NASA/TP-2001-209979

InternationalVLBIServicefor GeodesyandAstrometry

2000 ANNUALREPORT

Editedby

N.R. Vandenberg

and K.D. Baver

IVSCoordinatingCenter

February2001

22 _L -"'_-

¢ ,. , _ .-.
On the cover: The cover layout includes a photograph of the 32-m VI.BI

antenna at Tsukuba, Japan, operated by the Geographical Survey Institute
NASAITP-2001-209979 _, __:_

internationalVLBIServicefor GeodesyandAstrome_ry

2000 ANNUALREPORT

Editedby nber N.R. Vande g

and K.D. BaYer

IVSCoordinatingCenter

February2001

_- " _-_ .5"

/

Preface

This volume of reports is the 2000 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 who constitute the permanent components of IVS.

The IVS 2000 Annual Report documents the work of the IVS components for the period

March 1, 1999 (the official inauguration date of IVS) through December 31, 2000. The reports

document changes, activities, and progress of the IVS.

The entire contents of this Annual Report also appear on the IVS web site at

http ://ivscc. gsf c. nasa. gov/publicat ions/ar2000

This book and the web site are organized as follows:

• The first section contains general information about IVS, a map showing the location of the

components, information about the Directing Board members, and the report of the IVS

Chair.

• The second section of Special Reports contains a status report of the IVS Working Group

on GPS phase center mapping, a reproduction of the resolution making IVS a Service of

the International Astronomical Union (IAU), and a reprint of the VLBI Standard Interface

(VSI).

• The next seven sections hold the component reports from the Coordinators, Network Stations, Operation Centers, Correlators, Data Centers, Analysis Centers, and Technology Development Centers.

• Tile last section includes reference information about IVS: tile Terms of Reference, the lists

of Member and Affiliated organizations, the IVS Associate Member list, a complete list of

IVS components, the list of institutions contributing to this report, and a list of acronyms.

The 2000 Annual Report demonstrates the vitality of the IVS and the outstanding progress we

have made during our first 22 months.

nl

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 .................................................................... 11

IVS/IGS/ILRS Working Group on GPS Phase Center Mapping ...................................... 13

IAU Resolution (IVS is a Service of the IAU) ......................................................... 17

VLBI Standard Interface Specification ................................................................ 18

IVS Coordination ................................................................. 51

Coordinating Center Report ........................................................................... 53

Analysis Coordinator Report ......................................................................... 55

Network Coordinator Report ......................................................................... 65

Technology Coordinator Report ...................................................................... 67

Network Stations .................................................................. 71

Algonquin Radio Observatory . ....................................................................... 73

2000 Activities Report of Fortaleza Station ........................................................... 77

Gihnore Creek Geophysical Observatory .............................................................. 78

God(lard Geophysical and Astronomical Observatory . ................................................ 81

Hartebeesthoek Radio Astronomy Observatory (HartRAO) ........................................... 84

Kashima 34m Radio Telescope ....................................................................... 88

Key Stone Project VLBI Stations (Kashima, Koganei, Miura, and Tateyama) ......................... 92

Kokee Park Geophysical Observatory ................................................................. 95

Matera CGS VLBI Station ........................................................................... 98

Medicina Station Report ............................................................................ 102

Report from the Noto VLBI Station ................................................................. 104

NYAL Ny-Mesund 20 Metre Antenna ............................................................... 106

German Antarctic Receiving Station O'Higgins ...................................................... 110

The IVS Network Station Onsala Space Observatory ................................................ 113

Seshan VLBI Station Report ......................................................................... 117

Simeiz Station: Geodetical Experiments and Single Dish Observations ............................... 120

Svetloe Radio Astronomical Observatory . ........................................................... 123

JARE Syowa Station 11-m Antenna, Antarctica ..................................................... 127

Transportable Integrated Geodetic Observatory . .................................................... 131

Tsukuba 32-m VLBI Station ........................................................................ 135

Nanshan VLBI Station Report ...................................................................... 139

"_Vestford Antenna .................................................................................. 141

Station Report of the 20m Radiotelescope at Wettzell ............................................... 145

Observatorio Astrondmico Nacional ................................................................. 149

_(Mlowknife Observatory . ........................................................................... 153

v
Operation Centers ............................................................... 155

The Bonn Geodetic VLBI Operation Center ......................................................... 157

CORE Operation Center Report .................................................................... 159

U.S. Naval Observatory Operation Center ........................................................... 163

Correlators ....................................................................... 165

The Bonn Astro/Geo Mark IV Correlator ........................................................... 167

Haystack Observatory VLBI Correlator ............................................................. 170

KSP-VLBI Correlation Center Report ............................................................... 173

Tsukuba VLBI Center .............................................................................. 176

Washington Correlator .............................................................................. 178

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

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

Data Center at Communications Research Laboratory ............................................... 185

CDDIS Data Center Report ......................................................................... 188

Italy CNR Data Center Report ..................................................................... 192

Paris Observatory (OPAR) Data Center ............................................................. 194

Analysis Centers ................................................................. 197

Analysis Center of Saint-Petersburg University ...................................................... 199

Bordeaux Observatory Analysis Center Report ...................................................... 203

Matera CGS VLBI Analysis Center ................................................................. 207

Analysis Center at Communications Research Laboratory ........................................... 210

DGFI Analysis Center Annual Report 2000 ......................................................... 215

Combination of VLBI, GPS and SLR Data Analysis at FFI ......................................... 218

The GIUB/BKG VLBI Analysis Center ............................................................. 221

GSFC VLBI Analysis Center ........................................................................ 225

Analysis and Research at the Haystack Observatory . ................................................ 229

IAA VLBI Analysis Center Report for 2000 ......................................................... 232

Italy CNR Analysis Center Report .................................................................. 236

Vienna IGG Special Analysis Center Annual Report 2000 ........................................... 238

Paris Observatory Analysis Center OPAR: Report on Activities, March 1999 - December 2000 ....... 241

The IVS Special Analysis Center at tile Onsala Space Observatory . ................................. 245

Analysis Center Report from Shanghai Astronomical Observatory for 1999.03 2000.12 .............. 249

USNO Analysis Center for Source Structure Report ................................................. 253

Technology Development Centers .............................................. 257

Canadian VLBI Technology Development Center .................................................... 259

Technology Development Center at CRL ............................................................ 263

Combination of VLBI, GPS and SLR Software Development at FFI ................................. 267

GSFC IVS Technology Development Center Report ................................................. 269

Haystack Observatory Technology Development Center .............................................. 273

Institute of Applied Astronomy Technology Development Center .................................... 277

Technology Development at IEEC ................................................................... 279

The IVS Technology Development Center at the Onsala Space Observatory .......................... 283

vi
IVS Information .................................................................. 287

IVSTermsofReference............................................................................. 289

IVSMemberOrganizations......................................................................... 299

IVSAffiliatedOrganizations........................................................................ 300

IVSAssociateMembers............................................................................. 301

IVSPermanentComponents ........................................................................ 312

Addresses of Institutions Contributing to this Report ................................................ 316

List of Acronyms .................................................................................... 321

vii

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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 (tCRF

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.

REALIZATIONAND STATUSOFIVS

IVSconsistsof

• 30 Network Stations, acquiring high performance

VLBI data,

• 3 Operation Centers, coordinating the activities of a

network of Network Stations,

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

data to analysts,

• 6 Data Centers, distributing products to users,

providing storage and archiving functions,

• 20 Analysis Centers, analyzing the data and producing the results and products,

• 8 Technology Development Centers, developing new

VLBI technology,

• 1 Coordinating Center, coordinating daily and long

term activities.

Altogether

• 74 Permanent Components, representing 31 institutions in t5 countries,

• 250 Associate Members.

inaddltlen the IVShas:

• Directing Board, determining policies, standards

and goals; the board is composed of 14 members

(elected and ex officio), including

• Coordinators for the network, analysis

and technology.

IVS STRUCTURE

U_S

I

J 8s I

!
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.

_:_ _ _- ..... _::

Vienna University of Technology

Centro de R6dio Astronomia e

Aplica?_es Espaciais

Austria

Brazil

Space Geodynamics Laboratory

Geodetic Survey Division,

Natural Resources Canada

Dominion Radio Astrophysical

Observatory

Canadian Space Agency

Chinese Academy of Sciences

Observatoire de Paris

Observatoire de Bordeaux

Canada

Canada

Canada

Canada

China

France

France

Deutsches Geod_tisches

Forschungsinstitut

Bundesamt for Kartographie

und Geod_sie

Geodetic Institute of the University

of Bonn

Germany

Germany

Germany

Istituto di Radioastronomia CNR Italy

Agenzia Spaziale Italiana Italy

Geographical Survey Institute Japan

Communications Research Laboratory Japan

National Astronomical Observatory

of Japan Japan

National Institute of Polar Research Japan

Norwegian Defence Research

Establishment

Norwegian Mapping Authority

Astronomical Institute of

St.-Petersburg University Russia

Institute of Applied Astronomy Russia

Hartebeesthoek Radio As!ronomy

Observator_

Institut d'Estudis Espacials

de Catalunya Spain

Instituto Geografico Nacional Spain

Chalmers University of Technology

National Academy of Sciences, Kiev

Laboratory of Radioastronomy

of Crimean Astrophysical Observatory

NASA Goddard Space Flight Center USA

U. S. Naval Observatory USA

Jet Propulsion Laboratory USA

Norway

Norway

SouthAfrica

Sweden

Ukraine

Ukraine

IVS AFFILIATEDORGANIZATIONS

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.

Australian National University

University of New Brunswick

Australia

Canada

Max-Planck-lnstitut for Radioastronomie Germany

FOMI Satellite Geodetic Observatory Hungary

Joint Institute for VLBI in Europe (JIVE) Netherlands

Westerbork Observatory Netherlands

National Radio Astronomy Observatory USA

PRODUCTS

TheVLBItechnique contributesuniquelyto

• 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)

Furthersignificant productsare

• 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 VLBIdata and resultsin appropriate formats are archived

in data centers and publicly available for research in related

areas of geodesy, geophysics and astrometry.

http://ivscc.gsfc.nasa.gov
IVS COMPONENTSBY COUNTRY

Austria 1

Brazil 1

Canada 3

China 3

France 3

Germany 8

Italy 7

Japan 14

Norway 3

Russia 5

South Africa 1

Spain 2

Sweden 3

Ukraine 2

USA 18

Total 74

A complete list of IVS Permanent

Components is in the IVS Information

section of this volume.

_'_ Network Station

O Operation Center :_

O Correlator

Date Center

Anelyeis Center

Technology Development Center _

$_ Coordinating Center

_*O'Higgine
'Ny Alesund

_Onsala__ Svetl°_lAA

AIStPbU

_GIUB'--_ _BK G

_^-,. ......... _----_--_:ITI'_O ./_AO

'._ r_ ,_ u o)r____G F2_ettzell _

ParlsL.-_/_ _._ _'U Vlennac

Borde_X_,N _ediclna X'Simelz

IE EC_Y'_Nb:to _._ M ate r, [ _

_ Hartebeesthoek

/

_J_ukuba__-_ 2

-- := :_34

_'Koganel

• ! _-'Tateyama

§
NAME:WolfgangSchl6ter

AFFILIATION: Bundesamt fiJr

KartographieundGeodiisie,Germany

POSITION:ChairandNetworks

Representative

TERM:Feb1999to Feb2003

NAME:JamesCampbell

AFFILIATION: Universityof Bonn,

Germany

POSITION:lAGRepresentative

TERM:ex officio

NAME:EdHimwich

AFFILIATION:NVI, Inc./Goddard

SpaceFlightCenter,USA

POSITION:NetworkCoordinator

TERM:permanent

NAME:WayneCannon

IU:FIUIi11ON:SpaceGeodetic

Laboratory, Canada

POSITION:At LargeMember

TERM:Feb1999to Feb2001

NAME:KerryKingham

AFFILIATION: U.S.NavalObservatory,

USA

POSITION:CorrelatorsandOperation

CentersRepresentative

TERM:Sep2000 to Feb2003

NAME:NicoleCapitaine

AFfiLIATION:ParisObservatory,

France

POSITION:IAURepresentative

TERM:exofficio

NAME:TetsuroKondo

AFFILIATION: Communications

ResearchLaboratory, Japan

POSITION:TechnologyDevelopment

CentersRepresentative

TERM:Feb1999to Feb2001
NAME: ChopoMa

AFFILIATION: NASAGoddardSpace

FlightCenter, USA

POSITION: IERSRepresentative

andAnalysisandDataCenters

Representative

TERM: exofficio

NAME: NancyVandenberg

AFFILIATION: NVI,Inc./Goddard

SpaceFlightCenter, USA

POSITION: Coordinating Center

Director

TERM: exofficio

NAME: ShigeruMatsuzaka

AFFILIATION: Geographical Survey

Institute, Japan

POSITION: NetworksRepresentative

TERM: Feb1999toFeb2003

NAME: AlanWhitney

AFFILIATION: Haystack Observatory,

USA

POSITION: Technology Coordinator

TERM: permanent

NAME: AxelNothnagel

AFFILIATION: UniversityofBonn,

Germany

POSITION:AnalysisCoordinator

TERM:permanent

NAME:PaoloTamasi

AFFILIATION: CNRBologna,italy

POSITION:At LargeMember

TERM:Feb1999to Feb2003
WeUgangScblJter

Bundesamt fOrKartegraphieundGeodtsle

iNTRODUCTiON

This is the second issue of the Annual Report of the

International VLBI Service for Geodesy and Astrometry.

It is a very good documentation of our activities. The

Annual Report demonstrates the vitality of the IVS. With

the 1999 Annual Report - released before the end of

1999 - emphasis was placed on documenting the status

of the individual components. The 2000 Annual Report

documents changes, activities and progress of the

Service. I'm personally proud about the progress and

the results and also about the reliability of the IVS

Associate Members, that we can issue the Annual

Report 2000 in such a timely manner. Let me express

my thanks to all who have contributed.

EVENTSDURING 2000

The first IVS General Meeting was held February 21 to

24, 2000, with more than 120 participants, representing

mostly all components of the IVS. The purpose of the IVS

2000 General Meeting was to share information and to

plan future activities. One of the goals was to strengthen

our cooperation and to build bridges be_een the

various components for a better understanding. These

goals were considered by the program committee.

Tutorials were held in order to introduce the session topic

to those who work in different areas. I thank the members

of the program committee: Marshall Eubanks/USNO,

Hayo Hase/BKG, Ed Himwich/NVI, Inc./GSFC,

Yasuhiro Koyama/CRL, Chopo Ma/NASA GSFC, Arthur

Niell/MIT Haystack, Axel Nothnagel/GIUB, Hans Peter

Plag/SK, Rich Strand/GCGO, Nancy Vandenberg/NVI,

Inc./GSFC, and Alan Whitney/MIT Haystack.

The Proceedings of the IVS 2000 General Meeting

were released by the editors Nancy Vandenberg and

Karen Baver in August. The papers are electronically

available as well as in book form. The publication with

the tutorials is a valuable contribution not only to VLBI

experts and participants, but also to people who have

an interest in learning about VLBI.

study the feasibility of equipment, time required, and if it

could be done with accuracy sufficient to make it worthwhile". The members of the WG are Brian Corey/MIT

Haystack and Ed Himwich/NVI, Inc./GSFC for the IVS,

Tom Herring/MIT Boston and Tim Springer/AIUB for the

IGS, and Graham Appleby/UK and Richard Biancale/

CNES for the ILRS.I thank the members for their contribution. The activity and the status of the work can be seen

on the IVS home page http://ivscc.gsfc.nasa.gov. A

status report is given in this Annual Report.

On the last day of the 2000 General Meeting, February

24, the first IVS Analysis Workshop was held. The

Analysis Coordinator Axel Nothnagel, who became the

Analysis Coordinator on October 1, 1999, organized

and chaired the meeting. Standards, analysis models,

and contributions of the various Analysis Centers were

discussed. Five working groups were established in order

to share the workload. Access to all the information is

made available also via http://ivscc.gsfc.nasa.gov and

the home page of the Analysis Coordinator, which is

linked from the IVS home page.

In September 2000 the hardware VLBIStandard Interface (VSI-H) specification was released. The complete

specification is reprinted in this Annual Report. The VSI-H

specification was developed by an international committee of experts in VLBI instrumentation, led by Alan

Whitney/MIT Haystack, the IVS Technology Coordinator,

in a concerted effort to standardize interfaces to/from

VLBI data recording and playback systems. Adherence to

the VSI-H specification will allow data collected on

heterogeneous VLBI data systems to be processed

directly on VLBI correlators. A standardized software

interface, VSI-S, is expected to follow within the next

year. I would like to express my thanks to the committee

especially Alan Whitney/MIT Haystack-USA as the chair,

Wayne Cannon and Richard Worsfold/CRESTechCanada, Ralph Spencer/Jodrell Bank Observatory-UK,

Richard Ferris/CSIRO Telescope National FacilityAustralia, John Romney, George Peck/NRAO-USA, Brent

Carlson/Herzberg Institut of Astrophysics NRCCCanada, Tetsuro Kondo, Junichi Nakajima, Yasuhiro

Koyama, Mamorou Sekido and Hitoshi Kiuchi/CRLJapan and Mickael Popov/Astro Space Center of

Lebedev Physical Institute Moscow-Russia.

During the IVS 2000 General Meeting, a first meeting

was held of the IVS Working Group on "GPS phase

center mapping", which is a joint Working Group with

the International GPS Service (IGS) and International

Laser Ranging Service (ILRS).The objectives were "to

NEW IVS MEMBERS

During 2000 IVS received proposals from two institutions

applying to become IVS components. In January 2000

the Directing Board accepted the proposal from the U.S.
NavalObservatory to contribute with the "USNO

Analysis Center for Source Structure" and in December

2000 the Directing Board accepted the proposal from

the Institut fiJr GeodLisie und Geophysik of the Technical

University Vienna to contribute with an Associate Analysis Center based on OCCAM with special emphasis on

modeling the tropospheric refraction. I thank both

agencies for their willingness to cooperate with the IVS.

Their important contributions are appreciated very much.

The Directing Board changed the Termsof References in

order to extend the IVS membership to affiliated organizations. The affiliated organizations do not necessarily

support an IVScomponent but expressed their willingness

to cooperate with IVS on issues of common interest. The

Directing Board accepted proposals from the following:

Geodynamics Group, ResearchSchool of Earth Science,

Canberra/Aust[.alia; Westerbork Observatory, Dwingeloo/

Netherlands; FOMI Satellite Geodetic Observatory,

Budapest/Hungary; Department of Geodesy and

Geomatics Engineering of the University New Brunswick/

Canada; National Radio Astronomy Observatory (NRAO),

Socorro/USA; Max Planck Institute fLir Radioastronomie,

Bonn/Germany.

The Joint Institute for VLBI in Europe, Dwingeloo/Netherlands changed their membership category to that of an

Affiliated Member. I thank the Affiliated Member

organisations for their interest and for their willingness to

cooperate with IVS.

DIRECTING BOARD

The IVS Directing Board held its 3rd and 4th meetings in

2000. The 3rd Meeting was held in Wettzell on February 20, 2000, the day before the IVS 2000 General

Meeting. The 4th meeting was held in Paris/France on

September 17, 2000. Detailed information about the

meetings was mailed to the Associate Members through

the ivsmail, and it is also available at

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

We have had some personnel changes in 2000.

Marshall Eubanks has withdrawn from the IVS Directing

Board due to personal reasons. His successor as the

representative for the Correlators and Operation Centers

is Kerry Kingham, USNO. On behalf of the IVS I would

like to thank Marshall for all he has done for the IVSand

for the entire VLBI community especially in the field of

data analysis and investigations in Earth orientation. We

wish him success for his new business.

The terms of the representatives of the Analysis Centers

and of the Technology Development Centers were two

years, ending with the board meeting in February 2001.

The election, conducted by the election committee, which

included Shigeru Matsuzaka/Japan as chair, Paolo

Tomasi/ttaly and Nancy Vandenberg/USA, resulted in

the election of Harald Schuh, TU-Vienna/Austria as the

representative for the Analysis Centers and of Arthur

Niell from Haystack Observatory/USA as the representative of the Technology Development Centers. Also one of

the At Large positions ends after two years. The Directing

Board elected Yasuhiro Koyama from CRL/Japan.

Congratulations to all new elected board members. I

take the opportunity to thank Tetsuro Kondo and Wayne

Cannon for their contributions and their fruitful discussions during the first two years term. I'm sure both will

continue to support the IVS.

IVS IS A SERVICEOFTHE IAU

IVS has been recognized as a Service of the International Association of Geodesy (lAG) since July 1999

when the General Assembly was held in Birmingham/

England. Since the XXIVth General Assembly of the

International Astronomical Union IAU held in Manchester/England, August 2000 the IVS is also recognized as

a Service of the IAU. The fact of being an IAU Service

will open up more cooperation with radio astronomy

groups. You can find the IAU resolution reprinted in this

Annual Report.

ACKNOWLEDGEMENTS

The year 2000 has been a busy year for all of us. The

activities summarized above indicate the vitality of our

service. There is still a lot to do within the next years. We

have to establish our products in order to realize what is

expected from us as a service, we have to improve our

observing programs and the analysis steps to provide

and guarantee timeliness and highly reliable products.

The discussion on these issues has started.

I would like to express my gratitude to the IVS Coordinators

Ed Himwich, Axel Nothnagel and Alan Whitney, who have

to carry a heavy workload and responsibility. I thank

Nancy Vandenberg for all the work she has done for the

IVS as Coordinating Center Director suchas organizing

meetings, publishing proceedings, caring for the IVS

homepage and much much more. I'm aware that every

Associate Member supports IVS, so I will express my

appreciation to all of you. Let's continue our good work.

9

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MIT Haystack Observatory

2.o04..60 ;,

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Technology Development Center

IVS/IGS/ILRS Working Group on GPS Phase Center Mapping

Brian Corey

Abstract

A joint working group composed of representatives from the IVS, IGS, and ILRS is investigating

the feasibility of using VLBI observations of GPS satellites to measure the phase center locations of

the satellite transmitter antennas. This report describes the motivation behind the investigation, the

organization of the working group, and some key points from the initial discussions.

1. Motivation for establishing working group

Accurate knowledge of the location of the phase center of each GPS satellite transmitter antenna

is essential in high-accuracy GPS geodesy. Estimates of the scale of the terrestrial reference frame

(TRF) and of station zenith tropospheric delays are particularly sensitive to the phase center zcomponent, along the direction from the satellite toward the geocenter. A change of 1 meter in

the assumed z-component for all satellites causes a change in the terrestrial scale of _8 ppb (50

mm in station height) and a change in zenith delay of _,-5 ram.

Several related pieces of evidence point to significant errors in the phase center locations assumed in most GPS geodetic analyses. The instantaneous location of each satellite is normally

set equal to the vector sum of (1) the instantaneous position of the satellite center of mass, which

is believed to be known to < 10 cm in all three dimensions from GPS orbital solutions and from

SLR rangings on selected satellites, and (2) the nominal offset between the phase center and the

center of mass. When global GPS data sets are analyzed with these phase center locations and

with absolute phase patterns for the GPS receiving antennas, the scale of the GPS TRF is found

to differ from the scale of the VLBI and SLR TRF's by _-,15 ppb, or 10 cm in station height [1, 2].

An adjustment of the z-component of the phase center offsets by 2 m brings the scale of the GPS

TRF into agreement with VLBI and SLR. Furthermore, if the phase center z-component offsets

are estimated from the GPS data, differences from the nominal offsets of 1 2 m are found [1, 2].

The immediate impetus for the formation of the IVS/IGS/ILRS joint working group (WG)

on GPS phase center mapping was a series of discussions at the IGS Analysis Center Workshop

at the Scripps Institution of Oceanography in 1999 regarding the uncertainty in the location of

the phase centers of the GPS satellite transmitters. It was suggested at the workshop that VLBI

observations of the satellites could provide independent information on the phase center locations,

including perhaps the relative locations for the 12 individual radiating elements in the phased array

transmitters. An informal request was made to the IVS to lead an investigation of the feasibility

of such observations.

2. Establishment and organization of working group

At the second IVS Directing Board meeting in July 1999, the board decided to establish a

working group on this matter and to invite the IVS, IGS, and ILRS chairs to nominate representatives to serve on it. The charge to the working group was to study the feasibility of the proposed

VLBI observations, the equipment and time required, and the expected accuracy of the phase

center location estimates.

2000 IVS Annual Report 13
Technology Development Center MIT Haystack Observatory

Following the nomination of members from the three services, the WG was officially established

under the rules of the IVS at the third IVS Directing Board meeting on 20 Feburary 2000. The

members of tile WG are:

Graham Appleby

Richard Biancale

Brian Corey

Tom Herring

Ed Himwich

Axel Nothnagel

Wolfgang Schliiter

Tim Springer

Nancy Vandenberg

ILRS-nominated representative

ILRS-nominated representative

IVS-nominated representative and WG chair

IGS-nominated representative

IVS-nominated representative

IVS analysis coordinator, ex ojficio

IVS chair, ex officio

IGS-nominated representative

IVS coordinating center director, ex officio

The initial meeting of the WG was held on 23 February 2000 in KStzting, Germany, during the

first IVS General Meeting. The purpose of the meeting was primarily organizational, but some

technical issues regarding the phase center estimates from GPS observations and the proposed

VLBI measurements were also discussed.

3. Initial working group activities

A WG web site was set up in March 2000 at

http://ivscc, gsfc. nasa. gov/WG/wgl

Background information on the phase center problem, general information on the WG, and a WG

email archive are available on the web site.

Following official notification of the IGS and ILRS chairs by the IVS chair that the WG had been

established, a general email announcement was distributed to the IGS, ILRS, and IVS communities

to inform them of the existence and purpose of the WG. The announcement included an invitation

for interested individuals with expertise in relevant fields to participate in the WG studies. In

response to this invitation, the following IVS members have joined in the WG discussions: Wayne

Cannon, Hayo Hase, Maria Rioja, David Shaffer, and Vincenza Tornatore.

4. Summary of technical discussions in 2000

There are two related goals to the proposed VLBI observations:

A. Measure the mean phase center location of the full, 12-element phased array on each satellite.

B. Measure the relative signal phase and drive level of the 12 individual radiating elements in

each array.

The results of A could be compared directly against the GPS estimates, while the results of B might

provide clues to help understand the GPS and VLBI mean phase center results. The key questions

to be answered regarding both types of measurements are what the potential accuracy is and what

the technical roadblocks are to observing the satellites with a VLBI network, correlating the VLBI

data, and analyzing the results. The investigations to date have concentrated on assessing the

limitations on accuracy.

14 2000 IVS Annual Report
MIT Haystack Observatory Technology Development Center

4.1. Measuring the mean phase center location

VLBI phase center measurements will likely employ an observing strategy similar to narrowfield VLBI astrometry, in which the VLBI antennas alternately observe a target source (in this

case, a GPS satellite) and one or more extragalactic reference sources of accurately known position

that lie near the line of sight to the target. The small angular separation between target and

reference is intended to minimize errors from propagation media effects and from uncertainties in

various global parameters such as station locations. The nature of the GPS orbits sets two different

types of limits on how small the target-reference separation can be made:

• With an orbital period of 12 hours, a satellite moves 1° every 2 minutes. A reference source

that lies right on the path of a satellite will remain within 5° of the satellite for only 20

minutes, or a few antenna nodding cycles between satellite and reference.

• For a 5000-km baseline transverse to the satellite nadir direction, the parallax on the satellite

between the two ends of the baseline is 14°. If a reference source is coincident in direction

with a satellite at one station, it will be 14 ° from the satellite at the other station.

In order to measure the phase center z-component to 20 cm accuracy (5a over 1 m), say, the

differential range from satellite to ground between nadir and Earth limb (which is 14 ° away from

nadir) must be measured to an accuracy of (20 cm) × (cos0 ° - cos 14°) = 6 mm, or 11 ° phase

at the GPS L1 frequency of 1575 MHz. All error sources that affect the VLBI phase or delay

must be accounted for, to this level of accuracy. These error sources, which are currently under

investigation, include:

• Reference source positions The L-band positions of the reference sources in the global

celestial reference frame must be known to _0.2 mas to achieve the accuracy goal. Global

S/X-band astrometry on compact sources can achieve such small uncertainties, but reaching

this level at L-band may be difficult.

• Ionosphere The typical differential L-band ionospheric delay between two directions 5 °

apart is 1-2 orders of magnitude larger than the error budget, so the ionospheric delay

between satellite and reference sources must be either measured or modeled. Ionospheric

total electron content models derived from global GPS data appear to be too inaccurate [3].

The best approach may be to use the VLBI observations on the satellite and reference sources

to estimate the differential ionospheric delay directly from the fringe phase difference between

the GPS frequencies L1 and L2, in a manner similar to a technique developed for L-band

pulsar astrometry [4].

• Troposphere The tropospheric delay can be estimated from GPS measurements with

colocated geodetic GPS receivers. Systematic errors in the estimates of the differential tropospheric delay across 5° should be _3 mm.

• Instrumentation -- When pointing at a GPS satellite, the antenna temperature for a 20-

m antenna is of order 20,000 K over 20 MHz. Such high levels may cause problems with

saturation and distortion in the electronics, particularly in the VLBI baseband converters.

4.2. Mapping the satellite phased array

The second goal of the VLBI observations, which is equivalent to measuring the aperture field

distribution of the phased array, will ahnost certainly be more difficult to achieve than the first.

2000 IVS Annual Report 15
Technology Development Center MIT Haystack Observatory

The applicable technique is microwave holography, in which the far-field amplitude and phase

pattern of the test antenna (the GPS transmitter, in this case) is measured over a grid of points

spaced wavelength/(aperture size) radians apart; the Fourier transform of the pattern gives the

aperture distribution. For the GPS phased array, the grid spacing is 13°, so Earth-bound observers

can measure the far-field pattern at only a few grid points, and the resolution on the aperture field

map will be very poor only slightly better (i.e., smaller) than the overall size of the array

itself. Super-resolution techniques can sometimes be employed to improve the resolution, but they

typically require very accurate phase and/or amplitude measurements, which the error sources

noted above may well preclude.

References

[1] Rothacher, M., "Comparison of absolute and relative antenna phase center variations," GPS Solutions,

4(4), 2001 (in press).

[2] Springer, T.A., "Common interests of the IGS and the IVS," IVS 2000 General Meeting Proceedings,

pp. 296-305, 2000.

[3] Walker, C., and Chatterjee, S., "Ionospheric corrections using GPS based models," VLBA Scientific

Menlo 23, 1999.

[4] Brisken, W.F., et al., "Measurement of the parallax of PSR B0950+08 using the VLBA," Astrophys. J.,

541, pp. 959-962, 2000.

16 2000 IVS Annual Report
IAU resolution

IVS is a Service of the IAU

IVS was recognized as a Service of the International Association of Geodesy (IAG) effective July 1999 when the General Assembly was held in Birmingham/England. Since the

XXIVth General Assembly of the International Astronomical Union IAU held in Manchester/England, August 2000 the IVS is also recognized as a Service of the IAU. Here is the

IAU resolution:

IAU Resolutions BI.1 Maintenance and Establishment of Reference Frames and Systems

The International Astronomical Union

Noting

1. that Resolution B2 of the XXIIIrd General Assembly (1997) specifies that "the fundamental reference

frame shall be the International Celestial Reference Frame (ICRF) constructed by the IAU Working

Group on Reference Frames",

2. that Resolution B2 of the XXIIIrd General Assembly (1997) specifies "That the Hipparcos Catalogue

shall be the primary realisation of the International Celestial Reference System (ICRS) at optical

wavelengths", and

3. the need for accurate definition of reference systems brought about by unprecedented precision, and

Recognising

1. the importance of continuing operational observations made with Very Long Baseline Interferometry

(VLBI) to maintain the ICRF,

2. the importance of VLBI observations to the operational determination of the parameters needed to

specify the time- variable transformation between the International Celestial and Terrestrial Reference

Frames,

3. the progressive shift between the Hipparcos frame and the ICRF, and

4. the need to maintain the optical realisation as close as is possible to the ICRF

Recommends

1. that IAU Division I maintain the Working Group on Celestial Reference Systems formed from Division

I members to consult with the International Earth Rotation Service (IERS) regarding the maintenance

of the ICRS,

2. that the IAU recognise the International VLBI Service (IVS) for Geodesy and Astrometry as an IAU

Service Organization,

3. that an official representative of the IVS be invited to participate in the IAU Working Group on

Celestial Reference Systems,

4. that the IAU continue to provide an official representative to the IVS Directing Board,

5. that the astrometric and geodetic VLBI observing programs consider the requirements for maintenance

of the ICRF and linking to the Hipparcos optical frame in the selection of sources to be observed (with

emphasis on the Southern Hemisphere), design of observing networks, and the distribution of data,

and

6. that the scientific community continue with high priority ground- and spacebased observations (a) for

the maintenance of the optical Hipparcos frames and frames at other wavelengths and (b) for links of

the frames to the ICRF.

2000 IVS Annual Report 17
._. r: -- /' ,,j

MIT Haystack Observatory

VLBI Standard Interface Specification

Alan Whitney

International agreement and finalization of a VLBI Standard Interface (VSI-H) specification

has now been accomplished. The final specification was released in August 2000 after 18 months

of hard work by the dozen members of the VSI Technology Coordination Group.

This specification promises to help ease the long-standing incompatibility between various

VLBI data systems. The VSI-H specification is designed to allow heterogeneous VLBI digital-data

systems to be interchangeably connected to both data acquisition and data processing (correlator)

systems in a '_plug-compatile" fashion, something that is not currently possible. Furthermore,

looking to the future, the VSI-H specification is designed to be compatible not only with traditional recording/playback systems, such ms magnetic tape, but also with magnetic or optical discs,

optical fibers, network data-transmission, or whatever future data transmission technology may be

available.

The fledgling VSI concept leading to the current specification was first proposed at the time

of the GEMSTONE meeting in Tokyo in January 1999 and was discussed by a small interested

group at that meeting. With the support of IVS, as well as the a.ntronomy-VLBI community, a VSI

Technology Coordination Group was appointed, composed of experts representing all of the major

world institutions involved in the development of VLBI equipment. The members of the VSI-TCG

are Wayne Cannon (York University/Crestech, Canada), Brent Carlson (DRAO, Canada), Dick

Ferris (ATNF, Australia), Dave Graham (MPI, Germany), Tetsuro Kondo (CRL, Japan), Nori

Kawaguchi (NAO, Japan), Misha Popov (ASC, Russia), Sergei Pogrebenko (JIVE, Netherlands),

Jon Romney (NRAO, U.S.), I_lph Spencer (Jodrell, England), Alan Whitney (Haystack, U.S.,

Chairman) and Rick Wietfeldt (JPL, U.S.). The VSI- H specification was shaped by intensive

e-mail discussions, plus three (multi-hour!) international telephone conferences and a two-day

international VSI meeting held at Haystack Observatory in February 2000.

The current VSI-H specification is intended as a starting point from which to progress,

and will be extended and ameuded as needed. It is heartening that already at least three

groups are known to be developing or adapting VLBI data systems to meet the VSI-H standard. The full VSI-H specification is reprinted in this article, and is available on-line at

http://dopey.haystack.edu/vsi/index.html.

The next job of the VSI TCG is the definition of a companion VSI software standard, to be

called VSI-S, which we hope to have in place by the end of 2001.

18 2000 IVS Annual Report
VLBI Standard Hardware Interface Specification - VSI-H

Revision 1.0

7 August 2000

Table of Contents

O. Prologue

1. Introduction

2. Intent of the VSI-H Specification

3. Structure of the VSI-H Specification

4. Levels of Compliance

5. Assumptions on which VSI-H Specification is Based

6. Data Transmission System (DTS) Structure

7. Data Input Module (DIM)

7.1 DIM Interface

7.2 The Data-Observe-Time (DOT) Clock

7.3 Example of DIM Operation

8. Data Output Module (DOM)

8.1 DOM Interface

The Requested Observe Time (ROT) Clock

Speed-up/Slow-down Data Reproduction

8.2

8.3

8,4 Delay Offset

8.5 Example of DOM Operation

9. Signal Selection and Switching

9.1 DIM

9.2 DOM

10. Signal Descriptions

10,1 DIM Input Signals

10,2 DIM Output Signals

10.3 DOM Input Signals

10.4 DOM Output Signals

11. Signal Timing Relationships

11.1 General

11.2 Timing Ticks

12. Interconnect Hardware Specifications

12.1 LVDS Interfaces

12.2 TTL Interfaces

12.3 Control Interfaces

13, Test Vectors

13.1 General Characteristics

13.2 Test Vector Generator

13.3 Test Vector Timing Relationships

13.4 Test Vector Receiver

14. Other Notes and Comments

14.1 Data-Replacement Formats

14.2 Media Translation (Tape Copying)

14.3 Usage of PDATA/QDATA

14.4 Usage of PVALID/QVALID

14.5 Multiple Parallel DTS's

14.6 Multi-Port DTS

14.7 Validity per Bit Stream

14.8 Higher Clock Rates

15. Glossary

15.1 General

15.2 Signals

16. References

Appendix A: Revision History

19
Tables

Table l:

Table 2:

Table 3:

Table 4:

Table 5:

Table 6:

Table 7:

Table 8:

Table 9:

Table 10:

Table I I:

Table 12:

Table 13:

Figures

Figure 1:

Figure 2:

Figure 3:

Figure 4:

Figure 5:

Figure 6:

Figure 7:

DIM Input Signals

Required combinations of clock frequencies and internal bit-stream data rates

DIM Output Signals

DOM Input Signals

Required frequency combinations of DPSCLOCK and RCLOCK

DOM Output Signals

Timing-Tick Min/Max Durations

MDR-80 Pin Allocations (Data Interface)

MDR-14 Pin Allocations (Timing Interface)

Suggested Re,,erse-Channel Signal Assignments

LVDS Timing Specification and Values (ns) at Rated Frequencies

DB-9 Pin Allocations (EIA/TIA-574)

TVG data outputs for first 20 data bits following 1PPS/RIPPS

VSI-H Functional Block Diagram

LVDS Timing Relationships

LVDS Transmitter Output Eye Pattern

LVDS Receiver Input Eye Pattern

LVDS Waveform Transition Definitions

Test-Vector Generator Schematic

TVG Timing Relationships

20
O. Prologue

The incompatibility of various VLBI data systems has long been recognized as posing a

serious obstacle to the realization of the full potential of VLBI observations. Sporadic

efforts have developed over the years to define a common interface standard which would

allow observations recorded on different VLBI data systems to be processed at a common

correlator, but these efforts have foundered for various reasons.

The establishment of the Global VLBI Working Group (GVWG) in the early 1990's,

growing primarily from the space-VLBI community but serving the broader interests of

astronomy, and the International VLBI Service (IVS) in 1998, serving primarily the

geodetic VLBI community, provided an organizational framework for which efforts at

standardization could proceed in a more organized and sanctioned fashion. It was from

these roots that the present effort was initiated.

The fledgling VSI concept leading to the current specification was first proposed at the

time of the GEMSTONE meeting in Tokyo in January 1999 and was discussed by a small

interested group at that meeting. Support was then sought and received from 1VS and

GVWG to create a VSI Technology Coordination Group (VSI-TCG) comprised of

experts representing all of the major world institutions involved in the development of

VLBI equipment. The members of this committee are Wayne Cannon (York

University/Crestech, Canada), Brent Carlson (DRAO, Canada), Dick Ferris (ATNF,

Australia), Dave Graham (MPI, Germany), Tetsuro Kondo (CRL, Japan), Nori

Kawaguchi (NAO, Japan), Misha Popov (ASC, Russia), Sergei Pogrebenko (JIVE,

Netherlands), Jon Romney (NRAO, U.S.), Ralph Spencer (Jodrell, England), Alan

Whitney (Haystack, U.S., Chairman) and Rick Wietfeldt (JPL, U.S.).

Early in the discussions it was decided to separate the hardware and software VSI,

concentrating first on hardware, hence this VSI-H specification, to be followed by a

companion software specification, VSI-S. The VSI-H specification was shaped by

intensive e-mail discussions, plus three (multi-hour!) international telephone conferences

and a two-day international VSI meeting held at Haystack Observatory in February 2000.

The current VSI-H specification is intended as a starting point from which to progress,

and will be extended and amended as requirements and technology demand. It is

heartening that already at this writing at least three groups are known to be developing or

adapting VLBI data systems to meet the VSI-H standard.

The VSI-H specification represents the work of many individuals at many institutions,

even well beyond those named in the formal VSI-TCG. The chairman would like to

particularly acknowledge the important contributions of Dick Ferris, Jon Romney, Rick

Wietfeldt, the entire Japanese group, and the Crestech group in this effort.

Alan Whitney

MIT Haystack Observatory

25 July 2000

21
1. Introduction

This document defines a VLBI Hardware Standard Interface (VSI-H) to and from a VLBI

'Data Transmission System' (DTS) that allows heterogeneous DTS's to be interfaced to

both data-acquisition system (DAS) and data-processing system (DPS) with a minimum

of effort. The interface is defined to be compatible with traditional recording/playback

systems, network data transmission and even direct-connect systems. It is designed to

completely hide the detailed characteristics of the DTS and allow the data to be

transferred from DAS to DPS in a transparent manner.

The VSI-H specification defines the notion of a 'channel quantum', which is the

maximum data rate that can be carried on a single standard VSI-H data connector. The

basic VSI-H specification specifies a 'channel quantum' of 1.024 Gbps on a single 80-pin

connector, with extensions to 2.048 and 4.096 Gbps. Higher data rates may be realized

simply by parallel use of two or more 'channel quanta'.

A VLBI Standard Software Standard Interface (VSI-S) to accompany VSI-H is proposed

but does not yet exist.

2. Intent of the VSI-H Specification

The intent of the VSI-H specification is to define a standard electrical and timing

interface, along with a control philosophy. In this sense, VSI-H is not intended to be

completely 'plug and play', and will require at least some software customization in each

case; the future adoption ofa VSI-S specification will hopefully minimize the software

customization as well. Nevertheless, the adoption of a standardized interface at the

hardware level should help to relieve many of the existing incompatibilities that now

exist between various VLBI data systems.

