derived CRF based on

the assumption of zero motion of radio

sources to the classical one leads to bias in

the radio source positions up to several tens

of μas for catalogs at epoch J2000.0 [8].

– The OCARS catalog [3] has been supported

since 2008. The catalog provides redshift information, as well as visual and NIR magnitudes.

The improvements made in 2014 include addition of new sources and new measurements of

redshift and magnitude. A new file with detailed

IVS 2014 Annual Report
262 Malkin and Lopez

photometric data, ocars_m.txt, is now supported in addition to the main OCARS catalog

file, ocars.txt. The current basic statistics

of the OCARS catalog are given in Table 1.

• CPO and FCN related research. The main activities

and results in 2014 were the following:

– Two CPO and two FCN series were updated

daily and are available at the PERSAC Web

page [1].

– Several VLBI-derived CPO time series were analyzed with the goal of detecting the Free Inner Core Nutation (FICN) [9]. The series were

investigated by means of spectral and wavelet

analysis. It was shown that there are several periodic signals with close amplitude around the

expected FICN period without a prevailing one,

which can be associated with the FICN. So, it

seems to be necessary to improve the theoretical

estimates of the FICN period to make searching

for it in the observational series more promising.

– Corrections to the IAU 2000/2006 parameters

of the theory of precession and nutation were

calculated using five different series: two

individual series and three combined series that

have been used in the literature for this purpose. A comparison of the sets of corrections

obtained using the different series indicates

significant systematic differences between

them, which often substantially exceed the

corresponding random errors. At the same

time, existing studies have usually used data

obtained from one or two series chosen by

the authors without special justification. When

refining the theory of precession and nutation,

it is necessary to consider and compare various

available series of VLBI data if one wishes to

reduce the systematic errors in an improved

model [10].

• Studies on investigation of the mutual impact of

celestial and terrestrial reference frames, and

impact of astronomical and geophysical modeling

on ICRF. Analysis of measurements of the space

geodetic techniques requires the use of the best

available models describing the deformation of the

Earth’s surface. The goal is to have a set of models

which realistically describe changes in the station

positions on the Earth’s surface during the time

when the observations are carried out. We take

advantage of a long time span of measurements

(more than 29 years) gathered by the Very Long

Baseline Interferometry (VLBI) technique, and

we focus on the propagation of these unmodeled

effects in all three station coordinates to the radio

source positions building the celestial reference

frame (CRF). Two treatment approaches of the

unmodeled seasonal station displacement are

introduced. As the first, we model the surface deformation as a periodic movement with annual and

semi-annual periods, and in the second approach

we create an average annual model [11].

• Operational data processing of IVS Intensive sessions in automated mode and submission of results

to IVS was continued. The UT1 time series is available at IVS Data Centers and at the PERSAC Web

page [1].

• The PUL archive of VLBI data and products

obtained in the framework of IVS activity is

supported. At present, all available databases and

corresponding NGS cards for 1979—2014 are

stored (about 9.4 million observations) along with

the main IVS and IERS products. These archives

are continually updated as new databases become

available.

• Development of algorithms and software for data

processing and analysis continued.

• PUL staff members participated in activities of several IERS, IAG, and IVS projects, committees, and

working groups.

4 Future Plans

Plans for the coming year include:

• Continuing ICRF-related studies.

• Continuing CPO/FCN-related studies.

• Continuing UT1 Intensive data processing.

• Continuing OCARS catalog support.

• Continuing development of algorithms and software for data processing.

• Continuing support of the PUL archives of data and

products.

IVS 2014 Annual Report
Pulkovo Analysis Center (PUL) 263

Table 1 Current basic statistics of the OCARS catalog.

All sources ICRF2 sources ICRF2 defining

Sources 9,049 3,414 295

Sources with redshift information 4,901 (54.2%) 2,332 (68.3%) 262 (88.8%)

Sources with photometric data 5,973 (66.0%) 2,643 (77.4%) 286 (96.9%)

References

1. http://www.gao.spb.ru/english/as/persac/index.htm

2. http://www.gao.spb.ru/english/as/ac vlbi/

3. http://www.gao.spb.ru/english/as/ac vlbi/ocars.txt

4. http://www.gao.spb.ru/english/as/ac vlbi/

occultations approaches.pdf

5. Malkin Z., 2014, On errors of radio source position catalogs. In: Proc. Journees 2013 Systemes de Reference Spatio-  ́

temporels, Ed. N.Capitaine, Observatoire de Paris, 69–72.

6. Sokolova Y., Malkin Z., 2015, On impact of the correlation

information on the orientation parameters between celestial

reference frames. In: C. Rizos, P. Willis (eds.), IAG Symposia, v. 143, in print.

7. Malkin Z., 2014, On the Galactic aberration constant.

In: Proc. Journees 2013 Systemes de Reference Spatio-  ́

temporels, Ed. N.Capitaine, Observatoire de Paris, 44–45.

8. Malkin Z., 2014, On the implications of the Galactic aberration in proper motions for the Celestial Reference Frame.

MNRAS, 445(1), 845–849.

9. Malkin Z., 2014, On detection of the free inner core nutation from VLBI data. In: Proc. Journees 2013 Systemes de  ́

Reference Spatio-temporels, Ed. N.Capitaine, Observatoire

de Paris, 224–225.

10. Malkin Z.M., 2014, On the Accuracy of the Theory of Precession and Nutation. Astronomy Reports, v. 58(6), 415–425.

11. Krasn  ́ a H., Malkin Z., B  ́ ohm, J., 2014, Impact of sea-  ̈

sonal station displacement models on radio source positions. In: Proc. Journees 2013 Systemes de Reference Spatio-  ́

temporels, Ed. N.Capitaine, Observatoire de Paris, 65–68.

IVS 2014 Annual Report
SAI VLBI Analysis Center 2014 Annual Report

Vladimir Zharov

Abstract This report presents an overview of the SAI

VLBI Analysis Center activities during 2014 and the

plans for 2015. The AC SAI analyzes all IVS sessions for computations of the Earth orientation parameters (EOP) and time series of the ICRF source positions, and it performs research and software development aimed at improving the VLBI technique.

1 General Information

The SAI VLBI Analysis Center is located at Sternberg

State Astronomical Institute of Lomonosov Moscow

State University in Moscow, Russia. The Analysis Center participates in geodetic and astrometric VLBI analysis, software development, and research aimed at improving the VLBI technique especially for support of

the Radioastron mission.

2 Component Description

AC SAI performs data processing of all kinds of VLBI

observation sessions. For VLBI data analysis we use

the ARIADNA software package developed at SAI.

Version 4 was finished and tested in 2012. All reductions are performed in agreement with the IERS Conventions (2010).

ARIADNA uses files in NGS format as input data.

Sternberg State Astronomical Institute (SAI) of Lomonosov

Moscow State University

SAI Analysis Center

IVS 2014 Annual Report

The package ARIADNA (v. 4) is the basis of software named as ORBITA installed on the correlator of

the AstroSpace Center at the Lebedev Physical Institute. It is used for the correlation of the ground-space

interferometer data during the Radioastron mission. A

new modification of the software was developed to perform correlation in “Coherent” mode (see below).

3 Staff

• Vladimir Zharov, Prof.: development of the ARIADNA software, development of the methods of

parameter estimation;

• Nikolay Voronkov, scientific researcher: global solution;

• Svetlana Nosova, engineer: VLBI data processing;

• Natalya Shmeleva, engineer: VLBI data processing.

4 Current Status and Activities

• Software development for VLBI processing

The ARIADNA software is being developed to provide contributions to IVS products. The software is

used for calculating all types of IVS products. Version 4 was developed in 2012. The main features of

this version are performing all reductions in agreement with the IERS Conventions (2010), generation of SINEX files, and the combination of some

of the SINEX files to stabilize solutions.

The used version of this software was corrected in

2013: now it is possible to use the CIO-based trans264
SAI 2014 Report 265

formation matrix. New series of the EOP were obtained from observations that were made in 2013.

The method that uses the calculation of the

equinox-based transformation matrix for

precession-nutation was kept to compare new

series with old ones. The equinox-based matrix

Q(t) that transforms from the true equinox and

equator of date system to the GCRS is composed

of the classical nutation matrix, the precession

matrix including four rotations, and a separate

rotation matrix for the frame biases. New series of

the nutation angles will be used for the preparation

of our suggestion to improve the nutation theory.

Some corrections of the model of delay for the

ground-space interferometer were made and realized in the ORBITA software, which is used for

correlation and routine analysis of the Radioastron

observations.

There is a so-called “Coherent” mode for correlation of the ground-space interferometer data during the Radioastron mission. It was developed to

support an onboard reference frequency source by

synchronizing it from the ground based master Hmaser at a tracking station (TS). The phase stable

signal of the ground based H-maser frequency is

converted to RF, transmitted forward to Radioastron spacecraft and then, after coherent conversion,

is transmitted back to the TS. At the TS, both signals (transmitted and received) can be compared

to evaluate Doppler residuals and phases, and after

that, the timing of the data flow can be corrected.

The Coherent mode is the important procedure to

keep efficiency of the ground-space interferometer

in cases of outage events of the highly stable onboard H-maser. The Coherent mode processing algorithm is realized in the ASC FX correlator.

• Routine analysis

During 2014, routine data processing was performed with the ARIADNA software using the

least-squares method with rigid constraints, and

non-rigid constraints were used for generation of

SINEX files.

AC SAI operationally processed the 24-hour

and Intensive VLBI sessions. Forming the VLBI

sessions’ databases and processing of all sessions

is fully automated. The EOP series sai2014a.eops

and sai2014a.eopi were calculated. These series

were computed with the catalog VTRF2008 of station positions and velocities. Experimental series

sai2014c.eops was calculated for development of a

new nutation theory.

IVS 2014 Annual Report
SHAO Analysis Center 2014 Annual Report

Guangli Wang 1, Jinling Li 1, Minghui Xu 1,2, Li Guo 1, Fengchun Shu 1, Zhihan Qian 1, Liang Li 1

Abstract This report presents the routine work and

the research carried out at the SHAO VLBI Analysis Center (AC) during 2014. The SHAO AC continues the routine VLBI data analysis of 24-hour geodetic/astrometric sessions to generate products, and it

processes the CVN data, which will be submitted to

the IVS starting in 2015. We also carry out the navigation for the Chang’E mission, using the VLBI technique as usual, and some basic research in astrometry,

which are the systematical variations in the Celestial

Reference Frame and the effect of aberration.

1 General Information

The SHAO VLBI Analysis Center is located at

the Shanghai Astronomical Observatory, Chinese

Academy of Sciences, Shanghai, China. It is a part

of the astrometry research group in the department

of astro-geodynamics. Some members are from the

VLBI application in the Chinese deep space mission.

Therefore, we are processing the Chinese VLBI

Network (CVN) data, IVS 24-hr routine sessions, and

1-hr Intensive UT1 sessions.

1. SHAO, Chinese Academy of Sciences

2. GFZ

SHAO Analysis Center

IVS 2014 Annual Report

2 Activities during the Past Year

The SHAO Analysis Center analyzed all the IVS sessions and five CVN sessions (including resolving ambiguities and determining the ionospheric effect from

dual band data) by using the Calc/Solve and the nuSolve software package. During 2014, we continued

generating the ITRF2013 solution, which extends the

VLBI observations from the end of 2013 to 2014. We

provided VLBI products, i.e., EOP, CRF, and TRF, for

the Chinese EOP Services.

3 Current Status

• Resolving ambiguities. We investigated the principle and the methods that were used to resolve the

ambiguities of the VLBI group delay by using the

single band delay. Even though the ambiguity issue

was solved from the very beginning of the VLBI

technique, the deep understanding of this procedure

will facilitate both the data analysis and resolving

sub-ambiguities. Some ambiguity points can be effectively identified by comparing the ionosphere effects from the single band delay. This work was

partly carried out by using nuSolve, which is quite

helpful software with a GUI.

• Ionosphere effect. The ionosphere effect correction

is obtained from dual band data by using the

ionosphere effect free combination. It is calculated based on the effective frequency, which is

a weighted “mean” frequency depending on the

amplitude of the cross correlation and the number

of the accumulated period. Thus, it varies with

respect to time and also baseline due to the loss of

266
SHAO 2014 Report 267

data in some channels or lower amplitude at some

sidebands. As a result, if there is a constant offset

in a baseline between two bands after closing all

the triangles in the big network, this constant offset

can not be completely absorbed by the clock model

because this offset is not a constant after correcting

the ionosphere effect. There are other problems

left; for instance, its second order, the signal paths

not being totally the same for two bands, and the

scintillation.

• High frequency variation in source position.

CONT14 is a campaign of continuous VLBI

sessions, which was scheduled for observation

starting in early May 2014 (6-MAY-2014 00:00

UT through 20-MAY-2014 24:00 UT). With a

network size of 17 stations (ten in the northern

hemisphere and seven in the southern hemisphere),

it continually obtained more than 500 observables

per day for about eight radio sources (for example,

1739+522, 0016+731, and 0059+581). These data

provide a good opportunity to get high frequency

variation, two- or four-hour interval, in the position

of these radio sources, and to investigate these

variations.

• Different level of NNT and NNR constraints.

There are degeneracies of the normal equation

when one determines TRF, CRF, and EOP by using

VLBI. The common way of circumventing these

degeneracies is to apply in the least-square adjustment no-net-rotation (NNR) and no-net-translation

(NNT) constraints of the station positions and

velocities of a subset of stations with respect to

the ITRF, and NNR constraints to the defining

sources with respect to the ICRF. We investigate

the influence on the EOP, CRF, and TRF of three

different degrees of these constraints, 0.1 m, 1

mm, and 0.01 mm. The results show that different

degrees of the NNR and NNT constraints on the

TRF have no impact on the CRF and precession

but cause significant change in the TRF and ERPs.

When the constraints were reduced to 1.0 mm and

smaller, the difference was less than 1 mm for the

station coordinates. But when looser constraints,

such as 0.1 m, were used, big differences in the

station positions led to significant drifts in the ERP.

• Solar velocity. The motion of the barycenter with

respect to the CMB, probably steadily constant over

a few hundred years, can be reasonably taken as the

same as the motion of the object with respect to the

CMB and modeled into the effect of proper motion.

As we know, the motion of each individual object is

random over the sky, but the motion of the barycenter is identical for all objects. Therefore, there are

two systematic effects in those variations, which requires consideration for recently refined measurements in astrometry: the apparent proper motion

caused by the acceleration of the barycenter with

respect to the CMB (Xu et al., 2014), which has

been determined and discussed in a series of papers,

and the proper motion caused by the velocity of the

barycenter with respect to the CMB, which is actually the variation in the parallax effect caused by

this motion. Simulations and estimation from VLBI

data are being made to get interesting results.

• Aberration. Special efforts are still being made to

clarify this (Xu et al. 2014).

• CVN data. The CVN data analysis includes resolving ambiguities, determining the ionosphere effect,

detecting clock breaks, identifying the outliers, and

estimating the geodetic parameters. We are preparing to submit these data to the IVS so that they can

be widely used.

• ITRF2013. Due to the ITRF2013 solution having

been changed from 2013 to 2014 to include all the

2014 VLBI data available until February of 2015,

we continued the data analysis to provide the complete solution to the IVS.

4 Staff

During 2014, the staff of SHAO AC contained one consultant, the group leader Dr. Wang, three employees,

and two PhD students. Dr. Wang is also a member of

the Observing Program Committee in the IVS. Postdoc, Zhibing Zhang joined us at the end of this year.

5 Future Plans

Plans for the future include contributing to the ICRF3,

investigating the ionosphere effect, preparing the CVN

data, and submitting to the IVS. We will also collect

the resources and the staff to develop new VLBI data

analysis software, with which we can contribute more

to VLBI and VLBI2010.

IVS 2014 Annual Report
268 Wang et al.