The VSI-H specification is primarily aimed at normal data-taking and data-correlation

tasks commonplace to VLBI. However, note will also be made of other related activities

such as translation of tape media (i.e. tape copying) and parallel operation of multiple

DTS's.

3. Structure of the VSI-H Specification

The VSI-H specification is structured as a base specification plus a set of optional

extensions. Adherence to the optional extensions is desirable but not mandatory.

4. Levels of Compliance

Full compliance with the VSI-H specification is expected for all future systems designed

by parties agreeing to the VSI-H specification. Existing systems are expected to be

modified to comply on a best-effort basis only. For the purpose of indicating the degree

of compliance to the VSI-H standard, two levels of compliance are established:

Level A - Fully compliant with the base VSI-H specification

Level B - Compliant with the VSI-H base specification except for one or more of the

following:

1. Support for fewer than 32 bit streams (Section 7)

2. Incomplete signal-switching or active-signal-selection capability (Section 9)

3. Incomplete support of full range of fCLOCK(Section 10)

4. Incomplete delay-offset support (Section 8.4)

22
5. Lackof supportfor PDATA/QDATA and/orPVALID/QVALID signals

(Sections10and 11)

6. Incompletetest-vectorcapability(Section13)

7. Data-replacementformat(Section14)

Non-supportof theoptionalextensionsto 64and 128MHz doesnot affectVSI-H

compliance.

5. Assumptions on which VSI-H Specification is Based

The VSI-H specification is based on the following set of assumptions:

• The DTS is fundamentally a receiver and transmitter of parallel bit streams between a

Data-Acquisition System and a Data Processing System.

• The meaning of individual bit streams is not specified; normally, a bit-stream is a

stream of sign or magnitude bits associated with particular samples, but the actual

meaning is to be mutually agreed upon between the DAS and DPS.

• The received and transmitted bit-stream clock rates may be different (e.g. the

playback rate into the DPS may be speeded-up or slowed-down), however all received

bit-stream information rates on acquisition are the same, and all bit-stream clock rates

on transmit are the same.

• A single time-tag applies to all parallel bit streams. The DAS time-tag of every bit in

every bit-stream must be fully recoverable at the output of the DTS.

Note that, under these assumptions, no restrictions or specifications are placed on the type

or format of the medium used to transport the data through the DTS; magnetic tape, disk,

optical fiber, Internet or any other type of transmission medium is allowed.

6. Data Transmission System (DTS) Structure

For the purposes of the VSI-H specification, the DTS is divided into two logical modules,

as indicated in Figure 1:

1. The 'Data Input Module' (DIM) is responsible for accepting multiple parallel bit

streams, accompanied by a common clock and common 1-second tick, applying a

common time-tag ('observe time'), and sending them to a transmission medium (tape,

disc, fiber-optic, etc.).

2. The 'Data Output Module' (DOM) accepts data from the transmission medium,

decodes the accompanying 'observe-time' information, and recreates the data-streams

in accordance with an external clock and 'l-second' tick.

The entire DTS (DIM plus DOM) may reside either in a single physical module or in

separate physical DIM and DOM modules.

7. Data Input Module (DIM)

A simplified model of one 'channel quantum' of the Data Input Module is shown in

Figure 1.

7.1 DIM Intepface

7.1.1 Input signals from the DAS to the DIM1. BS0 through BS31 - 32 parallel bit-streams, all sampled by the DIM at the

same rate, which may be selected to be 2, 4, 8, 16 or 32 MHz,

23
corresponding to the 'bit-stream information rate' (fBs0. The maximum

aggregate DIM input data rate is 1.024 Gbps for one 'channel quantum'.

Any 1, 2, 4, 8, 16 or all 32 input channels may be selected and marked as

'active'. Only 'active' bit-streams are sampled and made available at the

DOM output.

Optional extension of fCLOCKto 64 and 128 MHz provides maximum

aggregate rates of 2.048 and 4.096 Gbps, respectively.

2. CLOCK - a clock accompanying the bit-streams, also providing a

reference frequency for the DIM, at 2, 4, 8, 16 or 32 MHz with optional

extension to 64 or 128MHz. Note fCLOCK_>fBSl.

3. 1PPS - a lpps tick which defines the corresponding parallel data bits

which are to be time-tagged on the integer second. The 1PPS signal is

timed to coincide with the data bit taken on the second _tick (the 'TOST'

bit).

4. PVALID - signal that specifies the 'validity' of the BSn bit streams. The

content and use of the PVALID signal is not defined by the VSI-H

specification.

5. A standard 8-bit ASCII asynchronous serial data stream, PDATA, which

may send a burst of up to 2048 bytes of information between each 1PPS

tick. The content and use of this information is not specified by the VSI-H

specification.

7.1.i DIM Control Interface

The DIM control interface is a 2-way communications interface,

implemented in both RS-232 and Ethernet, and normally connected to a

computer. The control interface both controls and monitors the operation

of the DIM. The DIM controller must be aware of 1PPS ticks to the extent

that certain critical messages can be reliably sent to the DIM between

specific 1PPS pulses, and that certain messages can be reliably

transmitted from the DIM between specific adjacent 1PPS pulses.

If the DIM and DOM reside in the same physical unit, they may share a

single set of control interfaces.

7.1.3 Other Signals

1. ALT 1PPS - an external (possibly asynchronous) signal which may be

selected as a substitute for 1PPS, as indicated in Figure 1. An example of

ALT1PPS might be the lpps tick from a station atomic clock.

2. DOTMON - a monitor signal from the DIM which allows confirmation of

the epoch of the DOT-clock second tick (see Section 7.2).

7.2 The Data-Observe-Time (DOT) Clock

As shown in Figure 1, the DIM maintains an internal Data-Observe-Time (DOT) clock

which has the following properties:

1. The DOT clock is the master clock within the DIM, and is used to unambiguously

mark each incoming data bit with its current reading to the full resolution of CLOCK.

2. The DOT clock may be set to a specified second of time (presumably UTC) on a

given 1PPS or ALT 1PPS tick.

24
3. Onceset,theDOT clock keepstimesolelyby countingCLOCKcycles(i.e.

subsequent1PPS/ALT1PPSticks areignoredby theDOT clockunlesstheDOT clock

is expresslycommandedto bereset).

7.3Example of DIM Operation

The following is an example of a typical sequence of operations of a DIM in a normal

observing situation:

1. Through the Control Interface, the DIM is configured to accept any particular subset

of 1, 2, 4, 8, 16 or 32 of the incoming bit-streams, all at a specified bit-rate. Only

these specified bit streams will be sampled by the DIM and relayed to the DOM.

2. Through the Control Interface, the DOT clock is commanded to be set to a specified

integer second of time on the next 1PPS (or ALT 1PPS) tick [see Note 6 below]. Once

set, the DOT clock keeps time by counting cycles of CLOCK, ignoring subsequent

1PPS/ALT 1PPS signals. The DOTMON monitor signal allows confirmation of the

DOT epoch setting.

3. Through the Control Interface, the DIM is commanded to begin transmitting the

selected input bit streams to the transmission medium. Each bit in each data stream

must be transmitted with its accompanying time tag, either explicitly or implicitly.

4. At the end of the observing period, the DIM is commanded (through the Control

Interface) to cease transmitting data.

Notes:

1. The method the DIM uses to record/transmit data or to time-tag data is irrelevant to

the VSI-H specification.

2. Each type of DIM may have various control and configuration requirements which are

outside the VSI-H specification.

3. It is the responsibility of the DAS to implement any multiplexing or de-multiplexing

that may be necessary to transform sampled data into bit streams presented to the

DIM. It is explicitly noted, however, that the DTS designer is free to implement any

DTS-internal multiplexing scheme so long as the DOM output bit-streams are faithful

reproductions of the DIM input bit-streams.

4. Some DIM systems may have the ability to transmit additional low-data-rate

information, such as bit-stream identification and high-level global validity (i.e.

'antenna on-source'), in addition to the bit-streams themselves. Such information

may be transmitted to the DIM via the Control Interface or, in some cases, via the

PDATA and/or PVALID data streams. The VSI-H specification neither requires nor

prohibits any such capability.

5. With the exception of ALT1PPS, DOTMON and the Control Interface, all DIM

interface signals are contained in a single 80-pin connector (see Section 12).

6. The Control Interface must be designed so that the controlling computer can, on

request, be notified in a timely way of the occurrence of a 1PPS/ALT1PPS tick so that

the control computer can unambiguously command the DIM to set the DOT clock to a

specified integer second of time on the next 1PPS/ALT 1PPS tick. The subsequent

relationship between 1PPS/ALT 1PPS and DOTMON can then be monitored either

internally within the DIM [preferred] or externally to verify the 1PPS/ALT1PPS vs

DOTMON relationship. In addition, the control computer should be able to verify the

25
DOTepochby requestingthattheDIM reporttheDOTsettingat theoccurrenceof

thenext DOTMON tick.

8. Data Output Module (DOM)

A simplified model of the Data Output Module is shown in Figure 1.

8.1 DOM Interface

$.1.1 Input timing signals from the DPS -

1. A clock, DPSCLOCK, from the DPS which acts as a reference frequency for the

DOM.

2. A 'l-pps tick', DPS1PPS, which is used to set an internal DOM clock called the

'Requested Observe Time' (ROT) clock to an integer-second epoch in a manner

similar to the way 1PPS sets the DOT clock in the DIM.

8.1.2 Output signals from the DOM to the DPS -

1. Reconstructed bit-streams, RBS0 through RBS31 - accurate reproductions

of the active sampled bit-streams transferred from the DIM except in so far

as (i) they may be collectively speeded up or slowed down with respect to

fBsl at the input to the DIM, and (ii) switching within the DOM allows an

arbitrary mapping of bit-streams to output signals RBS0..RBS31. The

reconstructed bit streams are at a common rate called the 'reconstructed

bit-stream information rate' (fRBSl).

2. RCLOCK - clock accompanying the reconstructed bit streams.

3. R1PPS - reconstructed 1PPS accompanying the bit streams, subject to the same

speed-up or slow-down as RBSn, but may be delayed by a specified amount with

respected to ROT1PPS. The R1PPS tick always marks the data bit(s)

corresponding to the 'TOST bit' at the DIM input.

4. ROT1PPS - lpps tick from ROT clock, subject to the same speed-up or slow-down

as the reconstructed bit streams.

5. QVALID - a l-bit global signal indicating that the reconstructed data are judged by

the DOM to be correct (i.e. tape is reproducing properly). May optionally be

extended to include more sophisticated validity indications, such as pulsar gating, or

as a pass-through of PVALID from the input to the DIM.

6. QDATA - A standard 8-bit ASCII serial data stream which may send a burst of up

to 2048 bytes of information framed between each R1PPS or ROTI PPS tick (user

can select to frame QDATA between either; see Section 14.2). The content and use

of this information is not specified by the VSI-H specification.

7. Control Interface --The DOM control interface is a 2-way communications

interface, encompassing both RS-232 and Ethernet, which both controls and

monitors the operation of the DOM. The DOM controller must be aware of

DPS 1PPS to the extent that certain messages can be reliably sent to/from the DOM

between specific adjacent DPS1PPS pulses. May be shared with DIM control

interface.

26
8.1.3Other Signals

ROTMON - a monitor signal from the DOM which allows confirmation of

the epoch of the ROT-clock second tick (see Section 8.2).

8.2 The Requested Observe Time (ROT) Clock

The DOM maintains an internal Requested-Observe-Time (ROT) clock which maintains

the reference time to which the re-constructed data are to be synchronized. The ROT

clock has the following properties:

1. The ROT clock is set to a specified second of time on a given DPS1PPS tick.

2. Once set, the ROT clock keeps time solely by counting DPSCLOCK cycles (i.e.

subsequent DPS1PPS ticks are ignored unless the ROT is expressly commanded to

be reset). The monitor signal ROTMON allows confirmation of the ROT epoch

setting.

8.3 Speed-up/Slow-down Data Reproduction

Some systems may also allow the DOM output bit rate (fRBS0 to be speeded-up or

slowed-down by compared to the DIM input rate (fBs0. In such cases, the ROT-clockincrement per DPSCLOCK-cycle must be commanded to change correspondingly. The

rates of RCLOCK, ROT 1PPS, R1PPS and RBS, will all change correspondingly.

The VSI-H specification does not mandate any speed-up or slow-down capability, nor

does it constrain the implementation of such capability.

8.4 Delay Offset

In a storage-based DPS system, where the data are actually captured to a transportable

storage medium and then replayed at a later time, a delay-offset capability in the DOM

allows control of data alignment into the DPS. In these storage-based systems, VSI-H

specifies that the DOM include the capability to offset the delay of the reconstructed bitstreams with respect to the ROT clock, as indicated in Figure 1. The delay is specified as

a bit offset. This allows adjustment of the data delay into the DPS for processing. When

the delay offset is set to a non-zero value, the RBSn bit streams, RI PPS and QVALID I

signals are delayed with respect to the ROT 1PPS tick by the amount specified. When the

delay offset is zero, ROT1PPS and R1PPS are coincident. QVALID indicates that valid

data with the proper delay is being output from the DOM.

The range of the available delay offset in a storage-based DPS system shall be sufficient

to cover at least + 0.5*ROT 1PPS. This allows an arbitrarily large offset (with respect to

some DPS master clock) to be specified with a combination of ROT setting and bit

offset, z

The design of the DOM should be such that the ROT clock and the delay offset can be set

independently without disturbing the other.

In a direct-transmission DPS system, where the data are transmitted directly from DIM to

DOM and not stored in a transportable medium, the required delay offsets are primarily a

That is to say that QVALID remains synchronized to the RBSn bit streams to which it pertains.

2 It has been pointed out that implementing a specified delay in the DIM between IPPS and the DOTgenerated lpps may also provide some useful features, such as test-vector verification in some cases, or in

compensating for a known epoch error in I PPS or ALT1PPS. The implementation of such a delay

capability in the DIM is optional and not part of the VSI-H specification.

27
function of the geographic extent of the VLBI data-collection network. In this case, the

DPS is assumed to implement the necessary data-delay requirements and VSI-H mandates

no delay capability.

8.5 Example of DOM Operation

The following is an example of a typical sequence of operations of a DOM in a common

data-playback situation:

1. Through the Control Interface, the DOM is configured to reproduce any desired

subset of the 'active' bit streams sent to it by the DIM.

2. Through the Control interface, the ROT clock is commanded to be set to a specified

UTC integer second of time on the next DPS 1PPS tick; a delay offset may also be

specified (see Section 8.4). Once set, the ROT clock keeps time by counting cycles of

DPSCLOCK, ignoring subsequent DPS 1PPS signals.

3. Through the Control Interface, the DOM is commanded to begin transmitting the

selected input bit streams synchronized to the ROT clock or specified bit offset from

the ROTclock. For tape-playback systems, this means the DOM must use a

combination of mechanical tape positioning and electronic buffering to synchronize

the recorded data to the ROT clock. When the output data are properly synchronized

(with a delay offset, if any) and valid, the QVALID signal is asserted logical 'true'.

4. At the end of the data-period of interest, the DOM is commanded (through the

Control Interface) to cease transmitting data.

Notes:

1. Note that the reconstructed data streams from the DOM are, except possibly for the

data-stream clock rate and for playback errors or intentionally replaced data (see

Section 14.1), identical to the data sampled by the DIM.

2. It is the responsibility of the DPS to do any manipulations necessary to transform the

reconstructed bit streams into usable data (such as multiplexing or demultiplexing).

3. Some DOM's may have the ability to reproduce additional low-data-rate information

transmitted from the DIM, such as bit-stream identification, etc. in addition to the bitstreams themselves. Such information may be accessed in the DOM via the Control

Interface or, in some cases, transmitted via the QDATA serial-data stream. When

performing a tape-copying operation, for example, QDATA may be used in

conjunction with its DIM counterpart, PDATA, to transfer time-tag data to execute

simple tape copying operations. The VSI-H specification does not mandate content or

usage of QDATA.

4. Since the DPS is presumed to have some internal buffering, ROT1PPS and RCLOCK

need not be precisely aligned with DPS1PPS and DPSCLOCK.

5. With the exception of DPS 1PPS, DPSCLOCK, ROTMON and the Control Interface,

all DOM interface signals are contained in a single 80-pin connector (see Section

12.1).

6. The procedure for setting and monitoring of the ROT clock is similar to that for the

DOT clock in the DIM.

28
9. Signal Selection and Switching

9.1 DIM

As implied in the discussions above, the DIM must include the capability to select as

'active' any subset of 1, 2, 4, 8 or 16 of the 32 potential BS, input data streams. Only the

selected set of bit-streams is required to be transmitted to the DOM. This enables the

DTS to more efficiently use the transmission medium in cases of reduced aggregate data

rates. 3

9.2 DOM

The DOM is required to reconstruct only the 'active' set of bit-streams transmitted to it

by the DIM. However, the DOM must include the capability to connect any of the

reconstructed bit-streams to any DOM RBSn output bit-stream. Figure 1 shows a 32x32

crossbar switch as a functional illustration of this capability, but the designer is free to

implement this specification in any satisfactory manner, including a separate external

module (presumably containing its own control interface).

10. Signal Descriptions

10.1 DIM Input Signals

Signal Frequency/Period

CLOCK

IPPS

ALT 1PPS

BSo

n=0 to 31

fCLOCK= 2, 4, 8, 16, 32 MHz

with optional extensions to 64 and

128 MHz (see Table 2); dynamic

variability up to +100 ppm

1 per fCLOCKcycles of CLOCK

(e.g. 1 per 32x106 CLOCK cycles

for 32 MHz CLOCK

Alternate 1PPS signal

Sampled by DIM at 'bit-stream

information rate' (fBs0;

fBSl _ fCLOCK

Voltage

LVDS(see

Section

12.1)

LVDS

LVDS

LVDS

Comments

fCLOCK sets maximum BS. sample rate; variability

to allow for high-velocity spacecraft applications

Rising edge should be synchronous with rising

edge of data bit to be tagged as 'taken on the

second tick' (the 'TOST' bit); see Figure 2

May be asynchronous with CLOCK

For all clock rates, TOST bit (see Section 11.1)

must be coincident with 1PPS; one data bit

accepted every 2kCLOCK cycles thereafter

PDATA 115 kbaud 8-bit serial data; LVDS Up to 2048 bytes to be received between each

one stop bit, no parity I PPS tick

Table 1: DIM Input Signals

fCLOCK

If.CLOCKI

(Mnz)

fnsl

IfRBSd

(Mbps)

4 16

2 Y

4 Y Y

8 Y Y Y

16 Y Y Y Y

32 Y Y Y Y Y

(opt) Z Z Z Z Z

128 (opt) Z Z Z Z Z

32 64 128

z

z z

Table 2: Required combinations of clock frequencies and internal bit-stream data rates

Table 2 notes:

1. 'opt' indicates optional

2. 'Y' indicates required. 'Z' indicates required if that optional clock frequency (or a higher

one) is implemented.

3 A signal-switching capability at the DIM input may be useful to order the bit-streams so that the default

DOM output bit-stream ordering is more directly compatible with a target DPS, but this capability is not

required. See also footnote in Section 13.4

29
Notes:

1.

3. Clock frequencies of 64 and 128 MHz are optional extensions to the VSI-H standard.

Use of ALT 1PPS is intended for systems where the station 1PPS is provided by an

independent external source such as a hydrogen maser. In such a case, the ALT 1PPS

cannot be guaranteed to be synchronous with CLOCK, which may result in a +1

CLOCK cycle ambiguity in the setting of the DOT clock. This will normally be of

little consequence so long as the DOT clock is not subsequently reset, which could

cause a timing discontinuity.

2. Strictly speaking, the ALT 1PPS signal need only be a single pulse to set the DOT

clock, but is typically a repetitive signal at a 1-pps rate. Following the setting of the

DOT clock, the DOTMON monitor signal generated by the DOT clock is a useful

indicator of proper DOT-clock synchronization.

3. Each input bit-stream, BSn, is sampled by the DIM only once every 2 k, k=0,1,2 ....

periods of CLOCK, where k is determined by the relevant cell value in Table 2. This

sample rate is known as the 'bit-stream information rate' (fBsI). This allows, for

example, the DAS samplers to always run at fCLOCK, even though fBSl is lower than the

DAS sample rate.

4. The inclusion of PDATA is primarily for future use, particularly for tape copying,

where the output of a DOM can be connected directly to the input of a DIM. In such

a case, the QDATA output from the DOM can dynamically transmit data time to the

DIM to automatically update the DOT clock. Other uses of PDATA are also possible

(see Section 14.2).

5. Any discontinuity or frequency change of CLOCK, other than the allowed dynamic

variability of+100 ppm, will normally require the DIM, including the DOT clock, to

be reset.

10.2 DIM Output Signals

Signal

DOTMON

Frequency/Period Voltage Comments

Same as 1PPS TTL For monitor purposes only

Table 3: DIM Output Signals

Notes:

1. The DOTMON signal provides a useful monitor that indicates the DOT is properly

synchronized to 1PPS/ALT 1PPS.

2. The inclusion in the DIM of other useful monitor signals is encouraged.

10.3 DOM Input Signals

Signal Frequency/Period Voltage Comments

DPSCLOCK Allowed frequency is dependent on LVDS Sets max fRas_;

fRCLOCK,as given in Table 5; dynamic variability to allow for high-velocity

variability up to +100 ppm spacecraft applications

DPS 1PPS 1 per fDPSCLOCKcycles of DPSCLOCK LVDS Sets epoch of ROT clock second

(e.g. 1 per 32x106 DPSCLOCK tick

cycles for fDPSCLOCK=32MHz

Table 4: DOM Input Signals

Notes:

30
1. The DPS 1PPS signal is used only once to set the ROT clock epoch upon command,

presumably at the beginning of a scan or tape.

2. Any discontinuity or frequency change in of DPSCLOCK, other than the allowed

variability of_100 ppm, will normally require the DOM, including the ROT clock, to

be reset.

fDPSCLOCK

(MHz)

16

32

64 (opt)

128 (opt)

Y

Y

Y

Y

Y

Y

Y

Y

Y

fRCLOCK

(MHz)

16

Y

Y Y Y Y Y

Z Z Z Z Z

Z Z Z Z Z

32 64 128

Z

Z Z

Table 5: Required frequency combinations of DPSCLOCK and RCLOCK

Table 5 notes:

1. 'opt' indicates optional.

2.

.

'Y' indicates required. 'Z' indicates required if that optional clock frequency (or a higher one)

is implemented.

CLOCK frequencies of 64 and 128 MHz are extensions to the VSI-H standard.

10.4 DOM Output Signals

Signal Frequency/Period Voltage Comments

RCLOCK fRCLOCKis dependent on fDPSCLOCK, LVDS Sets max output reconstructed bitaccording to Table 5 stream information rate (fRRsl)

R 1PPS 1 pulse per second of ROT clock LVDS Ratio of RI PPS to DPS 1PPS pulse

time frequencies depends on DOM

speed-up factor (see Notes)

ROT1PPS Same as RIPPS LVDS Coincident with R1PPS if delay=0

or delay option not implemented

RBSn fRBSI=fR¢,LOC_K/2 k, k:0,1,2 .... in LVDS May be arbitrarily re-mapped

n=0 to 31 accordance with Table 2

QVALID LVDS

QDATA

ROTMON

Global logical indication that data

is sync'ed and valid; no period

l 15 kbaud 8-bit serial data;

one stop bit, no parity

Same as ROTI PPS

LVDS

TTL

Up to 2048 bytes transmitted

bem:een successive R IPPS or

ROT 1PPS ticks (selectable)

For monitor purpose only

Table 6: DOM Output Signals

Notes:

1. Speed-up/slowdown on DOM playback is optional and may not be possible with all

systems.

2. If the DOM can operate with a speed-up/slowdown, the ROT increment per DPSCLK

must be specified to the DOM.

31
11. Signal Timing Relationships

11.1 General

Figure 2 shows the timing relationships between 1PPS, CLOCK and BSn; timing

relationships between R1PPS, RCLOCK and RBSn are similar. The sample points for

three different bit-stream information rates (fBsi'S) are shown to illustrate that the epoch

of the first sample taken after the rising edge of the 1PPS tick (the so-called 'TOST'

sample) must maintain a constant timing relationship with respect to 1PPS regardless of

the fCLOCKor fBsl. This guarantees that the epoch of the sampled data stream will not

change with fCLOCKor fBsl. After the TOST sample, subsequent samples are taken every

2 k CLOCK cycles, depending on the ratio of fCLOCKto fBSl.

11.2 Timing Ticks

Table 7 specifies the minimum and maximum durations of various periodic ticks:

Signal

1PPS

Type

LVDS

ALT 1PPS LVDS

DPS 1PPS LVDS

R1PPS LVDS

ROT 1PPS LVDS

DOTMON TTL

ROTMON TTL

Min duration

1 cycle of CLOCK

1 cycle of CLOCK

1 cycle of DPSCLOCK

1 cycle of RCLOCK

1 cycle of RCLOCK

Stretched for easy viewin$

Stretched for easy viewing

Max duration

500 ns (inverse 2 MHz)

No specification

500 ns

500 ns

500 ns

~10 ms

~10 ms

Table 7: Timing-Tick Min/Max Durations

12. Interconnect Hardware Specifications

12.1 L VDS Interfaces

Three physical LVDS interfaces are present in the DTS:

1. DAS-to-DIM 'data interface' on an 80-pin MDR connector with 4-40 jackscrews;

pinout specified in Table 8.

2. DOM-to-DPS 'data interface' on an 80-pin MDR connector with 4-40 jackscrews;

pinout specified in Table 8. This pinout is compatible with the DAS-to-DIM

connector to allow easy DOM-to-DIM connections.

3. 'Timing interface' on a 14-pin MDR connector with spring latch; pinout as

specified in Table 9. If the DIM and DOM are separate physical units, each will

have a 14-pin MDR connector.

The interfaces all conform to the LVDS differential format as defined by the

ANSI/EIA/TIA-644 standard. All connectors are Mini D Ribbon (MDR) with sockets on

both the transmitting and receiving equipment.

DAS-DIM DOM-DPS Pin(+) Pin(-) Comments

BS0 RBS0 1 2

BS1 RBS1 3 4

ll ii it ii

BS14 RBS14 29 30

BS15 RBS15 31 32

BSI6 RBS16 42 41

BSI7 RBS17 44 43

32
It tl tl tt

t! II vB ,I

BS30 RBS30 70 69

BS31 RBS31 72 71

1PPS RIPPS 33 34

Unused ROT 1PPS 35 36 See 12.1,6 Notes

PVALID QVALID 37 38

CLOCK RCLOCK 39 40

PCTRL QCTRL 74 73 Reverse-channel control:

' 1' (default) - forward only

'0' reverse permitted

PDATA QDATA 76 75

PSPARE1 QSPAREI 78 77 SparesignalI

PSPARE2 QSPARE2 80 79 Sparesignal2

Table 8:MDR-80 Pin Allocations (Data Interface)

Signal Pin(+) Pin(-)

ALT 1PPS 1 2

DPSIPPS 3 4

DPSCLOCK 5 6

Undefined (see 12.1.6 Notes) 7.. 14

Table 9: MDR-14 Pin Allocations (Timing Interface)

12.1.1 Reverse Channel Control

Due to requirements of some system designers, the base VSI-H specification requires the

use of only uni-directional signals in each of the two MDR connectors. In order to

accommodate the option that some reverse-channel functions be allowed, three signal

pairs (P/QCTRL, P/QSPARE1, P/QSPARE2) have been defined in the MDR-80 DataInterface connector in Table 8:

P/QCTRL - a control signal asserted received by the DAS (as PCTRL) or transmitted by

the DOM (as QCTRL) which specifies whether the two spare signal lines P/QSPARE 1

and P/QSPARE2 are in the 'forward' or are allowed to communicate in the 'reverse'

direction, as follows:

- P/QCTRL=I (default state): no change, i.e. all signal channels transmit in the

normal direction.

- P/QCTRL=0: Ports optionally fitted with transceivers for channels P/QSPAREI

and P/QSPARE2 will operate in the reverse direction, i.e. DPS to DOM or DIM to

DAS. Thus static two signal 'back channel' or conventional half-duplex operation

becomes possible.

Notes:

1. Equipment not installing the optional transceivers fix P/QCTRL in the default

state and may continue to use P/QSPARE1/2 in the normal direction for any other

"spare" purpose as desired.

2. Any combination of equipment with and without the optional transceivers may be

connected without complication. Any combination with less than both optioned

up, will by default operate in the normal (forward only) mode.

33
.

The tc_ crsc channels may only become active when explicitly commanded by the

DAS or DOM. A disconnected cable automatically forces transceivers to the

receive state.

.

LVDM (Multipoint) standard transceiver chips (e.g. SN65LVDM050/051 ) allow

terminations at both ends of the line by driving double the normal current into it.

Net waveform and timing specifications are indistinguishable from normal singleterminated LVDS.

5. No specific purpose is defined for the reverse channels, but see suggested usage

below.

12.1.2 Suggested Reverse-Channel Usage

If the optional reverse channel capability described above is implemented, the

PSPARE 1/2 lines can carry the clocking signals normally assigned to the Timing Cable,

integrating all 'reverse-channel' timing signals into the Data Cable and eliminating the

need tbr the Timing Cable (though the MDR-14 connector must be present as well).

Table 10 shows suggested signal assignments when P/QCTRL="0":

Signal

PSPARE 1

PSPARE2

New Assignment

TVGCTRL

DOT 1PPS

Direction

From DIM

From DIM

Comments

See Notes

See Notes

QSI}AP, ti 1 DPSCLOCKX To DOM Substitute for DPSCLOCK

QSI'Af_E2 DPSII'PSX To DOM Substitute for DPSIPPS

Table 10: Suggested Reverse-Channel Signal Assignments

Notes:

1. The use of QSPARE 1/2 here are simply direct replacements for the signals

DPSCLOCK and DPS [ PPS.

2. The purpose of DOT t PPS is to allow a DAS otherwise without a 1-pps signal to

receive DOT1PPS from the DIM via the Data Cable. This then enables the use of

a TVG in the DAS (pseudo-random noise functions only) without requiring either

a l-pps input or a control port on the DAS. It also enables the periodic PDATA

thnction which requires a 1-pps synchronizing signal.

12.1.3 Wavelbrm Specifications

Figures 3 through 5, along with Table 1 1, specify the timing characteristics of the LVDS

wavefornls.

Parameter

1

tl

t2

Spec.

I% t{)¢K

0.3T

0.35T

32MHz

31.3

9.4

64MHz

15.6

4.7

10.9 5.5

! 28MHz

7,8

2.3

2.7

t3 T-t I 21.9 10.9 5.5

t4 0.15T 4.7 2.3 1.2

i5 0.2T 6.3 3.1 1.6

t6 T-t4 26.6 13.3 6.6

t7,t8 _ 0.25 0.25 0.25 0.25

t7,t8 _<0.2T 6.3 3.1 1.6

fable I I' I.VDS Tinting Specifications and Values (ns) at Rated Frequencies

34
12.1.4 Transmitter Specifications

1. The transmitter will produce waveforms satisfying the transmitter output eye pattern

and transitions in Figures 3 and 5 when driving a standard LVDS receiver.

2. The default state of inactive signals is "1".

3. Pair to pair cross-talk • _<-40dB

12.1.5 Receiver Specifications

1. Line termination (pair) • 100f_ +5%.

2. Line receivers will fail-safe to a logical ' 1' state when disconnected.

3. The receiver will respond correctly to incident waveforms satisfying the receiver input

eye pattem in Figure 4.

12.1.6 Cable Specifications

When driven by any transmitter conforming to the transmitter output eye pattern in Figure

3 the cable assembly will deliver waveforms satisfying the receiver input eye pattern in

Figure 4, into a properly terminated receiver.

This formal specification is difficult to verify on such a wide interface so the following

indirect specifications are offered as a guide:

1. Differential (odd-mode) characteristic impedance (pair) • 100f_ _+10%

Pair to pair skew • _<0.1T

Rise time degradation :

4. Attenuation

5. Pair to pair cross-talk :

6. Aggregate cross-talk :

7. Rated frequencies

.

3.

Standard cable lengths are 5m,

Notes:

<0.1T

< 9dB at f = 1/T

< -40dB over 0.5/T < f< 5.5/T

_<-30dB over 0.5/T < f< 5.5/T

32MHz, 64MHz & 128MHz

10m and 20m.

1. Cable assemblies comprise n-pair screened or 2n-line multi-coax cables, terminated

by metal shrouded plugs which continue full screening through to the connection

plane. Corresponding shrouds on the equipment connectors directly ground the

shield to their respective chasses.

2. All input lines should be terminated normally even if a circuit is not implemented.

This provides proper loads for all drivers and avoids problems due to resonances in

floating wires in the cable.

3. MDR-80 only: 'Unused' signal on DIM connector pins 35-36 should be terminated

normally as it will be driven by ROT 1PPS when a DOM output is connected to a

DIM input.

4. MDR-14 only: Ground undefined pins on receptacles. Connectivity within the

cable not required. Grounding the spare pins reduces stray coupling on the board

and within the connector. It also provides convenient returns for the drain wires

from pair shields in some cable types. The enveloping cable shield is of course

continuous with and returned to chassis, by the metal connector shrouds.

35
12.2TTL Interfaces

The two monitor signals, DOTMON and ROTMON are the only TTL signals defined in

the VSI-H specification. They are to 'back terminated' 50f2 ports, implemented by

placing a ~50f2 resistor in series with the driver chip. 4 The rising edge of these signals is

the active transition. Duration is to be stretched to be conveniently observed on an

oscilloscope. The nominal time offset from 1PPS/ALT1PPS to DOTMON and from

DPS 1PPS to ROTMON should be provided to the user and is, ideally, independent of

fCLOCK (in the case of DOTMON) or fDSPCLOCK (in the case of ROTMON).

The DOTMON and ROTMON signals are to be carried on 50f2 BNC connectors.

12.3. Control Interfaces

The DIM and the DOM shall have both an Ethernet and an RS-232 control interface.

Both may be simultaneously active, though this is not required. Some of the control and

monitor functions, as discussed above, are quasi-real-time, in that control/monitor data

must be reliably communicated between 1PPS pulses (in the DIM) or DPS 1PPS pulses

(in the DOM) in order to properly set and monitor the DOT and ROT clocks.

If the DIM and DOM are in the same physical unit, they may share the Ethernet and

RS-232 control interfaces.

The details of the communications messages and protocols are to be specified in the

VSI-S document.

Control Interface:

RS-232:DB-9 configured as DCE (pinout in Table 12)

Ethernet: R J-45 jack (10Base-T or 10/100 Base-T)

Signal Description Direction Pin Comments

CD Carrier Detect From DTS I optional

RD Received Data From DTS 2 required

TD Transmitted Data To DTS 3 required

DTR Data Terminal Ready To DTS 4 optional

SG Signal Ground -- 5 required

6 not used

RTS Request to Send To DTS 7 optional

CTS Clear to Send From DTS 8 optional

RI Ring Indicator From DTS 9

Table 12:DB-9 Pin Allocations (EIA/TIA-574)

optional

4 This raises the output impedance of the driver chip to ~50f2 Given a 50_2 signal path all the way to the

monitoring device (scope, for example), the forward wave is completely reflected by the high impedance of

the monitoring device and absorbed back in the source.

36
The specifications of the control interfaces are:

1. RS-232: operating at least to 9600 baud, preferably higher (to 115 kbaud); 8-bit,

1 stop bit, no parity; software handshaking to be specified in VSI-S specification.

2. Ethernet: 10Base-T or 10/100Base-T

13. Test Vectors

Test-vector generators (TVG) and receivers (TVR) are used to validate the physical layer

connections between the Data Acquisition System (DAS), Data Input Module (DIM),

Data Output Module (DOM), and Data Processing System (DPS) components of the

VLBI Data Transfer System (DTS).

The VSI-H specification imposes no requirements on testing the interface through the

transmission medium from the DIM to the DOM, though designers are urged to

implement testing procedures suitable to the characteristics of the DTS.

13.1 General Characteristics

The philosophy of the TV specification is to fully test the connection of user equipment to

the DIM and DOM data interfaces. To this end, the TV system should have the following

characteristics (see Figure 1):

1. The DIM includes a TVR to validate data transmission from equipment connected to

the DIM data interface.

2. The DOM includes a TVG to validate data transmission from the DOM to external

equipment.

3. Each TVG is capable of generating 32 unique pseudo-random noise (PRN) bit

streams, denoted as TV0-TV3t, each of a fixed period of 215-1 (32767) bits.

4. All PRN bit-streams are re-synchronized at each 1PPS/R1PPS epoch.

5. The TV bit-stream data rate is always at the rate of the data which it replaces. This

implies that TV rates must be consistent with Table 2.

Though the VSI-H specification does not directly extend to the DAS or DTS, a complete

TV system would also include a TVG in the DAS 5 and a TVR in the DTS.

13.2 Test Vector Generator

Figure 6 shows an example gate-level design of the TVG (based on Crestech design) to

be used in VSI-H compliant DTS's. Each of the 32 output PNS bit-streams is reinitialized at each 1PPS/R1PPS tick. Table 13 tabulates the first 20-bits of each of the 32

TV bit-streams. Each bit stream has an approximate balance of the number of'ones' and

'zeroes', corresponding to a 'DC-bias' of ~50%. Note that, for illustration purposes, the

CLOCK signal in Figure 6 is shown to have the same frequency as the data-bit-stream

sample rate.

In addition, each TVG must be capable of producing an "all O's" or "all l's" signal on all

32 bit-stream outputs. In this mode, it is useful to verify that the TVR's reports an error

rate of ~50%.

5 Including a TVG in the DAS probably only makes sense when the DIM receives and uses lPPS from the

DAS. The use of an asynchronous ALT1PPS makes the use ofa DAS-TVG difficult.

37
t_ t2 t3 t4 ts t6 t7 ts t9 ho tu h2 tl3 tl4 tts tl6 tl7 tls t19 t2o

TVo 0 0 0 0 0 0 0 1 0 0 0 1 0 1 0 0 0 0 0 0

TVj 0 0 0 0 0 0 O I 0 0 0 1 0 1 1 0 0 0 0 0

TV2 0 0 0 0 0 0 1 1 0 0 1 1 1 1 1 0 0 0 0 0

TV3 0 0 0 0 0 0 0 1 0 0 0 1 0 0 1 0 0 0 0 0

TV4 0 0 0 0 0 1 1 1 0 1 1 0 1 1 1 0 0 0 0 1

TV5 0 0 0 0 0 1 0 1 0 1 0 0 1 0 1 0 0 0 0 1

TV6 0 0 0 0 1 0 1 1 1 0 0 1 0 1 1 0 0 0 1 1

TV7 0 0 0 0 0 0 0 1 0 0 0 0 0 0 1 0 0 0 0 0

TVs 0 0 0 1 0 1 1 0 0 0 1 0 1 1 1 0 0 1 1 1

TV9 0 0 0 i 0 1 0 0 0 0 I 0 1 0 1 0 0 1 I i

TVlo 0 0 1 1 1 0 0 0 0 1 1 1 0 1 1 0 1 0 0 1

TVit 0 0 0 1 0 0 0 0 0 0 1 0 0 0 1 0 0 1 1 0

TVI2 0 1 1 0 0 0 0 0 1 1 0 0 1 1 1 1 0 1 0 0

TVI3 0 1 0 0 0 0 0 0 1 0 0 0 1 0 1 1 1 0 0 0

TVI4 1 0 0 0 0 0 0 1 0 0 0 1 0 1 0 1 0 0 0 0

TVts 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0

TVI6 1 1 1 1 1 1 1 0 1 1 1 0 1 0 1 1 1 1 1 1

TVI7 1 ! 1 1 1 1 1 0 1 I ! 0 1 0 0 1 1 1 1 1

TVis 1 1 1 1 1 1 0 0 1 I 0 0 0 0 0 1 1 ! 1 1

TVI,_ 1 1 1 ! ! 1 1 0 1 1 1 0 1 1 0 1 1 1 I 1

TV:o 1 I I 1 i 0 0 0 1 0 0 1 0 0 0 1 1 1 1 0

TV21 1 1 1 1 1 0 1 0 1 0 1 1 0 1 0 1 1 1 1 0

TV22 1 1 1 1 0 1 0 0 0 1 1 0 I 0 0 1 1 1 0 0

TV2._ 1 1 1 1 1 1 1 0 1 1 1 1 1 1 0 1 1 1 1 1

TV24 1 1 1 0 1 0 0 1 1 1 0 1 0 0 0 1 1 0 0 0

TV2s 1 1 1 0 1 0 1 1 1 1 0 1 0 1 0 1 1 0 0 0

TV26 1 1 0 0 0 1 1 1 1 0 0 0 1 0 0 1 0 ! 1 0

TV27 1 1 1 0 I ! i 1 I 1 0 1 1 1 0 1 1 0 0 1

TV2_ 1 0 0 1 I 1 1 I 0 0 1 ! 0 0 0 0 1 0 1 1

TV29 1 0 I 1 i 1 ! 1 0 1 1 1 0 1 0 0 0 1 1 1

TV3o 0 1 1 1 1 1 1 0 1 1 1 0 I 0 1 0 1 1 1 1

TV31 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 1 1 1 1 1

Table 13: TVG data outputs for first 20 data bits following I PPS/RI PPS

13.3 Test Vector Timing Relationships

As indicated in Figure 7, the TVG is initialized at every 1PPS/R 1PPS tick in such a way

that the 'TOST bit' at to is undefined. From that point forward, the TVG increments

every sample clock period and has the same timing relationship to CLOCK as normal

user data. The TVG continuously cycles through the 32767-bit TVG sequence until the

next 1PPS/R1PPS tick, at which point the TVG is again re-initialized.

13.4 Test Vector Receiver

On command, the DIM-TVR will measure and report the bit-error rate (BER) and "DCbias" on each of the 32 input test bit-streams, either sequentially or simultaneously. In

order to untangle possible bit-stream 'mix-ups' (i.e. bit streams being directed to the

38
wrong place), a useful, but not required, capability of the TVR is to examine each

possible bit stream for each of the 32 possible TV sequences.

The TVR reporting period may be selected to correspond to any integer number of

1PPS/R1PPS periods, up to a reasonable number (say -64).

14. Other Notes and Comments:

14.1 Data-Replacement Format

Some systems may periodically replace small portions of data sampled by the DIM with

timing and synchronization information. The use of a 'data-replacement' lbrmat under

the VSI-H standard is allowed under Level B compliance. The QVALID signal must

accurately flag any replacement data as 'invalid' as it emerges from the DOM. In

addition, the use of standard VSI-H test-vector testing with the DAS and DPS may be

difficult or impossible with a data-replacement format.

14.2 Media Translation (Tape Copying)

With the use of the VSI-H interfaces, data may be easily copied from one medium to

another in a straightforward manner. The output of a DOM may be directly connected to

the DIM input. For this purpose, the DOM must have the capability of 'standalone

playback' without the connection of DPSCLK or DPS1PPS signals. In such case, the

ROT clock will be commanded to simply track the playback time on the tape.

Time-tag transfer between DOM and DIM can be accomplished by two different

methods. By using the DOM facility to transmit the ROT setting immediately following

a R1PPS tick, a control computer can read the ROT and appropriately set the DOT clock

in the DIM. Once ROT and DOT clocks are appropriately set, copying will take place

with no further intervention until a time discontinuity (tape stop and restart, for example)

when the DOT and ROT clocks must again be reset. Alternatively, time-tag transfer fi'om

DOM to DIM can be done through the QDATA/PDATA serial data lines (as discussed

below).

14.3 Usage of PDA TA/QDA TA

The usage and content of the PDATA/QDATA asynchronous serial-ASCII signals is not

specified under the VS1-H specification. A few possible uses of these signals are:

14.3.1 Media translation

During media-translation (i.e. tape copying) operations, where the DOM output is

connected to the DIM input, QDATA may be used to transmit the high-level time (e.g.

date and time to the unit-second level) to the PDATA input of the DIM between each

R1PPS tick. In this case, it is probably most useful if the QDATA time tag corresponds

to the epoch of the next R1PPS tick. This allows the DIM to dynamically set the DOT

clock to the proper time at the next 1PPS (RI PPS) tick in much the same way the DOT

clock is set in normal operation. Other auxiliary information may, of course, be

transmitted between the DIM and DOM in the same way.

6 It has been pointed out that placing a 32x32 crossbar switch in the DIM may aid in implcnaenting this

capability. In addition, the ability to route one selected data stream t(_ a front-panel monitor c_mneclor

could be of significant benefit in debugging difficult situations.

3g
14.3.2 Auxiliary information from DAS

If the DAS is capable of supplying PDATA information to the DIM, this information may

be used as the DIM sees fit. Possible information might include time, data-collection

parameters, antenna pointing, system temperature, etc. If the system is capable, some or

all of this information may be used to control the DIM, or perhaps transmitted to the

DOM for output to QDATA.

14.3.3 Model parameters to DPS: An attractive possible use of QDATA is to periodically

transmit station-model information to the DPS. This capability is particularly attractive if

the DOM includes the capability to delay the data according to a dynamic model supplied

to it by the host computer. If, for example, the ROT clocks of all DOM's are set to

represent a center-of-earth clock and each DOM dynamically delays its output data

according to a center-of-earth model, the DOM output data may be immediately available

for correlation processing with only a small amount of FIFO re-synchronizing (using

ROT 1PPS tick) necessary in the DPS. The QDATA model parameters, transmitted

between each ROT IPPS tick, would need only to carry such information as fractional bit

delay, rate, plus a phase model for each channel, in order to provide the DPS with all

necessary information to do proper processing.

14.4 Usage of PVALID/QVALID

The VSI-H specifies the use of the QVALID signal only to the extent that it indicates the

global validity status of the DOM output data streams. If available to the DIM, the

PVALID signal may be used to indicate that the DAS output data are 'valid'. This

information can be used by the DIM as it sees fit, including transmitting it to the DOM

for inclusion as a factor in controlling the QVALID output. If the DOM is sufficiently

capable, the QVALID signal may also be used, for example, as a pulsar-gating

mechanism to the DPS.

14.5 Multiple Parallel DTS's

In the event that a single DTS is not able to handle the required aggregate data rate,

multiple DTS's may be employed in parallel. In the case of the DIM, the DAS must be

able to support multiple DIM's in parallel, each being supported as if it were standalone.

Multiple parallel DOM's can be handled in the same way.

14.6 Multi-Port DTS

A DTS may support multiple channel quanta simply by the inclusion of multiple MDR-80

data connectors on the DIM and DOM. Only a single MDR-14 connector for other

timing signals is required. VSI-H imposes no requirements on signal connectivity

between channel quanta within a multi-port DTS.

14.7 Validi O, pet" Bit Stream

Some DTS systems may benefit by having the capability to specify per-bit validity at the

DOM output for each bit-stream individually. Currently the VSI-H specification says

nothing about such a capability, but two possible options for such a capability have been

discussed:

40
. A parallel MDR-80 connector from the DOM can carry validity-per-bit-stream

information. Depending on the resolution of the validity information, it may be

necessary to also carry parallel timing information in the validity connector

(RCLOCK, etc.). The pin-out of the validity connector would parallel that of the data

connector.

. Validity per bit stream can also be implemented without the addition of another

connector by employing a 'bi-phase' code on each of the RBS,, output bit-streams.

This works by using the second half of each R13S bit cell to indicate the validity state

of that bit, so that the negative-going transition of RCLOCK samples the validity state

of each bit cell of every RBS°; this means that the effective RBS data rate is doubled.

Coding is chosen so that a change of level in the second half of the bit cell signifies

invalidation; this coding means that a bit stream without per-bit-validation is identical

to a fully-valid bit stream with per-bit-validation. A DPS may choose to use this

information or not. The 'bi-phase' scheme effectively doubles the information rate on

the data connector, and as such may not be suitable for systems with clocking at 64

MHz or 128 MHz.

The bi-phase coding scheme is common in commercial applications. Note that only

DOM-generated signals are affected; these validity states are not transmitted from the

DIM to DOM.

In either of these cases, the conditions used to control the per-bit-stream validation

signals may presumably be specified by the user and are dependent on the details of the

DTS system.

14.8 Higher Clock Rates

The possibility to move to bit-stream clock rates even higher than 128 MHz, particularly

256 MHz, is moving rapidly towards reality, particularly with introduction of extremely

low-skew cable assemblies and higher-performance LVDS components. Though not

currently a part of the VSI-H specification, this issue may well be ripe for re-examination

in the future, and designers should keep the possibility in mind. At the appropriate time,

it will be necessary to write the detailed specifications necessary to support these higher

rates. Depending on high-speed-data technology developments over the next few years, it

may also be advantageous to consider extending the VSI-H specification to include other

well accepted data interfaces, such as high-speed serial links.

15. Glossary

15.1 General

BER Bit Error Rate

'Channel The data carried on a single 80-pin LVDS signal connector; the base VSI-H specification

Quantum' defines a 'channel quantum' at a data rate of 1.024 Gbps.

DAS Data Acquisition System; provides parallel bit-stream data to DIM

DIM Data Input Module

DOM Data Output Module

DOT Data Observe Time; maintained in DIM

DPS Data Processing System (most commonly a correlalor)

DTS Data Transmission System; includes DIM and DOM

fCLOCK Frequency of CLOCK signal

41
fr_PSCI.OCK Frequency of DPSCLOCK signal

fuse Bit Stream Information Rate at input to DIM (i.e. DIM sample rate)

fRBSI

LVDS

ROT

TOST bit

TV

TVG

TVR

Reconstructed bit-stream information rate at DOM output

Low-Voltage Differential Signaling

Requested Observe Time: maintained in DOM

Data bit 'Taken On the Second Tick'; the TOST bit maintains a constant relationship to

1PPS and is always transmitted regardless of the bit-stream sample rate.

Test Vector

Test Vector Generator

Test Vector Receiver

UTC Universal Coordinated Time

VSI VLBI Standard Interface

VSI-H VSI Hardware Specification

VSI-S VSI Software Specification

15.2 SignaLs"

Name Function Format

1PPS DIM input LVDS

ALT1 PPS DIM input LVDS

BSo DIM input LVDS

CLOCK LVDS

Description

One-second tick

Alternate one-second tick

Bit-stream n

DIM input Data clock

DOT 1PPS DIM output LVDS Optional reverse-channel I-pps from DOT clock

(suggested use of PSPARE2)

DOTMON DIM output TTL DOT clock 1-pps epoch monitor

DPSIPPS DOM input

DOM input

DOM input

DOM input

DIM input

DIM input

DPSIPPSX

LVDS

LVDS

LVDS

LVDS

LVDS

LVDS

DPSCLOCK

DPSCLOCKX

PCTRL

PDATA

DPS one-second tick to DOM

Optional reverse-channel substitute for DPS 1PPS

(suggested use of QSPARE2)

DPS clock to DOM

Optional reverse-channel substitute for

DPSCLOCK (suggested use of QSPAREI )

Reverse-channel enable/disable

115 kbaud asynchronous 8-bit data;

up to 2048 bytes per 1PPS 'tick';

content unspecified by VSI-H

PSPAREI DIM input/output LVDS Spare: optional use as reverse channel

PSPARE2 DIM input/output LVDS Spare; optional use as reverse channel

DIM input LVDS Global 'data-valid'

DOM output LVDS Reverse-channel enable/disable

DOM output LVDS 115 kbaud asynchronous 8-bit data;

up to 2048 bytes transmitted between tPPS or

ROT 1PPS 'ticks'

DOM input/output LVDS Spare; optional use as reverse channel

DOM input/output LVDS Spare; optional use as reverse channel

DOM output LVDS Global 'data valid'

DOM output LVDS 'Reconstructed' 1PPS

PVALID

QCTRL

QDATA

QSPARE1

QSPARE2

QVALID

R1PPS

42
RBSn DOMoutput LVDS 'Reconstructed' bit-streamn

RCLOCK DOMoutput LVDS 'Reconstructed' dataclock

ROT1PPS DOMoutput

ROTMON

LVDS ROT clock 1-pps

DOM output TTL ROT clock monitor

TVGCTRL DIM output LVDS Optional reverse-channel TVG control

(suggested use of PSPAREI)

16. References

3M Connectors:

http://www.mmm.com/Interconnects/prod con 0531.html

3M Pleated Foil Cable Assemblies:

http://www.mmm.com/Interconnects/Prod cas 0804.html

Gore Max-Band Cable Assemblies:

http ://www.gore.com/electronics/pages/cable/highdata/maxband.htm

TI LVDS Devices:

http://www.ti.com/sc/docs/schome.html

(At this site, perform "SC Parameter Search" for 'LVDS')

National Semiconductor LVDS Information

http://www.national.com/appinfo/lvds

(At this site, you can find the application notes by number or by category.)

Useful discussions of VSI interconnect issues:

VSI Interconnect Hardware Specifications. Dick Ferris, 15 March 2000

Derivation of Hardware Specs, Dick Ferris, 15 March 2000

43
Z

0

i-4

o

rr

C

0

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0

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0

o3

n

Q.

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<

80-pin MDR connector; all LVDS

80-pin MDR connector; all LVDS

E

03

£38

n

£3

o

o

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COo

I--.__

F--

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............. " ........... 454 mV

I I I

vi-'q vi m, tl , t2

'_" t 3

' ', I ___ I

'

-"-2-- CLOCK_ ' ' '

..........................................................

m/l I m/l I m/l I

, T I ,

r'4 _, I

Figure 3: LVDS Transmitter Output Eye Pattern

-454 mV

OV

454 mV

Figure 4: LVDS Receiver Input Eye Pattern

Transmitter

........................................................... Transitions I

/i i\ _OOmV

.................-/-T...................--r_............-i-....ov

-L-'- -L-Ai t 200_nV

--4! i_

t7 t8

Figure 5: LVDS Waveform Transition Definitions

46
Note:

"S"inputonDflip-flopsis

synchronous.

1PPS

DQ CLOCK

INIT

o

e

DSQ

DSQ • • •

DSQ • • •

DSQ • • •

S

D Q

D Q •

S

D Q •

S

D Q

DSQ •

DSQ

DSQ •

DSQ •

DSQ • •

DSQ

DSQ •

TV15

TV31

TV14

TV30

TV13

TV29

TV12

TV28

TV11

TV27

TV10

TV26

TV9

TV25

TV8

TV24

TV7

TV23

TV6

TV22

TV5

TV21

TV4

TV20

TV3

TV19

TV2

TV18

TV1

TV17

TV0

TV16

TVGEN.DRW

000422

Figure 6: Test-Vector Generator Schematic

47
1PPS/R 1PPS_ I

c,oc -I

RCLOCK --

E

TV12 pndefined

(at CLOCK rate)__l [

to

LI-IJ-_I-LI-I_-L

I

0 1 1 I 0 0 0

tl t2 t3 t4 t_ t6

(at CLOCK/2 TV12 rate_)_Jluo_fi_d 0 1 1 L

to t_ t2 t3

Notes:

1. TV12 bit stream is shown for illustration.

2. The TV data streams have exactly the same timing relationship to CLOCK/RCLOC

and 1PPS/R1PPS as actual data streams.

3. The TVG is initialized on every 1PPS/R1PPS tick. The TV value at tO is undefined

4. Starting with tl, the TVG continuously cycles through the 32767-bit TVG sequenc_

until the next 1 PPS/R1PPS tick, at which point the TVG is again re-initialized.

Figure 7: TVG Timing Relationships

48
Appendix A: Revision History

Revision 1.0, 7 August 2000

First issue

49

W_

. ,=+

m

" / -- 2 _//{/ : / '')

NASA Goddard Space Flight Center

59%x7

f ,-R

Coordinating Center

Coordinating Center Report

Nan O" R. _/hndenberg

Abstract

This report sunnnaxizes the activities of the IVS Coordinating Center fronl the establishmcnt of

IVS to tile end of 2000, and forecasts a_tivities planned for the year 2001.

1. Coordinating Center Operation

The IVS Coordinating Center is based at 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 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 comnmnity 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

The IVS web site's home page is organized into three main sections: Service, Communications

and Information, and Coordination. Within each main section there are three subsections, each

of which contains links to tables, files, or other pages. The design of the home page is a "portal"

style, which has many links on the top level and minimizes the number of clicks required to reach

information.

2. Initial Activities

During the period beginning with the official inauguration of IVS and ending in December

2000, the Coordinating Center supported the following IVS activities:

• Directing Board support: Coordinated four IVS Directing Board meetings, in Birmingham

(UK), Wettzell (Germany), Paris Observatory (France), and at Goddard Space Flight Center

(USA). Notes from each meeting were published on the IVS web site.

• Communications support: Maintained the IVS web site, e-mail lists, and web-based mail

archive files. The e-mail system and the web site arc the primary means of providing communication and information services to the IVS community.

• Publications: Published the first Annual Report in summer, 1999; proceedings of the first

IVS General Meeting in spring, 2000. Published the IVS flyer in fall, 2000. All publications

are available electronically as well as in print form.

• Master schedules: Generated master observing schedules for 2000 and 2001. Set up master

schedules for all prior years of VLBI sessions, for use by analysts and coordinators. Coordinated VLBI resources for observing time, Mark III/IV correlator usage, and tapes.

• Meetings: Coordinated, with Local Committees, support for the first IVS General Meeting

held in KStzting, Germany in February 2000 and the second Analysis Workshop held in

Greenbelt, MD in February 2001.

2000 IVS Annual Report 53
CoordinatingCenter NASA Goddard Space Flight Center

• IVS Logo: Worked with the Directing Board and graphic artist to develop the official IVS

logo, which may be seen (m the cover of this publication.

3. Staff

The staff of the Coordinating Center is drawn from individuals who work at Goddard. The

staff and their responsibilities are:

Name

Nancy Van(tent)erg

Cynthia Thomas

Frank Gomez

Karen Baver

Title

Director

Operation

Manager

Web Manager

Publication

Support

Programmer and

i Editor

Responsibilities

Web and data base design and

content, Directing Board support,

meeting support, session web pages,

publications

Master schedule, resource

management, meetings support,

special sessions support

Web server administration, mail

system maintenance, discussion

system maintenance, data center

support, session processing scripts,

mirror site liaison

Publication processing programs,

Latex support and editorial

_sistance

Allocation

75%

50%

50%

10%

4. Plans

During the year 2001 the Coordinating Center plans include the following:

• Publish the 2000 Annual Report (this volume).

• Coordinate the first Technical Operations Workshop (TOW), to be held at Haystack Observatory in March, 2001.

• Coordinate the second General Meeting and the third Analysis Workshop, to be held in

Tsukuba, Japan in February 2002.

• Support Directing Board meetings in Greenbelt, MD (February) and Barcelona, Spain

(September).

• Work with the Analysis Coordinator to improve the access by IVS Analysis Centers to data

and products via the IVS web site.

• Work with the Network Coordinator to improve the reporting of station performance data

via the IVS web site.

• Coordinate the 2001 master observing schedule and IVS resources, and coordinate the initial

version of the 2002 master schedule.

54 2000 IVS Annual Report
Geod_tisches Institut der Universit_it Bonn IVS Analysis Coordinator

Analysis Coordinator Report

A. Nothnagel, C. Steinforth

1. Introduction

The first 15 months of working as the IVS Analysis Coordinator have shown significant progress

towards making IVS a suecessflll service. Many small tasks have been completed, eventually leading

to a number of steps forward worth reporting.

Some of the ground work of the IVS Analysis Coordinator had already been laid by the IVS

Acting Analysis Coordinators prior to October 1, 1999 (EUBANKS, MA, VANDENBERG, 1999). In

the meantime 19 centers have been accepted either as IVS Analysis Centers or as IVS Associate

Analysis Centers. The distinction between these two groups has been streamlined in the current

IVS Terms of Reference (ToR) reducing the number of classes included in the initial version of the

ToR.

Although the ToR calls for regular submissions of a full list of IVS products, so far only EOP

results from 24 hour VLBI sessions and of Intensive UT1 observing sessions are available. By now

four IVS Analysis Centers

• Bundesamt fiir Kartographie und Geod/isie (BKG) Leipzig, Germany

• Institute for Applied Astronomy (IAA), St. Petersburg, Russia

• Astronomical Institute of St. Petersburg University (SPU), St. Petersburg, Russia

• NASA Goddard Space Flight Center (GSFC), Greenbelt MD, USA

regularly submit their EOP results from 24 hour sessions to the IVS Data Centers for use by many

scientists around the world. Up to now the four IVS Analysis Centers and the

• US Naval Observatory (USNO), Washington D.C., USA

have regularly submitted UT1 results from quasi-daily Intensive observations. Unfortunately,

USNO teminated its VLBI analysis activities in October 2{)00.

Currently all submissions are formatted according to the IERS submission format using one

data line per epoch with correlation coefficients only between EOP parameters of the same epoch.

No information on the terrestrial reference frames (TRF) underlying the EOP solutions are submitted as yet. Under a different directory of the IVS data structure the results of a single TRF

solution are available which are the basis of the current GSFC EOP solution.

The Analysis Centers have taken great efforts to organize their resources for regular analysis

activities and submissions of the results. The regular delivery is of particular importance for the

long term maintenance of consistent series. Currently, all Analysis Centers use a TRF of their

choice either by fixing the corresponding values in the least squares adjustment or by transferring

the TRF covariance information using pre-reduced normal equations.

Starting on October 1, 2000 the individual session EOP results are processed further in a

combination procedure at the Analysis Coordinator's office in order to generate a combined IVS

EOP product (see section 2). Before the comparison and combination activities of the EOP results

could be started a number of obstacles had to be removed in a concerted effort. The data format

and auxiliary information, although specified as standards, had to be corrected in some of the

2000 IVS Annual Report 55
IVS Analysis Coordinator Geod_itisches Institut der Universitiit Bonn

submissions. File names and directory structures were reorganized, and Analysis Centers had to

be sunnnoned to speed up their submissions. As of today the delay between observations and

result dissemination is on the order of 14 days.

The combination of the results of different solutions to one combined product serves several

tmrposes. In the combination process the individual solutions complement and control each other

leading to a higher accuracy and a higher reliability. Considering the facts that the constellation

of analysis centers may change for various reasons or that errors in data and product submissions

occur, the redundancy of analyses is of general importance: the more Analysis Centers contribute

the smaller the effect of taking out or adding a contributor. This improves not only the individual

results but stabilizes long-standing series in general. Any differences can be analysed for the

detection of outliers and their causes can be investigated. Another aspect of combination is that

more objective error bounds (:an be established which is of particular importance where formal

errors are not representative.

Although one of the fundamental rules of statistics is to never use an observation more than

once, it is still appropriate to produce combined results from submissions of different Analysis

Centers. They are using different software packages and/or different analysis strategies by e.g.

rejecting different data points, using different weighting schemes, or using different reference frames

for station coordinates or radio source positions. All this leads to independent analyses as well as

to independent and slightly different results.

An important aspect of carrying out the combinations is, of course, the correct relative weighting of the Analysis Centers. For this the use of the scatter in the nutation offset results of each

center relative to a combined average is currently deemed to be the most appropriate approach

which is unique for combinations of space geodetic results.

2. IVS Combination Procedure

On December 22, 2000, the availability of the combined IVS EOP products was officially

announced by the IVS Analysis Coordinator. This section provides a description of the combination

strategy being used. In addition, some topics are listed which will need further investigation to

refine this strategy or to mitigate known problems of the combination.

The combination strategy can be divided into two steps. In the first step, a comparison of the

results is carried out to derive relative weights for the Analysis Centers and to determine biases

to maintain consistency with a reference series. In the second step the results of the individual

Analysis Centers are combined into one solution by applying the weighting factors and the biases.

In the following formulae the total number of Analysis Centers contributing to the combination

is denoted by n, the index i designates the respective Analysis Center (AC). The total number of

epochs is m. the epochs are labelled by j.

In the current combination the full varianee/eovarianee matrix is used, whereas in the

following formulae the correlations between the parameters are omitted for more clarity.

2.1. Data Preparation

2.1.1. Weighting Factors

For the comparisons the question arises of how to establish relative weights for the individual

analysis ,:enters since weighted averages have to be computed as a first reference. It is quite clear

56 2000 IVS Annual Report
Geod_tisches Institut der Universit_it Bonn IVS Analysis Coordinator

that these cannot only depend on the formal errors assigned by the Analysis Centers alone. For

this purpose the scatter of the nutation angels de and de appears to be a suitable indicator.

The celestial reference frame a_ssuch is very stable at the sub-milliarcsecond level and deficiencies

of individual sources average out in the large number of sources used in geodetic VLBI series.

Therefore, most of the scatter to be found in the individual nutation offset series can be attributed

to the way the analysis is carried out, e.g. which software and parameterization is used (analyst's

noise).

Initial mean values are computed for each epoch where the input data is only weighted according

to the formal errors assigned by the Analysis Centers.

/t

Y_ Pd_ij d¢ij sin eo

dCj sine0 = i=l n (1)

Pd_

i=1

and

with Pd,pij

n

Pde_j dcij

d_j - i=ln (2)

i 1

and Pdei¢ being the respective weights

1

Pewit -- a2¢ij (3)

and 1

Pdeij -- O.2 (4)

deij

In the next step biases for each nutation offset and analysis center are computed from the residuals:

Vd_)_j sin co _- d¢ij sin co - d¢j sin co (5)

and

and

where Pd_/ ' and pld_ij

Vdeij = dcij - d_j (6)

m

E '

Pdwij Vd_ij sin eo

j=l (7) biasi,d_ sin eo = m

F_ p'

j=l d_p_j

m

t v

Pdeij deij

biasi,de _ J=lm (8)

E' Pdeij

j=l

are the weights of the respective residuals, computed from

1

' (9) Pd_ij -- 12

0. d_/) i j

2000 IVS Annual Report 57
IVS Analysis Coordinator Geod_itisches Institut der Universit_it Bonn

and

with

and

1

pt _

de i j Grt2

deij

t2 2 2

ad¢_j = XaCj (ad_,j n

_, Pd_i_

i=1

12 2 2

O'd_ij : Xdej (°d_ij n

E Pd_ij

i=1

with the respective X 2 per degree of freedom

(10)

) (11)

(12)

n

Pd¢ij V2_pi j sin eo

2 i=1

XdCj =

n--1

(13)

and

n

2

Y_ Pdeij Vdeij

X_e_ -i=1 (14) n--1

The quantity X2 is also called variance of unit weight (Koch 1988). Prom the bias-free series a

weighted root mean squared error (wrms) is computed for each analysis center combining both

nutation components in a root sum squared (rss) sense:

with

and

wrm,Si,nu t = wrmsi,dCsine ° -_ WTIt"_8 d_ (15)

i 771

j_lPtd¢,j sin e0(vgwi, - biasi,g¢ sin co) 2

- - m (16)

WrTltSi,d_ sin eo -- _ P_,Jg

j=l

I 7¢t

wrmsi,d_ = _-- --- (17)

E

j=l

The combined wrms of the nutation offsets are then used to derive new weighting factors for each

of the analysis centers:

fi- wrmsi,nut (18)

wr_rtsnut

where

wrmsnut = --1_--_ wrmsi,nut (19)

?_ i=1

58 2000 IVS Annual Report
Geod_tisches Institut der Universit_t Bonn IVS Analysis Coordinator

_(,_ew) _(new)

Finally new weights PdV,¢ and Pdcij for the input data are calculated:

(new) _. (old)

Pd_&j = JiPd¢ij

and

(2o)

p(neu,) , (otd) (21)

deij : fiP&ij

For fine tuning, the process is then repeated by applying the new weights to the input data

(Fig. 1). Table 1 gives an impression of the current level of agreement of the weighting factors.

Analysis Center A

Xp, Yp, UTI,

dpsi, deps

+ form. errors

Analysis Center

Xp, Yp, UT1,

dpsi, deps

+ form. errors

weighted means for dpsi, deps

per epoch

B Analysis Center C

Xp, Yp, UT1

dpsi, deps

+ form. errors -.

!

I

I

I

I

!

computation of a Bias for each EOP

removal of Bias and computation of WRMS

WRMS dpsi' WRMS depsPer Analysis Center

combined for nutation WRMS

weight factors

Figure 1. Comparison procedure

2.1.2. Offsets relative to IERS C04

Since the users of the combined series will also rely on the long term stability of EOP series

this requirement has to be taken into account in the combination process. While the nutation

offset series are fairly uncritical due to their young history and their direct connection to VLBI

observations, polar motion and UT1-UTC series have a long history. Consistency with the reference

series C04 of the International Earth Rotation Service (IERS) (e.g. IERS, 1996) is considered to

be of importance and should, therefore, be maintained. Tile next step before combination is,

2000 IVS Annual Report 59
IVS Analysis Coordinator Geod_itisches Institut der Universit_it Bonn

Table 1. Weighting factors

AC weighting factor

BKG 1.06

GSFC 1.00

IAA 0.90

SPU 1.06

thus, the determination of offsets between the individual series and the IERS C04 series. Biases

are computed from data sets of each individual Analysis Center which cover the period from

the beginning of 1999 to September 30, 2000, the date immediately prior to the first epoch of

combination. The computation is shown by example for the x component of polar motion.

At first, differences between the respective data point of each analysis center and the corresponding C04 point are calculated:

v_j - xco4d - xq (22)

The differences vx_ are then used to compute the biases:

m

Pxij VXij

biasi,x = j=l (23)

Pxij

j=l

As long ms no changes in the strategy of the solution are introduced the biases are frozen (cf. Table

2). New biases are computed from time to time for controlling purposes and may be applied if

necessary.

2.2. Final Combination

For each data point the respective bias and weighting factor are applied before a weighted

average is computed yielding the combined EOP value (Fig. 2). As an example the formula for

the combined x component of the polar motion for epoch j is given by the following equation (24):

n

fiPx_j (xij - biasi,x)

XJ, i=1 (2Zl) combi _ n

f iPx,j

i 1

and for y and UT1-UTC analogously. For the combination of the nutation offsets cf. equation

(27). The accuracy of one combination data point can be obtained by applying the law of error

propagation (Koch 1988):

52

2 0,x_ (25)

(TXj,combi -- n

i=1

60 2000 IVS Annual Report
Geodiitisches Institut der Universit_it Bonn IVS Analysis Coordinator

with the X2 per degree of freedom

n

fiPxij [Xj,combi -- (Xij -- biasi,x)] 2

_.2 2 i=1

O,Xj : XXj,comb i _-- n -- 1

(26)

In equation (24) the biases and the weighting factors are regarded to have no errors. In a refined

strategy, which has to be set up soon, these errors have to be taken into account, too.

No bias is applied to the combination of tile nutation offsets, only the weighting factors are

used

fiPd_ijdeij

dej,comb i = i=ln (27)

E fiPa_q

i=1

and for d_ analogously. The results of tile combinations are regularly updated. They are available

IERS

EOPC04

Xp, Yp, UTI

weight factors

Analysis Center A Analysis Center B Analysis Center C

Xp, Yp. UTI, [ Xp, Yp, UTI, Xp, Yp, UTI, + form. errors ] + [brm. errors + form. errors

t weighted mean differences fl)r

Xp, Yp, UTI perAC L__

F"

Bias for each Analysis Center |

/

[ removal of Bias ]

weighted means per epoch

¢

I

combined Xp, Yp, UTI ]

per epoch I

Figure 2. Combination strategy

both graphically and numerically on the IVS Analysis Coordinator's web page via the IVS Home

page or directly from http:///miro.geod.uni-bonn.de//vlbi/IVS-AC//index.html. As an example the

combined series for polar motion is printed in Figure 3 and Table 2 summarizes the average

statistics of the current combination solution.

2000 IVS Annual Report 61
IVS Analysis Coordinator Geod_tisches Institut der Universit_t Bonn

0.3

0.2

0.1

tO

0

o

0.0

.__

X -0.I

-0.2

-0.3 ......... i ........ i ......... _ ......... 1 ......... p .........

O0 0.1 0.2 0.3 0.4 0.5 0.6

Y pole in arcseconds

Figure 3. IVS combined polar motion

2.3. Further Investigations and known Problems

The strategy described above reflects the first steps towards a rigorous combination of Earth

orientation parameters. Of course, there are well-known problems of the current combination

procedures. These problems can be divided roughly into two groups:

• deficiencies of the stochastic model

• quality control and redundancy

The combination strategy presented implies actually a violation of the basic rule that the

same data cannot be used twice in an adjustment process. This is presently neglected by treating

the input data of the Analysis Centers as "new" data. The described deficiency can perhaps be

mitigated by introducing a kind of correlation between the Analysis Centers since the data from

VLBI experiments is limited. The question of the correct relative weighting has to be considered

carefully, too.

Another task is the implementation of a suitable method for outlier detection and elimination

to increase the reliability and robustness of the combined solution. A further extension to the

stochastic model will be the estimation of variance-covariance components. Different methods of

the estimation of variance-covariance components have to be checked. Furthermore, a rigorous link

between EOP and TRF on the basis of SINEX input should be established in a refined combination

procedure.

62 2000 IVS Annual Report
Geod_itisches Institut der Universitiit Bonn IVS Analysis Coordinator

BKG

GSFC

IAA

SPBU

Table 2. Current average statistics

xp yp UT1 - UTC dW sin e0 de

bias wrms bias wrms bias wrms bias wrms bias wrms

-109 56 20 62 18 3 -26 43 -1 36

22 66 -25 80 -17 3 8 45 20 60

87 77 -133 75 -6 3 -8 51 -9 44

42 73 -147 72 -15 3 28 47 -3 37

3. IVS Data Centers

One of the key issues of a service like IVS is a timely and reliable dissemination of the raw

observing data to the IVS Analysis Centers and of the results to the users. In this scenario the

IVS Data Centers play an important role since the necessity of permanent accessibility requires

constant maintenance of the equipment. A careful mirroring scheme guarantees that the data at

the three primary IVS Data Centers at

• Bundesamt fiir Kartographie und Geod£sie (BKG) Leipzig, Germany

• Observatoire de Paris (OPAL), Paris, France

• NASA Goddard Space Flight Center (GSFC), Greenbelt MD, USA

are always as consistent as possible. It is noteworthy that with this scheme and with the strong

commitments of the Data Centers the IVS data and the IVS products have been available worldwide

without interruption.

4. First IVS Analysis Workshop

On February 24, 2000 the first IVS Analysis Workshop was organized in conjunction with the

IVS 2000 General Meeting at KStzting on Feb. 21-24, 2000. In this workshop the many different

geodetic and astrometric analysis activities were discussed and some basic aspects were coordinated

(NOTHNAGEL, 2000). In view of the many tasks to be organized and to be distributed en route

to the establishment of a service covering all products to be generated eventually this workshop

was only a first basic step forward. A second workshop to be held in February 2001 will refine the

initial ideas taking into account the achievements and experience of the first year.

During the first IVS Analysis Workshop five IVS Analysis Working Groups were established.

However, the activities of the working groups were less enthusiastic than anticipated when they

were established, a fact which will have to be looked at in the next workshop as well.

So far only the Analysis Coordinator's office regularly publishes combined Earth orientation

parameters. However, other Analysis Centers are encouraged to take up this task in parallel in

order to establish quality control and redundancy. The comparison with independent series or

solutions is a helpful measure to reveal weaknesses or inconsistencies of the combination strategy

in use.

2000 IVS Annual Report 63
IVS Analysis Coordinator Geodiitisches Institut der Universitiit Bonn

Acknowledgements

The work of the IVS Analysis Coordinator would not have been possible without the many

individuals who submitted data and results or provided support in any aspect of operation. Of

equal importance axe those who contributed in the discussions and made suggestions, of which not

all could be realized. We axe thankfill for all these contributions.

References

Eubanks T.M., C. Ma, N. Vandenberg (1999): Analysis Coordinator Report, IVS 1999 Annual

Report, NASA Publication TP-1999-209243, 27-28

Koch K.-R. (1988): Parameter Estimation and Hypothesis Testing in Linear Models, Springer,

Berlin

Nothnagel A. (2000): Excerpts of the first IVS Analysis Workshop International VLBI Service for

Geodesy and Astrometry, 2000 General Meeting Proceedings; NASA/CP-2000-209893, Hanover

MD, 393-396

64 2000 IVS Annual Report
NVI,Inc./NASAGoddardSpaceFlightCenter NetworkCoordinator

Network Coordinator Report

Ed Himwich

Abstract

This report summarizes the activities of the IVS Network Coordinator from the establishment of

IVS to the end of 2000. It includes an assessment of the network performance in yielding usable data

over an approximately 12 month period. The report forecasts activities planned for the year 2001.

1. Network Coordination Activities

The activities of the Network Coordinator fell primarily into two areas: monitoring the status

of network station performance and developing station configuration files.

The main effort in network coordination was monitoring the performance of the stations. This

was done primarily by monitoring the "ivs-ops" messages from the stations, correlator reports

(both prepass and final), and analyst reports. There were virtually no analyst reports in this

period. The various reports were checked. If any problems were reported, they were pursued with

the station and cognizant experts. Because this information was reported on a per session basis, it

was rather difficult to get a clear view of how any particular station was performing. Consequently,

it was decided that a station performance data base that stores the information by station should

be developed. This data base was started in the spring of 2000. Currently, it is maintained by

hand as an Excel spreadsheet. A summary of the station performance is presented in a separate

section below.

One of the goals for network coordination is to develop a data base of information about each

site and its configuration. During 1999 an ASCII template of information was developed. Each

station can fill it out to describe the equipment and environment of the station. So far about half

the IVS Network Stations have completed the form. The completed forms can be viewed from the

Station Configuration Files link on the IVS Coordinating Center web page.

2. Network Performance

The station performance data base contains a wealth of information about station performance

and problems. It includes all reports of problems from correlator pre-passes, correlation reports,

analysts, and stations as well as a history of inquiries made about resolving problems. It was

started in May of 2000 and includes all information since then. There were no analysts reports

except for occasional e-mails about problems processing certain sessions.

It was decided that the correlator reports formed the most reliable, albeit not the most timely

basis, for monitoring station performance. (Within the data base, the issue of timely response is

addressed by the station and correlator pre-pass reports.) The coverage of sessions in the correlator

reports is somewhat spotty due to delays in processing sessions, the unevenness of the delays, and

problems related to the start up of the Mark IV. As of early January 2001 the set of correlator

reports in the data base covers many, but not all, of the sessions from November 1999 through

December 2000. The data base includes 69 sessions with 388 station days (about 5.6 stations per

session on average).

2000 IVS Annual Report 65
Network Coordinator NVI, Inc./NASA Goddard Space Flight Center

Any assessment of station performance is somewhat arbitrary, but the following approach was

used. For each station in each session an estimate is made of how large the data loss was. Each

station day was then assigned to one of the following categories: (A) No data loss (0% lost), (B)

Slight Data Loss (1-6% lost), (C) Moderate Data Loss (7-20% lost), (D) Severe Data Loss (21-

70% lost), and (F) Failed (71-100% lost). Again these categories are somewhat arbitrary. The

divide between slight and moderate loss was set so that loss of one channel (7%) was considered

moderate. Consequently, the slight category includes mostly some RFI, and short data losses, up

to a little less than 90 minutes. The divide between moderate and severe was set so that loss of

three channels (21%) would be severe. This means that the loss of two channels or gaps of up to

about 5 hours would be considered moderate. Severe data loss includes loss of three channels or

more, operation with a warm receiver, long data gaps, and other severe problems. Failure includes

any cases where the data from the station is not useful geodetically. The definitions of these

categories will probably undergo some refinements in the future.

Using the above criteria, the 388 stations days in the data base are distributed as follows: (A)

No Data Loss, 48%, (B) Slight Data Loss, 25%, (C) Moderate Data Loss, 12%, (D) Severe Data

Loss, 3%, and (F) Failure, 6%. In essence this means that 94% of the station days was usable,

although this statistic ignores the fact that some usable days were significantly degraded. In the

future reports, the cause of the data losses will be described as well.

3. Plans

During the year 2001, the plans for network coordination include: further use and development

of the station performance data base including possibly making it accessible from the web, encouraging the remaining stations that have not submitted site configuration files to do so, development

of a local site survey data base and the development of performance standards.

It was recognized in 2000 that it would be useful to develop a data base of site tie information,

both for connecting VLBI stations to local monuments, but also between VLBI and other collocated

techniques. This will be developed further next year.

66 2000 IVS Annual Report
?, y;/

f ,/

MIT Haystack Observatory

zoozooL/o1" 

Technology Coordinator

Technology Coordinator Report

Alan Whitney

Abstract

The main effort of the Technology Coordinator during 2000 was devoted to completing the VLBI

Standard Interface hardware specification (so-called VSI-H). This specification is now complete and

has been approved by both IVS and the astronomy community. _,Vork is now beginning on the software

counterpart, VSI-S. The VSI-H specification is available in the Special Reports section of this volume

and at http ://dopey. haystack, edu/vsi/index, html.

1. VLBI Standard Interface

After 18 months of effort, the VSI-H specification was formally approved on 7 August 2000 by

the VSI Technology Coordination Committee. This followed many discussions and many iterations

of VSI-H draft specifications, including an international 2-day meeting at Haystack Observatory in

January 2000. The specification has been subsequently approved and adopted by both IVS, representing the geodetic community, and GVWG, representing the astronomy community. The VSI-H

specification is the hardware part of the VLBI Standard Interface Specification, which will allow

the transmission of data to and from heterogeneous VLBI Data Transmission Systems (DTS). The

VSI goal is to specify a common interface to be compatible with traditional recording/playback

system, network data transmission and even direct-connect systems. In order to do this, the design

of the VSI must completely hide the detailed characteristics of the data-transport mechanisms and

deal only with the interfaces to the outside world.

The following assumptions were made in the development of the VSI specification:

• The DTS is fundamentally a receiver and transmitter of bit streams

• The meaning of individual bit streams is not specified; normally, a bit-stream will be a stream

of sign or magnitude bits associated with particular samples, but the actual meaning is to

be mutually agreed upon between the data-acquisition system and the correlator.

• The received and transmitted bit-stream clock rates may be different (e.g. the playback rate

to the correlator may be speeded-up or slowed-down); however all bit-stream clock rates on

acquisition must be the same, and all bit-stream clock rates on transmit must be the same.

• The data-acquisition time-tag of every bit in every bit-stream must be fully recoverable with

no ambiguity.

Some of the 'features' of the VSI-H specification include:

• definition of a 1 Gbit/sec 'Quantum Channel':

1. 32 parallel bits streams

2. 32 MHz (extensions to 64, 128 MHz for 2, 4 Gbit/sec 'quantum channel')

• One standard 80-pin connector per 'quantum channel"

• Standardized electrical and timing specifications

2000 IVS Annual Report 67
Technology Coordinator MIT Haystack Observatory

• Low-voltage differential-signal (LVDS) electrical signal interface

• Method of time-tagging data is totally internal to DTS and not specified by VSI-H

• Built-in Test-Vector Generator/Receiver capability

• Model-delay capability to simplify direct connection to correlator

• Two levels of compliance defined to ease transition to new systems

• Easy media translation (i.e. tape copying)

Work is now beginning on the software part of the VSI specification, dubbed VSI-S. We hope

to complete this effort by the end of 2001.

I wish to extend special thanks to all the other members of the VSI Technology Committee for

their many efforts to bring the VSI-H specification to reality:

• Wayne Cannon - York University, Canada

• Brent Carlson- DRAO, Canada

• Dick Ferris- ATNF, Australia

• Dave Graham - MPI, Germany

• Tetsuro Kondo - CRL, Japan

• Nori Kawaguchi - NAO, Japan

• Misha Popov - ASC, Russia

• Sergei Pogrebenko - JIVE, Netherlands

• Jon Romney - NRAO, U.S.

• Ralph Spencer- Jodrell, England

• Rick Wietfeldt - JPL, U.S.

The success of VSI-H may be measured in part by the fact that at least three institutions are

already developing equipment designed to be in compliance with the VSI-H specification. The full

30-page VSI-H specification, along with an interesting historical chronology of its development, is

reprinted in this volume and is available at http://dopey, haystack, edu/vsi/index .html.