Table 1 Staff members and the main tasks.

Dr. Guangli Wang VLBI2010, observing, data analysis, and head leader

Dr. Jinling Li Positioning, VLBI2010, and data analysis

MSc. Minghui Xu Data analysis, ITRF solution, CRF and astrometry in VLBI

Dr. Li Guo Positioning, data analysis

Dr. Fengchun Shu Scheduling, correlation, and data analysis

Dr. Zhihan Qian Consulting

MSc. Liang Li Data analysis and CRF

References

1. M. Xu, R. Heinkelmann, H. Schuh, M. Zhao, and G. Wang.

The acceleration of the origin of the ICRF. In D. Behrend,

K. D. Baver, and K. Armstrong, editors, Proceedings of the

Eighth IVS General Meeting: VGOS: The New VLBI Network, pp. 412-416, 2014.

2. M. Xu and G. Wang. On the definition of aberration. In D.

Behrend, K. D. Baver, and K. Armstrong, editors, Proceedings of the Eighth IVS General Meeting: VGOS: The New

VLBI Network, pp. 490-494, 2014.

IVS 2014 Annual Report
Tsukuba VLBI Analysis Center

Shinobu Kurihara 1, Tetsuya Hara 1,2

Abstract This report summarizes the activities of

the Tsukuba VLBI Analysis Center during 2014. The

weekend IVS Intensive (INT2) sessions were regularly

analyzed using c5++ analysis software. Several ultrarapid dUT1 experiments were implemented in association with Onsala, Hobart, and HartRAO.

1 Introduction

The Tsukuba VLBI Analysis Center, located in

Tsukuba, Japan, is hosted and operated by the Geospatial Information Authority of Japan (GSI). One of our

major roles as an operational Analysis Center is to

regularly analyze the weekend IVS Intensive (INT2)

sessions using the fully automated VLBI analysis

software c5++ developed by the National Institute of

Information and Communications Technology (NICT)

[1]. It should be noted that the UT1-UTC (= dUT1)

solution becomes available within a few minutes after

the end of the last scan of the session. A 10 Gbps

dedicated link to the SINET4 operated by the National

Institute of Informatics (NII) and several process

management programs make it possible to derive a

solution rapidly. The ultra-rapid dUT1 experiments

after some regular IVS 24-hour sessions and CONT14

sessions were implemented in 2014.

1. Geospatial Information Authority of Japan

2. Advanced Engineering Service Co., Ltd.

Tsukuba VLBI Analysis Center

IVS 2014 Annual Report

2 Component Description

2.1 Analysis Softwares

c5++, which is analysis software for space geodesy including SLR, GNSS, and VLBI, is officially used to

provide a dUT1 solution from a regular INT2 session.

Calc/Solve has been in continuous use since the

early days of VLBI work at GSI. It is used for the

analysis of JADE, which is the Japanese domestic observation for geodesy, in its interactive mode and for

global analysis in the batch mode. In June, we installed

νSolve released by the GSFC VLBI group. It has been

working well as a substitute for the legacy user interface of the interactive mode of Solve.

VieVS, developed by the Institute of Geodesy and

Geophysics (IGG) at the Vienna University of Technology, is also installed at the Tsukuba Analysis Center

[2].

2.2 Analysis Center Hardware Capabilities

c5++, Calc/Solve, and VieVS are installed on several

general-purpose and commercially-produced Linux

computers (Table 1). Individual RAIDs are mounted

on each computer for storing many VLBI data files

such as Mark III databases.

3 Staff

The technical staff at the Tsukuba Analysis Center are:

269
270 Kurihara and Hara

Table 1 Analysis Center Hardware Capabilities.

Number of servers six for VLBI analysis (c5++, Calc/Solve, and VieVS)

Operating System CentOS version 5.4, 5.5, 6.5, and Red Hat Enterprise Linux 6.3

CPU Intel Xeon @3.80GHz CPU x 2,

Intel Xeon 5160 @3.00GHz dual CPU x 2,

Intel Xeon X3360 @2.83GHz quad CPU,

Intel Xeon X5687 @3.60GHz quad CPU x 2

Intel Xeon E3-1270V2 @3.50GHz quad CPU

Total storage capacity individual RAIDs: 5.49 Tbytes in total

• Shinobu Kurihara: correlator/analysis chief, management.

• Tetsuya Hara (AES): correlator/analysis operator,

software development.

4 Analysis Operations

4.1 IVS Intensive for UT1-UTC

106 IVS Intensive sessions were analyzed at the

Tsukuba Analysis Center, and dUT1 results were

submitted as gsiint2b.eopi to the IVS Data Center

(Table 2). Only the dUT1 parameter was estimated,

with station positions fixed to a-priori. For the Tsukuba

station after the 2011 Tohoku Earthquake, the position

correcting its non-linear post-seismic motion provided

by NASA/GSFC was used. The Tsukuba–Wettzell

baseline and several other baselines were analyzed.

The observed data at Wettzell is e-transferred to the

Tsukuba Correlator in near real-time with the Tsunami

UDP protocol. The correlated data is rapidly analyzed

by c5++ as soon as all of the correlator output comes

in, and then a dUT1 solution is derived and submitted.

The dUT1 solution becomes available at the IVS Data

Center just after the session. The processes from data

transfer through the submission of the solution are

fully automated and done by unmanned operation.

Since 19 out of the 101 Tsukuba–Wettzell baseline

Table 2 Intensive sessions analyzed at the Tsukuba Analysis

Center.

Baseline # of sessions Average of dUT1 sigma

Intensive 2 TsWz 101 9.3 μsec

KkWz 3 12.7 μsec

KbWz 2 28.3 μsec

Total 106 9.7 μsec

analyses had some sort of problem in the observed

data or trouble at the stations, the automated analyses

for those sessions failed. In the other 82 sessions, we

succeeded in the rapid analysis with low latency, and

90% of them completed analysis within ten minutes

after the end of the last scan (Figure 1). The end time

of the IVS-INT2 sessions is 8:30 UT on every Saturday

and Sunday. Thus, the dUT1 solution is available at

the latest before 9 a.m. for users as an IVS product.

Our products are utilized for more accurate dUT1

prediction by the U.S. Naval Observatory (USNO) as

the IERS Rapid Service/Prediction Centre, which is

responsible for providing earth orientation parameters

on a rapid turnaround basis, primarily for real-time

users and others needing the highest quality EOP

information sooner than that available in the final EOP

series.

Figure 2 shows the differences between the dUT1

solutions of each Intensive baseline and IERS EOP 08

C04 from January 2013 through December 2014.

4.2 Ultra-Rapid dUT1 Experiment

This experiment started in 2007 as a joint project of

Japan (Tsukuba and Kashima) and Fennoscandia (Onsala and Metsahovi). It aims to derive a consecutive  ̈

time series of dUT1 (or full set of EOP) as soon as

possible. The observed data is sent in real-time via the

international optical fiber backbone to Tsukuba where

the data is correlated and analyzed. c5++ is used in

the whole analysis. Nowadays four countries — Japan,

Sweden, Australia, and South Africa — are involved in

association with Onsala, Hobart, and HartRAO.

In 2014, four regular IVS-R1 sessions and one

R&D session were processed with the ultra-rapid mode

(Table 3). Additionally, we operated the CONT14

IVS 2014 Annual Report
Tsukuba Analysis Center 271

0

10

20

30

40

50

60

70

80

90

100

0 1 2 3 4 5 6 7 8 9 10 11 12 13

Number of sessions [%] 

Latency [min] 

Fig. 1 Latency–number of sessions as % of 82 Tsukuba-Wettzell sessions. 19 sessions with some sort of trouble during the session

are excluded.

-200

-150

-100

-50

 0

 50

 100

 150

 200

2013 / 01 2013 / 07 2014 / 01 2014 / 07 2015 / 01

UT1-UTC w.r.t. IERS EOP 08 C04 (usec)

Year / Month

 TsWz : Bias = 7.09 (usec), WRMS = 22.92 (usec)

 KbWz : Bias = 126.72 (usec), WRMS = 5.49 (usec)

 KkWz : Bias = 11.32 (usec), WRMS = 13.56 (usec)

 KkNy : Bias = 6.09 (usec), WRMS = 14.17 (usec)

 KkSv : Bias = -84.21 (usec), WRMS = 78.10 (usec)

Fig. 2 The time series of UT1-UTC derived from IVS Intensive with respect to IERS EOP 08 C04. Error bars are 1 σ formal

uncertainties.

campaign with the ultra-rapid processing for the

Onsala–Tsukuba baseline. The Onsala data were

e-transferred in real-time to the Tsukuba correlator

using the Tsunami protocol. The data were correlated

with the corresponding data from the Tsukuba station

in near real-time, followed by a near real-time analysis

to determine dUT1. One dUT1 value was estimated

from the dataset of correlator outputs in a three-hour

period. When a new correlator output comes in, the

three-hour analysis period shifts forward and the oldest

data out of the period are left out, and then a new

analysis is performed. The analysis strategy is called

“sliding window” approach. As a result, we could

obtain a time series of dUT1 that is produced during

the ongoing session with very low latency through 15

days. The average of the latency through 15 days was

6 min 18 sec. Figure 3 shows the estimated time series

of dUT1, and Figure 4 shows differences between

estimated dUT1 and IERS Rapid Prediction.

5 Outlook

We will continue to analyze the data of the IVS-INT2

sessions and submit dUT1 products with a low latency.

IVS 2014 Annual Report
272 Kurihara and Hara

-274000

-272000

-270000

-268000

-266000

-264000

-262000

-260000

-258000

-256000

-254000

-252000

05/06 05/07 05/08 05/09 05/10 05/11 05/12 05/13 05/14 05/15 05/16 05/17 05/18 05/19 05/20 05/21

UT1-UTC (usec)

Month / Day

prediction

OnTs

Fig. 3 The time series of UT1-UTC derived from the Onsala–Tsukuba baseline from IVS-CONT14 ultra-rapid processing with the

prediction (Rapid Service/Prediction of Earth Orientation, finals2000A.daily).

-300

-200

-100

 0

 100

 200

 300

05/06 05/07 05/08 05/09 05/10 05/11 05/12 05/13 05/14 05/15 05/16 05/17 05/18 05/19 05/20 05/21

UT1-UTC w.r.t prediction (usec)

Month / Day

OnTs

Fig. 4 Residuals of UT1-UTC with respect to the prediction (Rapid Service/Prediction of Earth Orientation, finals2000A.daily).

Table 3 The ultra-rapid experiments in 2014. All experiments

were processed after the regular IVS sessions.

Exper. Date Time Dur. Stations #obs.

(skd) (cor)

R1624 Feb 10 17:00 24 HtOnTs 287 275

RD1402 Mar 26 18:00 24 HbHtOnTs 244 278

R1631 Mar 31 17:00 24 OnTs 201 201

R1632 Apr 07 17:00 24 OnTs 191 191

CONT14 May 06 00:00 360 OnTs 3262 3009

R1657 Oct 13 17:00 24 HbHtOnTs 328 86

References

1. Hobiger, T., et al.: Fully automated VLBI analysis with c5++

for ultra-rapid determination of UT1, Earth Planets Space,

62, 933-937, 2010.

2. Bohm, J., et al.: The New Vienna VLBI Software VieVS, In  ̈

Proceedings of IAG Scientific Assembly 2009, International

Association of Geodesy Symposia Series, 136, edited by S.

Kenyon, M. C. Pacino, and U. Marti, doi: 10.1007/978-3-

642-20338-1 126, 1007-1011, 2012.

IVS 2014 Annual Report
U.S. Naval Observatory VLBI Analysis Center

Alan Fey, Nicole Geiger, Christopher Dieck

Abstract This report summarizes the activities

of the VLBI Analysis Center at the United States

Naval Observatory for 2014. Over the course of the

year, Analysis Center personnel continued analysis

and timely submission of IVS-R4 databases for

distribution to the IVS. During the 2014 calendar

year, the USNO VLBI Analysis Center continued to

use the VLBI global solution designated usn2014a.

Earth orientation parameters (EOP) based on this

solution and updated by the latest diurnal (IVS-R1

and IVS-R4) experiments, were routinely submitted to

the IVS. Sinex format files based upon the bi-weekly

24-hour experiments were also submitted to the IVS.

During the 2014 calendar year, Analysis Center

personnel continued a program to use the Very Long

Baseline Array (VLBA) operated by the NRAO for

the purpose of measuring UT1–UTC. Routine daily

one-hour duration Intensive observations continued

using the VLBA antennas at Pie Town, NM and Mauna

Kea, HI.

1 Introduction

The USNO VLBI Analysis Center is supported and

operated by the United States Naval Observatory

(USNO) in Washington, DC. The primary services

provided by the Analysis Center are the analysis of

diurnal experiments and the production of periodic

VLBI global solutions for estimation of the Terrestrial

U.S. Naval Observatory

USNO Analysis Center

IVS 2014 Annual Report

Reference Frame (TRF), the Celestial Reference

Frame (CRF), and Earth Orientation Parameters

(EOP). The Analysis Center continued the submission

to the IVS of Intensive (EOP-I) and session-based

(EOP-S) Earth orientation parameters based on USNO

VLBI global solutions. Analysis Center personnel

maintain the necessary software required to continue

these services to the IVS including periodic updates

of the GSFC CALC/SOLVE software package. In

addition to operational VLBI analysis, Analysis Center

personnel are actively engaged in research related

to future reference frames, the electronic transfer of

VLBI data, and software correlation.

2 Current Analysis Center Activities

2.1 IVS Experiment Analysis and

Database Submission

During the 2014 calendar year, personnel at the USNO

VLBI Analysis Center continued to be responsible for

the timely analysis of the IVS-R4 experiments, with the

resulting databases submitted within 24 hours of correlation for dissemination by the IVS. Analysis Center personnel continue to be responsible for the analysis and database submission for the periodic IVS-CRF

experiments. Analysis Center personnel also continued analyzing IVS Intensive experiments for use in

the USN-EOPI time series and continued a new series

of Intensive sessions using the VLBA antennas at Pie

Town, NM and Mauna Kea, HI.

273
274 Fey et al.

2.2 Global VLBI Solutions, EOP and Sinex

Submission

USNO VLBI Analysis Center personnel continued

to use the periodic global TRF/CRF/EOP solution

usn2014a over the course of the 2014 calendar year.

Analysis Center personnel continued to submit the

USN-EOPS series, which is based upon the current

global solution and updated with new IVS-R1/R4

experiments. The updated EOPS series is submitted to

the IVS twice weekly within 24 hours of experiment

correlation and is included in the IERS Bulletin A.

Analysis Center personnel also continued routine submission of Sinex format files based upon the 24-hour

VLBI sessions. In addition to EOPS and Sinex series,

USNO VLBI Analysis Center personnel continued to

produce and submit an EOPI series based upon the

IVS Intensive experiments.

2.3 ITRF2014 Submission

The USNO VLBI Analysis Center generated and submitted Sinex format files based on its usn2014a global

VLBI solution for use in the IVS combined VLBI solution that will be used for ITRF2014.

2.4 Software Correlator

Over the course of the 2014 calendar year, Analysis

Center personnel continued the implementation, testing and evaluation of the DiFX software correlator.

Phase I of the software correlator has two management

nodes and 33 compute nodes (with each node having a

2.9 GHz dual-core processor with eight cores per processor for a total of 528 processing cores) and reached

operational capability in October.

Hardware for Phase II of the software correlator

was delivered in the second quarter of 2014 and will

double the processing power of the Phase I correlator but has not yet been implemented. Post-correlation

calibration and analysis of software correlated data is

now routinely performed using the standard geodetic

data reduction path including the use of the Haystack

Observatory Post-processing System (HOPS) for data

calibration and the GSFC CALC/SOLVE package for

data analysis.