2. Other Activities

Other planned and ongoing activities in the technology coordination area are:

1. Formation of a few small subgroups with interest in particular technology areas. The members of these subgroups will be drawn from IVS technology centers and other experts in the

field. These sub-groups, interacting primarily via e-mail, will be asked to develop a list of

concerns and goals and to suggest the steps needed to achieve them. The VLBI Standard

Interface group serves a.s a prototype for this type of activity.

68 2000 IVS Annual Report
MIT Haystack Observatory Technology Coordinator

2. Coordination of an index of published papers and memos in all of the relevant VLBI technology areas. Ideally, this will be a Web-based index with links to electronic versions of the

referenced material. All IVS technology development centers, as well as other experts in the

field, will be invited to contribute.

3. As an ongoing activity, promote and encourage inclusion of topical sessions on advanced

VLBI technology at international meetings and workshops.

2000 IVS Annual Report 69

j,_ _r 7 7-_;'-J /'_,,., ":c_

U

U/
,/Y_1
Geodetic Survey Division, Natural Resources Canada Algonquin Radio Observatory

Algonquin Radio Observatory

Mario Bdrubd, Calvin Klatt

Abstract

The Algonquin Radio Observatory (ARO) is situated in Algonquin provincial park, about 250 km

north of Ottawa and is operated by the Geodetic Survey Division of Natural Resources Canada in

partnership with the Space Geodynanlics Laboratory, CRESTech.

The antenna is involved in a large number of international geodetic VLBI experiments each year and

is a key site in the ongoing Canadian $2 developments. The ARO is the most sensitive IVS Network

Station.

This report summarizes recent activities at the Algonquin Radio Observatory.

Figure 1. Algonquin Radio Observatory 46m Antenna

1. Overview

The ARO 46 m antenna was used in the first successful VLBI experiment in 1967 and was

involved as early as 1968 in geodesy, when the baseline length between the ARO and a telescope

in Prince Albert, Saskatchewan was measured to be 2143 km (sigma=20 m).

2000 IVS Annual Report 73
Algonquin Radio Observatory Geodetic Survey Division. Natural Resources Canada

The GSD also maintains a permanent GPS monitoring station at Algonquin which is used

by all IGS Analysis Centers as a fiducial reference. Satellite laser ranging and absolute gravity

observations are also available for the site which is located on the stable pre-cambrian Canadian

Shield. Local site stability has been monitored regularly using a high-precision network.

2. Antenna Improvements

In order to improve the operational performance of Algonquin, GSD undertook a major upgrade

of the antenna control systemn which wa._ completed in 1997.

This antenna control system still uses the original azinluth and elevation encoders to deternfine

antenna position. We are in the process of upgrading them in a way that should not affect scheduled

operations.

The antemla field system was modified to allow satellite tracking.

The ARO is currently using a Mk3 VLBI system (on long-term loan from NASA) and we

expect to upgrade to Mk4 early in 2001. ARO is equipped with an $2 data acquisition system

and recording terminal and has played a crucial role in testing and development of the Geodetic

$2 system.

We are developing an L-band receiver for bi-static radar applications. This receiver may be

useful for reception of GPS signals.

Figure 2. Fox at the Algonquin staff h(ms¢,

3. General specifications

• Latitude : N 45 57 19.812

• Longitude : E 281 55 37.055

• Elevation : 260.42 m

• Reflector : 46 m diameter with first 36.6 m made of 0.(;31 ,,,,., :-_...............
Geodetic Survey Division, Natural Resources Canada Algonquin Radio Observatory

m of steel mesh.

• Foci : S and X band at prime focus. Gregorian capability with 3 m elliptical subreflector.

• Focal length : 18.3 m (prime focus)

• Focal ratio : f/D = 0.4 for full surface and 0.5 for solid surface.

• Surface accuracy : 0.32 cm for solid portion and 0.64 for mesh.

• Beamwidth : 3.0 arcmin at 3 cm wavelength (10Ghz)

• Azimuth speed : 24 degrees per minutes.

• Elevation speed : 10 degrees per minutes.

• Receiver : S and X cryogenic receiver.

• VLBI equipment : MkIII with thick tape drive. To be upgraded to MkIV in 2001.

$2 data acquisition and recording terminal.

• PCFS version : 9.4.13

• Time standard : NR Maser

• GPS receiver : Rogue

4. Antenna Survey

The antenna is surrounded by a high stability network made of thirteen concrete piers. This

network has been precisely measured five times to obtain the geodetic tie between the VLBI, the

GPS and the SLR reference points with a precision of a few ram. The VLBI antenna itself requires

a special indirect survey since the reference point cannot be accessed directly.

We have recently re-measured the network. In addition to tying GPS and SLR to VLBI, we

will attempt to study antenna deformation as a function of elevation angle.

Figure 3. Rapelling off the Algonquin 46 Ill Antenna
Algonquin Radio Observatory Geodetic Survey Division, Natural Resources Canada

5. Algonquin Operations

A new GSD staff member, Anthony Searle, has joined the VLBI group at GSD and has been

assisting with experiment operations.

Algonquin Radio Observatory is involved in several international VLBI networks. We summarize below the geodetic VLBI activities in the reporting period.

A number of additional experiments have taken place in recent years at ARO. In September

1999 ARO was used to transmit high energy pulses to assist in the characterization of sensors on

board satellites. ARO also participates in international astronomical observations as part of the

"Polar Bear Network".

In 2001, the ARO is scheduled in weekly NEOS experiments plus 12 CORE experiments.

We anticipate that it will also participate in 10-20 CGLBI (Canadian Geodetic Long Baseline

Interferometry) S2-based experiments.

Experiments Performed March 1, 1999-December 31, 2000

Experiment Type March-December 1999 January-December 2000

NEOS-A 10 31

CORE-A 21 6

CGLBI 6 17

CORE-B 6 3

CORE-1 0 6

NAVEX 2 0

CRF 1 1

76 2000 IVS Annual Report
/ 2_oOZ.oo L:, :,,

Centro de RAdio Astronomia e AplicaqSes Espaciais, CRAAE (Mackenzie, INPE, USP, UNICAMP)

2000 Activities Report of Fortaleza Station

Pierre Kaufmann, A. Macilio Pere/ra de Lucena, C1audio E. Tateyama

Abstract

This report summarizes the activities performed at Fortaleza Station (ROEN: RAdio Observat6rio

Espacial do Nordeste), Eus_bio, CE, Brazil, managed by CRAAE (Centro de RAdio Astronomia e

Ap|icaqSes Espaciais) in agreement with INPE (Instituto Nacional de Pesquisas Espaciais), in the time

period starting March 1, 1999 and ending December 31, 2000.

1. Geodetic VLBI Observations

Fortaleza participated in 123 geodetic VLBI experiments as detailed in the table below:

Experiment Number of Sessions

NEOS-A 91

IRIS-S 19

CORE-B 08

C ORE-OHIG 1 04

CRF 01

2. Development and Maintenance Activities

1. Replacement and alignment of magnetic heads of the tape recorder.

2. Antenna drives electrical alignment including controller card, high power amplifier, DC motor

and tachometer for the elevation antenna axis.

3. Installation of a new and updated FS computer.

4. Replacement of the cold-head refrigerator of the cryogenic system.

5. Repairs on the following circuits, modules, or systems: Mark III video converters, Mark III

decoder module, Mark III power supply module II, DC motor of elevation axis, UPS battery

system, monitoring system of receiver, noise calibration diodes controller, hydrogen maser,

the controller of motor-generator group, and the cryogenic system.

6. Creation of an english version of web site (http://www.roen.inpe.br) about ROEN activities.

3. GPS Operation

The IGS network GPS receiver operated regularly all the days. Data were collected and

uploaded to the IGS computer.

4. Research

Continuation of Washington correlator data analysis on various celestial sources. Significant

progresses obtained on structure of source 1803+784.

2000 IVS Annual Report 77
Gilmore Creek Geophysical Observatory NASA Goddard Space Flight Center _ "_

Gilmore Creek Geophysical Observatory

Rich Strand

Abstract

The following report provides a general technical description and operational overview of the

Gihnore Creek Geophysical Observatory located near Fairbanks, Alaska.

Figure 1. NOAA/NASA Data Acquisition and Geophysical Observatory. Fairbanks, Alaska

1. GCGO at Fairbanks

Gihnore Creek Geophysical Observatory (GCGO) is located 22 km NorthEast of Fairbanks,

Alaska. The observatory is co-located with the NOAA weather satellite command and data acquisition station. The station sits oll an 8,500 acre reservation that is mostly undeveloped wilderness.

Ten antennas are in operation. The GCGO telescope can be seen in the photo as the last antenna

on the right in the valley. GCGO wa_s instrumented by NASA's Crustal Dynamics Project in the

mid 80's for the Alaskan mobile VLBI campaign and used as the base station for those geodetic

measurements [1]. The GCGO is part of the NASA Space Geodesy program in cooperation with

the U.S. Naval Observatory.

Table 1. Address of GCGO near Fairbanks,

Gilmore Creek Geophysical Observatory

NOAA/NESDIS FCDAS

1300 Eisele Road

Fairbanks, AK 99712

http ://w_. fcdas, noaa. gov

2. Technical Parameters of GCGO

The 26 meter telescope, Monument Number 4047, X-East Y-North, Latitude N 64 ° 58'

43.81288" and Longitude E 147 ° 29' 42.18552" Height 306.418 meters is hydraulically operated

78 2000 IVS Annual Report
NASA Goddard Space Flight Center Gilmore Creek Geophysical Observatory

and controlled by a Modc()mp computer system (see table 2). The DAT rack is a VLBA terminal

and recorder (thin tape). The X/S band microwave receiw_r has a cryogenic low noise front end.

VLBI Field System version 9.4.14 is used with a PC. Hydrogen Maser Nit 5 is the time standard

with an HP Cesium for tile telescope computer. A CNS (TAC) receiver is monitored by the TAC32

software for GPS offset mea.surements. The station also runs two NASA/JPL Rogue receivers 8100

running JPL VO5 scintillation software. UCLA maintains the HIPAS receive system located in

the GCGO. The Institut Geographique National in France operates their new DORIS beacon that

is located near the NOAA VHF transmitter building.

3. Staff of the Gilmore Creek facility, Fairbanks, Alaska

GCGO is co-located with the NOAA data acquisition facility. The NOAA Manager is Jim

Budd. The site is operated by the Lockheed Technology Services Group with Doug Ooms as

Lockheed Project Manager and Roger Kermes, Lockheed Operational Manager. R. Strand and S.

Caskey are assigned to GCGO technical staff with T. Knuutila, Z. Padilla, H. Grotsema, and D.

Eubanks assisting. The telescope hydraulic system is maintained by M. Meindl, A. Sanders and

F. Holan.

Figure 2. GCGO Ops crew Knuutila, Caskey, Strand

4. Status of Gilmore Creek Geophysical Observatory

GCGO will be observing eight sessions per month oil average, with 102 sessions scheduled for

year 2001. We observe NEOS every other week and IRIS (race a month. CORE observing with

R&D, APSG, CRF and Survey completes the program. Several dewar swaps were made during

this reporting period. One 28V DC power supply failed in the DAR. The major data loss was

2000 IVS Annual Report 79
Gilmore Creek Geophysical Observatory NASA Goddard Space Flight Center

the failure of the Y axis hydraulic pump on the telescope in Aug 2000. Field System software

development continues by Ed Himwich, NVI, Inc., using the station's DAT racks and telescope for

testing.

Table 2. Technical

Parameter

owner and operating agency

year of construction

receiving feed

diameter of main reflector

focal length

surface accuracy of reflector

X Y mount

S-band

Tsys

SEFD(CASA)

G/T

X-band

Tsys

SEFD(CASA)

G/T

parameters of the GCGO radio telescope for geodetic VLBI.

GCGO

NOAA/NASA

1962

primary focus

26 meters

10.9728 meters

889 mm rms

1 degree per second

2.2 - 2.4, GHz

62K

650 Jy

35.3dB/g

8.1 - 8.9, GHz

58K

550 Jy

44.5 dB/K

Table 3. VLBI observing at Gilmore Creek between 03/01/98 and 03/(}1/99.

Year 1999 Experiments assigned to GCGO - 93

Observations scheduled - 23817

Observations recorded - 23353

Efficiency - 98.05%

Year 2000 Experiments assigned to GCGO - 67

Observations scheduled - 20613

Observations recorded - 19605

Efficiency- 95.11%

5. Outlook

Increased observing for 2001 is scheduled.

References

[1] C.Ma,J.Sauber,L.Bell,T.Clark,D.Gordon,W.Himwich, and J.Ryan Measurement of Horizontal _[otion

in Alaska Using VLBI 1990, In:Journal of Geophysical Research, vol 95, No.B13. Pg 21991-22011.

December 10,1990

• n_

80 2000 IVS Ammal Report
• //" i

NASA Goddard Space Flight Center

200 "7 L<,;.,_ / _....

Goddard Geophysical and Astronomical Observatory

Goddard Geophysical and Astronomical Observatory

Ja_" Redmond, Ch_,rh',_' Kodak

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 previous

year. The outlook lists the outstanding tasks to improve the performance of GGAO.

1. GGAO at Goddard

The Goddard Geophysical and Astronomical Observatory consists of a radio telescope for VLBI,

SLR site to include MOBLAS-7, SLR-2000 (development system), a 48" telescope for developmental two color Satellite Ranging, a GPS timing and development lab, meteorological sensors and a

H-maser. In addition, we are a fiducial IGS site with several IGS / IGSX receivers.

Figure 1. MV-3 VLBI antenna at GGAO.

GGAO is located on the east coast of the United States in Maryland. It is about. 15 miles NNE

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

2. Technical Parameters of the VLBI Antenna at GGAO

The radio telescope for VLBI at GGAO (MV3) was originally built as a mobile or transportable

station. It was previously known a_s Orion and was part of the original CDP. It is now being used

as a fixed site having been moved to Goddard and semi-permanently installed here since the spring

of 1991. The design criteria were

2000 IVS Annual Report 81
Goddard Geophysical and Astronomical Observatory NASA Goddard Space Flight Center

• transportability on two tractor trailers utilizing a 5 meter dish size to maximize receive and

mobility considerations,

• setup of the radio telescope within eight hours (although it has been used as a fixed site since

the spring of 1991)

Tabh 1. Location and addresse_ of GGAO at Goddard.

Longitude 76.8265 ° W

Latitude 39.0219 ° N

MV3

Code 299.0

Goddard Space Flight Center, (GSFC)

Greenbelt, Maryland 20771

http://www.gsfc.nasa.gov

The technical parameters of the radio telescope are summarized in Table 2.

Table 2. Technical parameters of the radio telescope of GGAO for geodetic

Parameter GGAO-VLBI

owner and operating agency

year of construction

diameter of main reflector d

azimuth range

azimuth velocity

azimuth acceleration

elevation range

elevation velocity

elevation acceleration

NASA

1982

5m

0...540°

3°/s

1°Is 2

0... 90 °

3°/s

l°/s 2

X-band 8.18 - 8.98 GHz

receiving feed

Tsys

Bandwidth

G/T

Cassegrain f ocus

24 K

800MHz, -2dB

32.1 dB/K

S-band 2.21 - 2.45GHz

receiving feed

Tsys

Bandwidth

G/T

VLBI terminal type

recording media

Field System version

primary focus

19K

240MHz, -2dB

21.2dB/g

MK4

thin-tape only

9.4.113 (9.5 BETA)

7LBI.

82 2000 IVS Annual Report
NASA Goddard Space Flight Center Goddard Geophysical and Astronomical Observatory

3. Technical Staff of the VLBI facility at GGAO

The GGAO VLBI facility gains from the experiences of the staff from the Research and Development VLBI support staff. GGAO is a NASA R&D and data collection facility, operated under

contract by Honeywell Technology Solutions Incorporated (HTSI). Table 3 lists the GGAO station

staff that are involved in VLBI operations.

Table 3. Staff working at the MV3 VLBI station at GGAO.

Name I Background Dedication Agency

Jay Redmond engineering technician 100% HTSI

TBD engineering technician 20% HTSI

4. Status of MV3 at GGAO

GGAO participated in several VLBI experiments which are listed in table 4. In addition to the

scheduled experiments listed in table 4, MV3 has participated in several unscheduled experiments

for VLBI developmental purposes and various other developmental activities.

Table 4. Participation of GGAO in

Date

1999-03-08

1999-05-11

1999-08-03

1999-11-23

2000-05-22

2000-07-06

2000-10-23

2000-12-24

VLBI Experiments from March 8, 1999 to December 24, 2000.

Experiment

RDV13

NA315

NA327

NA343

RDV21

RDV22

RDV23

RDV24

5. Outlook

GGAO will continue to support both scheduled experiments and developmental activities. The

plan for 2001 consists of:

1. Continue testing of pre-release versions of PC-FS and new Linux kernel releases.

2. Continue with research on Mk4 hardware development.

3. Continually striving to improve the performance of the entire MK4 data collection and station

specific equipment.

2000 IVS Annual Report 83
Hartebeesthoek Radio Astrono_my Observatory

zoo'Zoot!/o/

Hartebeesthoek Radio Astronomy Observatory (HartRA0)/'_' ]O_zJ

Hartebeesthoek Radio Astronomy Observatory (HartRAO)

L udwig Corn brin ck

Abstract

This report smnmarises the current technical parameters of the HartRAO VLBI station. It also

gives an overview of our geodetic VLBI activities during the period March 1999 to the end of 2000. A

brief description of our involvement with other space geodesy techniques is given. Surface upgrading of

the 26 m antenna which should improve tile performance of HartRAO as a VLBI station is discussed.

1. Geodetic VLBI at HartRAO

HartRAO is located north of Johannesburg, South Africa, in a valley of the foothills of the Witwaters motmtain range (see Table 1). HartRAO uses a 26 nmtre equatorially mounted Cassegrain

radio telescope built by Blaw Knox in 1961. The telescope was part of the NASA deep space

tracking network until 1975 when the facility was converted to an astronomical observatory.

Figure 1. The 26 metre radio telescope. Solid panels have been fitted on the outer ring as part of the surface

upgrade. All panels will eventually t)e replaced with non-perforated, higher tolerance panels. Typical rms

accuracy of these panels is 170 microns.

2. HartRAO Radio Telescope Surface Upgrade

The upgrade of the radio telescope is well underway with the outer ring completed. It is expected that total rms surface accuracy after completion will be less than 0.5 ram. Improvement

84 2000 IVS Annual Report
Hartebeesthoek Radio Astronomy Observatory (HartRAO) H artebeesthoek Radio Astronomy Observatory

Table 1. Location and addresses of Hart lRAO.

Latitude 25.889 ° S

Longitude 27.686 ° E

Hartebcesthoek Radio Astronomy ()bservatory

Geodesy Programme

PO BOX 443

Krugersdorp, 1740, SOUTH AFRICA

http://www.hartrao.ac.za/geodesy/geodesy/ndex.html

Table 2. Technical parameters of the radio telescope of HartRAO for geodetic VLBI.

Parameter

owner and operating agency

year of construction

radio telescope mount

receiving feed

diameter of main reflector d

focal length f

//a

surface contour of reflector

wavelength limit

pointing resolution

pointing repeatability

X-band

(standard u = 8.580GHz, A = 0.0349m)

T_y_

SSEFD

Point source

3 dB beamwidth

S-band

(standard u = 2.280GHz, A = 0.1316)

rsys

SSEFD

Point source

3 dB beamwidth

VLBI terminal type

recording media

Field System version

attended VLBI observations

HartRAO-VLBI

HartRAO

1961

offset equatorial

Cassegrain

25.914m

10.886m

0.424

:l:2 .0 m m

2.5 cm

0.001 °

0.004 °

8.180 - 8.980 GHz

65K

1500 ,Iy

17.1Jy/K

0.092 °

2.210 - 2.344GHz

40 K

1500 Jy

9.7 Jy/K

0.332 °

MKIV

thin-tape only

9.4.18

24h, mode C

at X band will be approximately 60%. The new panels are being manufactured on site. The

manufacturing technique includes the use of a 'bed of bolts' which can be adjusted very accurately. High precision mea_surements are made of each panel to monitor quality and shape of the

2000 IVS Annual Report 85
Hartebeesthoek Radio Astronomy Observatory Hartebeesthoek Radio Astronomy Observatory (HartRAO)

panels. Holography will be used to ascertain the parameters of the shape of the resurfaced dish

for adjustment and efficiency calculation purposes.

The technical parameters of the radio telescope are summarised in table 2.

3. Staff Members Involved in VLBI

The Geodesy Programme has undergone some changes in its staff complement. With the

addition of the MOBLAS-6 SLR unit, several new staff members were recruited as part of the

SLR project. We have incorporated several of these staff members into the VLBI operations and

envisage that they will improve and enhance our geodetic VLBI activities, after adequate training.

The staff members listed have direct VLBI responsibilities, but other staff are sometimes involved

in supporting and maintenance roles.

Table 3 lists the HartRAO station staff who are involved in geodetic VLBI.

Table 3. Staff supporting geodetic VLBI at HartRAO.

Name Background Dedication Function Programme

Ludwig Combrinck Geodesy 30% Programme Manager Geodesy

Jonathan Quick

William Morale

Astronomy

Technical

5%

30%

Hardware/Software

Shift Operator

Astronomy

Geodesy

Johan Bernhardt Technical 10% Shift Operator SLR

Marisa Nickola Logistics 10% Shift Operator SLR

4. Status of the HartRAO Geodetic VLBI Component

During the period of this report (March l, 1999 - December 2000) HartRAO participated in

the IRIS-S, CORE-A, RDV, COHG and SYOWA VLBI projects. We have been participating in

VLBI experiments on a regular basis since 1986. Currently about 15 percent of available telescope

time is allocated for geodetic VLBI. Upgrades to our VLBI equipment during 2000 includes:

1. 3.5cm Dual Polarisation receiver upgrade.

2. New Mark IV decoder installed.

3. Headstack replaced after repair long-standing reproduce problem now fixed.

4. $2 recorder transports underwent service replacement.

5. Future Plans

In order to bring geodesy cl()ser to home and the African continent, the Geodesy Programme

is in the process of establishing a Geodetic Institute for Africa. The purpose of this Institute

at HartRAO will be to take Afri('a into the filture by developing and nurturing country specific

projects ill space geodesy. These i)rojects will be tied in a unifying structure which will advance

and support Afri('a's role i_t geodesy. It will support and promote the activities of the IVS, ILRS

and IGS.

_,6 2000 IVS Annual Report
Hartebeesthoek Radio Astronomy Observatory (HartRAO) Hartebeesthoek Radio Astronomy Observatory

We are continuing our footprint survey, which has as its main purpose the determination of

eccentricities between the GPS, VLBI and SLR reference points as well as the maintenance of a

control network to enable stability monitoring of the site on a local scale. The current eccentricities

between VLBI and SLR (Table 4) were determined using GPS (Combrinck & Merry 1997) and the

SLR to GPS eccentricities values are from 1998 footprint results. We are processing HRAO in a 17

station regional (IGS) network and envisage processing the SLR (MOBLAS 6) data for eccentricity

determinations. This will strengthen collocation and with accurate eccentricities should tie the

independent ITRF (Table 5) coordinates to a high degree of accuracy. HartRAO has several

upgrades in progress which will affect VLBI and general radio telescope performance. The main

projects for 2001 are:

1. Upgrade of radio telescope surface.

2. Automation of dichroic.

3. Improvement of pointing map; especially the far south and north can do with improvement.

Table 4. Table of eccentricities, VLBI telescope to SLR and

Reference

SLR

SLR

SLR

HRAO

HRAO

HRAO

Coordinate

X

Y

Z

X

Y

Z

A

41.680

-66.564

-8.131

90.236

-132.190

-34.704

GPS (HRAO) reference points.

(mm)

15.8

7.5

3.9

15.8

7.5

3.9

Table 5. Table of Geodetic reference points, ITRF96 Epoch 1997, VLBI, SLR and GPS (HRAO).

Reference Coordinate Cartesian (m) ]a (m) ]Velocity (m) a (kxm)

VLBI X 5085442.780

VLBI Y 2668263.483

VLBI Z -2768697.034

GPS X ]5085352.500

GPS Y t2668395.681

GPS Z -2768731.692

SLR

SLR

SLR

X

Y

Z

0.006

0.005

0.005

0.009

0.007

0.006

5085401.135 0.101 0.0007

2668330.108 0.063 0.0192

-2768688.865 0.071 0.0164

0.0007 0.0009

0.0192 0.00101

0.0164 0.0007

0.0007 0.0009

0.0192 0.00101

0.0164 0.0007

0.0009

0.00101

0.0007

References

[1! ('omlwin(:k W.L. and Merry, C.L. "vT_ry long baseline interferometry antenna ax,s

d,l (_,'_,_,_r_tion ,sing GPS. JGR. Vol. 102. NO.B 11, pages 24_741-2,t.743. 1997.

offset and intersection
/ fl . ,

Kashima 34m Radio qk, lescope

zoo oo tI/ 2_ 5 5

rye'

Kashima Space Research Center, Cmnmunications Research Laboratory

Kashima 34m Radio Telescope

.]rmichi Xakajima, Eiji Kawai, Hiroshi Okubo

Abstract

Kashima 34m radio telescope is a facility of the Kashima Space Research Center, Communications Research Laboratory. The telescope is mainly used for geodetic VLBI and other astronomical

observations. Ilere we 1)r(_sc.nt its status as of year 2000 and progress of related project.

1. Introduction

Conmmnications Re.search Laboratory (CRL) constructed the Kashima 34m telescope in 1988.

Since the operation started, 12 years have passed. The telescope is kept in a good condition

and joined various VLBI ot)servations continuously. The Kashima Space Research Center of CRL

was founded in 196,1 near the Pacific ocean and is located 100 km east of Tokyo. The 34m

telescope shown in the figure is currently operated by Radio Astronomy Applications Group. The

telescope structure below lh(' alidade section is ahnost identical to NASA DSN 34m stations, but

the equipI)ed fre(luen(:y range, feed and electronics are different.

a.hnage of 34m

i! _,_._,_,,,° _/

b Structure

Figure 1. The Kashima 34m radio telescope

2. Antenna Specifications

2.1. Mechanical system

Although the Kashima 34m teles(:ope has a maximum slew rate of 1 degree per second in

azimuth, we reduced its speed to prevent wear. Telescope mechanical performance is shown in Table

1. Annual inspection of the electric motors and preparation of spare motors reduced unexpected

troubles. In recent years, there has been no observation failure due to mechanical trouble. Last year

major modifications to AZ and EL encoder system were carried out. Through the modifications we

replaced an old enc()der iut(_rface with a new one and the telescope system increased its reliability.

Sub-reflector FRP surface was cleaned and re-painted from metal paint layer. One third of backup

88 2000 IVS Annual Report
Kashima Space Research Center, Communications Research Laboratory Kashima 34m Radio Telescope

structure inspection and main reflector panel supports replacement were finished in 2000. The rest

of the telescope will be maintained in 2001.

Table 1. Mechanical Specification of the 34m Radio Telescope.

Maximum Speed Azimuth(deg/sec) 0.8

Maximum Speed Elevation(deg/sec) 0.64

Drive Range Azimuth(deg) +-270

Drive Range Elevation(deg) 7-90

Operation Wind Speed (m/s) 13

Panel Surface Accuracy r.m.s.(mm) 0.17

2.2. Receiver system

Available receivers are L, C, K and S/X band and they are summarized in Table 2. A computer

controls the feed groups in the cassegrain secondary focus. In our telescope feed groups are

mounted on elevator units named "trolley". With the trolley, the selected feed and receiver are

moved to the secondary focus. The other receivers are retracted to lower positions. In the case

of the C-band receiver additional sub-reflector adjustment is needed because of its feed position

offset. All receivers except C-band are cooled HEMTs around 12K physical temperature. The

C-band LNA, formerly in an ambient environment, is now cooled around 100K using closed cycle

refrigerator. We need approximately 15 minutes to 1 hour to switch the receivers to another band.

The IF (intermediate frequency from receiver) is transmitted from the telescope to the observation

room via optical fibers. The IF except K-band are in the range of commonly used 100-600 MHz

band. Additional up converters in the observation room can up convert the 100-500 MHz to 600-

1000 MHz. On the other hand the K-band receiver IF is 5-7 GHz. Whole IF bandwidth is also

transmitted with fibers, wide-band E/O and O/E. Then they are converted to baseband or other IF

frequency. Recently we have strong RFI interference in L-band. These are from artificial satellites

and mobile phone base station. With the satellite phone service, we negotiated to prohibit terminal

transmission near the telescope to prevent receiver saturation.

Table 2. Receiver Specification of the 34m Radio Telescope.

Band frequency(Hz) Trx(K) Tsys(K) Efficiency

L 1350-1750 18 43 0.68

S 2150-2350 19 83 0.65

C 4600-5100 25 108 0.70

X 7860-8680 41 52 0.68

K 21900-23900 300 330 0.57

2.3. Standard signals

Two K-4 type (Anritsu) hydrogen masers are used for frequency standard. The same masers are

also used for KSP Kashima 1lm station. We have another Russian maser for reference and backup.

2000 IVS Annual Report 89
Kashima 34m Radio Telescope Kashima Space Research Center, Communications Research Laboratory

As for H-1PPS comparison to the GPS-UTC, the AOA receiver and the Totally Accurate Clock-2

are in operation. Expensive GPS receivers will be replaced by the TAC-2. TAC-2 encouragement

to domestic institute and their TAC-2 kit assembly support is done by the CRL Kashima group.

2.4. VLBI back-end system

As of January 2000, K3-A (Mark-IIIA compatible), VLBA, K4, VSOP, S-2 and Gigs-bit VLBI

systems are available. The newly installed S-2 system and Gbit system are fully in operation. K4,

VLBA and $2 are controlled by the Field System (FS-9) as well as the telescope. Other equipment

are still controlled from their original field system. K4 and VSOP observations can use automatic

tape change robot during their observations. A digital spectrometer with auto-correlation and

total power recording by DAT are also possible.

3. On-going Projects and Major Result of 2000

Following are the major VLBI observation projects which are currently running at Kashima

34m radio telescope.

K4-TIE experiment In collaboration with the Geological Survey Institute and others, Intensive

K-4 TIE experiment to tie the KSP VLBI network to a global terrestrial reference frame

(ITRF) was carried out. Final session is planned in February 2000.

Pulsar VLBI (Asia Pacific Telescope) Since 1997 regular observations were carried out between the Kryazin 64m telescope in Russia and Kashima 34m. A K4 system is installed

on the Russian side. Periodic observations revealed the intrinsic motion of pulsars in high

resolution after data analysis. Pulsar timing observations were carried out too.

VSOP (VLBI Space Observatory Program) In collaboration with ISAS (Institute of Space

Astronautical Sciences), Kashima 34m joined the project as a ground telescope. Mainly Cband and L-band receivers are used. The Kashima 34m role is complementary work with

ISAS 64m.

J-NET (Japanese domestic astronomical VLBI network) With three other stations in

Japan (Nobeyama 45m, Mizusawa 10m and Kagoshima 6m), proposal based observations

were made. Focused on astronomical side, most of the JNET observations are tuned in

K-band water maser. A number of sources were found under intensive observations of the

VERA Survey in 2000. We found reference continuum sources near water maser sources

concentrated at low Galactic latitudes.

GALAXY (Giga-bit Astronomical Large Array with cross connect) Utilizing optical networks, three large telescopes in Japan are optically connected via ATMs. Kashima 34m and

Usuda 64m were connected in September 1998. Kashima 34m and Nobeyama 45m were also

connected on 7th June 1999. Koganei KSP correlator is now used for regular GALAXY

experiments. In 2000, we have tried to start Mitaka-FX as the second real-time correlator. A 2.4 Gbps optical transmitter was successfully developed at NAO. Real-time Giga-bit

observation using the network is planned in 2001.

GIFT (Gifu University Telescope) A 3m telescope of CRL was moved to Gifu university. We

have performed initial observations and geodetic analysis to start up the university site. A

90 2000 IVS Annual Report
Kashima Space Research Center, Communications Research Laboratory Kashima 34m Radio Telescope

Gbps system was also introduced and the small telescope was spot lighted again.

Giga-bit VL]3I Experimental Giga-bit observations were carried out both in geodesy and astronomy. High sensitivity Gbps observations for radio astronomy are starting now. The 1024

Mbps recorders work with JNET 256 Mbps simultaneously and double its sensitivity.

4. Technical Staff for the Kashima 34m Radio Telescope

Engineering and Technical staff members who are contributing to observations and operations

of the Kashima 34m are listed below.

• Eiji Kawai, Technical responsibility for overall operations and maintenance.

• Junichi Nakajima, Engineering leader of the 34m.

• Yasuhiro Koyama, Field system developments and monitoring software.

• Mamoru Seido, Hydrogen maser and standard signal distribution.

• Hiroshi Okubo, Technician for mechanical and RF maintenance

• Hiroo Osaki, Technician for software and mechanical maintenance.

• Yuki Watababe, Engineer from Rikei Corporation. Rikei is the contract agency of Vertex

corporation TIW division.

5. Outlook

The subreflector control unit will be replaced for high reliability. Receiver physical temperature

read out will be replaced too. A new HEMT 43 GHz receiver will be installed by Kagoshima

University and NAO. Publication of a special issue of CRL journal which summarizes related

recent results is planned in April 2001.

2000 IVS Annual Report 91
Key Stone Project VLBI Stations Kashima Space Research Center, Communications Research Laboratory

Key Stone Project VLBI Stations (Kashima, Koganei, Miura,

and Tateyama)

Yasuhiro Koyama

Abstract

Four stations of the Key Stone Project Network at Kashima, Koganei, Miura, and Tateyama continued frequent and automated VLBI observations throughout the period from March 1999 to December

2000. From the end of June 2000, unusual motions of Tateyama and Miura stations were detected as the

results of volcanic and seismic activities near the Miyakejima and Kozushima Islands. To investigate

and monitor the motions of Tateyama station, the frequency of the VLBI observations at Tateyama,

Kashima, and Koganei stations were included and the observations were performed every day almost

continuously from June 2000 through November 2000.

1. Introduction

The Key Stone Project (KSP) VLBI Network consists of the four stations at Kashima (Ibaraki),

Koganei (Tokyo), Miura (Kanagawa), and Tateyama (Chiba). The geographic locations of these

four stations axe shown in Figure 1.

/ 36iN30iN

35 k

TATEYAMA

139iE 1401E 141 iE

1301E 14_i E 150iE

Figure 1. Geographic locations of four Key Stone Project network sites.

Each station is equipped with an ll-m diameter antenna. Kashima, Koganei, and Tateyama

stations are connected with the real-time VLBI system while the Asynchronous Transfer Mode

(ATM) network to Miura station became unavailable in May 1999. Since the correlation processing

of the tape-based VLBI data takes longer than the real-time VLBI system, the frequency of the

VLBI observations at Miura station was decreased from every two days to every six days since

May 1999. Observation data rate is 256 Mbps since October 1998.

92 2000 IVS Annual Report
Kashima Space Research Center, Communications Research Laboratory Key Stone Project VLBI Stations

2. Activities

Table 1 lists the number of successful VLBI sessions performed at each station during the

period between March 1999 and December 2000.

Table 1. Number of successful VLBI sessions performed at each station.

Station names Number of successful sessions

Koganei 398

Kashima 391

Miura 123

Tateyama 394

The number of VLBI sessions performed with the Miura station is smaller than the other

three stations since the Miura station has participated only in the tape-based VLBI sessions which

were performed every six days since May 1999. Considering that the total number of days during

the period is 672 days, the other stations were performing VLBI observations about 60% of the

time. The reason why the number of VLBI sessions exceeded 50% by about 60 days was because

daily VLBI sessions were performed with four stations in March 1999 and with the three stations

except Miura station between July 22 and November 11, 2000. The daily VLBI sessions were

performed in March 1999 to obtain continuous VLBI data before the ATM network link to the

Miura station was terminated in May 1999. The other daily VLBI sessions from July 22, 2000

were performed to follow the unusual site motion of the Tateyama station due to the volcanic

and seismic activities near the Miyakejima and Kozushima Islands [1]. Both of these attempts to

perform daily continuous VLBI observations for such a long period were successful and valuable

data were obtained. These achievements demonstrated how robust the four KSP VLBI Network

stations are and the high reliability of the automated observation and data processing systems.

3. Future Plans

It was planned to terminate the operations of the Tateyama and Miura stations in September

2000 since the project was originally started as a five-year project. However, unusual site motions were detected for Tateyama and Miura stations in July 2000 and the operations of these

two stations were extended. The operation of the Miura station was extended for three months

and the operation of the Tateyama station was extended more than one year. The last VLBI

session with the Miura station was completed January 5, 2001. The antenna and the observation

facilities of the Miura station will be transported to the Tomakomai Experimental Forest of the

Hokkaido University (Figure 2). On the other hand, the antenna and the observation facilities of

the Tateyama station will be transported to the campus of the Gifu University in 2002. Both of

these stations will be used for geodetic and astronomical VLBI observations in the future.

References

[1] Yasuhiro Koyama, Ryuichi Ichikawa, Mamoru Sekido, Tetsuro Kondo, Hitoshi Kiuchi, Jun Amagai,

and Taizoh Yoshino: Site position displacements due to the seismic and volcanic activities in the area

2000 IVS Annual Report 93
Key Stone ProjectVLBI Stations Kashima SpaceResearchCenter,Communications ResearchLaboratory

of Izu islands detected by the KSP VLBI Network, CRL IVS Technology Development Center News,

No. 17, pp.8-10, November 2000.

_q

Figure 2. Geographic location of the Tomakomai Experimental Forest of the Hokkaido University. The

antenna and the VLBI observation facilities of the Miura station will be transported to the site in 2001.

94 2000 IVS Annual Report
National Earth Orientation Service

LoO O° j

,7

Kokee Park Geophysical Observatory

Kokee Park Geophysical Observatory

Clyde A. Cox

Abstract

This report summarizes the technical parameters and the technical staff of the VLBI system located

on the Island of Kauai. Included is an overview of the VLBI activities from March, 1999 through the

end of December 2000.

1. KPGO

Kokee Park Geophysical Observatory first participated in VLBI operations as part of the

GAPE experiments in 1984. At that time the station was part of the STDN (Satellite Tracking

Data Network). The 9-m system was modified by installing a focal point receiver, hydrogen maser,

data acquisition terminal, tape drive and computer system. This was operational for the summer of

1984. The system was removed after the GAPE '84 experiments and reinstalled again for summer

of 1985. It wasn't until 1986 that we became a continuous participant in VLBI operations.

In October 1989 NASA phased out the STDN operation on Kauai and the station was transferred to the Crustal Dynamics Project at Goddard Space Flight Center. The station started

weekly operation for the U.S. Naval Observatory as part of the NAVNET network.

Early in 1992 construction of USNO's present 20-meter antenna was started. The foundation

work was completed in August 1992 and the structure was started in September just as Hurricane

"Iniki" struck on September 11, 1992. Installation was completed in 1993 and first light was in

June 1993. Later the use of the 9-meter system was discontinued.

A Mark IV system was planned to be installed during 1999. However delays have the installation

date into the year 2001.

In July 2000 Kokee Park started daily (Monday through Friday) participation in the Intensive

sessions for NEOS.

Figure 1. Kokee Park Geophysical Observatory 20m

antenna.

2000 IVS Annum Report 95
Kokee Park Geophysical Observatory National Earth Orientation Service

Table 1. Location and Addresses of Kokee Park Geophysical Observatory

Longitude 159.665 ° W

Latitude 22.126 ° N

Kokee Park Geophysical Observatory

P.O. Box 538

Waimea, Hawaii 96796

USA

2. Technical Parameters of the VLBI System at KPGO

The receiver is of NRAO (Green Bank) design (dual polarization feed using cooled 15 K HEMT

amplifiers). The DAR rack and tape drive were supplied through Green Bank. The antenna is of

the same design and manufacture as ones at Green Bank and Ny/_lesund.

The technical parameters of the radio telescope are summarized in Table 2.

3. Technical Staff of the VLBI system at KPGO

The staff at Kokee Park consists of six people who are employed by Honeywell-TSI under

contract to NASA for the operations and maintenance of the Observatory.

4. Status of KPGO

Kokee Park has participated in many VLBI experiments since 1984. We started observing

with GAPE and are continuing until now with NEOS and CORE. We also participate in the RDV

experiments.

We averaged 1.5 experiments per week during calendar year 2000 and are increasing to an

average of 2 weekly experiments of 24 hours with daily Intensive experiments during year 2001.

Kokee Park also hosts other geodetic measurement systems, including PRARE, a DORIS beacon, and a Turbo-Rogue GPS receiver. Kokee Park is an IGS station. These thrce systems are

shown in Figure 2.

Figure 2. Kokee Park also hosts other systems; PRARE, DORIS Beacon, and IGS (Turbo-Rogue).

96 2000 IVS Annual Report
National Earth Orientation Service Kokee Park Geophysical Observatory

Table 2. Technical parameters of the radio telescope at KPGO.

Parameter Kokee Park

owner and operating agency

year of construction

radio telescope system

receiving feed

diameter of main reflector d

focal length f

f/d

surface contour of reflector

azimuth range

azimuth velocity

azimuth acceleration

elevation range

elevation velocity

elevation acceleration

USNO-NASA

1993

Az-E1

primary focus

20m

8.58m

0.43

O.020inchesrms

0...540 °

2°/s

l°/s 2

0... 90°

2°/s

l°/s 2

X-band 8.1 - 8.9 GHz

(reference u = 8.4GHz_ _ = 0.0357m)

40K

900 Jy

45.05 dB / K

0.406

2.2 - 2.4GHz

40K

665 Jy

35.15 dB/K

0.539

Tsys

SSEFD(CASA)

G/T

S-band

(reference u = 2.3GHz 7)_ = 0.1304m)

Tsys

SSEFD(CASA)

G/T

VLBI terminal type VLBA

recording media thin-tape only

Field System version 9.4.18

5. Outlook

Mark IV equipment is expected to be installed during the first part of this calendar year.

Increased operations are expected with the coming of CORE.

2000 IVS Annual Report 97
Matera CGS VLBI Station

' ooZ6O q,,:, , c,

5ssC: fi

Agenzia Spaziale Italiana

Matera CGS VLBI Station

Giuseppe Colucci, Domenico De1 Rosso, F?ancesco Vespe

Abstract

This report summarises the VLBI activities performed at the Matera VLBI station.

overview of the technical characteristics of the system and some staff addresses will be given.

Also an

1. General

The Matera VLBI station is located at the Italian Space Agency "Centro di Geodesia Spaziale"

(CGS) near Matera, a small town in the South of Italy. The "Centro di Geodesia Spaziale" (CGS)

Figure 1. The Matera "Centro di Geodesia Spaziale" (CGS)

of the Italian Space Agency came into operation in 1983 when a Satellite Laser Ranging SAO-1

System was installed at CGS. Fully integrated in the worldwide network, SAO-1 is in continuous

operation since 1983, providing high precision ranging observations of several satellites. The new

Matera Laser Ranging Observatory (MLRO), the most advanced Satellite and Lunar Laser Ranging

facility in the world, installation is in progress. CGS hosted also 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 radiotelescope. Since then, Matera performed 377 experiments up to December

2000. In 1996 the receiver was upgraded to standard wideband and at the end of 1999 a Mark IV

formatter and decoder were installed by MIT Haystack.

98 2000 IVS Annual Report
Agenzia Spaziale Italiana Matera CGS VLBI Station

In 1991 we started GPS activities, participating in the GIG 91 experiment installing in Matera

a permanent GPS Rogue receiver. In 1994 six TurboRogue SNR 8100 receivers were purchased in

order to create the Italian Space Agency GPS fiducial network (IGFN). At the moment 10 stations

are part of the IGFN and all data from these stations, together with nine other stations in Italy,

are archived and made available by the CGS WWW server GeoDAF (http://geodaf.mt.asi.it).

At the beginning of 1996 the operations of the Precision RAnge and Range-rate Experiment

(PRARE) started. Thanks to the colocation of all precise positioning space based techniques

(VLBI, SLR, GPS and PRARE), 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 also in remote sensing activities for present and future

missions (ERS-1, ERS-2, X-SAR/SIR-C, ENVISAT).

2. Technical/Scientific

The Matera VLBI antenna is a 20-meter dish with a cassegrain configuration and AZ-EL

mount. The AZ axis has ±270 degrees of available motion. The slewing velocity is 2 deg/sec for

both AZ/EL axis.

The technical parameters of the Matera VLBI antenna are summarised in Table 1.

The Matera Time and Frequency system is composed of three frequency sources (two Cesium

beam and one H-maser standard) and three independent clock chains. The EFOS-8 H-maser from

Oscilloquartz is used as frequency source for VLBI.

The control computer is a SWT Pentium/233 PC running Linux and FS version 9.4.13.

Table 1. Matera VLBI Antenna Technical Specifications

Input frequencies

Noise temperature

at dewar flange

IF output frequencies

IF Output Power with 300 K

at the input flange

Gain compression

Image rejection

Inter modulation products

T_ys

SEFD

s/x

s/x

s/x

s/x

s/x

s/x

s/x

s/x

s/x

2210 MHz to 2450 MHz / 8180 MHz to 8980 MHz

<20 K

190 MHz to 430 MHz / 100 MHz to 900 MHz

0.0 dBm to +8.0 dBm

<1 dB at +8 dBm output level

>45 dB within the IF passband

At least 30 dB below each of 2 carriers

at an IF output level of 0 dBm per carrier

 5/65 g

8OO/90O Jy

3. Staff

The list of the VLBI staff members of Matera VLBI station is provided in Table 2.

2000 IVS Annual Report 99
MateraCGSVLBIStation Agenzia Spaziale Italiana

Table 2. Matera VLBI staff members

Name Agency Activity E-Mail

Dr. Giuseppe Bianco ASI CGS Director bianco@asi.it

Dr. Francesco Vespe ASI CGS Geodesy Manager vespe@asi.it

Domenico Del Rosso Telespazio Operations Manager domenico_delrosso@telespazio.it

Luciano Garramone Telespazio Station Engineer garramone@asi.it

Giuseppe Colucci Telespazio VLBI contact colucci@asi.it

4. Status

The Matera station is involved in CORE-A and EUROPE experiments. Table 3 summarizes the

experiments performed during 2000. Figure 2 shows the summary of acquisition up to December

2000 in terms of hours of acquisition.

1200.0 .......

't000.O

_'° [ •

(_00.0

40G.O •

_o II _ •

o_ m.ll. .11LII,

Figure 2. Summary of acquisition from May 1990 to December 2000

Table 3. Summary of experiments

Month

January

February

March

April

May

June

July

August

September

October

CORE-A EUROPE

November 2

December 2

TOTAL 19 6

NEOSIRDVIESO

1 1

1

1

1

1

1

16 I1

100 2000 IVS Annual Report
Agenzia Spaziale Italiana Matera CGS VLBI Station

5. Outlook

During the current year (2001 a check of the antenna efficiency is planned.

References

[1] G.Colucci, D.Del Rosso, L.Garramone: "Matera VLBI Station Report on the Operational and Performance Evaluation Activities from January to December 1999", available on-line at this address:

http://geodaf.mt.asi.it/GDHTL/matera.html

2000 IVS Annual Report 10i
Medicina VLBI Station

2ooi_oo

76 0

Istituto di Radioastronomia, Stazione di Medicina

Medicina Station Report

Alessandro Orfei, b-]ranco Mantovani

Abstract

In the following we will briefly summarize the relevant events, changes and upgrading at the two

radio astronomy stations of Medicina during the recent past.

1. Maintenance

a) An inchworm motor broke. It was replaced with an EVN (spare part) inchworm.

b) A new degausser (model VglM) has been bought.

c) The Haystack dry air kit was mounted on the tape recorder.

d) Both the write and read heads were replaced in 1999. The new heads are triple cap made by

Spin Physics.

e) The latest version of the Field System (9.4.14) was installed.

f) The 8-16 MHz bandbass problem was fixed with the substitution of VC components.

g) The 0.125 MHz and 0.5 MHz filters were added to the first 8 VCs, which now have the full set

of filters.

2. Telescope Upgrading

a) Medicina will be a "thin tape only" station from September 2000 on for astronomical observations.

b) The frequency agility project was slowed down; the main reasons for the delay are that the active

surface project for the Noto antenna, which will allow the telescope to operate at 43 GHz with

good sensitivity, was started, and that unexpected problems occurred with the grout supporting

the azimuth rail of the antenna, which needed to be replaced.

c) The active surface project consists of a movable system for the primary mirror panels of the

antenna to recover the gravity deformations of the surface. The components that are required

are in mass production right now. The design for the network of electro-mechanical actuators is

ready. The control software is almost completed. For information about the installation see the

Noto Station report next.

d) The grout supporting the rail was changed. A new approach was followed: the rail is placed on

a continuous bed of steel plates (50mm thick); the interface between the foundation and plates is

made by a reinforced fibers grout.

102 2000 IVS Annual Report
Istituto di Radioastronomia, Stazione di Medicina Medicina VLBI Station

3. Geodetic VLBI Observations in year 2000

Project Date

EUROPE-53

VLBA19

EUROPE-54

VLBA20

EUROPE-55

EUROPE-56

VLBA21

VLBA23

VLBA24

EUROPE-60

27 January

31 January

07 February

13 March

16 March

15 May

22 May

23 October

04 December

06 December

2000 IVS Annual Report 103
Noto VLBI station

2__c)o2_ooi<>-1 S b f

lstituto di Radioastronomia del CNR, Stazione VLBI di Noto ff_Z_-

Report from the Noto VLBI Station

G. Tuccari, C. Stanghellini

Abstract

This report describes recent, current and planned changes at the Noto VLBI station. The report

also summarizes Noto's 2000 geodetic activities.

Figure 1. The Noto antenna.

1. Changes at the Noto VLBI station

The MKIV formatter is now used as the standard in the VLBA4 Terminal. This avoids manually switching between VLBA and MKIV modes, which requires connecting different cables and

changing the setup in the Field System. Such modification is to be considered as a simplification

in the station operations, improving the reliability.

The realisation of a new version of TTY distributor to be used in the VLBA4 environment was

completed. It has been produced for Cambridge, Effelsberg, Noto, Shanghai, Torun, Metsahovi,

Yebes, Pico Veleta, and three units for Haystack.

The assembly of the headstack boards for the Noto recorder and a second station is in progress

and at completion the recorder will be upgraded as a full two heads recording system for 1 Gbit/s

recordings.

The upgrade program (SXL-UHF receiver construction) was delayed, due to the delay in the

CSELT production of the L and S/X band feed systems. Production order was placed before the

104 2000 IVS Annual Report
Istituto di Radioastronomia del CNR, Stazione VLBI di Noto Noto VLBI station

end of 1999. The feeds are in construction and some parts realised. The third and last module of

the receiver is completed, while the other two have been successfully tested. The cryogenic section

is in construction. A new software environment is under development to drive the complex system,

operating on the full set of receivers, in primary and secondary focus.

The active surface for the Noto antenna, developed by the Medicina staff, will be installed in

the last quarter of 2001. The necessary parts are in the acquisition stage and will be assembled in

Medicina then transferred to Noto.

A Heybond bonding machine has been acquired. A study of cryogenic low noise amplifier was

undertaken that should produce L, S, C band front-end as first result.

Methods to realise microwave vacuum windows are under evaluation, and a dedicated oven has

been acquired to cure the foam.

2. Geodetic Experiments in Noto during 2000

Geodetic experiments in Noto need to deal with the heavy scheduling of the antenna for VSOP

experiments: nevertheless the Noto antenna is involved in Europe experiments and could participate in a couple of CORE B experiments. Problems at the correlators also caused the delay and

sometimes the deletion of planned geodetic observations.

During 2000 the following geodetic experiments have been done:

Table 1.

EURO53 27 Jan

EURO54 07 Feb

EURO56 15 May

EURO57 07 Aug

EURO58 04 Sep

CB801 12 Jan

CB802 02 Nov

2000 IVS Annual Report 105
_.., f* .. .-i + :

Ny-Alesund 20 metre antenna

200Z-oOU ,

555"7 z

Geodetic Institute, Norwegian Mapping Authority

NYAL Ny-Jllesund 20 Metre Antenna

Helge G. Digre, Hans-Peter Plag

Abstract

In the report period (April 1999 - December 2000), the 20 m VLBI antenna at the Geodetic

Observatory at Ny-Jdesund has participated in VLBI experiments at the scheduled level. Several

maintenance and repair activities were required and changes in station stal_ have occurred. Considerable

work has been devoted to footprint studies including classical surveys and GPS campaigns on the local

control network.

1. Introduction

"- ', .... o

t_?.._ __ :> Ny Aids,Jr, d

Figure 1. Location of the infrastructure of the Geodetic Observatory in Ny-Alesund. 1: VLB] antenna; 2:

SATREF (real-time GPS), CHAMP (low-latency GPS) and GLONASS receivers: 3: IGS receivers NYAL

and NYA1 as well as cryogenic gravimeter and absolute gravity point; 4: Relative LaCoste-Roniberg Earth

tide gravimeter, also seismic observatory; 5: tide gauge; 6: Tide gauge bench niark; 7: DORIS" 8: Water

vapour radio meter and balloon sounding. Scale is approximately 1:25000 and North is up. Pi'(>lii [3].

The Geodetic Observatory at Ny-/_lesund is located at 78.9°N and 11.9°E at the west _:<)a_l, of

Spitsbergen, Svalbard. Over recent years, the observatory has developed into a fundanicntai g(_()(letic station with co-location of most of the space-geodetic techniques and additional geophysical

instruments (see Figure 1). The VLBI antenna participates in experiments within VLBA/RDV,

CORE-B, VLBI-Europe, and NEOS. The different techniques are tied together by means (if a control network which is periodically re-surveyed both with classical methods and GPS. This so-called

inner network is embedded in an outer control network covering roughly an area of about 50 km

in diameter, which is observed in annual GPS campaigns. For a more detailed description of the

106 2000 IVS Annual Report
Geodetic Institute, Norwegian Mapping Authority Ny-/_lesund 20 metre antenna

geodynamic setting and other observational activities at the observatory, see e.g. [1]. For technical

details of the VLBI antenna, see [2].

The observatory participates in the Large Scale Facility (LSF) Ny-/_lesund 1 In the context

of this EU-funded programme, 11 research projects have been carried out in the report period at

the observatory with participants from several European VLBI groups. For more details, see [3].

2. Staff Related to the Space-Geodetic Observatory in Ny-]klesund

Table 1. Staff related to the operation of the VLBI in Ny-._lesund.

Honefoss: Section Manager: Rune I. Hanssen

Station responsible, H0nefoss: Svein Rekkedal

Ny-/_lesund: Station manager:

Permanent staff:

Rotation group:

6 months contract

Helge G. Digre

David C. Holland

Roar Kihle (05.1999 - 04.2000)

Kari Buset

Bente R. Andreassen (only one shift)

Kjetil Pdngen (only two shifts)

Tom Pettersen

Nils Petter Rognstad (10.2000-03.2001)

The "permanent" staff at the observatory is employed on the basis of renewable one-year

contracts. Expecting an increase in experiment activity for 2000, an extra person was employed

on a yearly contract in May 1999 (Table 1). With the lack of correlator capacity reducing activity

in 2000, this contract was not renewed.

The four members of the rotation group have or had permanent positions at the Norwegian

Mapping Authority (NMA). The contract period is three years ending in June 2001. Each member

spends 3 months at a time in Ny-/_lesund. It was planned that each member would serve a total

of 9 months at the observatory. However, one member resigned from NMA, while another one is

no longer available due to internal change of duties. Therefore, a new staff member was employed

on a temporary basis to fill the gap.

3. Status of the VLBI Antenna in Ny-/_lesund

The overall operation of the VLBI antenna in the report period has been smooth, though

some periods posed more problems than normal. The antenna participated successfully in 77

experiments, while for two experiments participation was unsuccessful due to technical problems.

A number of more or less routine upgradings, maintenance and repair operations were carried

out. For example, the maser had its scheduled bi-annual maintenance check in June 1999. The

field system is now FS 9.4.17. The TAC system has been upgraded to a CNS TAC with monitor,

counter and computer. The azimuth gears on the antenna have been checked and repaired. The

azimuth brakes have been renovated and are working again. The Peltier elements on the antenna

were checked in summer 2000 and worn fans were replaced. In autumn, both Peltier power supplies

had to be repaired after failures. In the helium system, the cold head was replaced in June 1999,

1see http://www.npolar.no/nyaa-lsf/.

2000 IVS Annual Report 107
Ny-/klesund 20 metre antenna Geodetic Institute, Norwegian Mapping Authority

and the compressor in November 2000.

A number of more serious crashes and break-downs happened, which partly are due to a more

rapid ageing of parts in the severe weather conditions at the observatory. Problems were caused by

fading and eventually disappearing antenna signals. After eliminating the connectors as a source

for these errors, it was found that all the signal cables were broken or damaged in the elevation

link. The cables have been repaired temporarily by cutting away the bad pieces of cable and

replacing them by new pieces of cable.

When one of the running encoders caused increasing problems, it was discovered that the spare

encoder was defective. The spare encoder returned from repair after 3 months just in time to

replace one of the working encoders, which died totally. Recently, there were severe problems in

getting the encoder signal. The source for these problems was located in a short circuit in one

cable out of the encoder.

The crash of a rather new hard disk in December 1999 happened at the worst possible time,

resulting in the setting up of a new back-up procedure for the disks.

In the often severe weather conditions, safety of staff during operations on the antenna requires

particular attention. In particular, a safety report was written in spring 2000, and equipment has

been acquired to make the manhole in the antenna safer.

The problem of radio interference (RFI) appears to be mounting even at the remote location of

Ny-/_lesund. The VLBI antenna is sheltered from RFI from geo-stationary satellites by mountains

to the south. However, local activities of other research institutes and the operator of the research

town are increasingly in conflict with the condition of radio-quietness imposed on Ny-Alesund.

For example, the operator of Ny-/_lesund, Kings Bay, operated a local wireless LAN-net in the

2.4 GHz area from February to June 2000. NMA is actively working to protect the important

environmental quality of radio-quietness by exploiting legal regulations as well as regular contacts

to all other groups active in Ny-/_lesund.

4. Site surveys and other activities

In summer 1999, a small instrument house was built above the existing stable platform previously used for absolute gravity measurements. This house was required for the superconducting

gravimeter (SCG), which was installed there in September 1999 by Professor Tadahiro Sato, Earth

Rotation Division, National Astronomical Observatory, Japan. Daily operation of the instrument

is provided by the station staff, while major maintenance work such as annual refill of liquid helium

is carried out by visitors of the Japanese team. After some minor initial problems, the instrument

is running smoothly and providing high-quality data. The data is accessible to the Japanese team

via Internet.

Prior to the building of the house, two GPS receivers (SATREF and NYA1) were operated on

steel masts mounted on the gravity platform. For the time being, NYA1 is continuing to operate

there. In addition, a semi-permanent receiver was set up at one of the pillars in the control network

in order to monitor any changes in NYA1 due to the building activities.

In 1999, a roof was built on an existing foundation about 300 m to the north-west of the VLBI

and IGS site (No. 2 on Fig. 1). This new construction provides an appropriate environment for

continuous GPS sites. In the centre of the large ground floor room, there is a 4x4x4-meter pedestal

with concrete walls, well insulated to reduce any temperature effects. Inside the pedestal, a data

room is located, which is connected to the net in the main building by a fibre optic cable. On top

108 2000 IVS Annual Report
Geodetic Institute, Norwegian Mapping Authority Ny-._lesund 20 metre antenna

of the pedestal, a stable tower reaches through the roof as the monument for GPS antenna.

Among others, a GPS receiver of the GFZ, Potsdam, has been installed at this new location,

which contributes to the low-latency network supporting the CHAMP mission.

Several LSF projects provided contributions relevant to the IVS goals. In particular, a GPS

antenna was installed permanently on the VLBI antenna. Whenever the antenna is in Zenith

position, the GPS data can be used to monitor the tie between VLBI and GPS directly. The

VLBI antenna has been surveyed with classical methods twice, providing accurate coordinates of

the antenna reference point. The inner control network was reobserved with classical techniques

by visiting groups in 1999 and by NMA staff in 2000. Absolute gravity measurements were carried

out in summer 2000 providing a calibration of the SCG and, additionally, a remeasurement of

gravity after initial measurements in 1998. NMA carried out GPS campaigns on the inner and

outer network in 1999 and 2000. Together with the campaign on the outer network in 1998, the

analysis results show a stability of the network on the 1 mm/yr level, except for one pillar which

apparently is moving [3].

5. Outlook

In 2001, the observatory will participate in the CORE-3 experiments as well as other experiments such as the VLBI Europe once. A number of repairs, maintenance, and upgrades are

planned. For example, the bi-annual maintenance of the maser is due in summer 2001. The FTS

8400 will be retired and shipped back to Honeywell.

The repair of the azimuth 1 antenna brake was temporary and some parts need to be replaced.

The elevation brakes need to be checked, and all signal cables will be replaced in the summer.

A re-routing in the elevation link area will be considered. The new encoder will arrive in spring.

The azimuth encoder then has to be sent to the manufacturer for check. The formatter will be

upgraded to be able to handle the CORE-3 experiments. The Field System will be upgraded to

the next Linux version.

Concerning station staff, the experience made with the rotation group arrangement will be

evaluated. A decision concerning future employment schemes for the staff at the observatory will

be made on the basis of this experience.

References

[1] Plag, H.-P., 1999: Measurements of vertical crustal motion in Europe by VLBI. Station report for Ny-

/_lesund, Norwegian Mapping Authority. In Schliiter, W. and Hase, H. (eds.): Proceed. 13-th Working

Meeting of European VLBI for Geodesy and Astrometry, Viechtach/Wettzell, February 12-13, 1999.

Bundesamt fiir Kartographie und Geodiisie, Frankfurt, 65-77.

[2] Digre, H. G., Rekkedal, S., Holland, D. C., Hanssen, R. I. and Plag, H.-P., 1999: NYAL Ny-_lesund

20-metre antenna. In Vandenberg, N. R. (ed.): International VLBI Service for Geodesy and Astrometry

Annual Report 1999. NASA, Greenbelt, MD, USA, 80-84.

[3] Plag, H.-P., Bockmann, L., Kierulf, H. P., Kristiansen, O., 2001: Foot-Print Study at the SpaceGeodetic Observatory, Ny-/_lesund, Svalbard. In Tomasi, P., Mantovani, F., and Perez-Torres, M.-A.

(eds.): Proceedings of the 14th Working Meeting on European VLBI for Geodesy and Astrometry,

Castel San Pietro Terme, Sept. 8 - Sept. 9, 2000. In press.

2000 IVS Annual Report 109
• . : J

German Antarctic Receiving Station O'Higgins

3 _j

J

Bundesamt fiir Kartographie und Geodgsie

German Antarctic Receiving Station O'Higgins

Andreas Reinhold, Reiner Wojdziak

Abstract

Ten VLBI sessions of 24 hours have been observed successfully during the last three Antarctic

campaigns. A H-maser failure stopped the last experiment. The local ties have been controlled.

Modifications of the timing system by a TAC have been done. The collocated geodetic systems (GPS,

PRARE, etc.) continued to provide data. The upgrade to MkIV is planned for the spring campaign

2001.

1. Observation Campaigns at O'Higgins 1999/2000

During the period from March 1999 to December 2000 three VLBI observation campaigns

were organized at the German Antarctic Receiving Station (GARS) O'Higgins by staff members

of BKG (Federal Agency for Cartography and Geodesy) in cooperation with the colleagues from

DLR (German Aerospace Center - responsible for SAR Data Acquisition).

Figure 1. Schmitt Island with the Chilean base and the annexed German station O'Higgins during the

Antarctic spring time October 1999.

During the three campaigns at O'Higgins altogether ten 24-hour VLBI experiments were carried out. The observations were mainly focused on the special IVS CORE O'Higgins (COHIG)

experiments, namely the experiments COHIG 7 to COHIG 13. In addition the O'Higgins telescope

was involved in IRIS South 144, 147 and 155 experiments. Due to a H-maser failure the IRISS 155

110 2000 IVS Annual Report
Bundesamt fiir Kartographie und Geod_isie German Antarctic Receiving Station O'Higgins

experiment had to be interrupted after about 14 hours of observation. The external ion pump of

the maser vacuum system was broken and the H-maser lost lock.

All the observed experiments could be correlated successfully and the data were used in various

analysis for station position determinations and Earth Orientation Parameter evaluations.

At the end of 1999 first experiments were conducted with the JARE station Syowa, which is

the second VLBI station in Antarctica.

2. Status of VLBI and Other Geodetic Equipment

There were no major changes in the VLBI equipment of the O'Higgins station since 1999. The

main components of the VLBA/MkIII equipment worked stably and with respect to the special

Antarctic conditions with sufficient quality.

Only the station timing system had to be modified. Since November 1999 the station sync is

realized by a TAC-GPS tracking system. The Cs-atomic frequency standard HP5061 failed. It is

planned to replace it by a new cesium frequency standard HP 5071 during the year 2002.

In January 2000 the survey of the antenna reference point was repeated. No changes in the

eccentricities between the various systems at O'Higgins station were detected.

Figure 2. The VLBI Antenna at O'Higgins, in front the GPS-Antenna and the PRARE ground unit

protected by different radomes (October 1999).

2000 IVS Annual Report 111
German Antarctic Receiving Station O'Higgins Bundesarat fiir Karto_raphie und Geod_ie

The additional geodetic systems collocated in O'Higgins are working continuously. Sometimes

interruptions in the continuous data acquisition occurred - especially during those periods when

the station is unmanned.

The permanent GPS tracking system, a TURBO ROGUE, is included in the IGS network. The

data and additional information can be found under the ID character OHIG and under the IERS

DOMES No. 66008M001.

The PRARE ground unit at O'Higgins can be found under COSPAR No. 7710.

Since February 1999 a new tide gauge system provides continuously data of the variations of

the sea surface level around O'Higgins.

3. Outlook

The upgrade of the O'Higgins station to a VLBA/MkIV station including the thin tape equipment and the field system 9.xx is in progress.

All the necessary racks, parts, computers and tools are shipped to the station and will arrive

there during the first weeks of the year 2001.

It is planned to install and to test all the new systems at the station during the first campaign

2001 in January/February. The first experiments employing the new equipment are scheduled for

the weeks 7 and 8 of the year 2001.

Regarding the installation of TIGO in Conception (Chile), it has to be pointed out that the

importance of O'Higgins VLBI station (GARS) as a reference point close by will increase and

common observations will improve the results tremendously. Therefore, it is planned to continue

the campaigns in the next years, if possible twice a year.

112 2000 Ivs Annual Report
/ /

Onsala Space Observatory (OSO)

2..50 56 r!.i '0

5 55"7o!

Onsala Space Observatory (_SO) I

The IVS Network Station Onsala Space Observatory

Riidiger Haas, Gunnar Elgered, Sten Bergstrand, Lubomir Gradinarsky, Borys Stoew,

and Karl-like Johansson

Abstract

We give a short overview of the status of the Onsala Space Observatory in its function as an IVS Network

Station. The activities during 1999 and 2000, the current status, and future plans are described.

1. Introduction

The IVS Network Station at the Onsala Space Observatory (OSO) has been described to some

extent in the last IVS annual report [1]. There are only minor changes in the technical setup of

the station. The staff associated with the IVS Network Station remained the same as reported in

[1] with the exception that Rune BystrSm left the observatory.

2. Geodetic VLBI observations

The observatory has been involved in the geodetic VLBI-series CORE-B, CORE-3, EUROPE

and RDV during 1999 and 2000 [2] (see Table 1). Two experiments have been lost due to pointing

problems and due to encoder problems, respectively. During one experiment we had tape recording

problems due to usage of wrong recorder vacuum for some period. The weak $1 channels during

two CORE-3 experiments were due to a problem in the formatter firmware with the 1-bit, 1:2

fanout observing mode. A PROM with the necessary firmware update to solve this problem was

shipped to us by Haystack Observatory and was installed successfully during November 2000.

Table 1. Geodetic VLBI experiments at the Onsala Space Observatory during 1999 and 2000.

Exper. Date Remarks (problems) Exper. Date Remarks (problems)

EURO47 990201

RDV13 990308

RDV14 990415

EURO48 990426

RDV15 990510

CB602 990519

RDV16 990622

EURO49 990629

CB603 990630

RDV17 990802

EURO50 990816

CB604 99O823

CB605 991004

EURO51 991011

EURO52 991013

CB606 991018

high parity errors

high parity errors

tape speed problems

lost due to pointing problem

tape speed problems

RDV18 991220

RDV19 000131

EURO53 000127

EURO54 000207

RDV20 000313

EURO55 000316

EURO56 000515

C3001 000712

EURO57 000807

C3002 000823

EURO58 000904

C3004 001018

C3005 001101

EURO59 001207

C3006 O01213

high parity errors on one tape

formatter jump

high parity errors

some recording problems

lost due to encoder problems

two bad tracks

channel S1 weak

channel S1 weak

2000 IVS Annual Report 113
Onsala Space Observatory (OSO) Onsala Space Observatory (OSO)

3. Monitoring the Performance of the VLBI System

The log file of each experiment is analysed in order to detect problems and fix them accordingly.

The cable delay, the difference between GPS and formatter time, the physical temperature in the

dewar for the front end HEMT amplifiers of the receivers, the measured system temperatures and

the parity errors are monitored (see figures 1 3). The monitoring of the parity errors indicates

some transient problem with tracks numbers 31-33 in recent experiments. Currently investigations

are ongoing to identify the reasons.

EURO54

. 13'51

. 12.4[

_ 12.2| ..... ":

- . • .." .. M-:-_:

.. • ". "_,. _ °.=1_,¢..

_ss

40

25

10

_ x x_

i13"5 I

t3.3 L

0 6 12 18 24

experiment time (hr)

5.4[

_.s.2t

0 6 12 18 24

experiment time (hr)

_" 70

• 40

lO

o..'.. ..... -. .

_x ×Xx×X×Xxxxxxx ×

6 12 18

experiment time (hr)

200[ ×

I × ×

I_ x "

24 0 6 12 18 24

experiment time (hr)

Figure 1. Cable delay, GPS-formatter time difference, dewar temperatures (20K station marked with crosses,

70K station marked with dots) and system temperatures (IF1 marked with crosses, IF2 marked with dots)

for EURO54 and CORE3005.

3O

28

26

24

22

_14

12

10

8

33

31

29

27

0 6 12 18 24

time (hr)

Figure 2. EURO54 parity errors. The colour code

covers 600 to 10000 parts per million (ppm), values below 600 ppm are shown in white.

0 6 12 18 24

time (hr)

Figure 3:CORE3005 parity errors. The colour

code covers 600 to 10000 parts per million (ppm),

values below 600 ppm are shown in white.

Since there have been tilting problems of the recorder heads, they had to be sent to Haystack

114 2000 IVS Annual Report
Onsala Space Observatory (OSO) Onsala Space Observatory (OSO)

Observatory for repair in early 1999. Since May 1999 no further changes were done to the head

assembly and its run time is now more than six thousand hours. In order to stabilise the recording

quality a dry air kit including humidity and temperature sensors has been installed.

Figure 4 shows daily mean values for the offsets GPS-maser and their corresponding rootmean-square (rms) scatter. Since end of February 1999 the Russian Kvarts Ch1-75 maser is used

as station clock• The data gap in December 1999 is due to problems with the monitoring computer.

The frequency of the maser has been adjusted in March 2000 and the next adjustment is expected

to be necessary in several years. Note also the drop in the rms-scatter due to the deactivation of

the selective availability (SA) for the GPS system in May 2000.

2O

O3

10

0

E

l

-10

O_ _

-_an99

I I [ [ I I I I I I

i i I I I I L i L

Apr99 Ju199 Oct99

Q)

E

, ,. • '-2 _o

". • . . ....._-. _.•'.:....a.-..it-.."-_._.v,

.:-=h.=__--'.--._:..-._'." .:-.--- ..-.=. -.: . -. ¢_

O

i , J L , i I , , L , , J --3--

Jan00 Apr00 Jul00 Oct00 Jan O_

Figure 4. GPS-rnaser daily offsets (stars, left scale) and root-mean-square scatter (dots, right scale).

4. Monitoring the telescope stability and local ties

The change of the vertical position of the telescope tower, mainly due to thermal expansion, is

monitored continuously using an invar rod measurement system [3] (see Fig. 5).

3

E

s

.E 2

O3

ec 1

E

E 0

cO

O3

C3

-2

1996 1997 1998 1999 2000 2001

Figure 5. Invar measurements of vertical height of the telescope tower (bottom curve left scale) and mean

temperature in the concrete wall of the foundation (top curve, right scale).

2000 IVS Annual Report 115
Onsala Space Observatory (OSO) Onsala Space Observatory (OSO)

During 1999 a new VLBI-GPS local tie at OSO has been established by mounting two GPS

antennas on top of the VLBI telescope [4]. The GPS measurements are performed on a campaign

basis whenever the telescope is available for our purposes and not occupied by astronomical observations or geodetic VLBI. The results are also compared to the vertical height changes measured

with the invar rod measuring system [5].

5. Outlook

The Onsala Space Observatory will continue to participate in the observation series CORE-3,

RDV and EUROPE. For the year 2001 a total of 24 experiments is planned.

A repeated measurement of the local footprint of the Onsala site and a classical survey of the

telescope reference point are planned for spring/summer 2001. The footprint measurements will

concentrate first on the inner network with baselines of an approximate length of 1 km and then

on the outer network with baselines reaching 20 70 km.

The measurement of the vertical height of the telescope tower with the invar rod measurement

system will go on continuously and the GPS observations on top of the VLBI telescope will be

repeated at regular intervals.

References

[1] Haas, R. G. Elgered and H.-G. Scherneck, Onsala Space Observatory - IVS Network Station, In:

International VLBI Service for Geodesy and Astrometry 1999 Annual Report, NASA/TP-1999-209243,

N. R. Vandenberg (ed.), 90-93, 2000.

[2] Bergstrand, S., R. Haas, and G. Elgered, Geodetic Very Long Baseline Interferometry at the Onsala

Space Observatory 1999-2000, In: Proc. of the 14th Working Meeting on European VLBI for Geodesy

and Astrometry, P. Tomasi, F. Mantovani and M.-A. Perez-Torres (eds.), 105-106, 2000.

[3] Elgered, G., and R. Haas, Geodetic Very-Long-Baseline Interferometry at the Onsala Space Observatory

1997 1998, In: Proc. of the 13th Working Meeting on European VLBI for Geodesy and Astrometry,

W. Schliiter and H. Hase (eds.), 60 64, 1999.

[4] Bergstrand, S., R. Haas, and J. M. Johansson, A new GPS-VLBI tie at the Onsala Space Observatory,

In: IVS 2000 General Meeting Proceedings, N. R. Vandenberg and K. D. Baver (eds.), NASA/CP2000-209893, 128-132, 2000.

[5] Bergstrand, S., R. Haas, and J. M. Johansson, An independent stability check of the Onsala 20m radio

telescope using the Global Positioning System, In: Proc. of the 14th Working Meeting on European

VLBI for Geodesy and Astrometry, P. Tomasi, F. Mantovani and M.-A. Perez-Torres (eds.), 83-88,

2000.

116 2000 IVS Annual Report
Shanghai Astronomical Observatory, Chinese Academy of Sciences

t_ f_M

565705

Seshan VLBI Station

Seshan VLBI Station Report

Xiaoyu Hong, Shiguang Liang, Xinyong Huang, Wenren Wei

Abstract

The following reports the status of the Seshan VLBI station, including its facilities, personnel,

observations made during the reporting period and its future plans.

1. Introduction

The Seshan 25 meter radio telescope is an alt-az antenna run by Shanghai Astronomical Observatory (SHAO), Chinese Academy of Sciences (CAS). The telescope is located about 30 km west

of Shanghai. It is one of the five main astronomical facilities of Chinese National Astronomical

Observatories. The VLBI station is a member of the EVN, APT and IVS.

2. Facilities

2.1. Receivers

Five bands of VLBI observations are available at Seshan Station. The parameters of the

receivers are listed in Table 1.

Table 1. VLBI Receivers of Seshan Satation

Band

(cm)

18

13

6

3.6

1.3

Bandwidth Efficiency Type System temperature

(MHz) (%) (K)

1620-1680 40 Room Temperature _ 100

2150-2350 45 Room Temperature _ 100

4700-5100 58 Cryogenic 45-50

8200-9000 48 Cryogenic _ 50

22100-22600 _20 Cryogenic _110

The Seshan station is equipped with S/X dual band receivers for astrometric and geodetic

observations.

The X-band system has been upgraded to the wideband system, from 8200 MHz to 9000 MHz,

successfully last year. We will join wideband experiments this year. The test experiment C3006 has

been done on Dec. 13, 2000. The correlated results showed good quality of data. The results also

showed the large increase in SEFD's from low to high frequency. The situation will be improved.

2.2. Recording System

VLBA, MK4 (VLBA4), and $2 recording systems are available now at Seshsan VLBI station.

Upgrade of Seshan MKIV recording system had been done successfully in the end of Aug. 2000.

MKIV upgrade of Seshan station has been carried out with the great help of Team China # 2

in April, 2000. Team China # 2 was composed of six experts from Europe and US. They are Dr.

2000 IVS Annual Report 117
Seshan VLBI Station Shanghai Astronomical Observatory, Chinese Academy of Sciences

Ralph Spencer, Dr. Les Parry, Dr. Michael Wunderlich, Dr. Gino Tucarri, Dr. Chopo Ma, and

Dr. Ed Himwich.

The first fringe test experiment was done on Apr. 14 with VLBA4 rack and recorder. It failed

to find good fringes, several tracks were dead, and the parity errors of several tracks were very high

because of problems with the fiat cables of the read/write modules, bad connectors, capacitors and

soldering. The problems were solved later on.

Fringes were found in the second fringe test with VLBA and MK4 formatters on Aug. 27.

Fringes were found also on FT003 and C00C3 experiments later. Seshan MKIV participated in

experiments of EVN, NASA, VSOP, APSG etc. since the end of Aug. 2000. Many thanks to JIVE,

EVN, NASA, Team China #2, Dan Smythe, and all people who worked on our upgrade.

3. Personnel

There are some changes of the staff in Seshan station. The main staff members at Seshan VLBI

Station are listed in Table 2.

Table 2 - The main staff in Seshan VLBI Station

Name Position email address

Xiaoyu Hong Research Professor and Chief Scientist xhong@center.shao.ac.cn

Shi-guang Liang Research Professor and Chief Engineer sgliang@center.shao.ac.cn

Zhiban Qian Research Professor qzh@center.shao.ac.cn

Xinyong Huang Senior Engineer xhuang@center.shao.ac.cn

Wenren Wei Senior Engineer wwr@center.shao.ac.cn

Zhuhe Xue Senior Engineer zhxue@center.shao.ac.cn

Jiazheng He Senior Engineer jzhe@center.shao.ac.cn

Qing-yuan Fan Senior Engineer qyfan@center.shao.ac.cn

Song-lin Chen Engineer slchen@center.shao.ac.en

Xiu-ling Chen Engineer xlchen@center.shao.ac.cn

The email a(:counts for the station are: seshan@center.shao.ac.cn; vlbish@online.sh.cn.

4. Geodetic Observations

13 geodetic experiments have been run by the Seshan Station from March 1999 to the end of

2000. The experiments are listed in Table 3.

5. Future Plans

The improvement of quickly switching frequencies of Seshan station will be implemented in

this year. After that, it will be easy to switch between S/X band and L- or C- or K-bands.

The Geodetic VLBI observation plan of Seshan VLBI station for 2001 is listed in Table 4.

118 2000 IVS Annual Report
Shanghai Astronomical Observatory, Chinese Academy of Sciences Seshan VLBI Station

Table 3 List of Geodetic VLBI observations From Mar. 1999 to Dec. 2000

DATE EXPERIMENT HOUR

07-APR 1999 CORE-B502 24.0

21-APR 1999 CORE-B503 24.0

26-JUL 1999 CRF-08 25.0

28-JUL 1999 CORE-B504 24.0

01-NOV 1999 APSG05 11.0

03-NOV 1999 APSG06 25.0

04-NOV 1999 CORE-B505 24.0

29-DEC 1999 CORE-B506 24.0

12-JAN 2000 CORE-B801 24.0

26-SEP 2000 CORE-1004 06.0

02-OCT 2000 APSG7 24.0

02-NOV 2000 CORE-B802 24.0

14-NOV 2000 CORE-3006 06.0

Table 4 The Geodetic observation plan of Seshan VLBI station for 2001

DATE EXPERIMENT HOUR

05-Feb 2001 CORE-1009 24.0

05-Mar 2001 CORE-1010 24.0

26-Mar 2001 CONT-M3 24.0

27-Mar 2001 CONT-M4 24.0

28-Mar 2001 CONT-M5 24.0

16-Apt 2001 CORE-1011 24.0

14-May 2001 CORE-1012 24.0

25-Jun 2001 CORE-1013 24.0

09-Jul 2001 CORE-1014 24.0

20-Aug 2001 CORE-1015 24.0

10-Sep 2001 CORE-1016 24.0

22-Oct 2001 CORE-1017 24.0

05-Nov 2001 CORE-1018 24.0

12-Nov 2001 APSG-8 24.0

19-Nov 2001 APSG-9 24.0

03-Dec 2001 CORE-1019 24.0

2000 IVS Annual Report 119
SimeizStation

 zoo U//z

SSS-7o 

Laboratory of Radio Astronomy of Crimean Astrophysical Observatory

Simeiz Station: Geodetical Experiments and Single Dish

Observations

N. Nesterov, A. Volvach

Abstract

This report summarizes an overview of the VLBI activities during 5 years. Horizontal station

velocity was determined and estimates of its accuracy were obtained. An overview about the single

dish activity and of the stability of the station with respect to local marks is given also.

1. Observations and Data Analysis

1.1. IVS

All available dual-band geodetic MARK III VLBI observations for 21 years, from 1979.59 till

2000.72 were used in the analysis: 3058 sessions, 3005651 observations including 36 successful

sessions with participation of the station Simeiz for 6 years: 1994.48-2000.36 with 19 631 good

measurements of group delays (Petrov et al., 2000).

Simeiz station moves with respect to the Eurasian tectonic plate considered as rigid with rate

2.8 + 0.9 mm/year in the direction with azimuth 27 dog. Thorough investigation of possible

systematic effects has been done and the reliability of the estimate of the uncertainty has been

evaluated. Performance of the receivers and H-maser was examined. The stability of the station

with respect to local marks was investigated and an enhancement of inclination of the azimuthal

axis (Pisa effect) of the telescope with velocity 2(_6 per year was disclosed (see Fig.l).

The following position of the station Simeiz at the epoch 1997.0 and its rate of change in the

ITRF97 system were obtained:

X = 3D3785231.070 ± 0.006 m -_ -- 3D6.8 • 10 -10 + 0.3 • 10-1° m/sec

Y -- 3D2551207.415 ± 0.004 m 1_ -- 3D5.0 • 10-l° ± 0.4 • 10 -l° m/see

Z -- 3D4439796.360 ± 0.008 m Z -- 3D2.1 • 10 -10 ± 0.8 • 10 -l° m/sec

The details of the analysis are stated in paper of Petrov et al., 2000.

1.2. Single Dish

The antenna temperatures from ten sources were measured by the standard ON OFF method.

Before measuring the intensity, we determined the source instrumental position by scanning. The

radio telescope was then pointed alternately on the source and on the distance of 5 beamwidths

off source. The antenna temperature from a source was defined as the difference between the

radiometer responses averaged during 10 s at two different antenna positions. Depending on the

intensity of the emission from sources, we made a series of 20-60 measurements and then calculated

the mean signal intensity and estimated the rms error of the mean. The fluxes from the objects

under study were calibrated using measurements of the calibration sources Cyg-A, Cas-A, Tau-A,

Vir-A, whose flux densities are given in Mark-IV Field System Documentation (1993).