2.5 VLBA Intensive Experiments

During the 2014 calendar year, Analysis Center personnel continued a program to use the Very Long Baseline Array (VLBA) operated by the NRAO for the purpose of measuring UT1–UTC. Routine daily 1-hour

duration Intensive observations continued using the

VLBA antennas at Pie Town, NM and Mauna Kea, HI.

High-speed network connections to these two antennas are now routinely used for electronic transfer of

VLBI data over the Internet to a USNO point of presence. Once fully operational, it is anticipated that these

VLBA Intensive sessions will be scheduled as IVSINT4 and that the data will be released to the IVS for

community-wide distribution.

3 Staff

The staff of the VLBI Analysis Center is drawn from

individuals in the Astrometry department at the U.S.

Naval Observatory. The staff and their responsibilities

are as follows:

Name Responsibilities

Alan Fey Periodic global CRF/TRF/EOP solutions

and comparisons; CRF densification research; software correlator implementation; VLBI data analysis.

Nicole Geiger software correlator implementation;

VLBI data analysis; EOP, database, and

Sinex submission.

Christopher Dieck software correlator implementation;

VLBI data analysis; EOP, database, and

Sinex submission.

4 Future Activities

The following activities for 2015 are planned:

• Continue analysis and submission of IVS-R4 experiments for dissemination by the IVS.

IVS 2014 Annual Report
USNO Analysis Center 275

• Transition to use of νSolve for interactive VLBI

analysis.

• Continue the production of periodic global

TRF/CRF/EOP solutions and the submission

of EOP-S estimates to the IVS updated by the

IVS-R1/R4 experiments.

• Continue submission of Sinex format files based on

the 24-hour experiments.

• Continue the analysis of IVS Intensive experiments

and submission of EOP-I estimates to the IVS.

• Continue the scheduling, analysis and database

submission for IVS-CRF and IVS-CRDS experiments.

• Continue post-processing and analysis of VLBI Intensive data from the MK and PT VLBA stations.

IVS 2014 Annual Report
USNO Analysis Center for Source Structure Report

Alan Fey, Ralph Gaume

Abstract This report summarizes the activities of the

United States Naval Observatory Analysis Center for

Source Structure for calendar year 2014 and the activities planned for the year 2015.

1 Analysis Center Operation

The Analysis Center for Source Structure is supported

and operated by the United States Naval Observatory

(USNO). The charter of the Analysis Center is to provide products directly related to the IVS determination of the “definition and maintenance of the celestial reference frame.” These include, primarily, radio

frequency images of International Celestial Reference

Frame (ICRF) sources, intrinsic structure models derived from the radio images, and an assessment of the

astrometric quality of the ICRF sources based on their

intrinsic structure.

The Web server for the Analysis Center is hosted

by the USNO and can be accessed by pointing your

browser to

http://rorf.usno.navy.mil/ivs saac/

The primary service of the Analysis Center is the

Radio Reference Frame Image Database (RRFID), a

Web accessible database of radio frequency images of

ICRF sources. The RRFID contains 7,279 Very Long

Baseline Array (VLBA) images of 782 sources at radio frequencies of 2.3 GHz and 8.4 GHz. Additionally,

U.S. Naval Observatory

USNO Analysis Center for Source Structure

IVS 2014 Annual Report

the RRFID contains 1,867 images of 285 sources at

frequencies of 24 GHz and 43 GHz. The RRFID can

be accessed from the Analysis Center Web page or directly at

http://rorf.usno.navy.mil/rrfid.shtml

The RRFID also contains 74 images of 69 Southern

Hemisphere ICRF sources using the Australian Long

Baseline Array (LBA) at a radio frequency of 8.4 GHz.

Images of ICRF sources can also be obtained from

the Bordeaux VLBI Image Database (BVID) at

http://www.obs.u-bordeaux1.fr/

m2a/BVID/

2 Current Activities

Our current activities are maintaining the Radio Reference Frame Image Database as a Web accessible

database of radio frequency images of ICRF sources.

3 Staff

The staff of the Analysis Center is drawn from individuals who work at the USNO. The staff of the Analysis

Center during 2014 consisted of Alan L. Fey and Ralph

A. Gaume.

276
Center for Source Structure 277

4 Future Activities

The Analysis Center currently has a program of active research investigating the effects of intrinsic source

structure on astrometric position determination. Results of this program are published in the scientific literature.

The following activities for 2015 are planned:

• Continue with the imaging and analysis of VLBA

2.3/8.4/24/43 GHz experiments.

• Maintain the Radio Reference Frame Image

Database (RRFID) as a Web accessible database of

radio frequency images of ICRF sources.

• Continue preparatory work for ICRF-3.

5 Relevant Publications

Publications of relevance to Analysis Center activities

are:

• “The Second Realization of the International Celestial Reference Frame by Very Long Baseline Interferometry,” by Fey et. al. 2015, AJ, submitted.

• “Relativistic Jets in the Radio Reference Frame Image Database. II. Blazar Jet Accelerations from the

First 10 Years of Data (1994-2003),” Piner, B. G.,

Pushkarev, A. B., Kovalev, Y. Y., Marvin, C. J.,

Arenson, J. G., Charlot, P., Fey, A. L., Collioud, A.,

and Voitsik, P. A. 2012, ApJ, 758, 84.

• “Characterization of long baseline calibrators at 2.3

GHz,” Hungwe, F., Ojha, R., Booth, R. S., Bietenholz, M. F., Collioud, A., Charlot, P., Boboltz, D.,

and Fey, A. L. 2011, MNRAS, 418, 2113.

• “The Position/Structure Stability of Four ICRF2

Sources,” Ed Fomalont, Kenneth Johnston, Alan

Fey, Dave Boboltz, Tamoaki Oyama, and Mareki

Honma, 2011, AJ, 141, 91.

IVS 2014 Annual Report
Vienna Special Analysis Center Annual Report 2014

Johannes Bohm, Sigrid B  ̈ ohm, Anastasia Girdiuk, Andreas Hellerschmied, Armin Hofmei  ̈ ster, Hana Krasn  ́ a,  ́

Younghee Kwak, Daniel Landskron, Matthias Madzak, David Mayer, Caroline Schonberger  ̈

Abstract The main activities in 2014 of the VLBI

group at the Department of Geodesy and Geoinformation of the Vienna University of Technology were

related to the application and the further development

of the Vienna VLBI Software (VieVS). For example,

we scheduled VLBI observations of the AUSTRAL

sessions as well as observations to satellites with

radio telescopes. Furthermore, we contributed to the

ITRF2014 by providing normal equations for more

than 5,000 sessions, and we assessed the impact of

various ways of troposphere delay modeling on geodetic parameters. The highlight from an organizational

point of view was the fifth VieVS User Workshop in

September 2014 in Vienna with the release of VieVS

version 2.2.

1 General Information

The Department of Geodesy and Geoinformation

(GEO) in the Faculty of Mathematics and Geoinformation of Technische Universitat Wien (TU Wien) is  ̈

divided into seven research groups. One of those, the

research group Hohere Geod  ̈ asie (Advanced Geodesy)  ̈

with about 15 members, is focusing on satellite

geodesy, system Earth, and geodetic VLBI.

Vienna University of Technology

VIE Analysis Center

IVS 2014 Annual Report

2 Staff

Personnel at GEO associated with the IVS Special

Analysis Center in Vienna (VIE) and their main research fields and activities are summarized in Table 1.

The staff members are partly paid by TU Wien and

partly they are funded by the Austrian Science Fund

(FWF) within several projects.

3 Activities during the Past Year

3.1 Global Solutions and Reference

Frames

Axis offset models have to be applied for VLBI

telescopes if the pointing axes do not intersect. We estimated the axis offsets for VLBI antennas in a global

adjustment of suitable IVS 24-hour sessions (1984.0

— 2014.0) with the Vienna VLBI Software (VieVS)

(Krasn  ́ a et al., 2015, [3]). In particular, we focused  ́

on the two radio telescopes of the Hartebeesthoek

Radio Astronomy Observatory (HartRAO) in South

Africa where a comparison with axis offset estimates

from other geodetic techniques, such as GNSS and

conventional local survey, was made. Furthermore, we

assessed the influence of differences in the axis offsets

on the estimated geodetic parameters, such as station

coordinates or Earth orientation parameters.

VLBA Calibrator Survey (VCS) observing sessions with ten radio telescopes in North America

were carried out with the primary goal of densifying

the International Celestial Reference Frame. We

investigated the impact of Earth orientation parameters

278
VIE Analysis Center Report 279

Fig. 1 Members of the Vienna VLBI group and participants at the 5th VieVS User Workshop in September 2014.

Table 1 Staff members ordered alphabetically.

Johannes Bohm ̈ Reference frames, atmospheric effects

Sigrid Bohm (on maternity leave)  ̈ Earth orientation

Anastasia Girdiuk (since 12/2014) Earth orientation

Andreas Hellerschmied Satellite observations with radio telescopes, VieVS admin since 12/2014

Armin Hofmeister Ray-traced delays in VLBI analysis

Hana Krasn  ́ a (on maternity leave since 12/2014)  ́ Global solutions, VieVS admin until 11/2014

Younghee Kwak (since 03/2014) Hybrid GNSS-VLBI observations

Daniel Landskron (since 06/2014) Troposphere delay models for VLBI

Matthias Madzak GUIs and special files in VieVS, Earth rotation

David Mayer Reference frames and scheduling, e.g. AUSTRAL sessions

Caroline Schonberger (since 12/2014)  ̈ Simulation of twin telescopes

on the estimated source positions. For that purpose

we applied the combined IERS C04 08 series as well

as Earth rotation parameters from GNSS observations

alone and compared the source coordinates to those

estimated in VLBI-only solutions.

We contributed more than 5,000 SINEX files

to the IVS Combination Center at BKG (Frankfurt,

Germany) for the International Terrestrial Reference

Frame 2014 (ITRF2014).

3.2 Troposphere Delays

Within the project RADIATE VLBI, which is funded

by the Austrian Science Fund (FWF), there is ongoing

development and enhancement of our new ray-tracing

program RADIATE (Hofmeister and Bohm, 2015, [2]).  ̈

With the use of real meteorological data provided by

the European Centre for Medium-Range Weather Forecasts (ECMWF) via numerical weather models with

horizontal resolutions as high as 0.125◦times 0.125◦,

our program RADIATE is able to determine slant path

delays for VLBI observations. In 2014, after the successful validation of our first ray-traced delays from

RADIATE against the delays from an international

comparison campaign of ray-tracing software (Nafisi

et al., 2012, [5]), we further enhanced our ray-tracing

program. A major step in the past year was the application of the ray-traced delays in VLBI analysis and

the validation of the results. For this task we used the

CONT11 campaign and calculated our ray-traced slant

delays. Using VieVS for the analysis, we investigated

the impact of our ray-traced delays on the VLBI solution by assessing baseline length repeatabilities.

In terms of improving troposphere delay models,

two aspects were considered in 2014: (1) an improvement of the coefficients of the Vienna Mapping Function 1 (VMF1) and (2) the development of a new horizontal gradient formula in order to better consider azIVS 2014 Annual Report
280 Bohm et al.  ̈

imuthal asymmetries. The latter approach uses expansions of the gradient formula based on spherical harmonics in order to compensate for the impact on the

delays which is caused by the non-spherical shape of

the Earth’s atmosphere, which is flatter at the poles and

thicker at the equator.

3.3 Simulation of Twin Telescopes

The Vienna VLBI Software was used to schedule

and simulate a global VLBI network following the

example of the CONT11 campaign, with the existing

ONSALA60 telescope or with a Twin Telescope

in Onsala. Different scheduling approaches (e.g.,

source-based scheduling with two or four sources at

a time, multidirectional or continuous mode) (Sun

et al., 2014, [7]) were compared by evaluating the

numbers of observations and scans as well as baseline

length repeatabilities, station positions, Earth orientation parameters, atmospheric parameters, and clock

estimates.

3.4 Scheduling VLBI Sessions

The VieVS scheduling module is used operationally to

schedule sessions for the AuScope VLBI network. This

is done in close cooperation with the University of Tasmania. The AuScope VLBI network consists of three

almost identical small (12-m) antennas distributed over

Australia. Other telescopes from New Zealand (12-m)

and South Africa (15-m) contribute on a regular basis.

For special experiments, the two big (26-m) telescopes

in Australia and South Africa are used as well. In 2014

the number of sessions observed with the Australian

telescopes increased tremendously with a continuous

campaign over two weeks in September and 57 regular Australian sessions. The schedules are created on

a relatively short notice, which allows us to adjust to

the current conditions and apply changes fast. Furthermore, more features were built into the software to fit

the specific needs, and the GUI was updated slightly

for more user-friendliness.

3.5 VLBI Observations to Satellites

Observations of GNSS satellites with large VLBI radio

antennas enable the realization of inter-technique ties

and seem to be a promising approach to accomplish a

vital interconnection between dynamical and kinematical reference frames (Plank et al., 2014 [6]). Although

several satellite observation experiments have been carried out in recent years, this approach is still far away

from being applied operationally. Limitations have already emerged at the observation planning level, because suitable scheduling software has not been available. On that account the current Vienna VLBI Software was upgraded by adding a module capable of creating satellite observation schedules (Hellerschmied et

al., 2015 [1]). The generated VEX-formatted schedule

files can be used directly to carry out satellite observations, where the satellites are tracked by repositioning

the VLBI antennas stepwise to define celestial coordinates. The first successful observations to GLONASS

satellites based on VieVS schedules were carried out

in January 2014 on the baseline Onsala—Wettzell. The

new VieVS satellite scheduling module provides a flexible tool to generate suitable schedule files for satellite

observations, which is particularly important to promote further research and development in this specific

field.

3.6 GPS-VLBI Hybrid Observation for

Geodesy

We started project GPS-VLBI Hybrid Observation for

Geodesy (Hybrid GPS-VLBI), funded by the Austrian

Science Fund (FWF), which combines GPS and VLBI

at the observation level. In 2014, we developed and validated the delay model of GPS satellites according to

the GPS-VLBI (GV) hybrid observation concept and

implemented it in VieVS. As a test of VieVS for GPS

delays, we set up a global GV hybrid network with several IVS CONT11 sites, which are stable and homogeneously distributed and moreover simultaneously acquire GPS data. GPS delays were created by differencing post-processed range measurements from a precise

point positioning (PPP) GPS solution with the C5++

software because we currently do not have any real observation data. The data were successfully processed

IVS 2014 Annual Report
VIE Analysis Center Report 281

in VieVS, and we found centimeter-level accuracy of

the models (Kwak et al., 2015, [4]). Compared to GPS

PPP solutions, the accuracy is still worse, which needs

to be further investigated. In 2015, we will combine

VLBI and GPS data, estimate common parameters at

the sites, and assess the impact of the GV hybrid combination solution on the geodetic parameters.

3.7 Development of VieVS

We have set up and maintained a wiki for the Vienna VLBI Software. This wiki is accessible at

http://vievswiki.geo.tuwien.ac.at/ and contains a lot

of useful information, not just for VieVS users. We

organized the 5th VieVS User Workshop from 17 to 18

September 2014 in Vienna. Additionally, Hana Krasn  ́ a ́

held a VieVS training course at Hartebeesthoek Radio

Astronomy Observatory (HartRAO), South Africa,

from 15 to 17 April 2014.

4 Future Plans

In 2015, we will continue the development of VieVS,

with special focus on satellite tracking, scheduling,

and the estimation of terrestrial and celestial reference

frames. We also plan to become an operational Analysis Center of the IVS. Moreover, we will organize the

6th VieVS User Workshop in September 2015.

Acknowledgements

We are very grateful to the Austrian Science Fund

(FWF) for supporting our work by projects P23143

(Integrated VLBI), P25320 (RADIATE VLBI),

P24813 (SPOT), M1592 (Hybrid GPS-VLBI), and

I1479 (ASPIRE). We also acknowledge the German

Research foundation (DFG) for funding project

D-VLBI (SCHU 1103/4-1).

References

1. A. Hellerschmied, J. Bohm, A. Neidhardt, J. Kodet, R. Haas,  ̈

L. Plank. Scheduling VLBI observations to satellites with

VieVS. Proceedings of the IAG Commission 1 Symposium

2014, Kirchberg, Luxembourg, October 2014, submitted,

2015.

2. A. Hofmeister, J. Bohm. Ray-traced Delays in the Atmo-  ̈

sphere for Geodetic VLBI. IVS 2014 General Meeting Proceedings, ed. by D. Behrend, K.D. Baver, and K. Armstrong,

2014.

3. H. Krasn  ́ a, M. Nickola, J. B  ́ ohm. Axis offset estimation of  ̈

VLBI telescopes. IVS 2014 General Meeting Proceedings,

ed. by D. Behrend, K.D. Baver, and K. Armstrong, 2014.

4. Y. Kwak, J. Bohm, T. Hobiger, L. Plank. On the analysis  ̈

of VLBI observations to GNSS satellites. Proceedings of

the IAG Commission 1 Symposium 2014, Kirchberg, Luxembourg, October 2014, submitted, 2015.

5. V. Nafisi, L. Urquhart, M. Santos, F. Nievinski, J. Bohm,  ̈

D. Wijaya, H. Schuh, A. Ardalan, T. Hobiger, R. Ichikawa,

F. Zus, J. Wickert, P. Gegout. Comparison of Ray-Tracing

Packages for Troposphere Delays. IEEE Transactions on

Geoscience and Remote Sensing, Vol. 50, No. 2, pp. 469–

481, 2012.

6. L. Plank, J. Bohm, H. Schuh. Precise station positions from  ̈

VLBI observations to satellites: a simulation study. Journal

of Geodesy, 88:659–673, 2014.

7. J. Sun, J. Bohm, T. Nilsson, H. Kr  ̈ asn  ́ a, S. B  ́ ohm, H. Schuh.  ̈

New VLBI2010 scheduling strategies and implications

on the terrestrial reference frames. Journal of Geodesy,

88:449–461, 2014.

IVS 2014 Annual Report

Technology Development Centers

Canadian VLBI Technology Development Center Report

Bill Petrachenko

Abstract The Canadian VLBI Technology Development Center (TDC) is involved in a number of activities contributing to the realization of the VLBI Global

Observing System (VGOS).

1 General Information

The Canadian TDC is a collaborative effort of the

National partners interested in the advancement of

VLBI technology, namely the Canadian Geodetic

Survey (CGS) of Natural Resources Canada (NRCan)

and the Dominion Radio Astrophysical Observatory

(DRAO) of the National Research Council of Canada

(NRC).

2 Activities during the Past Year

The Canadian TDC is focused on encouraging the realization of VGOS. This is done by Bill Petrachenko of

NRCan, who is the IVS Technology Development Coordinator, the chairman of the VGOS Technical Committee (VTC), and a member of the VGOS Project Executive Group (VPEG). In collaboration with others,

this year’s activities focused on the following areas:

• Completion and presentation of the VGOS Observing Plan.

Canadian Geodetic Survey, Natural Resources Canada

Canadian VLBI Technology Development Center

IVS 2014 Annual Report

• Compilation of comparisons of VGOS feeds, digital back ends (DBEs), and recorders.

• Collection of information regarding data acquisition equipment at VGOS sites. This is needed to

help to determine compatible international VGOS

observing modes.

• Study of more cost-effective broadband downconversion schemes.

• Study of efficient and robust broadband frequency

sequences.

• Development of FPGA code for VGOS digital back

ends.

In addition, NRC is involved in a number of Square

Kilometer Array (SKA) related activities that have potential applications to the IVS.

• Digital signal processing including development of

correlators, beam formers, and systems for pulsar

processing.

• Fabrication of a light, stiff, and cost effective 15-m

off-axis Gregorian top-fed composite antenna.

• Development of focal plane arrays.

3 Future Plans

The Canadian TDC plans to continue to actively encourage the realization of VGOS.

285
GSFC Technology Development Center Report

Ed Himwich, John Gipson

Abstract This report summarizes the activities of the

GSFC Technology Development Center (TDC) and describes plans for next year. The GSFC TDC develops station software including the Field System (FS),

scheduling software (sked), hardware including tools

for station timing and meteorology, scheduling algorithms, and operational procedures. It provides a pool

of individuals to assist with station implementation,

check-out, upgrades, and training.

1 Technology Center Activities

The GSFC IVS Technology Development Center

(TDC) develops hardware, software, algorithms, and

operational procedures. It provides manpower for

station visits for training and upgrades. Other technology development areas at GSFC are covered by other

IVS components such as the GSFC Analysis Center.

The current staff of the GSFC TDC consists of John

Gipson, Ed Himwich, and Rich Strand, all employed

by NVI, Inc. The remainder of this report covers the

status of the main areas supported by the TDC.

2 Field System

The GSFC TDC is responsible for development, maintenance, and documentation of the Field System (FS)

software package. The FS provides equipment conNASA Goddard Space Flight Center

GSFC Technology Development Center

IVS 2014 Annual Report

trol at VLBI stations. It interprets the .snp schedule

and .prc procedure files (both as prepared by drudg

from the .skd schedule). The FS controls the antenna,

data acquisition hardware, and related ancillary equipment needed for making VLBI measurements. All major VLBI data acquisition backends are supported. The

FS is customizable to allow it to control station specific

equipment. It is used at almost all of the IVS Network

Stations (more than 35) and also at many stations that

perform VLBI only for astronomical observations. The

only major VLBI facilities not using it are the VLBA

and VERA.

There were six minor releases of the FS (9.11.1-

9.11.6) during this year. Full details can be found in the

FS release notes, but most changes were fairly minor.

The most significant changes were:

• The addition of the bit streams command for specification of active channels for recording Tsys when

no supported recorder is being controlled. This is

typically used for e-VLBI.

• Support for DBBC version v104.

• Specification of the Mark 5B clock rate from a control file.

• A time-out feature for the ONSOURCE command

to support local testing.

• Support for FSL9 kernel distribution, based on Debian Wheezy.

• Enhancements for support of jive5ab controlled

Mark 5B recorders.

In addition several development projects were underway. These include:

• Patriot 12 m Interface. Development of the

interface for the Patriot Antenna Control Unit

(ACU) continued. Several improvements were

286
GSFC Technology Development Center Report 287

made, including the handling and the reporting of

status-word-represented errors and improvements

in cable-wrap handling to make it independent of

the limits for any particular antenna.

• VEX2. Considerable effort has gone into defining

the second version of VEX, which will provide

schedule file format support for new “samplingbefore-channelization” systems such as the RDBE.

2.1 Plans for Next Year

Several other improvements are expected in future releases, including:

• Support for parallel use of multiple RDBEG racks

for VGOS observing modes.

• Support for parallel use of multiple Mark 6

recorders, using cplane for control, for VGOS

observing modes.

• Support for single Mark 5C/Mark 6/Flexbuff

recorders that are running the jive5ab control

program.

• Support for DBBC PFB personality.

• Use of idl2rpc for remote operation.

• A complete update to the documentation and conversion to a more modern format that will be easier

to use and maintain.

• Conversion of the FORTRAN source to use the

gfortran compiler, which will enable use of the

source level debugger, gdb, for development and

field debugging.

• Chekr support for Mark 5A and Mark 5B systems.

• FS Linux 10, based on Debian Jessie.

• Support for periodic firing of the noise diode during

observations.

• Support for NMEA standard wind sensors.

• Completion of the VEX2 standard and implementation of it.

3 Sked and Drudg

The GSFC TDC is responsible for the development,

maintenance, and documentation of sked and drudg.

These two programs are very closely related, and they

operate as a pair for the preparation of the detailed observing schedule for a VLBI session and its proper execution in the field. In the normal data flow for geodetic schedules, first sked is run at the Operation Centers

to generate the .skd file that contains the full network

observing schedule. Then stations use the .skd file as

input to drudg for making the control files and procedures for their station. Catalogs are used to define

the equipment, stations, sources, and observing modes

which are selected when writing a schedule with sked.

Changes to sked and drudg are driven by changes

in equipment and by feedback from the users. The following summarizes some of the important changes to

these programs this year and plans for next year.

3.1 Sked Changes

• The tagging along of a new station to a schedule without that station was improved. The issue is

that internally sked uses one-letter codes as station

identifiers, where the default one-letter codes come

from the catalogs. There were problems if the new

station had the same one-letter code as a station already in the schedule. sked was modified to use a

new unused letter for the new station.

• sked was made more robust for observations near

the cable wrap.

• sked previously used two different routines for calculating similar quantities, SNR and duration. This

led to inconsistencies. Both pieces of code were

modified to call a subroutine.

• sked was modified to write VEX files differently

depending on whether the data was processed by

the VLBA or by BONN. This reduced hand-editing

of VEX files.

• Some cleanup was done in terms of removing taperelated parameters such as pass, footage, etc. This

was necessitated because sked could not read in

some VEX files that did not have this information.

There is still a fair amount of vestigial code dealing

with tapes, and this will be removed as time permits.

• The handling of the case in which sked does not

recognize the rack or recorder was improved. Previously both the rack and recorder had to belong

to a set list of valid types which was hard-coded.

If this was not the case, sked would close with an

error message. It will now continue running.

IVS 2014 Annual Report
288 Himwich and Gipson

3.2 Drudg Changes

• Support for Mark 5C.

• Some cleanup was done in terms of removing taperelated parameters such as pass, footage, etc. This

was done because drudg could not read in a VEX

file that did not have pass information.

• Support for LSB first LOs. Previously this existed

for Mark III ‘.skd’ files, but not for VEX files.

• Support for new hardware at the VLBA.

3.3 Plans for Next Year

Plans for next year include the following:

• We will support VEX2 files for both sked and drudg

if and when they become available.

• We plan to expand support for RDBEs and DBBCs.

This will involve changes to sked, drudg, and the

catalogs.

• If time permits we will convert sked to compile using a freely available compiler such as gfortran.

IVS 2014 Annual Report
MIT Haystack Observatory Technology Development Center

Christopher Beaudoin, Roger Cappallo, Geoff Crew, Russ McWhirter, Arthur Niell, Chet Ruszczyk

Abstract Technology development at MIT Haystack

Observatory was focused on the following three areas

in 2014: (1) KPGO 12-m Signal Chain, (2) VLBI Data

Acquisition Module, and (3) Mark 6. In this report,

we outline the three main sub-systems comprising the

KPGO signal chain and describe a new generic/opensource monitor and control module possessing a small,

modular form factor. Lastly, we describe the latest refinements applied to the Mark 6 16 Gbps recorder software suite.

1 KPGO 12-m VGOS Signal Chain

MIT Haystack Observatory is responsible for the design, fabrication, and installation of the signal chain

for the new KPGO 12-m VGOS system scheduled for

installation at Kokee Park, HI, in September 2015.

This signal chain is comprised of three separate subsystems: (1.1) frontend, (1.2), backend, and (1.3) calibration.

1.1 Frontend Sub-system

The frontend subsystem contains the very sensitive

low noise electronics and radio telescope feed necessary to achieve a system equivalent flux density of

2,500 Jy when integrated with the Intertronics Solutions Inc. 12-m antenna. The frontend also includes

MIT Haystack Observatory

Haystack Technology Development Center

IVS 2014 Annual Report

all supporting infrastructure (e.g. networking, power

supply distribution, and monitor/control) necessary to

operate the dual-linearly polarized cryogenic receiver

frontend. Furthermore, a phase/noise calibration signal

is injected directly into the frontend to provide a mechanism for instrumental delay/gain correction in postcorrelation processing. Within the frontend, the power

levels amplified are such that they are suitable to drive

the high-band, microwave-over-fiber link that is used

to downlink these signals to the backend sub-systems.

To conserve dynamic range in the high-band link, the

RFI afflicted S-band portion of the frontend frequency

range is downlinked separately over a coaxial downlink

which possesses significantly more dynamic range to

support observing in this frequency band. A block diagram of the signal chain frontend sub-system is shown

in Figure 1.

1.2 Backend Sub-system

The backend sub-system receives the microwave signals downlinked from the frontend sub-system for further processing. A block diagram of this backend subsystem is shown in Figure 2.

Both low and high band signals from the frontend

subsystem can be distributed to four independently tunable 2—14 GHz UDCs. This UDC supports 2 GHz

baseband output with fine LO tuning resolution (< 1

Hz) to accommodate compatibility with other VGOS

frequency conversion schemes. These features are provided by the next generation UDC V2.0, which incorporates an additional downconversion stage not included in its predecessor. The fine tunability of this

design is made possible by a custom LO that was de289
290 Beaudoin et al.

signed at Haystack and incorporates a finely tunable

DDS. Figure 3 displays a layout of the custom LO circuitry.

In the KPGO implementation, 512 MHz Nyquist

zone filters are incorporated in the UDCs to support

the sample rate of the RDBE (1024 MHz). Following

PFB processing by the RDBE, the digitized data are

recorded onto hard disk by a single Mark 6 recorder

capable of sustaining the 8 Gbps data rate onto a single

disk module.

1.3 Calibration Sub-system

The calibration sub-system is physically split between

the frontend (on the antenna) and backend (in the control room). This sub-system is responsible for generating phase and noise calibration signals in the frontend

sub-system. In this frontend, these signals are injected

into the receiver to facilitate correction of instrumental delay and gain variations in the radio source (e.g.,

quasar) signal path.

Accurate correction of the instrumental delay variations in this signal path is somewhat complicated by

the need to uplink the timing reference (i.e., 5 MHz

MASER reference) to the frontend. The complication

arises because the delay in this timing reference is subject to variations that are independent of the variation

in the quasar signal path downlink. A primary source

of these variations is mechanical stress fluctuations imparted on the reference cable by the motion of the antenna. Hence, the calibration sub-system must monitor

variations in this reference cable delay so that they may

be removed from the phase variations extracted by the

correlator.

The resultant instrumental phase estimate represents that imparted on the quasar signal as it propagates

through the signal chain. A proof-of-concept cable delay measurement system has been developed and is

currently being tested to address this requirement. The

calibration signal generator (i.e., the antenna unit) is

being redesigned to integrate this new capability. This

effort is expected to be complete in the first quarter of

2015.

2 VLBI Data Acquisition Module

MIT Haystack Observatory has developed the VLBI

Data AcQuistion (VDAQ) module as an open source

hardware development to address general purpose

monitor and control requirements at the generic VLBI

station. As a modular instrument, the VDAQ makes

dual use of Ethernet infrastructure, using the Ethernet

backbone to provide both communication and power

interfaces into the module. This feature of the VDAQ

serves to provide a small form factor (13x10x2.5 cm)

and allows it to be deployed to space-limited locations

where MCI is needed. Figure 4 presents a 3D CAD

model rendering of the VDAQ module.

This modular concept also serves to minimize issues related to signal integrity because sensors and signal monitors can be placed in close proximity to the

module which can also serve as a distributed power

source. The following provides a breakdown of the interfaces that the VDAQ module will support:

• Digital Communications

– RS232

– I

2C

– SPI

– Ethernet

• Isolated DC Power Sources

• 16 Analog Monitors

– Single-ended or Differential

– Isolated or Non-Isolated

– Configurable signal conditioning

• 40 Digital Monitors or Controls

– 10 Isolated Monitors

– 10 Isolated Controls

– 20 Non-isolated Monitors and/or Controls

3 Mark 6 Developments

In 2014, the software utility vdifuse was commited to

the DiFX repository. vdifuse mounts the disk modules

as local directories readable by the Mark 6 OS and performs the pointer mathematics necessary to navigate

the scattered nature of the Mark 6 recording methodology. In this way, vdifuse allows the Mark 6 user to

IVS 2014 Annual Report
Haystack Technology Development 291

interact with scans recorded on the Mark 6 disk module(s) as if they were contiguous files within the vdifuse-mounted directories. Using this utility, it is possibe to copy entire (and partial) scans from the mounted

disk modules to the OS (or external, e.g., USB) disk. It

is also possible to read these virtual files using standard Linux commands such as ls, more, head, and tail.