Table 1 shows measured flux densities of sources at 8 GHz as follows: column (1) - IAU source

designation, column (2) and column (3) - date and time of observations, column (4) - flux densities,

column (5) - the rms errors of the measured flux densities.

120 2000 IVS Annual Report
Laboratory of Radio Astronomy of Crimean Astrophysical Observatory Simeiz Station

100

5O

0

I I I I I I

li)

, , , , I , , , , I , , , , I , , , , I , , , , I , , , , I , , , , I

1970 1975 1980 1985 1990 1995 2000

Figure 1. Deviation of azimuthal axis of the radiotelescope with respect to the local plumb line (in arc

seconds) at different epochs.

Table 1. Single dish 8 GHz measured flux densities.

SOURCE DAT(YY.MM) TM(DD.UT) FLUX(Jy) SIGM(Jy)

0316+413

0528+134

0552+398

0642+449

1226+023

1253-055

2037+421

2145+067

2200+420

2251+158

97.09

97.12

97.09

98.02

97.09

97.09

98.02

98.04

98.06

97.08

97.08

97.09

97.12

98.02

98.02

98.02

98.02

4.931

10.668

5,149

1,685

4,999

30.294

1.622

20.303

23.474

29.651

29.668

4,898

10.661

2.344

2,355

3,406

3.417

22.4

20,9

3.3

3.1

5.2

1.9

3.3

2.7

2.5

30.5

22.3

19.2

21.2

20.9

6.2

3.8

11.2

1.1

1.4

0.7

0.9

0.5

0,3

0,9

0.8

0.5

3.7

1.4

1.6

0.7

1.0

1.3

1.3

1.7

2000 IVS Annual Report 121
Simeiz Station Laboratory of Radio Astronomy of Crimean Astrophysical Observatory

2. Discussion of Results and Conclusions

Estimates of the horizontal velocity of the radioastronomical station Simeiz were obtained using

VLBI observations carried out under geodynamics programs during 1994-2000. The complete set

of 3 million VLBI observations has been analyzed and it was found that the station moves with

respect to the Eurasian tectonic plate considered as rigid with rate 2.8 + 0.9 mm/yr in a north-east

direction. Thorough study of possible local systematic effects has been done and the reliability of

the estimate of the uncertainty has been evaluated. The stability of the station with respect to

local marks was investigated and an inclination of the azimuthal axis (Pisa effect) of the telescope

with velocity 2_.t6per year was disclosed. The estimate of vertical motion of the station 2.6 4- 3.0

mm/yr is not statistically significant.

The results of single dish S/X observations of sources used for geodesy investigations can be

then reviewed after experiment to check the consistency of data from each source.

46 °

44 °

42 °

40 °

North Anatolian fault']

-

28 ° 32 ° 36 ° 40 °

Figure 2. Motion of the station Simeiz.

References

[1] L. Petrov, O. Volvach, N. Nesterov //Astron. Let. 2000.-submitted.

[2] Mark IV Field System, Version 8.2, September 1,-1993,- Space Geodesy Program. NASA/Goddard

Space Flight Center.

122 2000 IVS Annual Report
- ,. -/i_> " ,l/

Institute of Applied Astronomy of Russian Academy of Sciences

555707

Svetloe Station

Svetloe Radio Astronomical Observatory

Sergey Smolentsey, Dmitriy Ivanov, Zinovy Malkin

Abstract

This report provides information about changes in the Svetloe Radio Astronomy Observatory status

in the period after the last IVS report.

1. Introduction

Svetloe Radio Astronomical Observatory was founded by the Institute of Applied Astronomy

(IAA) as the first station of Russian VLBI network QUASAR. Sponsoring organization of this

project is the Russian Academy of Sciences (RAS). The site is located at the Karelian Neck near

Svetloe village in about 100 km towards North from St. Petersburg. The basic instruments of the

observatory are 32-m radio telescope RTF-32 and technical systems provided realization of VLBI

observations. In addition, a permanent GPS receiver was installed at Svetloe in 1996.

During last two years Svetloe observatory regularly participated in various radio astronomy

programs including VLBI and RL VLBI observations of quasars, Sun, planets, asteroids using

recording terminal S2-RT.

Svetloe observatory participated in several regional and global geodetic projects and is a EUREF permanent station.

2. Radio telescope and VLBI equipment

The results of measurements of radiotelescope parameters (for LRP) are presented in Table 1.

Table 1. Parameters ofthe radio telescope RTF-32.

Wave band, cm SEFD Tsys, K

3.5 430 58

6 180 32

13 30O 43

Field System is now fully involved in observation, registration, and investigation process. Corrections for radio telescope deformations are determined and used for pointing.

A new automatic meteo station was installed at Svetloe in 2000. It has been manufactured

by the "Taifun" Enterprise, Obninsk, Russia, and provides measurement of temperature, pressure,

relative humidity, wind 3D velocity and direction.

Figures 1 4 show a common view of Svetloe observatory, RTF-32 radio antenna and other

equipment.

2000 IVS Annual Report 123
SvetloeStation Institute of Applied Astronomy of Russian Academy of Sciences

Figure 1. Radio telescope RTF-32.

124 2000 IVS Annual Report
Institute of Applied Astronomy of Russian Academy of Sciences Svetloe Station

Figure 2. Svetloe station: laboratory building and radiotelescope RTF-32.

t

Figure 3. R:TF-32 antenna, Trimble GPS and Javad Figure 4. Radio receivers for 3.5 and 13 cm wave

GPS/GLONASS receivers during IGEX (:ampaign. bands.

2000 IVS Annual Report 125
Svetloe Station Institute of Applied Astronomy of Russian Academy of Sciences

3. Geodetic Survey at Svetloe Observatory

104 103

101

110 106

50 m

109 108

Figure 5. Local geodetic network at Svetloe.

Local geodetic network at the Svetloe observatory includes 9 reference points (see

Figure 5): 102, 107, 108, 1(19 are ground

marks (the latter connected with a pad

for mobile systems), 101, 103, 104 are located at the roof of two story laboratory

building and designed for installation of

GPS/GLONASS receivers or conventional

geodetic units, 110 is the intersection of

radiotelescope RTF-32 axis, and 106 is intermediate mark on its foundation. GPS

receiver Trimble 4000SST is permanently

installed on the 101 mark (12350M001,

SVTL).

Since the last report several new measurements were made at the network and mutual eccentricity between marks were derived fl'om common adjustments of GPS

and conventional surveys made in 1993-

1999. Accuracy of the local geodetic network is about 2 mm and intersection of

radio telescope axis is tied to the network

with accuracy about 5 ram.

. Outlook

We plan for the near future:

• Begin experimental VLBI observations on Svetloe-Zelenchukskaya baseline (IAA observatory

Zelenchukskaya located in North Caucasus is the second station of the QUASAR network).

• Install the first two channels of the new DAS developed at the IAA.

• Install a new radio telescope control system.

126 2000 IVS Annual Report
i /

.<-- 2

National Institute of Polar Research

Y_6o Zoot-ff{:f

5 S5?a: 

JARE Syowa Station l l-m Antenna, Antarctica

Kazuo Shibuya, Shigeru Aoki, Koichiro Doi

Abstract

The Antarctic geodetic VLBI sessions with participation of Syowa Station (69.0 degS, 39.6 degE) llm S/X band paraboloid antenna continued during 1999-2000. Seven 24-hour experiments were made

each year with the University of Tasmania at Hobart 26-m antenna and the Hartebeesthoek Radio

Astronomical Observatory (HartRAO) 26-m antenna. In the year 2001, four similar experiments are

planned. Syowa antenna participated/will participate also in the CORE-OHiggins sessions.

1. Introduction

As reported in [1], regular geodetic VLBI experiments started from February 1998 at Syowa

Station (69.0 degS, 39.6 degE) by the 39th Japanese Antarctic Research Expedition (JARE-39).

The southern hemisphere VLBI sessions with participation of Syowa Station 11 m antenna, the

University of Tasmania 26 m antenna at Hobart and the Hartebeesthoek Radio Astronomical

Observatory (HartRAO) 26 m antenna, were named the SYW sessions and seven 24-hour experiments have been made in each year of 1999 and 2000. The observation system is maintained by

trained JARE wintering members. They change over at February 1 every year. We had already

6 wintered-over staffs: two for each of JARE-39 (1998 Feb. - 1999 Jan.), -40 (1999 Feb. - 2000

Jan.) and -41 (2000 Feb. - 2001 Jan.). Syowa Station is always being reformed and its overview

in February 2000 is shown in Figure 1.

Figure 1. Overview of Syowa Station in February 2000 and the antenna radome.

2. Antenna Specifications

There was no significant change to the configuration of the "mechanical system", "receiver

system", "hydrogen maser systems and time comparison", and "VLBI backend system" which

were described in the 1999 IVS Annual Report [2]. Therefore notices in the maintenance and

2000 IVS Annual Report 127
JARE Syowa Station ll-m antenna National Institute of Polar Research

changes in the operational procedure after the above report are briefly summarized. (1) Accidental

power failures occurred several times, and several modules (ACU control PC, DC power supply,

hard disk etc.) had damages. Changing to spare parts enabled uninterrupted experiments. (2)

In January 1999, HP workstation was installed to make a schedule file at Syowa Station, and

the file was transferred to the IVS Coordinating Center in order that the other two stations can

access the file. Schedule format was adjusted to the standard S2-FS9 system with the support

of the IVS Coordinating Center. (3) Test source receiving was repeated to obtain more precise

receiver performance and the revised parameters are summarized in Table 1. The tabulated values

correspond to good conditions of the air temperature above -10 degC, and they become worse as the

air temperature becomes lower. (4) Hobart antenna system was found to be affected by artificial

noise around the S-band 14th channel, so that the CDP narrow-band frequencies of the S band

were shifted 10 MHz lower than the previous one after the SYW995 (Sep. 09, 1999) experiment.

The recording rate (64 or 128 Mbits/s), channel number (8 ch) and the frequency range (2217

- 2302 MHz) were not changed. (5) One hydrogen maser set (Anritsu RH401A; 1002C) began

malfunctioning at 21 July 2000, but 1001C is operational under good conditions. The system

GPS timing receiver (Model 9000B from the TRAK Co. Ltd.) was also malfunctioning around

November 1999, but backup GPS receiver enabled us to monitor the UTC-recorder time offset

within 4 microseconds.

Table 1. Receiver-performance of the Syowa l l-m antenna.

Band Frequency (MHz) Tsys (K) Efficiency SEFD (Jy)

S 2200-2320 114 0.55 6000

X 7860-8600 128 0.53 7000

3. On-going Project

As part of JARE Earth science program titled "Study of dynamical process of the Earth by

geodesy and solid-earth geophysics", JARE-40 and-41 continued geodetic VLBI experiments at

Syowa Station after JARF_39. As compared to 48-hour experiments of SYW981 through SYW984

during JARE-39, 24-hour experiments were made by JARE-40 and -41 as summarized in Table 2.

For the year 2001, the number of the SYW experiments will be reduced to 4. Syowa Station also

participated in the CORE-OHiggins sessions. Although there were some uncertain points in the

performance of the overall Syowa system at changeover of JARE-39/-4(}, the SYW991 experiment

with Kashima (both use K4 system) gave reasonable ba,seline solution as referred to the 1990

experiment, which ascertained good performance of the Syowa system. The SYW Cxl)eriment data

are being processed at the VSOP correlator center of NAO Mitaka. The SYW981 (1998, Feb),

SYW982 (1998, May), and SYW984 (1998, Nov) data were correlated and the FITS database has

been created. However, geodetic solutions for these and the later experiments are not ol)tained

yet because of delay of the baseline analysis software adaptation for the FITS databa,_e. The

main difficulty with the VSOP correlated FITS database is deletion of time-tags during the $2-K4

copying. We are trying to solve this problem by making an $2-K4 copier which keeps the original

$2 time-tag and shifts it into the copied K4 tape, as this procedure will produce the MarkIII

database to be linked to the standard SOLVE software. Development of the K4-MarkIV copier in

128 2000 IVS Annual Report
National Institute of Polar Research JARE Syowa Station ll-m antenna

GSI enabled participation of Syowa Station in the CORE-OHiggins sessions [3].

Table 2. Summary of the SYW experiments ill the years 1999 and 2000

Code Start time Obs. hour Obs. number

SYW991 1999/Feb/17 05:00 24 h 123

SYW992 1999/May/13 06:00 24 h 172

SYW993 1999/Jul/15 08:00 24 h 163

SYW994 1999/Aug/26 08:00 24 h 180

SYW995 1999/Sep/09 08:00 24 h 189

SYW996 1999/Oct/07 08:00 24 h 199

SYW997 1999/Nov/18 08:00 24 h 220

SYW008 2000/Feb/02 10:00 24 h 183

SYW009 2000/Mar/20 08:00 24 h 215

SYW010 2000/Jul/03 08:00 24 h 182

SYW011 2000/Aug/09 08:00 24 h 175

SYW012 2000/Sep/ll 08:00 24 h 178

SYW013 2000/Oct/05 08:00 24 h 198

SYW014 2000/Nov/20 08:00 24 h 229

SYW015 2000/Dec/07 08:00 24 h 214

4. Staffs for the JARE Syowa Station ll-m antenna

• Kazuo Shibuya, Project coordinator at NIPR.

• Koichiro Doi, Liaison officer at NIPR.

• Seiji Manabe, Project coordinator at NAO Mizusawa.

• Takaaki Jike (from NAO Mizusawa), Chief operator of JARE-39 (Feb. 1998 - Jan. 1999).

• Teruhito Tanaka (from NEC), Antenna maintenance staff of JARE-39.

• Yoshihiro Fukuzaki (from GSI), Chief operator of JARE-40 (Feb. 1999 - Jan. 2000).

• Takeshi Ino (from NEC), Antenna maintenance staff of JARE-40.

• Koichiro Doi (from NIPR), Chief operator of JARE-41 (Feb. 2000 - Jan. 2001).

• Seiji Takao (from NEC), Antenna maintenance staff of JARE-41.

5. Collocated Observations

Syowa Station is located on the interior of the geologically stable Antarctic plate. It is situated

on firm bedrock without sedimentary layer. Syowa VLBI antenna was registered 66006S004 as

the IERS Domes Number, and 7342 as the CDP Number. Collocated observations by GPS (IERS

Dome Number 66006S002) and DORIS (IERS Dome Number 66006S003) are continuing. PRARE

(CDP Number 7711) stopped observations after 1997. Other geophysical instruments running are

broadband seismometer (STS-1), superconducting gravimeter (GWR TT70), pressure-type sea

level meter, fluxgate magnetometers_ etc.

2000 IVS Annual Report 129
JARE Syowa Station ll-m antenna National Institute of Polar Research

References

[1] Jike, T., Tanaka, T., Shibuya, K., Manabe, S., Tamura, Y., Sato, Kh., McCulloch, P., Costa, M.,

Nicolson, G., Quick, J. F. H., Shibata, K.M., Doi, K., Fukuzaki, Y., Jauncey, D. L. and Reynolds, J.

(1999): VLBI experiments at Syowa Station, Antarctica, in Proceedings of the International Workshop

on GEodetic Measurements by the colocation of Space Technique ON Earth (GEMSTONE), 150-156,

Communications Research Laboratory, Koganei, Japan.

[2] Shibuya, K. and Doi, K. (2000): JARE Syowa Station ll-m Antenna, Antarctica, in International

VLBI Service for Geodesy and Astrometry 1999 Annual Report, 105-109, NASA/TP-1999-209243.

[3] Fukuzaki, Y., Shibuya, K., Doi, K. and Shiba, K. (2000): VLBI experiment in southern hemisphere

terrestrial reference frame network including Syowa VLBI station, presented at the 20th Symposium

on Antarctic Geosciences 12-13 October 2000, Program and Abstracts, pll5.

130 2000 IVS Annual Report
._,___, _-,'" ,.7, _,/ ."tJ - "

Bundesamt fiir Kartographie und Geod'_sie

ZooLoo ¢/' 55s/ f

"IYanst)ortable Integrated Geodetic Observatory

Transportable Integrated Geodetic Observatory

Havo. Ha_"_'(

Abstract

This report suimnarises tile activities within the TIGO project to t)rovide a new fundamental station

for geodesy at Concepcidn, Chile. The VLBI module of TIGO will serve a.s a new IVS network station.

1. Progress in the TIGO Project

The Transportable Integrated Geodetic O1)servatory (TIG()) consists of a 6 m radio telescope

for VLBI, a 50 cm optical telescope fi)r SLR, a GPS array of four GPS permanent receivers, a

super-conducting gravity meter, a broad st)ectrum seism<>meter, meteorological sensors including a

water vapour radiometer and an ensemble <>fatomic clocks like cesium clocks and hydrogen masers

(see [1]). In 2000 TIGO was still h)(:ate<t at the site of the Fundamentalstation Wettzell, where it

was constructed and tested during the last 5 years (see Fig. 1).

Figure 1. TIGO at the Fundamentalstation \'v_ttzell 1999-2000.

During 1999 an "Announcement of Opt)ortunity" was sent worldwide to many agencies, institutions and universities which are working in geodesy or geoscience. By the deadline September

2000 IVS Annual Report, 131
Transportab!e I_ntegrated Geodetic Observatory Bundesamt fiir Kartographie und Geodgsie

30, 1999, twelve promising locations had been proposed which were inspected during November/December 1999 (see Fig. 2).

..a

9O

N}

30

0

-30

-60

-90 t

-180 -150

Proposed Sites for TIGO

J i i i i i i i i

• 7

" _ Wettzell

Bangalore : 0Q_ezon

, - l_avao

- Fortaleza ---"-'--t:mmonexa_" _

Brasilia Serpofrg Yogyakarta

Antofagasta Cprdoba

Concepmon _ Buenos Aires ,.

i I I I I 1 1 I i k

-120 -90 -60 -30 0 30 60 90 12(1 150

Longitude

180

Figure 2. TIGO sites which were proposed by interested institutions, September 30, 1999.

On January 21, 2000, the German Scientific Committee of the Research Group for Satellite

Geodesy (FGS) gave first priority to the applying Chilean consortium of Universidad de Concepcidn (UdeC), Universidad del Bio B[o (UBioBio), Universidad Catdlica de la Santisima Concepcidn (UCSC) and Instituto Geogrgfico Militar (IGM), Santiago, which offered to host TIGO at

Concepcidn. Concepeidn is the most southern location among the offers, which is of importance

for improving existing networks. The consortium could also fulfill the demand of BKG to supply

11 engineers/operators which will work under the supervision of three experts from BKG in the

operation of TIGO.

In March 2000 several sites in the surroundings of Concepcidn had been investigated due to the

microwave pollution in S- and X-band. Finally a hill about 2.5 km distance from the university

campus was defined to be the selected TIGO site (see Fig. 3, Tab. 1).

Figure 3. The selected TIGO site is on top of the left hill at the campus area of Universidad de Concepci6n.

On June 21, 2000, an arrangement between BKG and UdeC on behalf of the Chilean consortium

for hosting TIGO was signed at BKG Frankfurt by the president of BKG, Prof. Dietmar Griinreich,

132 2000 IVS Annual Report
Bundesamt fiir Kartographie und Geod_ie Transportable Integrated Geodetic Observatory

Table 1. Approximate coordinates of the TIGO site in Concepcidn (taken from topographic map). The IVS

letter code is "Te = TIGOCONC'.

Longitude +73°01t25" W (_ +73.023611 °)

Latitude -36°50_30" S (_ -36.841667 °)

Altitude 150 m

and the rector of UdeC, Prof. Sergio Lavanchy. TIGO will be in Concepci6n for a minimum period

of 3 years with the option of extensions year by year.

In August/September 2000 the three BKG experts visited Concepci6n for discussions of platform details for the construction and for taking Spanish classes. Among tile five cooperating partner

institutions a scientific board for the scientific use of TIGO constituted itself. The scientific board

selected the first four Chileans who will work at TIGO in the future.

In October/November/December 2000 the four Chileans Eduardo Carvacho (UdeC), Carlos

Bustamante (UBIoBio), Raul Escobar (UCSC), Oscar Cifuentes (IGM) visited Wettzell for a first

introduction and training on the TIGO instruments.

In order to ship TIGO to Chile and get residential and work permission for the BKG experts a

bilateral note needs to be exchanged between Chile and Germany. This bureaucratic process was

initiated in August 2000 and is hoped to be finished during 2001. The ratification is a necessity

before TIGO can be shipped from Wettzell to Concepcidn.

In the beginning of 2001 a platform for TIGO and the access road to the platform will be built.

It is envisaged that the TIGO operation will start at Concepcidn in mid 2001.

2. Status of the TIGO VLBI module

TIGO's VLBA4 terminal was finally completed with the installation of the Mk4 formatter and

decoder during 2000.

It is intended to equip the VLBI module of TIGO also with the Canadian $2 VLBI data

acquisition system in order to complete existing $2 VLBI networks across the Pacific. The delivery

is anticipated for 2001.

TIGO participated also during 1999/2000 in several VLBI experiments (see Tab. 2).

3. Outlook

During 2001 a new fundamental station will be realized by TIGO in Concepcidn for a minimum

period of 3 years. The joint operation between BKG and the Chilean consortium will be dedicated

to the international services like IVS, ILRS, IGS and BIPM. Scientific projects in relation to TIGO

will be supervised by the Scientific Board of TIGO, while the operation of TIGO will be supervised

by the three TIGO experts from BKG.

The VLBI part of TIGO will be operated under thc supervision of the author by three Chilean

engineers who will be novices to geodetic VLBI, but with some experience in microwave techniques,

electronics and computers.

Due to the lack of a dense space geodetic network in South America we expect a regular

scheduling of the TIGO instruments. The VLBI module of TIGO is prepared for serving the IVS

2000 IVS Annual Report 133
Transportable Integrated Geodetic ()bservatory ....Btmdesamt fiir Kartographie und Geodiisie

with regular observations.

Table 2. Participation in VLBI-Experinmnts of TIGO 1999-2000. Experiments with reference frequency

offset. (SMHz - 0.1Hz) allowed short baseline determinations with the Wettzell 20m-radio-telescope.

Date Experiment Remarks

1999-02-01

1999-02-04

1999-02-23

1999-02-25

1999-06-29

1999-07-01

1999-08-16

1999-10-11

2000-01-28

2000-02-07

2000-05-16

2000-06-19

2000-07-24

2000-11-13

2()00-12-18

EUROPE-47

WZTIE-1

NA304

WZ4TS

EUROPE-49

BRD01

EUROPE-50

EUROPE-51

EUROPE-52

EUROPE-53

EUROPE-56

IRIS-S151

IRIS-S152

IRIS-S156

IRIS-S157

reference frequency offset

reference frequency offset

reference frequency offset

reference frequency offset

reference frequency offset

reference frequency offset

reference frequency offset

reference frequency offset

reference frequency offset

reference frequency offset

reference frequency offset

reference frequency off,set

References

[1} Has< tt.. BSer, A.. Riepl, S.. Schlfiter W., Cecioni, A.: TIGO - Transportable Integrated Geodetic

Observatory. VI Congreso Imernacional de Cien(:b_s de la Tierra, Santiago de Chile, August 7-11, 2000,

htt p://www, wol tzell.ifag.de/publ/wtz 153.pdf

134 2000 IVS Annual Report
....? / .... f ..l/i'_"¢":_

Geographical Survey Institute, JAPAN Tsukuba 32-m VLBI Station

Tsukuba 32-m VLBI Station

Yoshihiro F_kuzaki

Abstract

This report summarizes the activity at the Tsukuba 32-m VLBI station (Fig 1) by the Geographical

Survey Institute (GSI) VLBI group. The Tsukuba 32-m VLBI station has participated in several

international VLBI sessions. Domestic experiments (JADE sessions) are carried out periodically using

GSI's domestic network, which includes the Tsukuba 32-m VLBI station. We have a plan to increase

the JADE sessions and perform collocation surveys at the Tsukuba and Aira stations.

1. Activities

Tsukuba 32-m VLBI station has participated in several international VLBI experiments that

are listed in Table 1.

GSI has five permanent stations in Japan. Distributions of these stations are shown in Fig

2. The network is named GARNET (G_SI Advanced _Radiotelescope Network). In 1999 and 2000,

domestic experiment using GARNET was carried out four times a year. This session is named

JADE (Japanese _Dynamic Earth observation by VLBI). From JADE-0003 Gifu station with 3m

antenna owned by Gifu University has participated in JADE session. The network has now six

stations and ten baselines. The result of the JADE sessions is available on the GSI VLBI Web

page (http://vldb.gsi.go.jp/sokuchi/vlbi/english).

A tie experiment among the stations that have a large antenna, Kashima 26-m, Kashima 34-m

and Tsukuba 32-m, was carried out in 2000. This session is named JPNTI. The purpose of JPNTI

sessions is to transfer the coordinates of Kashima 26-m and Kashima 34-m established by a long

period of observation to Tsukuba 32-m VLBI station. Four KSP stations also participate in this

session.

The data for CORE-OHIG6,7,9,12 sessions in Syowa station, Antarctica were dubbed from K4

into MarkIIIa at Tsukuba 32-m VLBI station. These data were correlated at Bonn Correlator and

analyzed at GSFC.

Table 1. International experiments at Tsukuba 32-m VLBI station after Nov. 1999

Experiment Code

CORE-A CA075,76,77,79,80,81,82,83

CORE-1 C1001,02,03,04,05,06,07

CORE-B CB701,702

VLBA RDV19,20,21,22,23,24

JPNTI JPNTI2,3,4,5,6

Other NEOS-A351, SURVEY001, CRF09, APSG07

2. Changes

The staff of VLBI group at GSI has changed. Table 2 lists the present staff.

2000 IVS Annual Report 135
Tsukuba 32-m VLBI Station Geographical Survey Institute, JAPAN

Figure 1. Tsukuba 32-m VLBI antenna.

Six months after installing Tsukuba 32-m antenna, the Azinmth rail, which was 73 kg per

meter and 10 cm width, was cracked because the stress from the wheel was larger than the value

designed by the antenna manufacturer. In April 1999, the rail was replaced with a larger one (Fig

3). So far, no significant problems with the rail have occurred. By this replacement of Azimuth

rail, the height of the reference point of Tsukuba 32-m antenna has changed +43.7mm.

GSI's internet domain name has been changed from gsi-mc.go.jp to gsi.go.jp since January

2001.

Table 2. Staff working at GSI VLBI group

Name Position Jobs

Shigeru MATSUZAKA IVS Networks Representative

Yoshihiro FUKUZAKI Leader of VLBI group

Tadayuki AKIYAMA Collocation chief Collocation, Operation

Kousei SHIBA Operation chief Experiments Coordination,

Operation

Kazuhiro TAKASHIMA Visiting scientist at GSFC Improvement of software

for VLBI analysis

Masaru YAZAWA Analysis chief Baseline Analysis, Operation

Shinobu KURIHARA Operator Baseline Analysis, Operation

Michiko ONOGAKI Operator Antenna and H-maser maint.,

Operation

Kohei MIYAGAWA Correlation chief Correlation, Operation

Kyoko KOBAYASHI Assistant Correlation, Operation

136 2000 IVS Annual Report
Geographical Survey Institute, JAPAN Tsukuba 32-m VLBI Station

(ASHII4A 26m

,

i

.I

ICHICHIJIMA

Figure 2. GSI domestic VLBI network and Gift1 station.

Figure 3. Azinmth rail replacement (Left: before Right: current).

3. Prospect

It is planned to increase ,JADE sessions from four times a year to eight.

2000 IVS Annual Report 137
Tsukuba 32-m VLBI Station Geographical Survey Institute, JAPAN

IGS station (TSKB) is close by the 32rn VLBI antenna (300m) at Tsukuba station, and a

GPS station of GSI Earth Observation Network is close by the VLBI antenna at Aira station.

Collocation survey at Tsukuba and Aira station will be performed in 2001.

References

[1] Ishihara, M., K. Nemoto, M. Iwata, K. Shiba, K. Takashima, and S. Matsuzaka: Tsukuba 32-m VLBI

station, IVS 1999 Annual Report, pp.ll5 118, August 1999

[2] Ishihara, M., K. Nemoto, M. Iwata, K. Shiba, K. Takashima, and S. Matsuzaka: Tsukuba VLBI Center,

IVS 1999 Annual Report, pp.160-163, August 1999

[3] Takashima, K., S. Kurihara, M. Ishihara, K. Nemoto, M. Iwata, K. Shiba, M. Onogaki, and K.

Kobayashi: Status and Results of GSI Domestic VLBI Networks, Bull. Geograph. Surv. Inst., Vol.

46, pp.1 9, March 2000

138 2000 IVS Annual Report
1

Urumqi Astronomical Observatory, Chinese A(:a(lemy of Sciences

555V/ 

6,3

Urumqi Astronom!cal Obser'_,at_.or),

Nanshan VLBI Station Report

15, Ximlg, Zlmn[4 .fin

Abstract

q_his report sumInarises the VLBI activities, I)arameters and staff changes at Nanshan station of

the Urumqi Astron(,mical Obsmvatory from 1st March 1999 to the end of 2(100.

1. The VLBI Activities

The VLBI geodesy experiments of NASA CORE-B and APSG projects were operated during

the time t)eriod; they are CB502, CB503, CB504. APSG5, APSG6, CB505, CB506, CB801, CB802,

APSG7.

A new horn for 13 cm band was installed; th(,, system temperature at this band is 130 K.

The cables fi'om the IF devi(:es to the backend were tel)laced with new ones. The communication

between the, Nanshan station and _)utside world has 1)een nmch improved with the installation of

a new opti('al fiber link to Urum(ti. Thus, it is now t)ossible to reach Nanshan via telephone and

email (teh 86-0991-5933075, e-maih uao((_nmil.wl.xj.en). The station was evaluated by a Visiting

Board of the Chinese Academy of Sciences in Septenfl)er of 1999. The L-band dual-polarization

system with the frequency range 1380-1700 MIIz has t)een completed and installed at the 25 meter

radio teles(:ope. A new horn fiw three t)an(ts 30 cm, .'19 cm and 92 (:m and their receivers are under

(:onstruetion here.

A new FS computer fi'om U.S. arrived at Nanshan station in 1999. With help fl'om Ed Himwich

and Xue Zhuhe, Liu Xiang and Yang Wenjun have installed a new Y2K-compliant Field System

(version 9.4), adapted for the specific hardware ('onfiguration at NanshalL In early 2000, with hel t)

from IIimwieh, Wang Na, Chen Maozheng, Liu Xiang worked on the conmmnication between the

FS comt)uter and the antenna e(mtrol computer. It was nearly finished when TeamChina came.

In April, TeamChiila came and worked on upgrading Nanshan to thin tape and MKIV. The team

inembers were tl.alph St)enter, Chopo Ma, E(t Himwich, Les Parry, Michael Wunderlich and Gino

_mcari. First, Miehaet worked on the recorder, then the others came and joined the work on

recorder, installing formatter, modifying FMd Systeln and inspecting baseband converters, and

later, Gino Tu(:cari continued to work ()n the system at Urumqi. The local staff Zhang Hongbo and

Yang WeI\iml were involved in the work. Ed Himwi(:h also worked on the communication between

the FS comtmter and the antenna PC with the stalt' here, and they completed it in time. Now

the anteima ('an be (:ontrolled t)y FS an(t also can (to t)ointing and on-off measurement via FS.

The MKIV upgrade of Nanshan was succ(_ssful; it gives fi'inges fi'om experiments EVN: C00C3,

C00L4 and NASA: CB802. But some t)rol)lems t()ok place after that ext)eriment in the recorder;

investigation and tixing are now under way.

The problems of the MKIV re('order arc ext)ected to be resolved, and also minor problems

of phase-cal and cat)le uieasurement. One H-maser will be sent to Shanghai for evaluation and

upgrade, h, 2001, we will participale in the CBg01, CB902, CB903, CB904, APSG8, APSG9

experiments ()f g_()(tesy.

2000 IVS Annual Report 139
Urumqi Astronomical Observatory Urumqi Astronomical Observatory, Chinese Academy of Sciences

Table 1. Receiver parmneters

Band Frequency range LO Pol.

1.3 cIn

3.6 cm

6 cm

13 cm

18 cm

30+49 cm

92 cm

22100-24000MHz

8200-8600

4750-5150

2150-2450

1380-1700

under construction

317-337

22000MHz

8080

4620

2020

1300

Tsys SEFD

LCP 180 K 2732 Jy

RCP 40 330

LCP 35 320

RCP 130 1762

LCP+RCP 85 1394

90 1265

Table 2. Nanshan staff

Prof. Zhang Jin

Zhang Hongbo

Liu Xiang

Wang Na

Aili Yusup

Dong Yousuo

Shao Minhui

Wang Weixia

Sun Zhengwen

Chen Maozheng

Aili E

Jarken Y

Yang Wenjun

Ma Lu

Wang Meifang

chief scientist and general engineer, zhangj@ms.xjb.ac.cn

vice general engineer, zhanghb@ms.xjb.ac.cn

scientist, head of vlbi operation group, liux@ms.xjb.ac.cn

scientist, mainly working on single dish observation

engineer, vice general engineer

engineer, vice general engineer

engineer, responsible for H-masers

engineer, responsible for receivers

engineer, responsible for receivers

engineer, responsible for receivers

staff of the operation group

staff of the operation group

staff of the operation group

secretary

secretary

140 2000 IVS Annual Report
--._-y .."7,?.,',,'W/_.-

MIT Haystack Observatory "West ford

Westford Antenna

Michael Poirier

Abstract

Technical information is provided about the antenna and VLBI equipment at the Westford site of

Haystack Observatory, and about changes to the systems since the 1999 IVS 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.

Figure 1. The radome of the Westford Antenna.

The Westford antenna was constructed in 1961 as part of the Lincoln Laboratory Project West

Ford that demonstrated the feasibility of long-distance communication by bouncing radio signals

off a spacecraft-deployed belt of copper dipoles at an altitude of 3600 km. In 1981 the antenna was

converted to geodetic use as one of the first two VLBI stations in 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 test bed in the development of new equipment

and techniques now employed in geodetic VLBI worldwide. Primary funding for geodetic VLBI at

Westford is provided by the NASA Space Geodesy Program.

2000 IVS Annual Report 141
Westford MIT Haystack ()h_rvatx_ry

Table l. Location and addresses of \Vest ford anl_,nna.

L_mgit ude

L at. it ude

Height above m.s.l.

r w I

42.61 ° N 1

1

: _MIT ttayst.ack Observatory

()ft' Route 40

! \'Vesttbrd, MA {)1886-1299 U.S.A_

2. Technical Parameters of the Westford Antenna and Equipment

The technical parameters (ff the Westtbrd antenna, which is shown in Figure 2, are summarized

in Table '2.

Figure 2. Wide-angle view of Weslfi_rd anienna inside the radomc. The VLBI S/X receiver is located at,

the prime focus. The subre.flector in front of the receiver is installed when _bserving with the TAL receiver

(see Section 4), which is located at t.l,(_ Cassegrail_ ['(,cus.

The antenna is enclosed in a 28-meter-diameter, air-intlaled radome made of 1.2-ram-thick,

Teflon-coated fibergla_ss scc Figure 1. When the radomc is wet, systmn temperatures increase by

10 20 K at X-band and by a bmallcr anlOllllt ;tl. S-band.

'/'he lllajol components of the VI,BI data acquisition systmn nre a Mark IX; clcct.ronics rack, a

142 2000 IVS Annual Report
MIT Haystack Observatory Westford

Table 2. Technical parameters of the Westford antenna for geodetic VLBI.

Parameter Westford

primary reflector shape

primary reflector diameter

primary reflector material

S/X feed location

focal length

antenna mount

antenna drives

azimuth range

elevation range

azimuth slew speed

elevation slew speed

frequency range

Tsu, at zenith

aperture efficiency

SEFD at zenith

symmetric paraboloid

18.3 meters

aluminum honeycomb

primary focus

5.5 meters

elevation over azimuth

electric (DC) motors

90 ° _ 470 °

4 ° _ 87 °

3 ° S-1

2 ° s-i

X-band system S-band system

8180-8980 GHz

50 55 K

0.40

1400 Jy

2210-2450 GHz

70 75 K

0.55

1400 Jy

Mark IV tape drive, which is used for recording thin tapes only, and a Pentium-class PC running PC

Field System version 9.4.12. The primary frequency and time standard is the NR-4 hydrogen maser.

A CNS Clock GPS receiver system provides independent timing information and comparisons

between GPS and the maser.

Westford also hosts the WES2 GPS site of the IGS network. A Dorne-Margolin GPS antenna is

located on top of a tower _60 meters from the VLBI antenna, and a TurgoRogue receiver acquires

the GPS data.

A meteorology package provided by the NOAA Forecast Systems Laboratory continually logs

meteorological data, which are downloaded daily and are available from the IGS and cignet archives.

3. Westford Staff

are:

The personnel associated with the VLBI program at Westford and their primary responsibilities

John Ball

Joe Carter

Brian Corey

Ellen Lautenschlager

Glenn Millson

Michael Poirier

Alan Whitney

pointing system software

antenna controls

VLBI technical support

observer

observer

site manager; chief observer

site director

2000 IVS Annual Report 143
Westford MITHaystackObservatory

4. Status of the Westford Antenna

Westford participates regularly in the CORE-l, CORE-3, IRIS-S and RD-VLBA series of

geodetic experiments, as well as in occasional NEOS experiments, fringe tests_ and various ad hoc

experiments. During the period 1999 March 1 - 2000 December 31, Westford participated in a

total of 74 24-hour geodetic experiments.

Upgrades to the antenna and VLBI systems over the same time period include:

• Installation of secondary drive motor systems in both azimuth and elevation. This has

allowed more precise positioning control of the antenna.

• Replacement (in progress) of the 17 bit incandescent bulb encoders with 19 bit LED-based

encoders. The elevation encoder has been replaced and the azimuth replacement is expected

in the near future.

The only significant equipment failure during this time period occurred in the hydrogen maser

microprocessor and vacion pumps. Allied Signal (now HTSI) replaced the faulty items and coinpleted repairs quickly.

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-

kin-long terrestrial air link designed to study atmospheric effects on the propagation of wideband

communications signals at 20 GHz.

5. Outlook

With the increased efficiency of the Mark IV correlators and the more intensive observing of

the CORE program, we anticipate being able to participate in all seventy-two experiments that

are scheduled for Westford in 2001.

144 2000 IVS Annual Report
• 2; ./ _S" //"

{

. _j" j' .

Bundesamt fiir Kartographie und Geodiisie, Fundmentalstation Wettzell

,22 C' _-_::

5 55 71;

20m-Radiotelescope Wettzell _

Station Report of the 20m Radiotelescope at Wettzell

Richard Kilger, Ehrhard Bauernfeind, Gerhard Kronschnabl, Raimund Schatz,

Walter Schwarz, Reinhard Zeitlh6fler, Rudolf Zernecke

Abstract

As in past years, the main activities in the year 2000 with the 20m Radiotelescope \Vettzell have

been concentrated on participation in geodetic and astrometric observing programs of the IVS. Some

technical improvements have been carried out during regular maintenance. A GPS receiver has been

placed on top of the radiotelescope, right behind the secondary reflector for measuring deformations of

the 20m antenna and for deriving elevation dependencies of the GPS antenna. A repetition of the local

survey has been performed in order to control the ties of the reference point of tile VLBI telescope to

the other geodetic systems.

1. Participation in the Observing Programs

Since 1983 the Radiotelescope Wettzell has contributed to geodetic and astroinetric observing

programs. Extended times series exist for the station position and for the velocity. In 2000 the

20m Radiotelescope participated in experiments. Due to the transition of the MKIII to MKIV

Table 1. Summary of observation activities.

52 NEOS-A

12 IRIS-S

228 DUT1 Intensive

7 EUROPE

6 RDV

6 CORE

3 Astronomy

correlator, which limited the correlator throughout 2000, the amount of observation was slightly

less compared to the previous years.

Due to consequent maintenance the system failures have been minimized; nevertheless some

components failed and resulted in loss of observations. Unexplained problems in the interference

resistance were the reason for unexpected failures of the Antenna Control Unit (ACU), which

required occasionally a reset. Unexpected power failures e.g. during lightning led to failures of the

cooling system of the S/X receiver. Both events occasionally caused losses of tracks.

2. Technical Improvements

Some technical improvements have been made in order to increase reliability and automation.

The current implemented Field System version is FS-9.4.18. A software routine has been set up

which automatically controls the transfer of log files and schedule files to and from the respective

data bases to make sure that the last versions of those files were received. As an extension to the

regular Field System a software routine has been implemented which allows tracking of satellites.

So far an old HP 5316A counter was used for measuring the cable delays and the flnout - gps

2000 IVS Annual Report 145
20m-Radiotelescope Wettzell Bundesamt fiir Kartographie und Geod_.sie, Fundmentalstation Wettzell

values. The old system has been replaced by an HP 53132A counter. The required GPIB driver

has been written for the integration into the Field System.

Last year the automatic antenna control unit was replaced by a new system. Due to unexplained

effects, occasionally unexpected interferences occurred and resulted in undefined status of the ACU.

This leads to failures of the 20m antenna. In 2000 some efforts and investigations have been made

to overcome the problem. So far it has been minimized but not sufficiently solved. Actions were

the employment of an uninterruptable power supply, the replacement of the RS232 connection by

fiber optics and improvements in grounding. Futher investigations are ongoing.

The MKIII decoder has been replaced by a MKIV unit.

The thermal insulation of the antenna concrete support construction (basement up to the

moving part), which minimizes the influence of the direct sunshine to the construction, has been

completely replaced. Over the years water penetrated the shielding and decreased the insulation

capacity (figure 1).

Figure 1. 20m raxiiotelescope with new insulation of the concrete supporting construction.

A K4 system - on loan from the Communications Research Laboratory (CRL) / Japan - had

to be removed and returned at the end of 2000. The system has been used for joint observations

with Tsukuba and Kashima. We are obliged to thank CRL for having the system for a long time

in Wettzell.