It is not possible to utilize vdifuse to perform write operations on these mounted directories (e.g., the Linux

delete rm command).

Lastly, Mark 6 software v1.2d was developed to resolve an IRQ bug that was discovered through testing.

This bug introduced a loss of data at 16 Gbps data rate

due to a non-uniform distribution of record processing

load across the available CPUs. This software release

is available through the EHT wiki at the following address: http://eht-wiki.haystack.mit.edu. Login credentials are required to obtain the package and can be obtained by contacting the EHT wiki webmaster at the

aforementioned Web link.

Fig. 1 Block diagram of the signal chain frontend sub-system.

External connections into the frontend from the top/bottom represent those to the backend/calibration sub-systems. External

connections into the frontend from the left/right represent those

from the site’s general infrastructure (not provided by Haystack).

m

Fig. 2 Block diagram of the signal chain backend sub-system.

External connections into the backend from the top represent

those to the frontend sub-system. External connections into the

frontend from the left/right represent those from the site’s general infrastructure (not provided by Haystack).

Fig. 3 PCB layouts of electronics designed for custom LO circuitry in UDC third downconversion stage.

Fig. 4 3D CAD model rendering of the VDAQ module identifying its physical interfaces.

IVS 2014 Annual Report
IAA Technology Development Center Report 2014

Alexander Ipatov, Irina Ipatova, Vyacheslav Mardyshkin, Alexander Evstigneev, Evgeniy Khvostov, Alexey Lavrov,

Vitaliy Chernov, Dmitry Marshalov, Evgeny Nosov, Leonid Fedotov

Abstract This report discusses the aspects of the IAA

RAS Technology Development Center in 2014.

1 Tri-band Receiving System for the

Interferometer

The interferometer receiving system [1] is applied

at the IAA RAS stations “Zelenchukskaya” and

“Badary”. It operates in S-band (2.2-2.6 GHz), X-band

(7.0-9.5 GHz) and Ka-band (28-34 GHz) with a

multiband feed. The design of the feed gives the

possibility for cooling and operating with dual circular

polarization simultaneously. All receiver units are

placed in the focal container (Figure 1) which is

mounted at the secondary focus of the antenna. The

container is specially designed for the 13.2-m dish and

provides rigid airtight housing. The design of the focal

container makes cool air circulation available inside.

The multiband feed and low noise amplifiers are

placed in a special cryostated container (cryostat) (Figure 2) and are cooled by a cryogenic system of closed

cycle to a temperature at the level of hydrogen. All the

equipment of the cryostat for both polarizations of all

three bands is tightly placed in the space between the

feed and coldhead flange. The S- and X-band signal

lines are coaxial, and Ka-band is fully waveguide. The

equipment is screened with the metal heat shield. The

infrared filter is placed between the feed and the vacuum window. It is made of 0.1 mm teflon film. Cooling

Institute of Applied Astronomy of Russian Academy of Sciences

IAA RAS Technology Development Center

IVS 2014 Annual Report

Fig. 1 Tri-band receiver focal container (without housing).

with the use of a Sumitomo closed cycle refrigerator

takes seven hours. The measured feed physical temperature is about 26 K, and the temperature of the amplifiers is about 20 K.

The external vacuum window is closed with radio

transparent covering, which consists of two parts. The

external sealing surface is made of Mylar film 0.05

mm thick. The film is supported by the inner layer of

solid foam polyester with 17 mm thick. The covering is

blown with warm air through a special nozzle to protect

from atmospheric precipitation.

It is then focused with antenna electromagnetic

waves that get to the feed inside the cooled unit through

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IAA RAS 2014 Report 293

Fig. 2 Cryostat assembly: equipment, container with vacuum

window, thermal screen.

the radio-transparent cover. They are separated to three

bands and two circular polarizations, mixed with the

noise and phase calibration signals, and amplified with

cooled LNAs. Almost all of the equipment located inside the cryostat is cooled to a temperature near 20 K,

significantly reducing noise temperature of the “radio

telescope-radiometer” system.

Amplified signals are directed to the intermediate frequency converter units. These units provide sub

channel splitting and frequency conversion to the IF

band of the digital acquisition system. Sub channels to

record are selected by the commutator unit. The calibration unit contains an adjustable noise source for

each band. External picoseconds pulses for the phase

calibration are used, and the calibration unit has a special input for them.

For measuring the noise temperature of the cooled

unit, special broadband-matched loads were applied.

These wide-aperture loads are enclosed in a Dewar and

can be filled with liquid nitrogen, providing “cold” reference points (“hot” points can be achieved with an

empty Dewar). There are loads for lab tests (Figure 3)

and loads for telescope measurements (Figure 4).

The first results of the total noise temperature measurements for the stand-alone receiving system and the

complete radio telescope are the following. X-band has

the best results — 15 K for the receiver, 25 for the radio

telescope. Ka-band with improved LNAs has the noise

temperature 50 K and 75 K accordingly; this is 40%

lower than the results with the first samples of LNAs.

Fig. 3 Laboratory receiver calibration with load.

Fig. 4 Telescope receiver calibration with load.

The measurements of noise temperature in the S-band

are obstructed by the RFI even in a far location. The

approximate result is 20 K and 35 K. The difference

between left and right circular polarization channels is

insignificant.

2 Putting BRAS into Operation

The eight-channel digital Broadband Acquisition System (BRAS) was developed and manufactured by IAA

RAS [2, 3]. Key features of BRAS are summarized in

Table 1.

On September 4, 2014 the first test observations

(Ru-TEST 108) with BRAS were carried out on radio telescopes RT-32 at the “Badary” and “‘Zelenchukskaya” observatories. BRAS was connected to the Xband receiver outputs at both stations. Mark 5C was

IVS 2014 Annual Report
294 Ipatov et al.

Table 1 Key features of BRAS.

Number of channels 8

IF inputs 1024 - 1536 MHz

Channel bandwidth 512 MHz

ADC 8 bits, Fs=1024 MHz

Output samples width 2/8 bits

Total data rate 16/64 Gbps

Data frames format VDIF

VDIF payload size 1000, 1024, 1280, 1600, 2000, , 8000,

8192 bytes

Output interface 10G Ethernet, X2 transceiver,

fiber/copper

Output headers modes Pure Ethernet frame, Ethernet+IP,

Ethernet+IP+UDP

Control interface 10/100 Ethernet

Sync signals 5/10/100 MHz, 1 PPSx2

Automatic gain control For each channel, 31 dB

Analysis features Signal power,

2-bit data statistics,

PCAL extraction,

Both 8 and 2-bit signal capture

(1024 samples),

Spectrum analysis of captured

signal and extracted PCAL

(implemented in software),

1 PPS int.-ext. delay monitoring

Telemetry Power circuit current,

temperature of PCBs and ADC

Power consumption 75 W

Size 19” case 483x314x242 mm (WxHxD)

used as the recording system. The recording was carried out in a single 512 MHz frequency band located

from 8592.00 to 9104.00 MHz. All scans were transferred through the network to St. Petersburg and processed in the IAA correlator [4]. In this session, the 24

sources from the RFC 2012c catalog with a flux density from 0.6 Jy to 7.6 Jy were observed. Good fringes

were received for each of the observed sources. The

fringe quality is good enough for high-precision group

delay measurement (see Figure 5).

The first BRAS sample was mounted on the 13-

m radio telescope (RT-13) at the “Badary” observatory

(see Figure 6). We are going to put BRAS into operation at the RT-13 “Badary” and “Zelenchukskaya” observatories in 2015.

Fig. 5 Fringe plot for scan of 1803+784 source, X-band, BRAS,

and Mark 5C.

Fig. 6 The BRAS on the RT-13 radio telescope at the Badary

observatory.

3 Multipurpose Digital Backend (MDBE)

The development of BRAS gave the required experience to design a more complex and advanced backend

- Multipurpose Digital Backend (MDBE). MDBE is

intended to upgrade the backends of “Quasar” network

antennas and allow it to operate both in conventional

downconverter mode for compatibility with existing

data acquisition systems and in broadband channel

mode. The MDBE has two 4-channels ADC with 1024

MHz sampling frequency giving overall eight channels

IVS 2014 Annual Report
IAA RAS 2014 Report 295

with 512 MHz bandwidth (Figure 7). By using ADC

interleaving mode, the MDBE can combine adjacent

channels and operate in 4-channel mode with 1024

MHz bandwidth per channel. The powerful FPGA

with an embedded dual-core ARM processor used in

the MDBE can perform quite complex digital signal

processing. Along with remote firmware reloading

supported by MDBE, it allows utilization of the

device for many radio astronomical tasks besides

conventional VLBI applications. For example, the

spectrometer and radiometric backend modes are

planned to be implemented. That is, the MDBE can

combine all required backends in one device which can

greatly simplify signal chain structure (Figure 8). The

MDBE will be located in the focal cabin of the antenna

which allows elimination of long coaxial cables and

auxiliary equipment used for signal transmission from

antenna to control room and replacement with fiber

optics. Digital signals transmitted through fibers are

insensitive to EMI, frequency response distortions,

group delay variations, and so on. Using it can improve

the quality of VLBA data.

Fig. 7 Multipurpose Digital Backend structure.

The data recording system based on the COTS

components will be used to buffer the data [5]. It is

also possible to copy data from the data recording

system to Mark 5B in the case that the e-VLBI mode

is unavailable. MDBE is designed to be functionally

compatible with existing VLBI equipment to support

operations in international observations.

Fig. 8 Planned upgrade of signal chain for RT-32 antennas.

References

1. A. Ipatov, I. Ipatova, V. Mardyshkin, A. Evstigneev, E.

Khvostov, A. Lavrov, V. Chernov. Tri-band System for the

Russian Interferometer, IVS 2014 General Meeting Proceedings, Science Press, Beijing, China, 2014, pp. 118-121.

2. D. Marshalov, E. Nosov, L. Fedotov. IAA Technology Development Center Report 2012. IVS 2012 Annual report. pp.

339 - 341. NASA/TP-2013-217511.

3. E. Nosov, A. Berdnikov, S. Grenkov, D. Marshalov, A. Melnikov, L. Fedotov. Current Development State of the Russian VLBI Broadband Acquisition System. IVS 2014 General Meeting Proceedings, Science Press, Beijing, China,

2014, pp. 82 - 85.

4. V. Ken, V. Mishin, D. Pavlov, N. Sokolova, I. Surkis. Design of a VGOS Software Correlator Based on GPUs. IVS

2014 General Meeting Proceedings, Science Press, Beijing,

China, 2014, pp. 183 - 187.

5. I. Bezrukov, A. Salnikov, A. Vylegzhanin. Russian Data

Recording System of New Generation. IVS 2014 General

Meeting Proceedings, Science Press, Beijing, China, 2014,

pp. 130 - 133.

IVS 2014 Annual Report
NICT Technology Development Center 2014 Annual Report

Kazuhiro Takefuji, Hideki Ujihara

Abstract The National Institute of Information and

Communications Technology (NICT) is developing

and testing VLBI technologies and conducting observations with this new equipment. This report gives

an overview of the Technology Development Center

(TDC) at NICT and summarizes recent activities.

1 NICT as IVS-TDC and Staff Members

The National Institute of Information and Communications Technology (NICT) publishes the newsletter

“IVS NICT-TDC News (former IVS CRL-TDC

News)” at least once a year in order to inform people

about the development of VLBI-related technology as an IVS Technology Development Center.

The newsletter is available at the following URL:

http://www2.nict.go.jp/aeri/sts/stmg/ivstdc/newsindex.html. Table 1 lists the staff members at NICT

who are contributing to the Technology Development

Center.

2 General Information

We have been developing a new broadband VLBI system called Gala-V, which not only meets the VGOS

(VLBI2010 Global Observing System) requirements,

but also includes upgrading the Cassegrain 34-m anKashima Space Technology Center, National Institute of Information and Communications Technology

NICT Technology Development Center

IVS 2014 Annual Report

Table 1 Staff Members of NICT TDC as of January, 2015 (in

alphabetical order).

Shingo Hasegawa Eiji Kawai

Tetsuro Kondo Yasuhiro Koyama

Yuka Miyauchi Mamoru Sekido

Kazuhiro Takefuji Hiroshi Takiguchi

Masanori Tsutsumi Hideki Ujihara

tenna by replacing the feed horn. Distinguishing the

features of Gala-V, we applied a direct sampler called

the K6/OCTAD-G (code name Galas) and a broadband

feed horn called Iguana. Here we report the current

progress and activities.

First, the compact antenna (MARBLE1) was

moved from GSI in Tsukuba to the National Metrology Institute of Japan (NMIJ) also in Tsukuba for

the purpose of time and frequency (T&F) comparison

between NICT and NMIJ. Both NICT and NMIJ

keep the national time standard UTC(NICT) and

UTC(NMIJ). Before the time and frequency comparison, the position of MARBLE1 was determined

by geodetic VLBI sessions in X-band. Moreover we

made a fringe test by broadband frequencies. Next,

we made a VLBI experiment for broadband with the

recently inaugurated GSI Ishioka 13-meter antenna in

December 2014. We could successfully detect fringes

in a 10 GHz and 13 GHz frequency range with 1024

MHz of bandwidth. It was also the memorial first

fringe for the Ishioka station.

296
NICT TDC 2014 Report 297

3 Time Comparison between NICT and

NMIJ by Compact Antennas

For the sake of the time and frequency transfer (T&F),

we moved the MARBLE1 compact antenna to NMIJ

in Tsukuba (Figure 1 shows MARBLE1 on the roof of

NMIJ). Before the T&F, we carried out several VLBI

sessions for determining the position of MARBLE1.

Each backend of the compact antenna is a direct

sampling system with no analog down-converters.

Normally, 1024 MHz bandwidth of X-band single

channel is recorded. Because we cannot obtain any

fringes between MARBLE1 in Tsukuba and MARBLE2 at the NICT headquarters in Tokyo, a time

difference between UTC(NICT) and UTC(NMIJ) is

measured by calculating an epoch difference (baseline

AB) between MARBLE1-Kashima34m (baseline

AO) and MARBLE2-Kashima34m (baseline OB) via

the large 34-m antenna. We take the Earth’s rotation

into account with epoch conversion, and the epoch

difference is obtained by the following equation,

τAB = τOB −τOA −τ ̇AB ×τOA (1)

where τ shows a delay and its subscript variable shows

a station. Figure 2 shows a recent time comparison

result including VLBI and GPS and UTC(NICT)—

UTC(NMIJ) provided by BIPM on 1 and 3 August

2014. GPS has a day boundary caused by an uncertain

satellite orbit, but VLBI had no day boundary and was

also consistent with GPS and BIPM results.

4 Broadband Fringe Test between Gala-V

of Kashima 34 m and MARBLE1

In the latest NICT TDC IVS annual report, we reported the simultaneously received 6.7 GHz and 12.2

GHz methanol maser lines with the Gala-V system [1].

We carried out a VLBI experiment of double maser

lines. Each frequency down-converter was made for

Gala-V for the purpose of the methanol maser lines.

On the other hand, we set a DBBC frequency of the

direct sampler (nickname Galas) for MARBLE1. Figure 3 shows the fringes in the frequency domain of the

6.7 GHz and 12.2 GHz methanol maser lines from the

star-forming region of W3OH. The 12.2 GHz fringe

of methanol maser was lighter than the 6.7 GHz one.

Fig. 1 The MARBLE1 compact station on the roof of the NMIJ

building in Tsukuba.

VLBI

GPS(ppp)

UTCr

-4.5

-4

-3.5

-3

-2.5

-2

-1.5

-1

-0.5

 0

 56870 56871 56872 56873 56874 56875

UTC(NMIJ)-UTC(NICT) [nsec]

MJD

NMIJ-NICT(UTCr:BIPM)

NMIJ-NICT(GPS)

NMIJ-NICT(VLBI)

Fig. 2 A time comparison result between NICT and NMIJ. Plots

include VLBI, GPS, and time difference provided by BIPM.

But we could identify the methanol line by checking the frequency. Kashima 34 m joined in cooperative observations of the Japanese VLBI network (JVN)

for the methanol C-band session in October 2014. Because other JVN stations receive circular polarization,

our linear polarization will make low SNR fringes. To

make better fringes, we will install a linear-to-circular

polarization converter.

IVS 2014 Annual Report
298 Takefuji and Ujihara

0.0e+00

1.0e-03

2.0e-03

3.0e-03

4.0e-03

5.0e-03

6.0e-03

7.0e-03

8.0e-03

9.0e-03

0 200 400 600 800 1000

Amplitude

Frequency [MHz]

Epoch : 2014/161 05:23:00

Station-1: kas34

Station-2: mbl1

Source : w3oh

Length : 59.999986[sec]

Sampling : 2048000000[sps]

Frequency: +6000.000000[MHz]

Peak Amp : 0.884039[ % ]

Peak Phs : -106.197273[deg]

Peak Freq: +669.775020[MHz]

Rate : +30.853279[mHz]

SNR : 30.602917 

0.0e+00

1.0e-03

2.0e-03

3.0e-03

4.0e-03

5.0e-03

6.0e-03

7.0e-03

0 200 400 600 800 1000

Amplitude

Frequency [MHz]

Epoch : 2014/281 06:23:00

Station-1: kas34

Station-2: mbl1

Source : w3oh

Length : 60.000000[sec]

Sampling : 2048000000[sps]

Frequency:+11414.000000[MHz]

Peak Amp : 0.755263[ % ]

Peak Phs : 96.430956[deg]

Peak Freq: +767.138633[MHz]

Rate : +11.454010[mHz]

SNR : 16.599317 

Fig. 3 Fringes of the 6.7 GHz and 12.2 GHz methanol maser lines from W3OH between the Gala-V system of Kashima 34 m and

MARBLE1.

Fig. 4 First fringes between the Kashima 34-m and Ishioka 13-m antennas.

IVS 2014 Annual Report
NICT TDC 2014 Report 299

5 Broadband Fringe Test with a

VGOS-type Ishioka 13 Meter

We made a VLBI observation for broadband with

the recently inaugurated GSI Ishioka 13-meter antenna in December 2014. Ishioka is northwest of

Kashima (about 60 km). A Field System and backends, including down-converters, digital samplers,

and VSI-recorders were moved from Kashima and

installed in Ishioka. We then carried out the broadband

session in the 10 GHz and 13 GHz frequency ranges.

A frontend cartridge of Ishioka consisted of an Elevenfeed system assembled by Omnisys. The cartridge

can be replaced by other feed systems such as the

Tri-band feed and the Quad-ridge flared feed horn

(QRFH). Each frequency had a 1024 MHz bandwidth

by 2048 MHz sampling speed and 1-bit quantization.

Unfortunately, there was no Internet connection in

Ishioka, and we had to send VLBI data classically,

by car. Figure 4 shows the fringe map. They were

memorial fringes for Ishioka. We will expand the

bandwidth of the Gala-V system at Kashima 34 m

from 3.2 GHz to 18 GHz, so that much wider VLBI

observations are planned for next summer or autumn.

6 New Wideband Feed ( NINJA )

Two types of the wideband feed NINJA have been undergoing development for the 34 m and MARBLE in

the 3.2-14.4 GHz frequency range for Gala-V. First, the

parabolic focus feed was initially designed for MARBLE which has a -10dB beam width of 50-60 degrees

opposite of the parabolic mirror. But for getting a better SNR, we decided to replace the main mirror of the

MARBLE from 1.6 m to 2.4 m, from prime focus to

Cassegrain focus. The NINJA feed was also redesigned

for a sharper 20-30 degree beam width. Figure 5 shows

the initial version of the NINJA feed under the far field

measurement of the Kyoto University METLAB. Next,

the Iguana daughter feed #2 that was deployed in 2014

will be left at the 34 m. The NINJA feed, which is

newly developed for the 34 m, will be installed beside

the Iguana in this spring. Figure 6 shows the NINJA

feed and Iguana prototype #1. The near side feed shows

prototype, which is currently used for initial checking

such as aperture efficiency in early 2014. The far side

feed will be for the 34 m without a beam-shaping lens.

Fig. 5 Initially designed wideband NINJA feed equipped beamshaping lens.

Fig. 6 The NINJA feeds displayed at the Micro Wave Exhibition

2014 in Yokohama, Japan.

7 Future Plans

The Kashima 34-m antenna is being upgraded for

wider bandwidth such as 3.2-18 GHz. The NINJA feed

will be installed in Spring 2015. We also have a plan

to install cryogenic receivers hopefully during the next

fiscal year.

References

1. Kazuhiro Takefuji, Hideki Ujihara, NICT Technology Development Center 2013 Annual Report, in International VLBI

Service for Geodesy and Astrometry 2013 Annual Report,

edited by K. D. Baver, D. Behrend, and K. L. Armstrong,

NASA/TP-2014-217522, 2014.

IVS 2014 Annual Report
Onsala Space Observatory – IVS Technology Development

Center Activities during 2014

Miroslav Pantaleev1, Rudiger Haas  ̈

1

, Bhushan Billade1, Leif Helldner1, Karl-Ake Johansson  ̊

1

, Lars Petterson1,

Christophe Granet2, Mark Bowen3, Alex Dunnin3

Abstract We give a brief overview on the technical

development related to geodetic VLBI done during

2014 at the Onsala Space Observatory.

1 Activities during 2014

Our activities in technical development for VLBI concentrated on the following topics:

• The Onsala Twin Telescope project

• Broadband feeds for VLBI2010

• A new 4.00–12.25 GHz front-end for the 20-m radio telescope

• FlexBuff and FILA40G

2 The Onsala Twin Telescope Project

The procurement of the telescopes for the Onsala Twin

Telescope project was started in June. Several tenders

were received. After a thorough study of the submitted tenders, a contract was signed in December to buy

two 13.2-m VGOS telescopes from MT Mechatronics.

In parallel to the procurement, preparations for the infrastructure work started. Figure 1 depicts the planned

location of the northern telescope. Both telescope locations consist of bed rock and at the same height within

a few centimeters. The distance between the telescopes

1. Chalmers University of Technology, Department of Earth and

Space Sciences, Onsala Space Observatory

2. BAE Systems Australia

3. CSIRO Astronomy and Space Science

OSO Technology Development Center

IVS 2014 Annual Report

is 75 m. The surrounding area around the northern location has been partially filled with blasted rockshot

rock, and the construction of a small road to connect

the two locations has been started.

Fig. 1 Aerial view of the planned location for the northern telescope of the Onsala Twin Telescope project. The southern telescope location is just outside the photo to the right.

3 Broadband Feeds for VLBI2010

We continued our collaboration with the Gothenburgbased company Omnisys Instruments and provided

support for the cryogenic and mechanical design

of a cryostat for the integration of the Eleven feed,

and further issues related to system integration. We

also supported receiver Y-factor tests which were

performed at the observatory during July 2014. Results

are shown in Figure 2. The three lines represent three

successive measurements of the receiver temperature,

performed with ten-minute intervals in order to study

the system stability.

300
OSO – IVS Technology Development Center 301

Fig. 2 On-sky tests of the VLBI2010 receiver developed by Omnisys in collaboration with the Onsala Space Observatory.

4 A New 4.00–12.25 GHz Front-end for the

20-m Radio Telescope

We started the design work for a 4.00–12.25 GHz cryogenic receiver for the 20-m telescope. The IVS observations at the 20-m antenna are currently conducted

with a dual S/X system. The S-band (see Figure 3) uses

an offset horn and a tertiary reflector that has a small

dichroic window through which the X-band signal is

collected by the current X-band horn.

One of the issues of the current S/X system is that it

is located off-axis, with the center of the aperture of the

current X-band horn being located at the position x =

379 mm and y = 240 mm. Furthermore, the design of

both feeds is narrow band and does not allow extension

of the S-band bandwidth beyond 250 MHz.

Fig. 3 The current S/X feed system on the 20-m radio telescope.

The interest for a wider bandwidth from both the

IVS and the EVN communities initiated a survey study

to localize a suitable design of components and suppliers that will allow extending the bandwidth for continuous coverage from C- to Ku-band. The survey study

concluded that, because the geometry of the 20-m telescope is designed for mm-wave optics, it will be very

challenging to find a commercial feed horn. The subreflector of the antenna has a half-subtended angle of

only 6.09oand to achieve an edge taper of –12 dB at

6.09o, a horn with very high gain must be designed.

After some investigation, we made an agreement with

BAE Systems to make a feasibility study for the design

of such a horn covering the 4.00–12.25 GHz band.

The next critical component in the receiver chain

is the Ortho Mode Transducer. The design made

by CSIRO Astronomy and Space Science (CASS)

for the Australia Telescope Compact Array (ATCA)

22-m telescope was found to be very suitable for our

application. In order to provide input to BAE for the

mechanical layout and position of the feed we made a

preliminary mechanical design of the receiver and the

location of the feed-receiver system in the cabin.

Fig. 4 The proposed mechanical arrangement of the 4.00–

12.25 GHz horn for the 20-m telescope.

IVS 2014 Annual Report
302 Pantaleev et al.

Fig. 5 Theoretical aperture efficiency with the “long” geometries (top) and the “short” geometries (bottom) of Horn-A, Horn-B, and

Horn-C (left, middle, and right, respectively).

One of the constraints in the design was to provide

a legacy mode for IVS observations in S- and X-band

and also provide the primary operation in the wideband 4.00–12.25 GHz. Therefore, the horn will be designed in sections, with at least one mechanical flange

at a position of 816 mm from the input of the horn and

a diameter of no more than 366 mm (see Figure 4),

thus the existing tertiary with the dichroic window can

then be used for S/X observations. This feed geometry is referred to as the ”short” feed. The overall length

of the complete 4.00–12.25 GHz horn will be set to be

1800 mm with an aperture diameter target of around

550 mm. This geometry is referred to as the ”long”

feed. This modular design with two sections will allow

both operation modes, i.e., legacy S/X and wide-band

4.00–12.25 GHz, however not simultaneously.

During the feasibility study done by BAE, a number of different optimization runs were performed with

various degrees of weighting for the different parameters and optimization goals. The following results report on the performance of three distinct horn geometries, all with the same input diameter and length, but

with different profiles and performance. The three optimized horns are labelled Horn-A, Horn-B, and Horn-C

and can be used in either their “long geometries” or

“short geometries”. The Horn-A and Horn-B geometries were optimized to try to have even performance

over the whole 4.00–12.25 GHz band while the HornC geometry was optimized to improve the performance

over the restricted 4.3–7.5 GHz to the detriment of the

upper band (7.50–12.25 GHz).

The theoretical aperture efficiency of the antenna,

with the various feeds on axis and at the correct position with respect to their phase-center positions, are

presented in Figure 5. This feasibility study shows that

the project can be carried out successfully.

5 FlexBuff and FILA40G

The FILA40G has been designed at Onsala Space Observatory within the FP7 RadioNet3 DIVA work package, as a unit to receive 4 x 8 Gb/s UDP (User Datagram Protocol) streams and then perform any needed

processing on these streams, before ultimately writing the data out to sets of disks, retransmitting via a

40 Gigabit Ethernet (GbE) interface, or a combination of the two. It is intended to be connected to a

DBBC3 [1] to allow the transmission and/or recording of the sampled data, but it is generic enough to

allow for connection to other sampling equipment so

long as they can provide data via Ethernet links. The

current FILA40G software is based on a modified verIVS 2014 Annual Report
OSO – IVS Technology Development Center 303

Fig. 6 Flow diagram and features for the FILA40G board.

sion of the jive5ab-2.5.1 software. A selection of features intended to be offered by the FILA40G, as well

as a general flow diagram is presented in Figure 6. Currently VDIF threading and packet filtering are implemented and verified, corner turning is partially implemented, and plans are being made for pulsar gating.

The FILA40G also acts as a timekeeper for the DBBC,

transmitting short UDP packets containing the current timestamp over the 10 GbE links to the DBBC3s’

CORE3 boards. The timestamps are generated from the

FILA40G’s system clock, which can be synchronized

by NTP (Network Time Protocol), or a GPS receiver if

a network connection is unavailable.

References

1. Tuccari G (2012) DBBC3 – A Full Digital Implementation of the VLBI2010 Backend. In: Proc. of

the IVS 2012 General Meeting, 76–80, edited by

D. Behrend and K. D. Baver, NASA/CP-2012-217504.

http://ivscc.gsfc.nasa.gov/publications/gm2012/tuccari.pdf

IVS 2014 Annual Report
IGN Yebes Technology Development Center

Jose Antonio L  ́ opez–Fern  ́ andez, Francisco Colomer, Pablo de Vicente, F  ́ elix Tercero, Jos  ́ e Manuel Serna, Juan  ́

Daniel Gallego, Ma Carmen D ́ıez, Inmaculada Malo, Laura Barbas, Ruben Bolano, Susana Garc  ́  ́ıa–Espada,

Carlos Albo, Alberto Barcia, Jesus G  ́ omez–Gonz  ́ alez  ́

Abstract The activities in technical development related to geodetic VLBI done during 2014 at IGN Yebes

Observatory were focused on different topics that are

detailed below.

1 RAEGE Radio Telescopes

The RAEGE radio telescopes at Yebes and Santa Mar ́ıa

are fully assembled, and the Yebes radio telescope,

“Jorge Juan”, is now fully equipped with a tri-band receiver. On November 26, 2014, the 13.2-meter “Jorge

Juan” radio telescope participated for the very first time

in a geodetic S/X session together with our 40-meter

radio telescope, confirming its first fringe detection.

During 2014, the onsite work at the Santa Mar ́ıa station

have been focused on the infrastructures around the radio telescope (the control and power supply buildings).

The receiver installation (a tri-band one) and the first

light are planned for 2015.

2 LNA Development

During 2014, several Yebes-developed low noise cryogenic amplifiers at S, C, X, and Ka bands were allocated to equip VLBI receivers at Yebes Observatory, Azores, Ishioka (Japan), and Wettzell (BKG, Germany). The design for S-band has been transferred to

the industry, and a Spanish company has produced the

Instituto Geografico Nacional (IGN)  ́

IGN Yebes Technology Development Center

IVS 2014 Annual Report

LNAs. X-band has benefited from the developments

accomplished for ALMA IF, and presently 4-12 GHz

amplifiers are being used as VLBI frontends. Ka-band

amplifiers are the fruit of a long-term successful collaboration with the Fraunhofer IAF and the University of Cantabria; they include mGaAs MMICs with

good cryogenic performance. A remarkable new development in Ka-band was made together with the ETHZurich in the framework of an ESA contract. The amplifier is a compact hybrid design with interchangeable I/O ports 2.9 mm coaxial or WR-28 waveguide.

Its ETH HEMT transistors are based in InAs. This

new material has shown exceptional performance with

record noise temperatures of 10 K averaged in the

25.5—32.5 GHz band, extremely high gain, and very

low power dissipation. Unfortunately, the availability

of these experimental devices is currently very limited.

Finally, we are working towards an ultra-wideband

amplifier covering the 2—14 GHz band, following two

approaches: an MMIC-based version and a hybrid amplifier. The first hybrid units produced were tested with

different transistors in the first stage. The best results,

obtained with NGST transistors, yield average noise

temperatures of 7.5 K. These devices are subject to severe export regulations and, for the moment, can only

be used on our premises. We are devoting our best efforts to ensure a reliable source of low noise transistors

for radio astronomy applications in Europe.