3. Local Survey

A GPS antenna (ASHTECH-Choke ring) was installed behind the secondary reflector centered

on the telescope pointing axis (figure 2). The receiver itself was placed in the elevation cabin to

monitor GPS observations. The objective is to observe bending or deformation of the 20m antenna

: and to derive elevation dependencies of the GPS antenna. Usually, when no VLBI program is

:' observed and the 20m antenna is not in use for some hours, GPS observations should be taken.

GPS derived positions will be compared with the positions derived by taking into account the

146 2000 IVS Annual Report
Bundesamt fiir Kartographie umt Geodfi+sie, Fundmentatstation Wettzell 20m-iRadiotelescope \Vettzell

VLBI reference point anti the ('orrest'onding eccentri(:ities calculated fl'om the pointing angles of

the antenna and the radial distance t)etween GPS and Ant, cram referen(:e t)(fint. So far observations

have been taken at various elevation and various azimuth t)ositions.

Figure 2. GPS Antenna nl()unted behind the Secondary Refl(,ct()r in line of th(' l)()inting axis.

The measurements emt)loying an invar wire for measuring |lm variations in height due to

tenq)erature variations in the telesc'ope sut)port structure have t)('.en l)erti)rmed successfully in

2000. Figure 3 shows the time series. The. ret>lacenlent ()f"the refer<'nc<> mass <)f lkg t)y 2kg at the

h)wer end of the wire changed the zero point by a constant offse| in February 2000.

Invar measurements of the heighl

:It .r_ .200

o| lhe radio telesco te in Wettzell

r !

t

t

1.5

Height variations measured with inver [mm]

.... 1.o

eight 2 kg

--_ o i o

)erature at+_-ncrele wali_.

I

i¢_ ! I I , I [

Correction ot invar wire expansion due to temperature ,

9 tO 11 l_.

months of the year 2OOO

Figure 3. Height variations of the VLBI reference point (Its(, t() t(,mp(wal uro, moasured wil h an invar wire.

The local survey of the Fun(tamentalstation Wettzell has been repeated for lhe control of the

local ties between the various geodeiic systems and for the inclusion of ||ie new I_asergyroscope

"G". The k)cal network is shown in figure 4.

2000 IVS Annual Report 1,17
20in-liadi_telesc(qJe Wettz(,ll Bundesamt fiir KartographieundGeod_ie_Fundmentalstation Wettzell

\

Figure 4. Local survey network of Fundamentalstation Wettzell.

148 2000 IVS Annual Report
t

Observatorio Astrondmico Nacional

...... 5 $57t5

Observatorio Astrondmico National Yebes

Observatorio Astrondmico Nacional

Francisco Colomer

Abstract

This report updates the description and details of the OAN facilities as a network station in IVS.

The 14 meter radiotelescope at Yebes participates regularly in the geodetic VLBI caanpaigns (EUROPE

and CORE), as well as astronomical VLBI experiments as part of the European VLBI Network (EVN).

The institute staff is also involved in technical development and geodetic research.

1. The OAN Facilities

The Observatorio Astrondmico Nacional (OAN) of Spain operates a 14 meter radioteles(:ope

at Yebes (Guadalajara, Spain; see location in Fig. 1). This facility is a network station in IVS,

and participates regularly in the geodetic VLBI campaigns to study the tectonic plate motions in

Europe (project EUROPE), Earth rotation, and pole motion (project CORE).

The institute is currently involved in the construction of a new 40 meter radiotelescoi)e (Fig. 2)

which is expected to be available for geodetic VLBI observations in 2004.

Figure 1. Map of the Yebes site, showing the location of the current 14 m and fllture l0 m radiotelescopes.

2000 IVS Annual Report 149
ObservatorioAstron6nm:oNationalYet)es Observat<)rio Astron6micoNational

: 7:

t:'igurv 2. Staius of the conslruction of the new 4tj hinter radiotelescope of ()AN at 5'_,bes (Guadalajara,

Spain). The tinish('d c<mct_q(, tn*d_,slal is shown.

2. Description of the OAN Station at Yebes

Th(, main instrument at ()AN is nowadays the 14 meter radio tele.scope used for VLBI. There

have not lm(m any substanlial (:hanges in the equipment since the last IVS Annual Report in 1999.

Rehwani ('haug(,s at(' list(,d in Table 1.

Tabh, 1. Characterislics of the VLBI equipm(mt.

VLBI terminal tyIm

re('ording media

_I>lescot)(_ (:ontrol (:omi)uter

VLB[ system comt)ut(w

Operating system

Field System version

VLBA4 (Mark IV formatter,

VLBA-G rack and VLBA recorder)

thick and thin tape, 1" wide

ItP1000 + HP2100

Pentium II/350

Debian 2.1r3 (kernel 2.0.34)

FS 9.4.6

H-maser fl'equ(mcy standard KVARTZ CH1-75

(]PS receiver 6 channel TrueTilne XL-DC-602

Meteorological station SEAC-300

()n the other hand. tim ()AN engineers have t)(.'en continuously working since 1985 in the

development of cryogenic HEMT amplifiers to be used in receivers at Centro Astrondmico de

Yel)es (CAY), and in other ra(tio a._tronomy observatories. One of the last products is the low

noise anlplifi(,r at X-band ((:(qll<_red at 8.3 GHz) designed and built for ESA tracking stations.

t5(} 2000 IVS Annual Report
Observatorio Astron6mico Nacional Observatorio Astron6mico Nacional - Yebes

The CAY laboratories are completely prepared for the fabrication and test of cryogenic amplifiers with modern equipment. The workshop uses CNC milling machines for the preparation

of chassis. The microwave printed circuits are engraved on soft substrates using an LPKF CNC

milling machine or photolitographic techniques. Chassis and circuits are also gold plated in our

laboratories. As HEMT devices in chip form are employed in the amplifiers, special equipment

has to be used for their assembly (ultrasonic wire bonding and welding machines, stereo microscopes and metallurgic microscopes). For noise and gain measurements, and stability analysis at

cryogenic temperatures, a dedicated cryostat with a CTI 350 cryogenic refrigerator is used. Noise

temperature is measured with a computer controlled noise figure meter, with special software to

obtain adequate accuracy at cryogenic temperatures (using the cold attenuator method). A vector

(up to 50 GHz) and a scalar (up to 110 GHz) network analyzer are also available for gain and

reflection measurements. Spectrum analyzers and power meters are used to check the stability.

Finally, a computer controlled quad power supply is used for DC analysis of active devices.

Finally, we will mention that the reference station of the permanent GPS network in Spain

(coded "YEBE") is operated at Yebes by the Instituto Geogr£fico Nacional (IGN) of Spain, host

institute for OAN. The data are analysed and sent weekly to the coordinating center of EUREF

in Frankfurt. More information can be found at the URL http://_, geo. iga. es/.

3. OAN Staff Working in VLBI

There have been no changes in OAN staff for VLBI since our 1999 report. Contact information

is provided at the URL http://ww, r. oan. es/vlbi/.

4. Status of the Geodetic VLBI Activities at OAN

The main contribution of OAN to IVS is the realization of geodetic VLBI observations in

the EUROPE and CORE projects: the OAN radio telescope at Yebes has participated in eight

EUROPE and six CORE experiments since March 1999. Problems with the antenna control

system, plus failure of an element of the MKIV formatter, prevented successful participation in

the experiments of the last quarter in 2000. The institute also participates in the European VLBI

Network (EVN) for astronomy, taking part in its logistics and carrying out technical development.

On the other hand, several projects of geodetic scientific research are being developed:

• Combination of geodetic space techniques (VLBI and GPS) to investigate the potential of

new analysis techniques that could provide a better estimate of the parameters of interest:

a combination of GPS estimates of the tropospheric delay into the VLBI data analysis. If

proven successful, the technique would have a large impact also in astronomy, making possible

longer integrations at millimeter wavelengths.

• Determination of the phase-center of a VLBI antenna (Ny /_lesund 20m), comparing the

VLBI and GPS results (which differ in particular in the vertical component). Two epochs of

observations are planned to study the stability of the antenna structure.

2000 IVS Annual Report 151
Observatorio Astron6mico National Yobes Observatorio Astron6mico Nacional

5. Outlook

The OAN radio telescope ttt Yebes continues participating regularly in the campaigns for the

EUROPE and CORE projects.

We foresee the upgrade of the VLBI equipment to high capacity by installing the needed

haa'dware (second headstack and electronics for high speed tape operation at the recorder, new

firmware, etc.). We az'e also working on the upgrade of the telescope control system, to replace

the current HP2100 computer by a VME programmable computer.

Finally, the construction of a new 40 meter radiotelescope at Yebes is progressing well. The

concrete tower, that will serve as pedestal for the instrument, is finished. This telescope is expected

to be operational at S/X bands in 2004.

References

[1] L6pez-Ferndndez, I., Gallego-Puyol, J.D., Homan, O.J., Barcia-Cancio, A. Low-Noise Cryogenic XBand Amplifier Using Wet-Etched Hydrogen passivated InP HEMT Devices. IEEE Microwave and

Guided Wave Letters, Vol. 9, No. 10, p. 413 (October 1999).

[2] Rioja, M.J., Tomasi, P., Sarti, P., P_rez-Torres, M.A. Integrating GPS Zenith Path-Delay Measurements into VLBI Analysis of Geodetic Observations with the European Network. In: Proceedings of the

13th Working Meeting on European VLBI for Geodesy and Astrometry, Ed. P. Tomasi, F. Mantovani,

M. Pbrez-Torres, p.23 (2000).

[3] Tomasi, P., Sarti, P., and Rioja, M.J. The determination of the reference point of the VLBI antenna

in Ny Alesund. In: Memoirs of National Institute of Polar Research, Special Issue 54 (2000).

152 2000 IVS Annual Report
/

Geodetic Survey Division, Natural Resources Canada

 ooZOoff!z F

b

Yellowknife Observator S _,

Yellowknife Observatory

Mario Bdrubd, Calvin Klatt

Abstract

The Yellowknife VLBI antenna is a 9 meter diameter antenna which was formerly the "MV-I"

mobile antenna. The MV-1 was a proof-of-concept for mobile VLBI and in 1991 NASA and NOAA

offered the system for use at Yellowknife. The antenna is located at the Yellowknife Geophysical

Observatory and is operated by the Geodetic Survey Division, Natural Resources Canada. This report

gives an update on recent activities.

Figure 1. Yellowknife Geophysical Observatory 9m VLBI Antenna

1. Overview

Formerly the "MV-I" mobile antenna, the Yellowknife antenna was used as a proof of concept

for mobile VLBI under the ARIES (Astronomical Radio Interferometric Earth Surveying) program.

Following the successful proof of concept, the MV-2 and MV-3 mobile antennas were built and

used extensively during NASA's Crustal Dynamics project. The MV-1 antenna was then stationed

at Vandenberg Air Force Base. In 1991 NASA and NOAA offered the system to Energy, Mines

and Resources, Canada, for use at Yellowknife. With support of the Crustal Dynamics Project

the Yellowknife VLBI observatory came on the air in the summer of 1991.

The antenna is located at the Yellowknife Geophysical Observatory and is operated by the

Geodetic Survey Division, Natural Resources Canada. The Yellowknife Geophysical Observatory

is operated by the Geological Survey of Canada, Pacific Division, Natural Resources Canada.

2000 IVS Annual Report 153
Yellowknife Observatory Geodetic Survey Division, Natural Resources Canada

2. General Specifications

• Latitude : 62.48 North

• Longitude : 114.48 West

• Reflector: 9m

• Receiver : S and X cryogenic

• Azimuth speed : 40 degrees per minute

• Elevation speed : 40 degrees per minute

• PCFS version : 9.4.17

• VLBI equipment : Mk III and thick tape drive. $2 data acquisition and recording terminal.

• Time standard : NR Maser

• GPS receiver : Rogue

3. Antenna Improvements

Since being installed in Yellowknife, MV-1 has not required any major upgrades. The antenna

is parked every winter because the antenna is unable to operate in low temperatures (December till

March). Once spring arrives, the Yellowknife team prepares the antenna for the upcoming season.

Mechanical maintenance was performed in 1998 and the antenna has performed reasonably

reliably since. The antenna control unit will be looked at in the spring of 2001 and may be

replaced with one similar to that at Algonquin.

Yellowknife has had an $2 recording terminal and data acquisition system installed and a

number of experiments have been performed using this new equipment.

4. Antenna Survey

The Yellowknife antenna is surrounded by a high precision survey network which has been

measured three times since 1990. This network has been precisely measured to obtain the geodetic

tie between the VLBI, the GPS and the DORIS reference points with a precision of a few mm.

5. Operations March 1999 - December 2000

In 1999 Yellowknife was involved in 5 CORE-B and 4 NEOS experiments. In addition, Yellowknife was involved in 2 CGLBI experiments (2 24-hour geodetic sessions).

In 2000 Yellowknife was involved in 1 CORE-B and 4 NEOS experiments. In addition, Yellowknife was involved in 8 CGLBI experiments (4 24-hour geodetic sessions).

In 2001 Yellowknife is currently scheduled to participate in 13 CORE and NEOS experiments.

We anticipate that it will also participate in 5-10 CGLBI experiments.

154 2000 IVS Annual Report
n

m

"/ "i (i's_ ,.,
f

IJ

_L
Geod_itisches Institut der Universitiit Bonn

f

25

Operation Center at the Geodetic Institute Bonn

The Bonn Geodetic VLBI Operation Center

A. Nothnagel

Abstract

This report summarizes the activities of the IVS Bonn Operation Center.

1. Center Activities

The GIUB VLBI Operation Center is located at the Geodetic Institute of the University of

Bonn, Nussallee 17, D-53115 Bonn, Germany. In the past year the activities of the GIUB VLBI

Operation Center were concentrated on the preparation and organization of several different observing programs.

• International Radio Interferometric Surveying - South (IRIS-S):

12 Sessions per year with the stations Wettzell, HartRAO, Fortaleza, Fairbanks, Hobart,

O'Higgins and Westford

• Measurement of Vertical Crustal Motion in Europe by VLBI (EUROPE)

6 sessions in 1999 and 7 sessions in 2000 with the stations Nyltlesund, Onsala, Wettzell,

Simeiz, Madrid (DSS65), Yebes, Medicina, Matera and Noto. Effelsberg participated once

per year, TIGO-WTZL participated occasionally.

_4 ¢" _ ",-,

. (

i '-_ , %>:-....._ ;, t] ll'Malera_ ;:= '_

l ............. '. i L-;2:2 " '

Figure 1. European VLBI network

2000 IVS Annual Report 157
Operation Center at the Geodetic Institute Bonn Geod_tisches Institut der Universit_t Bonn

• Continuous Observations of the Rotation of the Earth (CORE-OHIG):

with stations HartRAO, O'Higgins, Fortaleza, Hobart, Kokee and DSS45 plus the Japanese

Antarctic station Syowa

The operational tasks mainly consisted of preparing the detailed observing schedules for all

sessions listed above. The schedu]es were prepared with the SKED software on HP-UX platforms.

The work also involved sending of tapes, communication with stations, fault analysis, and arrangements for special sessions and testing schemes. Arno Mfiskens takes care of the IRIS-S and the

CORE-OHIG sessions while Axel Nothnagel is responsible for the EUROPE project.

158 2000 IVS Annual Report
/

NASA Goddard Space Flight Center

Zoo ZooW'25 5557/I

CORE Operation Center

CORE Operation Center Report

Cynthia C. Thomas

Abstract

This report gives a synopsis of the activities of the CORE Operating Center from March 1999 to

December 2000. The report forecasts activities plaamed for the year 2001. The outlook summarizes

the evolution of the different CORE programs,

1. CORE Program Description

The continuous observations of the rotation of the Earth (CORE) program was initiated by

the geodetic very long baseline interferometry (VLBI) community in 1997. The program is being

carried out using geodetic VLBI stations for data acquisition and VLBI analysis centers for data

processing and analysis. The CORE program will evolve over the period 1997-2003.

The goal of the CORE program is to generate a continuous high accuracy Earth rotation data

set for Earth science and global change research. The program will produce basic observational

data for studies of the continuous momentum exchange among the solid Earth, the atmosphere,

and the hydrosphere, enabling exciting research areas that heretofore have been impossible.

The current Earth orientation parameter goal of the pre-CORE Mark III experiments is to

attain precision of at least 3.5 #s for UT1 and 100 #as in pole position. The full CORE program

has the potential for a typical precision of 2-2.5 #s in UT1 and 30-40/,as in pole position, for daily

sessions with a 6-station network.

The availability of continuous, high accuracy Earth rotation data will be possible due to the

Mark IV technology that became available during the third quarter of 2000. The Mark IV correlator

became as efficient as the Mark III correlator during the last quarter of 2000. Improved sensitivity

of the Mark IV data acquisition system together with the high playback efficiency of the Mark IV

correlator are both necessary to produce the expected results for CORE.

CORE sessions were run with five basic network configurations: CORE-A, CORE-B1, COREB2, and CORE-B3 during 1997 and 1998. During 1999, the networks of the CORE-B sessions

changed and the sessions were named CORE-B4, CORE-B5, and CORE-B6. The CORE-A sessions

were simultaneous with NEOS sessions and CORE-B and NEOS sessions were on sequential days

during both 1998 and 1999. During 2000, the CORE-3 sessions started in July and were performed

in Mark IV mode. It was decided that the CORE-A/NEOS series of 76 sessions was sufficient for

the analysis of EOP estimated from different networks and it was therefore ended. To start the

process of filling in the observing week that will eventually be continuous in CORE, the CORE-A

network was moved from Tuesdays to Mondays and renamed CORE-1.

2. CORE Sessions During April 1999 to December 2000

This section displays the purpose of the CORE-A, CORE-B, CORE-1 and CORE-3 sessions.

It also lists other programs used by CORE.

• CORE-A/CORE-l: These experiments validated the CORE concept of measuring EOP

continuously using different networks.

2000 IVS Annual Report 159
CORE Operation Center NASA Goddard Space Flight Center

The network for CORE-A included Fairbanks, HartRAO, Hobart, Algonquin, Matera and

Westford during 1998. During 1999 the network consisted of three constant stations: Fairbanks, HartRAO, and Algonquin. The other three stations consisted of Medieina, Westford,

Tsukuba, Matera, and Hobart.

In 2000, the CORE-As were scheduled once per month until July. In July, the CORE-As

were moved to Mondays and renamed CORE-1 because Algonquin was added to the NEOS

weekly sessions. The network for the CORE-A and CORE-1 was Algonquin, Fairbanks,

HartRAO, Matera, Tsukuba, and Hobart.

• CORE-B: The purpose of these sessions is to provide additional data for comparison of

EOP measurements, to obtain long 48-hour data sets for geophysical studies and to provide

observing sessions during which the stations can demonstrate their performance and their

ability to participate in future regular CORE sessions.

• CORE-3: These sessions started in July of 2000 and were observed monthly. The CORE-3

series was named for the third day of the work week since it is scheduled for Wednesdays

following the NEOS sessions. The CORE-3 sessions were the first of the regular, operational

CORE sessions, recorded in a Mark IV mode.

There is data from other programs established by Bonn (IRIS-S, CORE-OHIGGINS, and EUROPE), USNO (NEOS, NAVEX, CRF), and GSI (APSG) that are used by the CORE program.

Some of the data is used to help determine the direction of the CORE program during its evolution.

3. Current Analysis of CORE

Comparisons of daily EOP estimates made by the CORE-A and NEOS networks show that

there are biases at the level of about 50 gas in polar motion and 2 #s in UT1 between simultaneous

CORE-A and NEOS measurements. The wrms differences are 232 I*as, 165 #as, 9.8 Its between

X, Y, and UT1 estimates, respectively. The source of these differences is most likely unmodeled

or mismodeled site motion, which we are currently investigating.

One of the measures of performance of the CORE experiments is the size of the formal EOP

uncertainties. The uncertainties range from about 70-100 #as for X-pole, 50-100 #as for Y-pole,

and 2.5-3.5 #s for UT1. Based on the observed differences between simultaneous CORE-A and

NEOS sessions, the formal EOP precisions should be multiplied by about a factor of 1.5. The

observed uncertainties are generally less than the minimal goal of 100 ILas for PM and 3.5 its for

UT1.

4. The CORE Family

Table 1 lists the key technical personnel and their responsibilities so that everyone reading this

report will know who to contact about their particular question.

5. Evolution of CORE

As of the end of 2000, the CORE observing program for 2001 and tile Mark IV correlator plans

were proceeding.

• The CORE-1 sessions have been scheduled monthly and will be observed in a Mark IV mode.

160 2000 IVS Annual Report
NASA Goddard Space Flight Center CORE Operation Center

• The CORE-3 sessions have been scheduled bi-weekly during the year. In addition, a second

CORE-3 network will begin bi-weekly starting July of 2001.

• The correlator has been operating as efficiently as the Mark III Correlator.

Table 1. Key Technical Staff of the CORE Operations Center

Name Responsibility Agency

Tom Buretta Recorder and electronics maintenance Haystack

Brian Corey Analysis Haystack

Irv Deigel Maser maintenance HTSI

Frank Gomez Software engineer for the Web site Raytheon/STX

David Gordon Analysis Raytheon/STX

Ed Himwich Network Coordinator for CORE stations NVI, Inc./GSFC

Chuck Kodak Receiver maintenance HTSI

Cindy Lonigro Analysis Raytheon/STX

Dan MacMillan Analysis NVI, Inc./GSFC

Leonid Petrov Analysis NVI, Inc./GSFC

David Shaffer Sources and antenna parameter maintenance Radiometrics/NVI, Inc.

Dan Smythe Tape recorder maintenance Haystack

Cynthia Thomas Coordinate master observing schedule and NVI, Inc./GSFC

prepare CORE experiments observing

schedules

Nancy Vandenberg Organizer of CORE program and sked NVI, Inc./GSFC

manager

William Wildes Procurement of materials necessary for CORE GSFC/NASA

operations

The tentative CORE evolution plan for the next few years is summarized in Table 2.

Table 2. Planned CORE Evolution

Start Date Experiment Name Avg Days per Week Notes

l-Feb-2000 CORE-A monthly 2.0 Mark IV Correlator efficiency

< Mark III Correlator

l-Jul-2000 CORE-3 monthly 2.0 Discontinued CORE-A

1-Jan-2001 CORE-1 monthly 2.4

l-Jan-2001 CORE-3 bi-weekly 2.4

l-May-2001 CORE-C 8 sessions 2.5

l-Jul-2001 CORE-3 weekly 2.8 two different CORE-3 networks

We are working on identifying the participating stations for each new CORE network. We will

need more antenna observing to fulfill this plan. The goal for CORE is continuous observing but we

2000 IVS Annum Report 161
CORE Operation Center NASA Goddard Space Flight Center

recognize that it will be very difficult to fill in the weekend days for CORE-5, -6, and -7. Weekend

observing is costly both in funding and in inconvenience to operators. We would appreciate any

ideas you have about how to attack this problem. Volunteers for weekend observing would be very

welcome!

6. CORE Review Panel

A panel, co-sponsored by NASA and IVS, met in early 2001 to review the CORE program and

make recommendations about the best way VLBI can contribute to space geodesy programs. The

report of the panel will be input to the master schedule planning for 2002 observing.

References

[1] Clark, T.: CORE White Paper, June 2, 1997

162 2000 IVS Annual Report
U.S. Naval Observatory NEOS Operation Center at USNO

U.S. Naval Observatory Operation Center

Kerry Kingham, M.S. Carter

Abstract

This report covers the activities of the NEOS Operation Center at USNO for 1999 and 2000.

1. VLBI Operations

NEOS operations in the period covered consisted of one 24-hour duration NEOS-A observing

session, on Tuesday-Wednesday of each week, for Earth Orientation, together with daily one-hour

duration "intensives" for UT1 determination. The operational NEOS-A network has included

VLBI stations at Gilmore Creek (Alaska), Kokee Park (Hawaii), Wettzell (Germany), Fortaleza

(Brazil), Ny-Alesund (Norway), Algonquin Park (Canada), Westford (Massachusetts), Matera

(Italy), Yellowknife (Canada) and Green Bank (West Virginia). No more than six stations were

used in any given NEOS-A.

During the reporting period, the Green Bank station was closed and is no longer available.

The daily intensive sessions switched from the Green Bank - Wettzell network to the Kokee Park

- Wettzell network.

All sessions are correlated at the Washington Correlator, which is located at USNO and is run

by NEOS.

2. Staff Changes

During the reporting period, T.M. Eubanks left USNO to pursue opportunities in the private

sector. B.A. Archinal left USNO for a job at the U.S. Geological Survey in Flagstaff, AZ. M.S.

Carter has assumed the scheduling duties.

2000 IVS Annual Report 163



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Geodiitisches Institut der Universit_t Boni_.

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Bonn MPIfR/BKC- Correlator

The Bonn Astro/Geo Mark IV Correlator

Arno Miiskens, I_lter Alef

Abstract

The Bonn MKIV VLBI correlator was officially opened on November 17th, 2000; it is operated

jointly by the MPIfR (Bonn), the GIUB (Bonn) and the BKG (Frankfurt). The final installation will

permit the simultaneous correlation of 16 channels of MK IV or VLBA formatted data for all baselines

from 9 station playback units, in both cross- and parallel-hand polarizations.

1. History

Back in 1990 a "Prototype Next Generation Correlator" Project was initiated by a consortium of institutions on the East Coast of the United States. In 1993 the International Advanced

Correlator Consortium (IACC) was founded and the construction of a completely newly-designed

successor for the existing MK III(A) VLBI data acquisition and recording system was started at

Haystack Observatory under the designation "MK IV Correlator Project". The aim of a working

next generation VLBI correlator was achieved in 1999.

A MK IV correlator was installed by members of the Haystack Observatory at the MPIfR

(Max-Planck-Institute for Radioastronomy, Bonn) in December 1999 [Alef et al.] shortly after the

first operational correlator tests had been performed at the Washington VLBI correlation center

at the United States Naval Observatory (USNO) [Kingham and Martin].

The Bonn MK IV correlator is jointly operated by the MPIfR for astronomical observations

and by the Bundesamt fiir Kartographie und Geodiisie (BKG) in cooperation with the Geodetic

Institute of the University o.f Bonn (GIUB) for geodetic applications.

Figure 1. Present MK IV VLBI Correlator at Bonn (MPIfR/BKG).

2000 IVS Annual Report 167
Bonn MPIfR/BKG Correlator Geod£tisches Institut der Universit_t Bonn

2. Status and Capabilities of the Bonn MK IV VLBI correlator

At the time of this report 6 playback drives can be used simultaneously with 15 baselines, 16

channels, and 32 lags. This limitation is caused by the current software which can only handle

2 of the 16 correlator boards. Other modes with fewer stations but more lags are also possible.

Multiple passes have to be done for observations with more than 6 stations: e.g. 7, 8 or 9 stations

have to be done in 3 passes, 12 stations in 6 passes. The next release of the software will handle 9

playback units with some limited set of correlator modes.

All tape drives can play back thick and thin tape; the equalizers of 5 playback drives are

optimized for thin tapes at present.

Supported playback speeds are 80 ips for thin tapes and 135 ips for thick tapes, which is due to

the tape drives having only one set of equalizers. Due to another software limitation the playback

speeds have to be the same as the recording speeds (speed-up factor has to be 1). One playback

is equipped with a newly-designed switchable equalizer board which has 3 sets of equalizers; at

present it can switch between 80/135/270 ips playback.

The supported formats are MKIIIA_ MK IV and VLBA, both MK IV and VLBA with 1- or

2-bit sampling. Fan-in modes are not supported while all the fan-out modes 1:1 and 1:2 and 1:4

are possible. Any number of up to 16 frequency channels can be used, both upper and lower

sidebands.

Multiple passes as needed for modes with more than 16 channels are not supported by the

present software release. Channel bandwidths of 2, 4, 8 and 16 Mhz are usable.

The different playback modes are: MK III modes B and C, and those shown in Table 1.

128-16-1 128-16-2 128-8-1

128-8-2 128-4-1 128-4-2

thin tape only 128-2-2 256-16-1 256-16-2

thin tape only 256-8-1 256-8-2 256-4-2

Table 1. Overview MK IV correlator modes

The geometric correlator model is CALC 8.

Single-tone phase-cal extraction at 10 kHz is implemented. The possibility to extract other

phase-cal frequencies as well as multi-tone phase-cal are planned. The pre-averaging time is flexible

from 0.5 to 5 seconds.

Fringe-fitting is done off-line by the program fourfit. Dual frequency observations are done in a

single execution of the program while dual/cross-polarization experiments have to be fringe-fitted

in multiple executions.

The raw and fringe-fitted data is archived on DDS2 DAT cassettes. The archive contains the

root, the raw correlator data (type 1 files), the fringe-fitted data (type 2), and the station-based files

(type 3 files). All the processed geodetic data are also exported with the geodetic post-correlation

software interface CALC/SOLVE.

3. Correlator Operations

Approximately 50% of the correlator time is allocated to IVS related tasks. It is used for setup

and production processing of IRIS-S, EUROPE and CORE (Core-3, Core-OHIG) experiments.

168 2000 IVS Annual Report
Geod_itisches Institut der Universit/it Bonn Bonn MPIflR/BKG Correlator

The remaining 50% are used for astronomy correlation like the processing of millimeter-wave

radio astronomy observations and other MPIfR-based VLBI observations. The total available

processor time has to be reduced by 10% for such tasks as correlation fringe check, testing station

performance, maintenance of processor software and playback recorder units and test experiments

for geodesy and astronomy. Over the past year more than 25 geodesy sessions and test experiments

were processed at Bonn MK IIIA / MK IV eorrelators.

4. Outlook

A new contract between GIUB and BKG was made to support IVS with the processing of

about 50 experiments per year at the MPIfR/BKG correlator. At the end of 2001 it has to be

reviewed if the commitment towards IVS can even be increased. This will also depend on further

improvements of the MK IV processing software. Especially eorrelator post-processing software is

still rudimentary and causes a lot of extra work.

5. References

Alef W, Graham D A, Zensus J A, Miiskens A, Schliiter W (2000) The Bonn MK IV Correlator Project, Proceedings of the First IVS General Meeting, N.R.Vandenberg and K.Baver,

Eds., NASA Center for AeroSpace Information, 7121 Standard Drive, Hanover, MD 21076

1320, Publ.No. NASA/CP-2000-209893.; p.210-214

Kingham K A, Martin J O (2000) Early Experiences with the Mark 4 Correlator, Proceedings of the First IVS General Meeting, NASA Center for AeroSpace Information, 7121 Standard Drive, Hanover, MD 21076-1320

Miiskens A. et.al. (2000) Comparison of MK III and MKIV Correlation using a 4-station

IRIS-S experiment, held at 14th Working Meeting on European VLBI for Geodesy and

Astrometry at Castel San Pietro Terme (Italy) from Sept. 8 - Sept. 9, 200(}, edited by

P.Tomasi, F.Mantovani, M. Perez Torres, S125-136

Whitney, A. R. (1994) The Mark IV VLBI Data-Acquisition and Correlation System, In: Developments in Astronomy and Their Impact on Astrophysics and Geodynamics, edited by I.I

Mueller and B. Kolaczek 151-157,1994.

2000 IVS Annual Report 169
P, / ._

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Haystack Observatory Correlator MIT Haystack Observatory

Haystack Observatory VLBI Correlator

Mike Titus, Brian Core), Roger Cappallo, Arthur Niell

Abstract

This report presents the status of the Haystack Correlator, focusing oil its activities, its current

and future hardware capabilities and its st'aft.

Figure 1. Haystack Mark IV Corretator

1. Introduction

The Haystack Observatory Mark IV VLBI correlator, located in Westford, Massachusetts, is

supported by the NASA Space Geodesy Program and by the National Science Foundation. The

available correlator time is divided approximately equally between processing geodetic VLBI observations for IVS and processing millimeter-wave radio astronomy observations for the Coordinated

Millimeter VLBI Array. In addition to its role as an operational processor, the Haystack Correlator

also serves ms a development system for testing new correlation modes and hardware improvements

and for diagnosing correlator problems encountered either at Haystack or one of the identical cotrelators at the U.S. Naval Observatory or at the Max Planck Institute for Radioastronomy. This

flexibility is made possible by the presence on site of the team that designed the correlator hardware

and software.

170 2000 IVS Annual Report
MIT Haystack Observatory Haystack Observatory Correlator

2. Summary of Activities

Since the last correlator report, major changes have occurred. As projected in the previous

annual report, in December 1999 the Mark IIIA correlator was decommissioned and the Mark IV

was brought oil line. This transition, though difficult, has been a success. Geodetic production

processing from Haystack experienced a short gap in service, and all correlation at Haystack is

now done Oll the new Mark IV correlator. Since the transition, development efforts have focused

on increasing the reliability and efficiency of operations and on enabling new modes of processing.

Some examples of this development work include:

• Improve/repair capabilities of the Station Units (internal code and control software).

• IInprove and increase capabilities, efficiency, accuracy and details of all aspects of the correlator control software (from tape drive control through operator interface).

• Examine and correct or enhance the quality, accuracy, and ret)orting of data.

• After testing, ext)ort software improvements to the Washington and Bonn sites.

3. Experiments done

Since the last report (July 99), 37 geodetic experiments have been processed, with 5 done on

the Mark IIIA and 32 on the Mark IV. These are broken down into 4 CORE A's, 6 CORE l's, 13

CORE B's and 5 CORE 3's (CORE '3's were all done on the Mark IV since they are recorded in a

fanout mode that cannot be processed on a Mark IIIA). A collection of various test experiments

comprise the remaining 9 (correlator tests, rack tests, station fringe tests, etc .... ).

4. Current/Future Hardware/Capabilities

Current hardware installed and functional on the new system are 6 tape units, 6 station units,

4 (operational) correlator boards, 1 (:rate, and miscellaneous other support hardware, with the

ability to process all baselines for 6 stations at once in the standard geodetic modes. In the near

future we plan to add two more tape and station units and fully enable the 2 crate mode, utilizing

all 16 correlator boards. Other planned improvements:

• Add decoder as tool for examining recordings.

• Enable multiple streams and st)eedu p factors in playback processing.

• Implement multiple speed parallel equalizers in playt)ack drives.

• Address repeatability an(t reliability issues to reduce, reprocessing requirements (mostly related to station unit).

• Improve capabilities and tools for examining correlator output and inanaging flow of data

through system.

5. Staff:

Staff who participate in aspects of Mark IV developInent and operations include:

2000 IVS Annual Report 171
HaystackObservatory Correlator MIT Haystack Observatory

5.1. Software Development Team:

• John Ball - operator interface, playback

• Roger Cappallo- leader, system integration

* Kevin Dudevoir - correlation

• Colin Lonsdale - post processing

• Alan Whitney - system architecture

5.2. Operations Team:

• Peter Bolis - correlator maintenance

• Tom Buretta - playback drive maintenance

• Brian Corey - experiment correlation oversight, station evaluation, technique development

• Dave Fields - playback drive maintenance

• Ellen Lautenschlager - correlator operator

• Glenn Millson - correlator operator

• Art Niell - experiment correlation oversight, technique development

• Don Sousa - correlator operator, experiment setup, tape library and shipping

• Mike Titus - correlator operations oversight, experiment setup, computer services

• Ken Wilson - correlator maintenance, playback drive maintenance

6. Conclusion/Outlook:

Operationally, we hope that these and other improvements will increase efficiency and throughput in the near future. The potential for additional improvements in this area, and the possibility

to record and process many new types of experiments, should be realized in the next phase of

development and production work. Over the next year the Mark IV system is expected to attain

its full potential, which will greatly increase the sensitivity, flexibility, output, and power of the

correlator as a tool for the IVS conmmnity.

172 2000 IVS Annual Report
i ,:_/'xl i /'"!.-."

/

Communications Research Laboratory Key Stone Project, VLBI Correlation Center 5-_

KSP-VLBI Correlation Center Report

Mamoru Sekido, Hitoshi Kiuchi, Yasuhiro Koyama

Abstract

Communications Research Laboratory has been regularly operating Key Stone Project (KSP) VLBI

experiments to monitor crustal deformation around the Tokyo metropolitan area. The KSP system

detected crustal deformation in the south part of the Kanto region due to volcanic activities at Izu

islands in 2000. Daily 23.5-hour VLBI experiments were performed to monitor the crustal motion. Such

frequent experiments could not be performed without a real-time VLBI system. At beginning of 2001,

Miura station was closed and the other three stations will continue monitoring of crustal movement.

Optically linked real-time VLBI experiment with Usuda 64m antenna and Kashima 34m antenna was

also performed several times.

1. Introduction

Communications Research Laboratory (CRL) has been doing regular geodetic VLBI experiments to monitor crustal deformation around the Tokyo metropolitan area. The name of the

project is Key Stone Project (KSP) [1]. The KSP VLBI has two types of correlation processing

systems. One is a tape-based VLBI correlation system [2][3] and the other is a real-time VLBI

correlation system [4][5][6] (Figure 1). Both systems are operated at a data rate of 256 Mbps. KSP

VLBI with four stations started in tape-based mode from fourth quarter of 1996 and 256 Mbps

real-time VLBI observation started third quarter of 1997 by using Asynchronous Transfer Mode

(ATM) network under collaboration with NTT (Nippon Telephone and Telegraph Corporation).

Tape-based and real-time VLBI correlation processing is performed with 6 units of single baseline correlators, correlation controller and operation software with GUI interface designed for easy

operation [7].

2. Correlation Center History of Routine KSP Operation

Real time VLBI experiments had been operated every other day with three stations (Kashinm,

Koganei, and Tateyama) for 23.5 hours, since optical fiber link of Miura station was closed in

May 1999. The reason for the observation interval is to reduce abrasion of antenna system. Fourstation tape-based VLBI observation had been performed once every 6 days. The reason for the low

frequency of observation with the four-station tape-based system was that correlation processing

of tape-based data took much time. Tape-based observations every other day is hard for both

operator, tape recorder, and tape changer machine. Mechanical motion is the most frequent cause

of the troubles in routine operation. From this point of view, real time VLBI was indispensable

for daily VLBI observation as described in a later section.

In July 2000, shortening of the Kashima-Tateyanm baseline was detected and the observation

schedule was changed from every other day to every day with three stations and tape-based fourstation VLBI observation every 6 days. The crustal deformation was found to be caused by

volcanic activities in the Izu islands located about 100km south west of Tateyama. The daily

VLBI observation continued to 11 November 2000, then the observation mode was changed to the

same as before July, since rapid changing of the baseline length was finished and the change rate

returned to the same state as before July. Minra station was closed after tape-based four-station

2000 IVS Annual Report 173
Key Stone Project VLBI Correlation Center Communications Research Laboratory

Figure 1. The KSP tape-based VLBI correlation system (left) and the KSP real-time VLBI correlation

system (right) at Koganei, In the left figure, four racks at the left are automatic tape changer (DMS24). The right three racks contain correlators, output interfaces, and correlation controller. All of these

tape-based equipment will be transported to Kashima Space Research Center in near future.

VLBI observation on 4th January, because it had been planned before. After that date, routine

KSP VLBI observations have been carried out by real-time VLBI with three stations.

Except for the routine KSP VLBI observation, domestic VLBI observation campaign has been

performed for connection of KSP stations and Japanese geographical reference frame to international reference fi'ame. The name of the campaign is JPNTI. The JPNTI VLBI experiments

using KSP 4 stations, Kashima 34m antenna, Kashima 26m antenna, and Tsukuba 32m antenna

were conducted in March, June, September, October, and November in 2000. The next JPNTI

experiment is planned in February 2001. Most of these experiments were processed with the KSP

correlation system.

KSP VLBI Kashima-Koganei baseline was also used for Giga-bit VLBI system performance

check experiments, which were named GEX series. GEX-8 in May and GEX-9 in June 2000 were

organized for delay measurement accuracy comparison between KSP and Giga-bit VLBI system.

3. Optically Connected VLBI Experiments

Optically linked VLBI experiments with large diameter antennas named GALAXY were performed several times under mutual collaboration among CRL, NTT, National Astronomical Observatory (NAO), and Institute of Space and Astronautical Science (ISAS). Kashima 34m antenna

(CRL), Usuda 64m antenna (ISAS), KSP llm antennas, and rarely Nobeyama 45m antenna (NAO)

joined the observations. Currently the only established real-time VLBI correlation system is the

KSP correlator in Japan. Thus all the real-time VLBI experiments are processed at Koganei Correlation center at present. Also distributed multi-baseline correlation processing was demonstrated

with the KSP eorrelator by sending observed data via ATM network at NTT R&D Forum 2000.

NAO's Mitaka FX correlator is raider preparation for adapting to real time processing.

174 2000 IVS Annual Report
Communications Research Laboratory Key Stone Project VLBI Correlation Center

. Technical Staff for the KSP VLBI Correlation Center

Technical staff members who are contributing to the KSP correlation center are listed below.

• Tetsuro Kondo, Responsible for overall operations and performance.

• Taizoh Yoshino, Leader of the Key Stone Project team in CRL.

• Hitoshi Kiuchi, Developments of correlation system and real-time VLBI interfaces.

• Jun Amagai, Responsible for management of correlation center.

• Mamoru Sekido, Development of correlation processing software.

• Naoki Goto and Muneo Takeda, Hiroyuki Shibata, Operator at the correlation center, Space

Engineering Development Co., Ltd.

5. Current Status and Future Plans

After tape-based data processing including JPNTI experiments have finished, tape-based correlation system (Figure 1) will be transported to Kashima Space Research Center for data processing

of experimental VLBI observation.

References

[1] Taizoh Yoshino: Overview of the Key Stone Project, J. Commun. Res. Lab., Vol. 46, No. 1, pp.3-6,

March 1999

[2] Hitoshi Kiuchi, Tetsuro Kondo, and Mamoru Sekido: KSP VLBI System; Correlation Processing System,

J. Comnmn. Res. Lab., Vol. 46, No. 1, pp.47-53, March 1999

[3] Mamoru Sekido, Hitoshi Kiuchi, and Tetsuro Kondo: KSP VLBI System; Correlation Processing Software, J. Commun. Res. Lab., Vol. 46, No. 1, pp.55-66, March 1999

[4] H.Kiuchi, M.Imae, T.Kondo, M.Sekido, S.Hama, T.Hoshino, H.Uosc, and T.Yamamoto,"Real-time

VLBI system using ATM network", IEEE-TGRS, Vol.38, No.3,pp.1290-1297, May 2000.