3 Tri-band (S/X/Ka) Receiver

A cryogenically cooled tri-band receiver has been successfully designed and developed. Currently three of

these receivers have been built: two of them for the

304
IGN Yebes Technology Development 305

Fig. 1 2—14 GHz cryogenic amplifier picture, and noise and gain measurements at 15 K. InP NGST HEMT in the first stage.

Fig. 2 Tri-band receiver installed in its frame positioner.

RAEGE radio telescopes in Yebes and Santa Mar ́ıa,

and one for the GSI’s Ishioka station. This receiver allows simultaneous dual circular polarization observations at S, X, and Ka bands. The tri-band feed is actually made of three feeds in a coaxial arrangement. The

S- and X-band feeds are fed by four symmetric ports

at 90 degrees apart. The Ka-band feed output is a circular waveguide that interfaces to a septum polarizercoupler developed in-house. The cryostat is built over

a two-stage Sumitomo closed cycle refrigerator inside

a cylindrical dewar made of steel with suitable multilayer insulation. The LNAs and 90o hybrid circuits are

in-house designs developed at Yebes Labs. The averaged receiver noise temperatures are below 25 Kelvin.

The receiver is fully integrated in a frame box positioner that facilitates the installation at the radio telescope feed cone.

IVS 2014 Annual Report
306 Lopez–Fern  ́ andez et al.  ́

4 Broadband Feed

In collaboration with the Carlos III University in

Madrid, Yebes is developing an alternative broadband

feed. The CQSA feed (Conical Quad-Spiral Array)

is implemented as four elements, each one being a

conical spiral antenna. The CQSA is double circular

polarization with a symmetric pattern between 2 and

14 GHz. The phase center is not constant in the whole

band, but its variation in the 4—14 GHz band is

only one centimeter. The first prototype was made of

titanium in order to assure the stiffness of the feed.

The dimensions are 170 mm in height and 150 mm

in diameter. The low conductivity of the titanium is

compensated by a 10 micron silver plating layer. The

feed has been measured in our anechoic chamber

showing excellent performance. The RAEGE radio

telescope performance has been simulated by means of

PO software package GRASP and shows 70% aperture

efficiency in the whole band. During the first months

in 2015 the feed will be cooled, and the performance

of the full receiver with our LNAs will be tested.

Fig. 3 CQSA feed prototype.

5 Control Software Development

During 2014 we worked on debugging the software for

the control and monitoring of the 13-m RAEGE antenna in Yebes, as well as on characterizing the antenna. The work was oriented towards two different

facets: single-dish observation and VLBI observations.

We have investigated the RFI along the S, X, and Ka

bands and its dependency on elevation and azimuth,

finding that the RFI at S-band, although present, is less

important in the 13-m than in the 40-m radio telescope.

X-band seems to be a band almost free of RFI. Care

was taken to avoid internal RFI sources inside the elevation cabin, where communication equipment and cables have been shielded.

We also determined pointing models for the antenna and the optimum focus using several sessions

and following an iterative procedure. The noise diodes

were calibrated using the atmosphere, and a hot load

and gain curves at S, X, and Ka bands were determined

while tracking sources from the horizon to zenith.

The connection between the Field System and the

control system developed at Yebes is done via UDP

sockets. Information from the weather station and

the gps-maser comparison uses the same protocol.

The Field System also transfers commands for the

receivers: local oscillator frequency, attenuation, and

noise diode on/off switching. Tests were performed

to test the quality and the speed of the connectivity

between both systems.

In August 2014, we received a DBBC2 equipped

with four IFs/ADB2s/CORE2s to be used with the 13-

m antenna. Once the equipment was configured and

tested, we connected it to a Mark 5B+ recorder, and

we performed a 24-hour VLBI session (R1656) with

the 40-m telescope in parallel with the VLBA5 system.

Fringes were found, and hence both the 13-m DBBC2

and the Mark 5B+ were validated.

OnOff sessions controlled by the Field System were

also conducted to determine the SEFD of the telescope

at S and X bands and to fine tune the calibration from

the noise diodes. These tests were also important to debug the control software and the communication between the Field System and the local control system.

Finally, in November 2014, selected scans from an

IVS session (R4663) were observed in parallel with the

VLBA5 system connected to the 40-m telescope and

the DBBC2 connected to the 13-m antenna. Fringes

IVS 2014 Annual Report
IGN Yebes Technology Development 307

Fig. 4 O’Higgins receiver upgraded at Yebes.

were found at X-band. The lack of fringes at S-band

was due to a problem with the signal from the IF.

Our near term goal is to have the 13 m be scheduled

in 2015 as tagged along in some IVS sessions in which

the 40-m antenna takes part. This will allow us to thoroughly test the whole receiving chain, detect problems,

and correct them. It will also determine the position of

the 13-m antenna and prepare the telescope for standard IVS observations. The midterm goal is to equip

the antenna with a broadband receiving system and to

start VGOS observations by the end of 2015.

6 S/X Receiver Activities

During 2014, several activities were carried out for

the upgrade of cryogenic receivers belonging to BKG

(Germany). One of the S/X Wettzell dewars was upgraded by fixing some bugs (vacuum leaks, multilayer

insulation,...) that deteriorated the cryogenic performance. The O’Higgins station in Antarctica was also

fully upgraded by installing new LNAs and a custom

waveguide coupler designed and built in our labs. Several receiver modules such as the down converter, noise

calibration, and LO’s were also upgraded. The functionalities of the receiver (setting and monitoring output power level, LO’s lock status, noise cal, phase cal,

and LNAs bias) can be controlled via Ethernet, using a

remote control system developed in our labs.

Acknowledgements: The development of the tri-band

and the broadband receivers is supported by project

FIS2012-38160 financed by the Spanish Ministry of

Economy and Competitiveness (MINECO).

IVS 2014 Annual Report

Bibliography

Bibliography

1 Introduction

The following bibliography compiles papers that were

published in the field of geodetic and astrometric VLBI

during 2014. There is no distinction between peerreviewed, reviewed, or proceedings publications. This

list is by no means exhaustive.

2 Geodetic and Astrometric VLBI

Publications of 2014

Y. AOYAMA, K. DOI, K. SHIBUYA: “JARE Syowa

Station 11-m Antenna, Antarctica”. International

VLBI Service for Geodesy and Astrometry 2013

Annual Report, edited by K. D. Baver, D. Behrend,

and K. L. Armstrong, NASA/TP-2014-217522,

167–170, 2014.

T. ARTZ, A. SPRINGER, A. NOTHNAGEL: “A complete VLBI delay model for deforming radio telescopes: the Effelsberg case”. Journal of Geodesy,

88(12), 1145–1161, DOI: 10.1007/s00190-014-

0749-1, 2014.

U. BACH AND A. KRAUS: “Effelsberg Radio Observatory 2013 Annual Report”. International VLBI Service for Geodesy and Astrometry 2013 Annual Report, edited by K. D. Baver, D. Behrend, and K.

L. Armstrong, NASA/TP-2014-217522, 104–105,

2014.

S. BACHMANN, M. LOSLER  ̈ , L. MESSERSCHMITT,

R. SCHMID, M. BLOSSFELD, D. THALLER:

“BKG/DGFI Combination Center Annual Report

IVS 2014 Annual Report

2013”. International VLBI Service for Geodesy

and Astrometry 2013 Annual Report, edited by

K. D. Baver, D. Behrend, and K. L. Armstrong,

NASA/TP-2014-217522, 257–260, 2014.

S. BACHMANN, L. MESSERSCHMITT, D. THALLER:

“IVS Combination Center at BKG: ITRF2013

Preparations and Source Position Combination”.

International VLBI Service for Geodesy and

Astrometry 2014 General Meeting Proceedings

‘VGOS: The New VLBI Network’, edited by

D. Behrend, K. D. Baver, and K. L. Armstrong,

Science Press (Beijing), ISBN 978-7-03-042974-2,

243–247, 2014.

C. BARACHE AND S. LAMBERT: “Paris Observatory

(OPAR) Data Center”. International VLBI Service

for Geodesy and Astrometry 2013 Annual Report,

edited by K. D. Baver, D. Behrend, and K. L. Armstrong, NASA/TP-2014-217522, 244–245, 2014.

S. BASU, A. DE WITT, J. QUICK, A. BERTARINI,

L. LEEUW: “Multi-epoch Study of Source Morphology in the Southern Hemisphere”. International

VLBI Service for Geodesy and Astrometry 2014

General Meeting Proceedings ‘VGOS: The New

VLBI Network’, edited by D. Behrend, K. D. Baver,

and K. L. Armstrong, Science Press (Beijing), ISBN

978-7-03-042974-2, 426–430, 2014.

K. BAVER AND J. GIPSON: “Balancing Sky Coverage and Source Strength in the Improvement

of the IVS-INT01 Sessions”. International VLBI

Service for Geodesy and Astrometry 2014 General

Meeting Proceedings ‘VGOS: The New VLBI

Network’, edited by D. Behrend, K. D. Baver, and

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311
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C. BEAUDOIN: “Design of a Circularly-Polarized

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VLBI Observations”. International VLBI Service for Geodesy and Astrometry 2014 General

Meeting Proceedings ‘VGOS: The New VLBI

Network’, edited by D. Behrend, K. D. Baver, and

K. L. Armstrong, Science Press (Beijing), ISBN

978-7-03-042974-2, 73–76, 2014.

C. BEAUDOIN, P. BOLIS, B. COREY, M. DEROME,

C. ECKERT, A. NIELL, C. RUSZCZYK, R.

MCWHIRTER, A. WHITNEY: “A Cost and Complexity Survey on Emerging Technologies for the

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and Astrometry 2014 General Meeting Proceedings

‘VGOS: The New VLBI Network’, edited by

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53–59, 2014.

C. BEAUDOIN, A. NIELL, R. CAPPALLO: “Haystack

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D. Behrend, and K. L. Armstrong, NASA/TP-2014-

217522, 341–344, 2014.

D. BEHREND: “Coordinating Center Report”. International VLBI Service for Geodesy and Astrometry 2013 Annual Report, edited by K. D. Baver,

D. Behrend, and K. L. Armstrong, NASA/TP-2014-

217522, 83–85, 2014.

D. BEHREND, C. THOMAS, E. HIMWICH, D.

MACMILLAN: “CONT14: Preparation and

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and Astrometry 2014 General Meeting Proceedings

‘VGOS: The New VLBI Network’, edited by

D. Behrend, K. D. Baver, and K. L. Armstrong,

Science Press (Beijing), ISBN 978-7-03-042974-2,

196–200, 2014.

I. BEZRUKOV, A. SALNIKOV, A. VYLEGZHANIN:

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and Astrometry 2014 General Meeting Proceedings

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for Geodesy and Astrometry 2013 Annual Report,

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SUN, K. TEKE: “Vienna VLBI Software: Current

Release and Plans for the Future”. International

VLBI Service for Geodesy and Astrometry 2014

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VLBI Network’, edited by D. Behrend, K. D. Baver,

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S. BOLOTIN, K. BAVER, J. GIPSON, D. GORDON, D.

MACMILLAN: “The VLBI Data Analysis Software

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Future”. International VLBI Service for Geodesy

and Astrometry 2014 General Meeting Proceedings

‘VGOS: The New VLBI Network’, edited by

D. Behrend, K. D. Baver, and K. L. Armstrong,

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253–257, 2014.

R. BOUFFET, P. CHARLOT, S. LAMBERT: “Effects

of AGN Jet Evolution on VLBI Astrometric Positions”. International VLBI Service for Geodesy

and Astrometry 2014 General Meeting Proceedings

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D. Behrend, K. D. Baver, and K. L. Armstrong,

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N. CAPITAINE, J. C. LIU: “The Evaluation of the

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R. CURTIS: “Kokee Park Geophysical Observatory”. International VLBI Service for Geodesy

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D. DALE, L. COMBRINCK, A. DE WITT: “A Strategic

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P. DE VICENTE, R. BOLANO ̃ , L. BARBAS: “Control

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A. GIRDIUK AND O. TITOV: “Plan and Schedule

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D. GORDON: “Revisiting the VLBA Calibrator

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LEHMANN, S. MAHLER  ̈ : “The Usage of Recursive

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IVS 2014 Annual Report
IVS Information

IVS Terms of Reference

1 Summary

1.1 Charter

The International VLBI Service for Geodesy and Astrometry (IVS) is an international collaboration of organizations which operate or support Very Long Baseline Interferometry (VLBI) components. IVS provides

a service which supports geodetic and astrometric work

on reference systems, Earth science research, and operational activities. IVS is a Service of the International

Association of Geodesy (IAG) and of the International

Astronomical Union (IAU).

1.2 Objectives

IVS fulfills its charter through the following objectives:

1. foster and carry out VLBI programs. This is accomplished through close coordination of the participating organizations to provide high-quality VLBI

data and products.

2. promote research and development activities in all

aspects of the geodetic and astrometric VLBI technique.

3. advance the education and training of VLBI participants through workshops, reports, and other means.

4. support the integration of new components into

IVS.

5. interact with the community of users of VLBI products. IVS represents VLBI in the Global Geodetic

IVS 2014 Annual Report

Observing System (GGOS) of the IAG and interacts closely with the International Earth Rotation

and Reference Systems Service (IERS).

In support of these objectives, IVS coordinates

VLBI observing programs, sets performance standards for VLBI stations, establishes conventions

for VLBI data formats and data products, issues

recommendations for VLBI data analysis software,

sets standards for VLBI analysis documentation, and

institutes appropriate VLBI product delivery methods

to ensure suitable product quality and timeliness.

IVS coordinates its activities with the astronomical

community because of the dual use of many VLBI

facilities and technologies for both astronomy and

astrometry/geodesy.

1.3 Data Products

VLBI data products contribute uniquely to these important activities:

• defining and maintaining the celestial reference

frame,

• monitoring universal time (UT1), and

• monitoring the coordinates of the celestial pole (nutation and precession).

These results are the foundation of many scientific and practical applications requiring the use of an

accurate quasi-inertial reference frame, such as highprecision positioning, navigation, and timing. In addition IVS provides a variety of VLBI products with

differing applications, timeliness, detail, and temporal

resolution, such as:

331
332 IVS Terms of Reference

• all components of Earth orientation parameters,

• terrestrial reference frame,

• baseline lengths, and

• tropospheric parameters.

All VLBI data and products are publicly available

in appropriate formats from IVS Data Centers.

1.4 Research

The IVS data and products are used for research in

many areas of geodesy, geophysics, and astronomy,

such as:

• UT1 and polar motion excitation over periods of

hours to decades,

• solid Earth interior research (e.g., mantle rheology,

anelasticity, libration, and core modes),

• characterization of celestial reference frame

sources and improvements to the frame,

• tidal variations (solid Earth, oceanic, and atmospheric),

• improvements in the terrestrial reference frame, especially in the scale,

• climate studies (e.g., sea level change, deglaciation,

and water vapor),

• regional and global geodynamics, and

• general relativity.

To support these activities, there are ongoing research efforts to improve and extend the VLBI technique in areas such as:

• instrumentation, data acquisition, and correlation,

• data analysis techniques,

• spacecraft tracking and navigation (Earth-orbiting

and interplanetary), and

• combination of VLBI data and results with other

techniques.

2 Permanent Components

IVS acquires, correlates, and analyzes VLBI data to

produce geodetic, astrometric, and other results that are

archived and publicized. IVS accomplishes its objectives through the following permanent components:

• Network Stations,

• Operation Centers,

• Correlators,

• Analysis Centers,

• Data Centers,

• Technology Development Centers, and

• Coordinating Center.

2.1 Network Stations

The IVS observing network consists of high performance VLBI stations.

• Stations may either be dedicated to geodesy or have

multiple uses (including astronomical observations

or satellite tracking applications).

• Stations comply with performance standards for

data quality and operational reliability specified by

the Directing Board.

• Stations provide local tie information, timing and

meteorological data to the IVS Data Centers.

• VLBI data acquisition sessions are conducted by

groups of Network Stations that may be distributed

either globally or over a geographical region.

2.2 Operation Centers

The IVS Operation Centers coordinate the routine operations of specific networks. Operation Center activities include:

• planning network observing programs,

• supporting the network stations in improving their

performance,

• generating the detailed observing schedules for use

in data acquisition sessions by IVS Network Stations, and

• posting the observing schedule to an IVS Data Center for distribution and archiving.

IVS Operation Centers follow guidelines from the

Coordinating Center for timeliness and schedule file

formats.

IVS 2014 Annual Report
IVS Terms of Reference 333

2.3 Correlators

The IVS Correlators process raw VLBI data. Their

other tasks are to:

• provide timely feedback to the Network Stations

about data quality,

• jointly maintain the geodetic/astrometric community’s media pool and transport,

• manage electronic data transfer,

• make processed data available to the Data Centers,

and

• regularly compare processing techniques, models,

and outputs to ensure that data from different Correlators are identical.

2.4 Analysis Centers

The IVS coordinates VLBI data analysis to provide

high-quality products for its users. The analyses are

performed by:

• Operational Analysis Center,

• Associate Analysis Centers,

• Special Analysis Centers for Specific Observing

Sessions, and

• Combination Centers.

All Analysis Centers maintain and/or develop appropriate VLBI analysis software.

Operational Analysis Centers are committed to producing results to the specifications of the IVS Analysis

Coordinator and always on schedule to meet IVS requirements. In addition, Operational Analysis Centers

may produce Earth orientation parameters, station coordinates, and source positions in regular intervals.

Operational Analysis Centers place their final

results in IVS Data Centers for dissemination to

researchers and other users. They adhere to IVS

recommendations for the creation of high-quality

products and their timely archiving and distribution.

Any deviations that an Operational Analysis Center

makes from IVS recommendations are properly

documented. Operational Analysis Centers provide

timely feedback about station performance. In addition

to these regular services, Operational Analysis Centers

may also perform any task of an Associate Analysis

Center.

Associate Analysis Centers are committed to regularly submit specialized products using complete series or subsets of VLBI observing sessions. The analysis is performed for specific purposes as recognized

by the Directing Board, such as exploitation of VLBI

data for new types of results, investigations of regional

phenomena, reference frame maintenance, or special

determinations of Earth orientation parameters. The

Associate Analysis Centers place their final results in

IVS Data Centers for dissemination to researchers and

other users. They adhere to IVS recommendations for

the creation of high-quality products and their timely

archiving and distribution. Any deviations that an Associate Analysis Center makes from IVS recommendations are properly documented.

Special Analysis Centers for Specific Observing

Sessions have responsibility for ongoing series-related

investigations of one or more existing session types.

They perform detailed and comparative analyses of

each session of a series within a reasonable time after

correlation. In addition, they report deficits and technical complications to the observing sites, the correlators,

and to the schedulers as well as to the IVS Network and

Analysis Coordinators.

Combination Centers are committed to produce

combination results from the individual submissions

of the Operational Analysis Centers as official IVS

products. For this purpose they monitor the quality of

the submissions. The official IVS products include,

but are not limited to, EOP time series derived from

session-based results for 24-hour network sessions and

one-hour Intensive sessions. Combination Centers also

contribute to the generation of the official IVS input

to International Terrestrial Reference Frame (ITRF)

computations. The combination work is done in a

timely fashion and in close cooperation with the IVS

Analysis Coordinator.

2.5 Data Centers

The IVS Data Centers are repositories for VLBI observing schedules, station log files, data and products.

Data Centers may mirror other Data Centers to make

the distribution and maintenance of data more efficient

and reliable.

• Data Centers are the primary means of distributing

VLBI products to users.

IVS 2014 Annual Report
334 IVS Terms of Reference

• Data Centers work closely with the Coordinating

Center and with the Analysis Centers to ensure that

all the information and data required by IVS components are quickly and reliably available.

Data Centers provide the following functions:

• receive and archive schedule files from Operation

Centers,

• receive and archive log files and ancillary data files

from the Network Stations,

• receive and archive data products from the Analysis

Centers, and

• provide access and public availability to IVS data

products for all users.

2.6 Technology Development Centers

The IVS Technology Development Centers contribute

to the development of new VLBI technology for improvement of the VLBI technique. They:

• investigate new equipment and approaches,

• develop, test, and document new hardware,

firmware, and software for operations,

• assist with deployment, installation, and training

for any new approved technology, and

• maintain and support operational equipment.

2.7 Coordinating Center

The IVS Coordinating Center is responsible for coordination of both the day-to-day and the long-term activities of IVS, consistent with the directives and policies

established by the Directing Board. Specifically, the

Coordinating Center monitors, coordinates, and supports the activities of the Network Stations, Operation

Centers, Correlators, Data Centers, Analysis Centers,

and Technology Development Centers. The Coordinating Center works closely with the Technology Coordinator, the Network Coordinator, and the Analysis Coordinator to coordinate IVS activities.

The primary functions of the Coordinating Center

are to:

• coordinate observing programs approved by the Directing Board,

• create and maintain the master schedule of observing sessions in coordination with IVS Network Stations and astronomical observing programs,

• foster communications among all components of

the IVS,

• coordinate the best use of community resources,

• develop standard procedures for IVS components,

• organize training in VLBI techniques,

• organize workshops and meetings, including IVS

technical meetings,

• produce and publish reports of activities of IVS

components,

• maintain the IVS information system and archive

all documents, standards, specifications, manuals,

reports, and publications,

• coordinate IVS outreach and educational activities,

• provide liaison with the IAU, IAG, GGOS, IERS,

and other organizations, and

• provide the Secretariat of the Directing Board.

2.8 Becoming a Permanent Component

IVS will accept proposals at any time to become a permanent component. Such proposals will be reviewed

for approval by the Directing Board.

3 Coordinators

Specific IVS activities regarding network data quality,

products, and technology are accomplished through the

functions performed by three coordinators: a Network

Coordinator, an Analysis Coordinator, and a Technology Coordinator.

3.1 Network Coordinator

The IVS Network Coordinator is selected by the Directing Board from responses to an open solicitation to

all IVS components. The Network Coordinator represents the IVS Network Stations on the Directing Board

and works closely with the Coordinating Center. The

Network Coordinator is responsible for stimulating the

maintenance of a high quality level in the station operIVS 2014 Annual Report
IVS Terms of Reference 335

ation and data delivery. The Network Coordinator performs the following functions:

• monitors adherence to standards in the network operation,

• participates in the quality control of the data acquisition performance of the network stations,

• tracks data quality and data flow problems and suggests actions to improve the level of performance,

and

• coordinates software development for station control and monitoring.

The Network Coordinator works closely with the

geodetic and astronomical communities who are using

the same network stations for observations. The Network Coordinator takes a leading role in ensuring the

visibility and representation of the network stations.

3.2 Analysis Coordinator

The IVS Analysis Coordinator is selected by the Directing Board from responses to an open solicitation to

the IVS Analysis Centers. The Analysis Coordinator

is responsible for coordinating the analysis activities

of IVS and for stimulating VLBI product development

and delivery. The Analysis Coordinator performs the

following functions:

• fosters comparisons of results from different VLBI

analysis software packages and different analysis

strategies,

• encourages documentation of analysis and combination software,

• participates in comparisons of results from different

space geodetic techniques,

• monitors Analysis Centers’ products for high quality results and for adherence to IVS standards and

IERS Conventions,

• ensures that IVS analysis and combination products from all Analysis Centers are archived and are

available to the scientific community, and

• supervises the formation of the official IVS products specified by the IVS Directing Board.

The Analysis Coordinator plays a leadership role in

the development of methods for generation and distribution of VLBI products so that the products reach the

users in a timely manner. The Analysis Coordinator interacts with GGOS and the IERS and promotes the use

of VLBI products by the broader scientific community.

The Analysis Coordinator works closely with the astronomical communities who are using some of the same

analysis methods and software.

3.3 Technology Coordinator

The IVS Technology Coordinator is selected by the Directing Board from responses to an open solicitation to

the IVS Technology Development Centers. The Technology Coordinator performs the following functions:

• stimulates advancement of the VLBI technique,

• maintains awareness of all current VLBI technologies and ongoing development,

• coordinates development of new technology among

all IVS Technology Development Centers,

• encourages technical compatibility with the astronomical community,

• encourages and oversees development of VLBIrelated technical standards,

• coordinates the distribution of and access to technical documents and standards, and

• helps promulgate new technologies to the IVS community.

The Technology Coordinator works closely with

the astronomical community, both to maintain technical compatibility between the geodetic and astronomical communities and to take advantage of technology

development activities in the astronomical community.

4 Directing Board

4.1 Roles and Responsibilities

The Directing Board sets objectives, determines policies, adopts standards, and sets the scientific and operational goals for IVS. The Directing Board exercises

general oversight of the activities of IVS including

modifications to the organization that are deemed appropriate and necessary to maintain efficiency and reliability. The Directing Board may determine appropriate actions to ensure the quality of the IVS products.

IVS 2014 Annual Report
336 IVS Terms of Reference

The Directing Board will receive and review proposals for non-IVS research programs that request IVS

resources.

4.2 Membership

The Directing Board consists of representatives of the

IVS components, members at-large, appointed members, and ex officio members. The members are:

Representatives of IVS Components (see below):

• Correlators and Operation Centers representative

(1)

• Analysis and Data Centers representatives (2)

• Networks representatives (2)

• Technology Development Centers representative

(1)

Elected by the Directing Board upon recommendation from the Coordinating Center (see below):

• Members at large (3)

Selected by Directing Board upon review of proposals from IVS Member Organizations:

• Coordinating Center Director

• Network Coordinator

• Analysis Coordinator

• Technology Coordinator

Appointed members:

• IAU representative

• IAG representative

• IERS representative

Through a reciprocity agreement between IVS and

IERS, the IVS serves as the VLBI Technique Center

for IERS, and as such its designated representative(s)

serve on the IERS Directing Board. In turn, the IERS

Directing Board designates a representative to the IVS

Directing Board. This arrangement is to assure full cooperation between the two services.

Total number: 16

The members appointed by IAU, IAG, and IERS

are not subject to institutional restrictions.

The six members who are the representatives of

the IVS components are elected by the IVS Associate

Members. All elected members serve staggered fouryear terms once renewable.

At-large members are intended to ensure representation on the Directing Board of each of the components of IVS and to balance representation from as

many countries and institutions and IVS interests as

possible. At-large members serve two-year terms once

renewable.

A Directing Board member who departs before the

end of his/her term is replaced by a person selected by

the Directing Board. The new member will serve until the next official elections. The position will then be

filled for a full term.

An individual can only serve two consecutive full

terms on the Board in any of the representative and

at-large positions. Partial terms are not counted to this

limit. After serving two consecutive full terms, an individual becomes eligible again for a position on the

Board following a two-year absence.

The three Coordinators are selected by the Directing Board on the basis of proposals from IVS Member Organizations. On a two-thirds vote the Directing

Board may call for new proposals for any Coordinator

when it determines that a new Coordinator is required.

Coordinators are encouraged to give at least six months

notice before resigning.

4.3 Elections

Election of Board members from the IVS components

shall be conducted by a committee of three Directing

Board members, the chair of which is appointed by the

chair of the Directing Board. The committee solicits

nominations for each representative from the relevant

IVS components. For each position, the candidate who

receives the largest number of votes from the Associate

Members will be elected. In case of a tie the Directing

Board will make the decision.

4.4 Chair

The chair is one of the Directing Board members and is

elected by the Board for a term of four years with the

IVS 2014 Annual Report
IVS Terms of Reference 337

possibility of reelection for one additional term. The

chair is the official representative of IVS to external

organizations.

4.5 Decisions

Most decisions by the Directing Board are made by

consensus or by simple majority vote of the members

present. In case of a tie, the chair decides how to proceed. If a two-thirds quorum is not present, the vote

shall be held later by electronic mail. A two-thirds vote

of all Board members is required to modify the Terms

of Reference, to change the chair, or to replace any of

the members before their normal term expires.

4.6 Meetings

The Directing Board meets at least annually, or more

frequently if meetings are called by the chair or at the

request of at least three Board members. The Board

will conduct periodic reviews of the IVS organization

and its mandate, functions, and components.

5 Definitions

5.1 Member Organizations

Organizations that support one or more IVS components are IVS Member Organizations. Individuals associated with IVS Member Organizations may become

IVS Associate Members.

5.2 Affiliated Organizations

Organizations that cooperate with IVS on issues of

common interest, but do not support an IVS component, are IVS Affiliated Organizations. Affiliated Organizations express an interest in establishing and maintaining a strong working association with IVS to mutual benefit. Individuals affiliated with IVS Affiliated

Organizations may become IVS Corresponding Members.

5.3 Associate Members

Individuals associated with organizations that support

an IVS component may become IVS Associate Members. Associate Members take part in the election of the

incoming members of the Directing Board representing

the IVS components.

5.4 Corresponding Members

IVS Corresponding Members are individuals who express interest in receiving IVS publications, wish to

participate in workshops or scientific meetings organized by IVS, or generally are interested in IVS activities. Ex officio Corresponding Members are the following:

• IAG Secretary General

• Chair of GGOS

• President of IAG Commission 1 – Reference

Frames

• President of IAG Commission 3 - Earth Rotation

and Geodynamics

• President of IAU Division I – Fundamental Astronomy

• President of IAU Commission 8 – Astrometry

• President of IAU Commission 19 – Rotation of the

Earth

• President of IAU Commission 31 – Time

• President of IAU Commission 40 – Radio Astronomy

• President of URSI Commission 52 – Relativity in

Fundamental Astronomy

• President of URSI Commission J – Radio Astronomy

Individuals are accepted as IVS Corresponding

Members upon request to the Coordinating Center.

Last modified: 23 September 2011

IVS 2014 Annual Report
Links to Additional IVS Information

This page provides links to information about the

individuals and groups that support IVS. Member

organizations are organizations that support one or

more permanent components. Permanent components

are groups that formally commit to provide support

in one of six categories: coordination of network

operations (Operation Centers), collection of VLBI

data (Network Stations), processing of raw data (Correlators), archival and distribution of data and products

(Data Centers), analysis of data and generation of

products (Analysis Centers), and development of new

technology (Technology Development Centers).

Information Category Link

Associate Members

(listed alphabetically by last name) ivscc.gsfc.nasa.gov/about/org/members/assoc name.pdf

(listed alphabetically by their organization’s country) ivscc.gsfc.nasa.gov/about/org/members/assoc org.pdf

Permanent Components

Network Stations http://ivscc.gsfc.nasa.gov/about/org/components/ns-list.html

Operation Centers http://ivscc.gsfc.nasa.gov/about/org/components/oc-list.html

Correlators http://ivscc.gsfc.nasa.gov/about/org/components/co-list.html

Data Centers http://ivscc.gsfc.nasa.gov/about/org/components/dc-list.html

Analysis Centers http://ivscc.gsfc.nasa.gov/about/org/components/ac-list.html

Technology Development Centers http://ivscc.gsfc.nasa.gov/about/org/components/td-list.html

Member Organizations http://ivscc.gsfc.nasa.gov/about/org/members/memberorgs.html

Affiliated Organizations http://ivscc.gsfc.nasa.gov/about/org/members/affilmemberorgs.html

IVS 2014 Annual Report

Associate Members are individuals that are associated

with a member organization and have been granted Associate Member status. Associate Members generally

support IVS by participating in the activities of one or

more components.

Affiliated organizations cooperate with IVS on

matters of common interest but do not support a

component.

338