[5] Hitoshi Kiuchi, Tetsuro Kondo, Mamoru Sekido, Yasuhiro Koyama, Michito Imae, Takashi Hoshino, and

Hisao Uose: KSP VLBI System; Real-Time VLBI Data Transfer and Correlation System, J. Commun.

Res. Lab., Vol. 46, No. 1, pp.83-89, March 1999

[6] Mamoru Sekido, Tetsuro Kondo, and Hitoshi Kiuchi: KSP VLBI System; Real-Time Correlation Processing Control Software, J. Comnmn. Res. Lab., Vol. 46, No. 1, pp.91-96, March 1999

[7] Mamoru Sekido, Yasuhiro Koyama: Key Stone Project Correlation Center, IVS Annual report 1999,

pp.156-159, August 1999

2000 IVS Annual Report 175
d

Tsukuba VLBI Correlator

Zooz.oo . 3o 55 5"72,v

Geographical Survey Institute _f _-_

Tsukuba VLBI Center

Kohei Miyagawa

Abstract

In this report, we present the summaries of the activities of correlator and related topics at the

Geographical Survey Institute (GSI) from M_. 1999 to Dee. 2000.

1. Correlator Processing

From Mar. 1999 to Dec. 2000, GSI K4 Correlator processed VLBI sessions as below.

• GSI domestic experiments (experiment code JADE, 9 times)

• Experiment between SYOWA and KASHIMA (Feb. 1999)

• Experiments between WETTZELL and TSUKUB32 (May and .hm. 1999)

• Remote controlled experiment between TSUKUB32 and AIRA (Dec. 2000)

Regarding GSI domestic experiments, we processed the data recorded with 64 Mbps before JADE0002 in Jun. 2000. From this session, the data recorded with 128 Mbps was processed, and fringes

were detected. Correlator summaries on domestic experiments are available on the GSI VLBI Web

page from JADE-0002. URL is

http://vldb, gsi. go. j p/sokuchi/vlbi/english

Froln JADE-0003 in Sep. 2000, GIFU3 took part in JADE session. We processed and analyzed the

data including GIFU3. In processing the data of the SYOWA experiment, fringes were detected

for the first tilne with K4 correlator. The data of the WETTZELL experiments were processed

with GSI correlator and analyzed at Bonn. For the remote controlled experiment, fringes were not

detected, because Cesium, not H-maser, was used as a frequency standard at AIRA station.

2. Program Update for System Controller (CRC-9511-CNT1)

The problem that System Controller, which controls the correlator devices, incorrectly recognized record times was foml(t. As system controller read the process time of each observation and

station from temporary file generated from schedule file, system controller, in some cases, read the

process times unrelated to the processing stations. As a consequence, correlation was not processed

with the correct accumulation time. This error of the program for system controller was corrected

and updated in Nov. 20(}0.

3. Y2K Problem

In application software for correlator, Kety KUS880419, Y2K problem occurred, and correlator

processed incorrectly. The program was modified to fix the problem and now processing is correctly

done.

176 2000 IVS Annual Report
Geographical Survey Institute Tsukuba VLBI Correlator

4. Modification to Program for Bandwidth Synthesis

The program for bandwidth synthesis developed by CRL was modified. Length of data that

could be processed by the program was originally less than 300 PP. Moreover parameter period

was set to 1 sec, so the maximum data length wa_s 300 sec. As a result of this modification and a

change of PP to 2 see., we can process the data of maximum 1024 sec. We are now reprocessing

the data that is longer than 512 sec.

5. Staff

VLBI Staff at GSI are listed in the following table.

Table 1. Staff working at GSI VLBI group

Name Position Jobs

Shigeru MATSUZAKA IVS Networks Representative

Yoshihiro FUKUZAKI Leader of VLBI group

Tadayuki AKIYAMA Collocation chief Collocation, Operation

Kousei SHIBA Operation chief Experiments Coordination,

Operation

Kazuhiro TAKASHIMA Visiting scientist at GSFC Improvement of software

for VLBI analysis

Ma_saru YAZAWA Analysis chief Baseline Analysis, Operation

Shinobu KURIHARA Operator Baseline Analysis, Operation

Michiko ONOGAKI Ot)erator Antenna and H-maser maint.,

Operation

Kohei MIYAGAWA Correlation chief Correlation, Operation

Kyoko KOBAYASHI Assistant Correlation, Operation

References

[1] Ishihara, M., K. Nemoto, M. Iwata, K. Shiba, K. Takashima, and S. Matsuzaka: Tsukuba VLBI Center,

IVS 1999 Annual Report, pp.160 163, August 1999

[2] Ishihara, M., K. Nemoto, M. Iwata, K. Shiba, K. Ta "kashima, and S. Matsuzaka: Tsukuba 32-m VLBI

station, IVS 1999 Annual Report, pp.ll5 118, August 1999

[3] Takashima, K., S. Kuriharm M. Ishihara, K. Nemoto, M. Iwata, K. Shiba, M. Onogaki, and K.

Kobayashi: Status and Results of GSI Domestic VLBI Networks, Bull. Geograph. Surv. Inst., Vol.

46, pp.1 -9, March 2000

2000 IVS Annual Report 177
7/_ lJ/'".-"-'.__.._

XVashington Correlator

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U. S. Naval Observatory _.$ 2___.

Washington Correlator

James O. Martin, Kerry A. Kingham

Abstract

This report summarizes the activities of the Washington Correlator from the establishment of IVS

to the end of 2000. The Washington Correlator provides 136 hours of processing per week, primarily

supporting Earth orientation and astrometric observations.

1. Introduction

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 spends more than 90 percent of its time

on these experiments. All of the weekly NEOS-A sessions, all of the daily intensives, and most

of the CORE-A sessions are processed at WACO. The remaining time is spent on reference frame

and astrometry sessions. From March, 1999 until the end of December, 1999 the facility utilized a

Mark IIIA correlator. Beginning in January, 2000 processing switched to the Mark IV correlator.

The first data from the new correlator was published in the IERS Bulletin A for January 11, 2000.

2. Correlator Operations

During the reporting period, the remaining two Mark IIIA playbacks were upgraded to Mark

IV. For all of the calendar year 2000, the correlator operated with 6 Mark IV, thin tape capable,

playback tape drives. All are capable of processing high density recordings and all are equipped

with dryer units to prolong head life.

The correlator facility operates 136 hours per week, and is fully loaded at this level. During

the first part of the reporting period, the Mark IIIA correlator was used at its normal efficiency.

By the end of 1999, some degradation of processing throughput occured due to the installation

and checkout of the Mark IV processor.

After the introduction of the Mark IV correlator, correlator efficiency decreased due to training

on the new correlator and also due to the primitive state of the whole operational system. Efficiency

slowly improved, and by the end of 2000, the efficiency was beginning to approach Mark IIIA

standards, although much more work needs to be done to fully realize the promise of the new

correlator.

Due to the Mark IV startup period, NEOS-A and the Daily Intensives were the only sessions

processed during the first few months of operations. As the correlator efficiency improved, more

non-NEOS sessions, and some of the backlog were processed.

3. Staff

The Washington Correlator is under the management and scientific direction of the Earth

Orientation Department of the U.S. Naval Observatory. USNO personnel continue to be responsible

178 2000 IVS Annual Report
U. S. Naval Observatory Vv'ashington Correlator

for overseeing the scheduling and processing. During the period covered by this report, a private

contractor, AMSC, continued to supply a contract manager and eorrelator operators.

Dr. Kerry Kingham (USNO) VLBI Correlator Project Scientist, responsible for the scientific

integrity of correlated data, hardware and software maintenance and upgrades.

James O. Martin (USNO) VLBI Correlator Project Manager, responsible for process scheduling and evaluation of correlated data. Oversees session setups and prepasses. Evaluates

station performance.

Bruce Thornton (AMSC) Operations Manager, responsible for eorrelator operator scheduling, daily operations, and tape shipping.

Harvis Macon (AMSC) Correlator operator, NEOS-A setups.

Valerie Bockarie (AMSC) Correlator Operator

Steven Springer (AMSC) Correlator Operator

Lawrence Dorsey (AMSC) Correlator Operator

Joseph Granderson (AMSC) Correlator Operator

Roxanne Watkins (AMSC) Tape Librarian

4. Outlook

The Washington Correlator, at present, is able to process 6-station geodetic VLBI sessions in

a single pass. As the Mark IV development continues, and at least two additional tape drives are

added, the Correlator facility will be able to handle 8-station sessions in a single pass, or subdivide

into as many as 4 simultaneous sessions. More of the Mark IV capabilities will become operational

allowing new observation formats.

2000 IVS Annual Report 179

n

Bundesamt fiir Kartographie und GeodKsie

 .00 Z- i'

55Sq2 1

BKG Data Center

BKG Data Center

_,blkmar Thorandt, Reiner _bjdziak

Abstract

This report summarizes the activities and background information of the IVS Data Center

from the establishment of IVS to the end of 2000. 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 CDDIS Data

Centers by mirroring the OPAR file stock 6 times per day. The following sketch shows the principle

of mirroring:

BKG <--> OPAR <---> CDDIS

IVS components can choose one of these Data Centers to put their data into the IVS network

by using its incoming area which each of them has at its disposal. These areas are protected and

the users need to obtain username and password to get access.

An incoming script is watching this incoming area and checking the syntax of the files sent by

IVS components every hour. If it is o.k. the script moves the files into the datacenter directories;

otherwise the files will be sent to a badfile area. Furthermore the incoming script informs the

responsible staff at Data Center by sending e-mails about its activities.

For public access to the BKG Data Center users can do it through FTP:

ftp. leipzig, ifag. de

uid: anonymous

pw: e-mail address

cd vlbi

respectively WWW:

http ://www. leipzig, ifag. de/VLBI

Structure of BKG IVS Data Center:

vlbi/

ivs-iers/

ivs-pilot2000/

ivscontrol/

ivsdata/

ivsdocuments/

ivsproducts/

: root directory

: VLBI products for IERS

: directory for special investigations

: controlfiles for data center

: VLBI observation files

: IVS documents

: analysis products

(earth orientation, terrestrial and celestial frames)

2000 IVS Annual Report 183
BKG Data Center Bundesamt fiir Kartographie und Geod_ie

Aside from this IVS related data bank another data bank for analysis purposes exists.

contains about 7400 X-Band databases and 7300 superfiles.

2. Technical Equipment

HP 9000/D280/1 (HP UX 10.20 operating system)

dis(: space: 190 GBytes (Raid system)

internet rate: 2 MBit/sec

backup: tape library

3. Staff Members

Volkmar Thorandt (coordination, data analysis, vt@leipzig.ifag.de)

Gerald Engethardt (data analysis, engelhardt@leipzig.ifag.de)

Dieter Ullrich (data analysis, dul@leipzig.ifag.de)

Reiner Wojdziak (data flow, web design, rw@leipzig.ifag.de)

It

184 2000 IVS Annual Report
Kashima Space l_esearch Center, Communications Research Laboratory Data Center at CRL

Data Center at Communications Research Laboratory

Yasuhiro Koyama

Abstract

The Data Center at Communications Research Laboratory archives and releases the analysis results

processed at the Analysis Center at Cormnunications Research Laboratory. Regular VLBI sessions with

the Key Stone Project VLBI Network are the primary objects of the Data Center. In addition, JPNTI

and K4TIE series of geodetic VLBI sessions were processed and archived. Recent changes during the

period between March 1999 and December 2000 will be reported and future plans of the Data Center

will be described.

1. Introduction

Tile IVS Data Center at tile Communications Research Laboratory (CRL) archives and releases

the analysis results processed by the IVS Analysis Center at CRL. Major parts of the data are

from the Key Stone Project (KSP) VLBI sessions [1] but other regional and international VLBI

sessions are also archived and released. Such additional sessions include JPNTI series and K4TIE

series. The former series have been repeatedly performed with Tsukuba 32m, Kashima 26nl,

Kashima 34m, and KSP stations to precisely determine site coordinates of the Tsukuba 32m and

KSP stations on the International Terrestrial Reference, Frame (ITRF) by using the site positions

of Kashima 26m and 34m stations on the ITRF. The later series were performed twice with the

Fairbanks, Kashima 26m, Kashima 34m, and KSP stations to demonstrate international geodetic

VLBI ot)servations with the K4 observation systems.

2. Data Products

The KSP VLBI sessions were perforined with four KSP IVS Network Stations at Kashima,

Koganei, Miura, and Tateyama in a daily or bi-daily (once every two days) basis until May 1999.

Duration of each session is about 23.5 hours. Daily observations were performed from March 1

until April 1, 1999 to obtain continuous VLBI data series for various investigations such as studies

about the atmospheric delay models and for the improvements of the data analysis technique.

The high-speed ATM (Asynchronous Transfer Mode) network line to the Miura station became

unavailable in May 1999 and the real-time VLBI observations with the Miura station became

impossible. After this time, the real-time VLBI sessions were performed with three stations at

Kashima, Koganei, and Tateyama. Once every six days (one session per three sessions), 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 three stations except for the Miura station were processed in real-time and the analysis results

were released promptly after the obsexvations completed. A (lay later, the observed tapes were

transported to the Koganei station and the data were correlated. After the correlation processing

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 since July 22,

2000 IVS Annual Report 185
DataCenteratCRL Ka.shima Space Research Center, Communications Research Laboratory

2000. The daily sessions were continued until November 11, 2000, and the site motion of the

Tateyama and Miura stations were monitored in detail. During the period, it was found that

Tateyama station moved about 5 cm to the northeast direction. Miura station also moved about 3

em to the north. The unusual site motions of these two stations gradually settled and the current

site velocities are almost the salne as tile site velocities before June 2000. By investigating the

time series of the site positions, the unusual site motion started from 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 thought to have caused the

regional crustal deformation near the area, and the unusual site motions at Tateyama and Miura

can be explained by the event.

Table 1 and Figure 1 show tile number of geodetic VLBI sessions and number of valid observed

delays used in the data analysis for each year.

Table 1. Number of sessions and observed delays

2000.

used in the data analysis for each year up to December

Year Number of Number of

sessions valid observed delays

1994 2 261

1995 171 15837

1996 345 66005

1997 308 287452

1998 183 474783

1999 198 351162

2000 235 339246

Total 1,142 1534746

400

Number of VLBI sessions

500000

Number of valid observed delays

300

200

1oo

1994 1995

400000 t_

-- 300000

__ ___ ,__ _ __ 200000100000

' 0

1994 1995 1996 1997 1998 1999 2000

!II

1996 1997 1998 1999 2000

Figure 1. Number of sessions andobserved delay, used in the data anNysisfor each 3'ear as of March 1,

1999.

In December 2000, the server system for the WWW (World Wide Web) and FTP (File Transfer

186 2000 IVS Ammal Report
Kashima Space Research Center, Communications Research Laboratory Data Center at CRL

Protocol) accesses was changed as shown in the Table 2. The URL (Unified Resource Locator)

of the WWW service remained the same, but the URL for the FTP service was changed. Data

analysis results are available in SINEX (Solution Independent Exchange) file format and in various

formats including ASCII data and data plots.

Table 2. URL and IP a<ldress of the WWW and FTP server system.

Service URL IP address

WWW http://ksp.crl.go.jp/ 133.243.3.35

FTP ftp://ksp.crl.go.jp/pub/j/j144/ 133.243.3.35

3. Future Plans

The operation of the Miura KSP VLBI station was terminated in January 2001. The antenna

and the observation facilities at the site will be transported to the Tomakomai Experimental Forest

of Hokkaido University. The Tateyama station will also be closed in 2002, and the antenna and

the observation facilities will be transported to the campus of the Gifu University. The tape-ba_sed

correlator system at Koganei will be transported to tile Kashima Space Research Center of CRL.

In spite of these changes, the IVS Data Center at CRL will continue its service and will archive

and release the analysis results produced by the IVS Analysis Center at CRL.

References

[1] Special issue for the Key Stone Project, J. Commun. Res. Lab., Vol. 46, No. 1, March 1999

2000 IVS Annual Report 187
/

CDDIS Data Center

/

5 r_L) :Z__ 7

el

NASA Goddaxd Space Flight Center _- t__

CDDIS Data Center Report

Carcy E. Noll

Abstract

This report summarizes activities for the year 2000 and future plans of the Crustal Dynamics

Data hiformation 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, staffing supporting the system, archive contents, and future plans for the CDDIS within

the IVS.

1. Introduction

The Crustal Dynamics Data Information System (CDDIS) has supported the archive and

distribution of Very Long Baseline Interferometry (VLBI) data since its inception in 1982. The

current and future plans for the system's support of the International VLBI Service for Geodesy

and Astrometry are discussed below.

2. Background

The CDDIS has been operational since September 1982, serving the international space geodesy

and geodynamics community. This data archive was initially conceived to support NASA's Crustal

Dynamics Project; since the end of this successful program in 1991, the CDDIS has continued to

support the science community through the Solid Earth and Natural Hazards activity within

NASA's Earth Science Enterprise. The main objectives of the CDDIS are to store all geodetic

data products acquired by NASA programs in a central data bank, to maintain information about

the archival of these data, and to disseminate these data and information in a timely manner

to authorized investigators and cooperating institutions. Furthermore, science support groups

analyzing these data subnfit their resulting data sets to the CDDIS on a regular basis. Thus, the

CDDIS is a central facility providing users access to raw and analyzed data to facilitate scientific

investigation. A large portion of the CDDIS holdings of GPS, GLONASS, laser ranging, VLBI,

and DORIS data are stored on-line for remote access. Infornmtion about the system is available

via the WWW at the URL http://cddisa.gsfc.nasa.gov/cddis welcome.html.

The CDDIS successfully responded to the 1998 Call for Participation in the International VLBI

Service tbr Geodesy and Astrometry (IVS). This response stated that the CDDIS would support

data center activities by providing access to an archive of schedule files, log files, data bases, data

products, and other auxiliary files.

3. System Description

The CDDIS archive of VLBI data and products are accessible to the tmblic via anonymous ftp

access.

188 2000 IVS Annual Report
NASA Goddard Space Flight Center CDDIS Data Center

3.1. Computer Architecture

The CDDIS is operational on a dedicated Compaq AlphaServer 4000 running the UNIX operating system. This facility currently has over 300 Gbytes of on-line magnetic disk storage;

approximately 25 Gbytes will be devoted to VLBI activities. The CDDIS is located at NASA

GSFC and is accessible to users 24 hours per day, seven days per week.

3.2. Staffing

Currently, a staff consisting of one NASA civil service employee and three contractor employees

supports all CDDIS activities:

Table 1. CDDIS Staff

Name Position

Ms. Carey Noll

Dr. Maurice Dube

Ms. Ruth Kennard

Ms. Laurie Batchelor

CDDIS Manager

Head, CDDIS contractor staff and senior programmer

Request coordinator and programmer

Data te(:hnician

4. Archive Content

The CDDIS has supported GSFC VLBI coordination and analysis activities for the past several

years through an on-line archive of schedule files, experiment logs, and data bases in several formats.

This archive has been expanded for tile IVS archiving requirements.

The IVS data center content and structure is shown in Table 2. In brief, an incoming data area

has been established on the CDDIS host computer, cddisa.gsfc.nasa.gov. Operations and Analysis

Centers deposit data files and analyzed results using specified file names to appropriate directories

within this filesystem. Automated archiving routines, developed by GSFC VLBI staff, peruse the

directories and migrate any new data to the appropriate public disk area. These routines migrate

the data based on the file name to the appropriate directory as described in Table 2. Index files

in the main subdirectories under ftp://cddisa.gsfc.nasa.gov/pub/vlbi are updated to reflect data

archived in the filesystem. F_lrthermore, mirroring software has been installed on the CDDIS host

computer, as well as all other IVS Data Centers, to facilitate equalization of data and product

hohtings among these Data Centers. At this time, mirroring is performed between the IVS Data

Centers located at the CDDIS, the Bundesamt fiir Kartographie und Geod£sie (BKG) in Leipzig,

and the Observatoire de Paris. Figure 1 illustrates the flow of information, data, and products

between the various IVS components.

The public filesystem in Table 2 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 data base and NGS card image formats). A products disk area has

also been established to house analysis products fi'om the individual IVS analysis centers as well

as the official combined IVS products. A documents disk area contains format, software, and other

descriptive files.

2000 IVS Annual Report 189
CDDIS Data Center NASA Goddard Space Flight Center

_,rvs s_, / . ,,_ °

_. IVS NetworkStations _-__

Lo Files Data Tapes

IVS Correlators

• Receive data tapes

• Correlate data

• Create reports and export files

It,

I ._ IVS Operation Centers

Export • Generate observlng schedules

Files • Receive export files

• Make data bases and NGS cards

• Produce weather and cable

calibration files

Correla Reports & chu,e Log_iles &Oa:--W.a,!er, N_aro Cable C_. Files

IVS Data Centers

• Archive data base flies and ancillary files

• Archive IVS products

• Update Index files

• Mirror data and products between data centers

Schedule

Files

lib

I

Ancillary Files i

IVS Analysis Centers

Data Base Files Analysi iResults

I

I

• Retrieve data t

• Produce products I

Figure 1. The flow of data, product, and log files from various IVS components to the IVS data centers.

190 2000 IVS Annual Report
NASA Goddard Space Flight Center CDDIS Data Center

Table 2. IVS Data and Product Directory Structure

Directory Descript ion

Data Directories

vlbi/ivsdata/db/yyyy

vlbi/ivsdata/ngs/yyyy

vlbi/ivsdata/sinex/yyyy

vlbi/ivsdata/aux/yyyy/ssssss

VLBI data base files for year yyyy

VLBI data files in NGS card image format for year

YYYY

VLBI data files in SINEX format (future) for year

YYYY

Auxiliary files for year yyyy and session ssssss; these

files include: log files, wx files, (:able files, schedule

files, correlator notes

Product Directories

vlbi/ivsproducts/crf

vlbi/ivsproducts/eopi

vlbi/ivsproducts/eops

vlbi/ivsproducts/trf

vlbi/ivs-iers

vlbi/ivs-pilot2000

CRF solutions

EOP-I solutions

EOP-S solutions

TRF solutions

IVS contributions to the IERS

IVS Analysis Center pilot project (2000)

Other Directories

vlbi/ivscontrol IVS control files (master schedule, IVS on-line directory and file information, etc.)

vlbi/ivsdocuments IVS document files (analysis documentation, etc.)

5. Future Plans

The CDDIS staff will continue to work closely with the IVS Coordinating Center staff to ensure

that our systenl is an active and successful participant in the IVS archiving effort. The st'aft hopes

to secure funding for some computer system enhancements, including a large RAID disk system.

2000 IVS Annual Report 191
/>'i/J 2---

Italy CNR Data Center

2-0 L Z <:::>" 5.

955730

Istituto di Radioastronomia Bologna

Italy CNR Data Center Report

P. Tomasi

Abstract

This report stmmlarises the situation of the Italian CNR VLB[ data center. It will give the fundamental iilformation about the structure of the center, its locations, and its activity.

1. Introduction

The Italy CNR VLBI data (:enter is tile joint effort of two Institutes of Consiglio Nazionale

delle Ricerche (CNR) to improve, working together, the capability of VLBI data storage in Italy.

The two Institute are:

a) the Istituto di Radioastronomia (Institute of Radio Astronomy IRA) located in Bologna,

where the main research activity is carried out, both in radioastronomy and geodesy, but also

managing the two VLBI antennas in Medicina (near Bologna) and Noto (in Sicily);

b) the Istituto di Tecnologia Informatica Spaziale (Institute of Informatiea and Technology for

Space ITIS), located in Matera at the Center of Spatial Geodesy (of the Italian Space Agency),

where VLBI antenna, laser ranging telescope, permanent GPS receiver and PRARE antenna are

located. Also a different data <:enter is located here (GeoDAF). All these structures are properties

of the Italian Space Agency and run by Telespazio.

However the two institutes mentioned above will become quite shortly a single institute, the

"Istituto di Radioastronomia", with a section located in Matera. The new CNRs institute will carry

on the same commitment to IVS as the previous two institutes. W'e have specialised the Bologna

part to store and analyse single databases, using CALC/SOLVE software. In Bologna we have

introduced CALCg.1 and all the databases stored here have been reCALCed. We are also using

f-solve (release Nov. 2000) and that means a complete new series of superfiles have 1)een produced,

according to the new format introduced. This point is only of interest for CALC/SOLVE users.

The IRA has started to store VLBI geodetic databases from 1989 but the databases archived

in Bologna are mostly concerned with data including European antennas, starting fi'om 1987.

In particular most of the databases present here have VLBI data with at least three European

antennas. However we are also storing all the databases with the Ny Alesund antenna data. All

the databases have been processed and saved with the best selection of the parameters for final

arc solution.

In sonm cases we have introduced the wet delay coming from GPS in the European databases

(at t)resent only for EUROPE experiments for the year 1998), as if it was pro(hwed by WVR.

Also these databases are available and stored with a different code from the original database. In

Matera we have stored part of the databases and all the superfiles. In fact, we are using the faster

computer there mostly for global solutions. However at the moment the f-solve version we are

using there is the June 2000 version of f-solve, with supcrfiles format not compatible with the ones

produced in Boh)gna. We will inove quite soon to a new version of f-solve also in Matera and then

also there we will have the supcrfiles in the new tbrmat.

192 2000 IVS Annual Report
Istituto di Radioastronomia-Bologna Italy CNR Data Center

2. Computer Available and Routing Access

In Bologna the main computer is HP715/80, the computer name is boira6.ira.bo.cnr.it and the

databases are stored in different directories and in different disks as well. The complete list of

directories where databases are stored is the following:

1 = /datal/mk3/datal

2 = /datal/mk3/data2

3 = /AREA/geo/data

4 = /data6/dbase6

6 = /data5/dbase5

5 = /data4/dbase4

7 = /dataT/dbase7

8 = /data8/dbase8

9 = /data9/dbase9

10= /GEO/data

11= /GEO/1999

12= /GEO/2000

As you can see, comparing the previous annual report, a new big area (/GEO), has been added.

At the moment this storing area is subdivided into three directories and its total storing area is

about 35 Gbytes.

The username for accessing the database at the moment is geo. Password can be asked by sending a mail to tomasi(@ira.bo.enr.it. In the near future the database will be accessed by anonymous

ftp.

In Matera the main computer is an HP282 computer with internet name hp-j.itis.mt.cnr.it.

The databascs are stored in different directories and the fi_ll list will follow:

1 = /datal/mk3/datal

2 = /datal/mk3/data2

6 = /data5/dbase5

5 = /data4/dbase4

7 = /dataS/dbase8

8 = /datal0/dbasel0

9 = /data13/dbase13

10 = /data14/dbase14

The super files are stored in different directories:

/data2/super

/datal0/superl0

/data9/super9

/data14/super14

and the list of superfiles is stored in the file/datal/solvefiles/SUPCAT. The data can be accessed

using tile username geo, and the password can be asked of tomasi@ira.bo.enr.it.

For the moment all the data are stored on magnetic disk, but we are planning to move the

whole catalog of databases to optical disk. The area available on a jukebox (already installed in

Matera) will be of 80 Gb on line.

2000 IVS Annual Report 193
Paris Observatory (OPAR) Data Center

.... '_>0 ,'_ ':j " -

sS-73)

Observatoire de Paris, DANOF/UMR8630 f,, _-_

Paris Observatory (OPAR) Data Center

Najat Essai'Ii

Abstract

This report smnmarizes the OPAR Data Center activities over 2000. Included are information

about functions, architecture, status future plans, and staff members of OPAR Data Center.

1. OPAR Data Center Functions

Tile Paris Observatory (OPAR) has provided since 1999 a Data Center for the International

VLBI Service for Geodesy and Astrometry (IVS). The OPAR as well as CDDISA 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 (auxilliary, database, products, documents),

• mirrors the other ones every three hours,

• gives free FTP access to the. files.

I I

T T

CDDIS

(USA)

BKG

(GERMANY)

I I I

T T T

I

T

This protocol gives 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.

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

194 2000 IVS Annual Report
Observatoire de Paris, DANOF/UMR 8630 Paris Observatory (OPAR) Data Center

script checks the file and puts it in the right directory. The script is in permanent improvement

and takes into account the IVS component requests.

Structure of IVS Data Center has evolved since 1999, and has actually six primary directories:

ivscontrol/

ivsdata/

aux/

db/

ngs/

sinex/

ivsproducts/

eopi/

eops/

crf/

trf/

ivs-iers/

ivs-pilot2000/

ivsdocuments/

: provides the control files needed by the data center

(session code, station code, solution code...)

: provides files related to the observations:

: auxilliary files (schedule, log...)

: observation files in data-base CALC format

: observation files in NGS format

: observation files in SINEX format\\

: provides results from Analysis Center:

: Earth Orientation Parameters, intensive sessions

: Earth Orientation Parameters, sessions of 24h

: Celestial Keference Frame

: Terrestrial Reference Frame\\

: provides products for IEKS Annual Report

: provides products for special investigations

: provides documents and descriptions about IVS products\\

3. Current Status

The OPAR Data Center is operational on a HEWLETT PACKARD 9000 Model 715 located

at Paris Observatory and running the HP-UX 10.20 operating system. To make all IVS products

available on-line, this server is equipped with a 20 Go disc storage for VLBI activities.

The OPAR server is accessible 24 hours per day, seven days per week through Internet connection with 2Mbit/s rate. Users can get the IVS products by using the FTP protocol. Access to

this server is free for users.

FTP access:

ivsopar.obspm.fr

userilalne : anonymous

password : your e-mail

cd vlhi (directory of IVS produts)

4. Future plans

The OPAR staff will continue to work with the IVS comnmnity. To ensure better access to the

OPAR Data Center, a new enhanced computer system will replace the current one, within a few

months. The disc space will also be increased with regards to IVS products.

5. Staff Members

Staff members who are contributing to Data Center and OPAR Analysis for IVS are listed

below:

2000 IVS Annual Report 195
Paris Observatory (OPAR) Data Center Observatoire de Paris, DANOF/UMR 8630

,, Najat Essa'ifi, Data Base manager.

• Anne-Marie Gontier, responsible for GLORIA analysis software.

• Martine Feissel, scientific developments.

• Daniel Gambis, interface with IERS activities.

6. Contact information

To obtain information about OPAR Data Center please contact:

Najat Essaifi

Observatoire de PARIS

61, Avenue de l'Observatoire

75014 Paris - FRANCE

Phone : 33 1 40 51 22 33

Fax: 33 1 40 51 22 91

E-mail : essaifi@hpvlbi.obspm.fr

196 20(}0 IVS Annual Report
-II-II
7
.: /j j.c-- ......

Astronomical Institute of Saint-Petersburg University

5 557%

Saint-Petersburg University Analysis Center

f

Analysis Center of Saint-Petersburg University

Oleg Titov, Maria Kudryashova, Veniamin Vityazev

Abstract

This report contains information about current and future activities of Analysis Center of SaintPetersburg University.

1. Introduction

Our Analysis Center is located at the Astronomical Institute of Saint-Petersburg University. It

began its activity in 1998. Initially we made an analysis of NEOS-Intensives VLBI sessions only.

Since 2000 year we have started to process the weekly NEOS-A experiments.

2. Staff

The staff and their responsibilities are:

V.Vitayzev - Director of Astronomical Institute of Saint-Petersburg University, PhD, General

coordination and support of activity at the Astrononfical Institute.

O.Titov - Assistant Professor of Saint-Petersburg University, PhD. Current processing of VLBI

data.

M.Kudryashova Postgraduate student of Saint-Petersburg University. Current processing of

VLBI data.

3. Data Analysis

The Analysis Center participates in regular submission of EOP from both NEOS-Intensives

and NEOS-A observational programs. We use OCCAM (version 3.4) package to get the solutions.

VLBI data files are downloaded in NGS format from Paris Observatory database (IVS component).

Ahnost all reductional calculations are in accordance with IERS Convention 1996 and later modifications (Explanatory Supplement). Relativistic corrections are from IERS Recommendations

1992. Seculax polar motion for pole tide correction is given by formulae from The Explanatory

Supplement. Station coordinates are referred to ITRF97. The celestial reference frame wa_s fixed

to Reference Frame Navy 1997-8.

Values of UT1-UTC are estimated within the scope of EOP's operative service. For the purpose

we use short (1-2 hours) VLBI sessions obtained by NEOS-Intensive program. Data are processed

by OCCAM software using weighted least squares method. Wettzell is used as reference station for

all sessions. Its wet delay, clock offsets and clock rates for other stations are regularly estimated.

The solution SPU00001.EOPI contains 778 estimates of the UT1-UTC since 01 September 1997.

As to processing of NEOS-A VLBI sessions, five parameters of Earth Rotation (pole coordinates, UT1-UTC, nutation offsets) are estimated by Kalman filter technique. For the reDrence

station (Wettzell on default) only wet delay is estimated. Wet delay, clock offsets are also estimated

for other stations. A random walk model has been chosen to adjust the stochastic behaviour of

the wet delay and clock offset. Usually clock rate is a constant parameter. For the last years clock

behaviour for WETTZELL is not perfect sometimes. In this case we use another suitable VLBI

2000 IVS Annual Report 199
Saint-Petersburg University Analysis Center Astronomical Institute of Saint-Petersburg University

site as reference. Moreover, in this case we have to use a random walk model to adjust the clock

rate for WETTZELL ms well. The solution SPU00001.EOPS contains 987 estimates of all five

EOPs since 07 February 1983. Fig.l-3 demonstrate the residuals between the solution and IERS

C04 system for 1996-2000.

4. Outlook

During the year 2001 we are planning:

• to make weekly comparison and combination of Intensive Series EOP.

• to upgrade OCCAM software jointly with groups from DGFI and Vienna Technical University.

5. Acknowledgments

The Analysis Center activity is supported financially by Russian Foundation of Basic Research

(grant 99-{}2-18059) and Federal program "Integration".

o References

1. D.McCarthy (ed.), IERS Recommendations 1992, Paris Observatory, 1992.

2. D.McCarthy (ed.), IERS Conventions 1996, Paris Observatory, 1996.

3. H.Schuh (ed.), Explanatory Supplement to the IERS Conventions (1996) Chapters 6 and 7,

DGFI Report 71, Munchen, 1999.

4. O.Titov, Analysis Center of Saint-Petersburg University, IVS 1999 Annual Report, 1999.

5. O.Titov, Influence of adopted nutation model on VLBI NEOS-Intensives Data Analysis,

Proceedings of IAU 180 Colloquium, Washington, pp. 259-262, 2000.

6. O.Titov, N. Zarraoa, OCCAM 3.4. User's guide, IAA Communications, 69, Saint-Petersburg,

1997.

7. O.Titov, Estimation of subdiurnal tidal terms in UT1-UTC from VLBI data analysis, IERS

Technical Note 28, Paris Observatory, pp. 11-14, 2000.

200 2000 IVS Annual Report
Astronomical Institute of Saint-Petersburg University Saint-Petersburg University Analysis Center

E

v

X

1 --

O.5 --

0 --

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-1 -

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E I ' I ' I _ I

50400 50800 51200 51600

Julian epoch (2400000+...)

Figure 1. Residuals SPUO0001 - IERS C04 for X-coordinates.

520O0

1 --

0.5 --

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÷

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2000 IVS Annual Report 201
Saint-Petersburg University Analysis Center Astronomical Institute of Saint-Petersburg University

0.08 --

0 --

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+

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Figure 3. Residuals SPU00001 - IERS C04 for UT1-UTC.

202 2000 IVS Annual Report
ObservatoiredeBordeaux

555757_,,

Bordeaux Observatory Analysis Center P__A t_

Bordeaux Observatory Analysis Center Report

Patrick Chariot, Bruno Viateau, Alain Baudry

Abstract

This report summarizes the activities of the Bordeaux Observatory Analysis Center from the establishment of IVS to the end of 2000. During this period, most of our efforts have been devoted to the

development of an astrometric project on the European VLBI Network for densifying the International

Celestial Reference Frame (ICRF). Another achievement is the evaluation of the astrometric quality

of the ICRF sources based on their observed structures, and the diffusion of this information through

a web page. Additionally, we have contributed to the implementation of a geodetic VLBI model in

a multi-technique software, GINS, developed by the GRGS group in Toulouse. Changes in staff and

equipment are also described, and the outlook for 2001 is given.

1. Celestial Frame Activities

As mentioned in our initial IVS report [1], our major scientific interest is the celestial frame,

especially the maintenance and extension of the International Celestial Reference Frame (ICRF).

The main achievements in this area since the establishment of IVS are reviewed below.

1.1. ICRF Densification

Along the lines described in [2], we have initiated an astrometric project on the European VLBI

Network (EVN) for densifying the ICRF in the northern hemisphere. The aim of this project is

to add 150 new sources at carefully selected sky locations to fill the "empty" regions of the frame

and improve the overall source distribution. Most notably, the addition of these new sources will

reduce the distance to the nearest ICRF source for any randomly-chosen location in the northern

sky from a maximum of 13° (as it is now for the current ICRF-Ext. 1 frame) to a maximum of 6°.

Further details on the source selection strategy are given in [2].

Table 1. Network used in ICRF densification experiment.

EVN telescopes Non-EVN telescopes

Effelsberg Algonquin Park

Medicina Goldstone (DSS 13)

Noto Green Bank (NRAO 20)

Onsala

Wettzell

Urumqi

Shanghai

Hartebeestoek

Ny-Alesund

As a first step, a proposal was submitted to the EVN for observing 50 of these new sources.

This proposal was approved and the subsequent experiment was carried out on May 31, 2000,

using seven EVN telescopes along with five external non-EVN geodetic stations that agreed to

participate in this project. The participating telescopes are listed in Table 1. The new sources

2000 IVS Annual Report 203
Bordeaux Observatory Analysis Center Observatoire de Bordeaux

were scheduled jointly with a set of 10 highly-accurate ICRF sources so that their positions can

be linked directly to the ICRF. Correlation of these data has just been carried out with the Bonn

Mark IV correlator. A quick look at the correlation results indicates that all 50 new sources have

been detected.

1.2. Source Classification Based on Observed Structure

Another achievement is the completion of source structure effect evaluation for most of the

ICRF sources north of -20 ° declination [3]. For possible use by IVS operational and analysis

centers, we have created a web page with false color images showing the magnitude of these effects

at X band and S band as a function of baseline length and orientation. The current web page 1

provides such an evaluation for 392 ICRF sources and contains a total of 784 images. It also

provides "structure indices" which reflect the astrometric suitability of each source according to

the median structure effect in the bandwidth synthesis delay, as defined in Table 2.

structure index

1

2

3

4

Table 2. Structure index and astrometric quality.

astrometric quality median effect (ps) observed structure

very good 0-3 point-like

good 3-10 resolved

use with caution 10 30

not acceptable > 30

extended

very extended

Based on the above evaluation, we have searched for correlations between the observed radio

structure and the ICRF source position accuracy and stability. Such correlations have been found

and they indicate that the more extended sources have larger position uncertainties and axe less

positionally stable than the more compact sources [3]. This study also revealed that 16 ICRF

defining sources have a structure index of 4, indicating that they are spatially extended and thus

are not appropriate for defining the celestial frame with the highest level of accuracy [3].

2. Software Development

A collaboration has been established with the GRGS group (Groupe de Recherches de G@od@sie

Spatiale) in Toulouse (France) to implement a geodetic VLBI model in the GRGS space-geodesy

software GINS for analysis of both Earth-based and space VLBI observations. The major goal

of this project is to process space VLBI delay and delay rate measurements from the HALCA

satellite to test the concept of space VLBI geodesy. Ultimately, the software will also be able to

process standard Earth-based geodetic VLBI data and to combine them with other space geodetic

measurements (SLR, GPS, DORIS) for multi-technique Earth orientation estimation and reference

frame unification.

Progress on this project has been reported in [4]. Our contribution in Bordeaux has been

especially to test the implemented geodetic VLBI model by carefully comparing results obtained

with GINS to those obtained with the MODEST VLBI analysis software [5]. This comparison

showed a very good agreement and indicates that the VLBI model in GINS is currently accurate

l http: / /www.observ.u-bordeaux.fr / public /radio /PChaxlot /structure.html

204 2000 IVS Annual Report
Observatoire de Bordeaux Bordeaux Observatory Analysis Center

at the few millimeter level. The new VLBI capability of GINS has also been used to process the

space VLBI delay data acquired during a HALCA experiment carried out on December 4, 1997.

The results of this analysis, although preliminary, suggest that the reconstructed HALCA orbit

at the time of the experiment is accurate at the few meter level, somewhat better than the 10 m

nominal accuracy given for this satellite [4] .

3. Staff and Equipment

• One member of our team (Bruno Viateau) spent 10 months (June 1999-April 2000) as a

post-doc fellow in the VLBI group at the Jet Propulsion laboratory. Unfortunately, despite

the experience gained there, he did not obtain a permanent research position after his return

in Bordeaux. He left the Observatory in July 2000 and now works for a private company.

• One of us (Patrick Charlot) spent a few days at NASA/GSFC in April 2000 to learn the

basics of the SKED scheduling software. This software was then successfully installed in

Bordeaux and used for scheduling the ICRF densification experiment described above.

• Computer equipment has been significantly upgraded with two new Unix workstations, a

Compaq DS20 acquired in September 1999, and a Compaq ES40 acquired in September 2000.

The MODEST analysis software has been installed on these workstations, while the Goddard

data base system and related software like SKED remain on our old HP workstation.

4. Outlook

• Starting next fall, we expect to have a new engineer for IVS analysis activities. This should

allow us to increase our level of activity and develop regular analyses related to the celestial

frame. Our goal is to produce time series of source positions and study the ICRF source

position stability as initially proposed [1].

• In the immediate future, our aim will be to process the data of the ICRF densification

experiment described above and to assess the results. This analysis will be carried out with

the MODEST VLBI analysis software [5]. Once we have these results, a new proposal will

be submitted to the EVN for observing the remaining 100 sources.

• Additionally, we will continue to evaluate the astrometric quality of the ICRF sources as new

maps are available, and make structure indices and false color images available through our

web page. Future work will also be targeted at incorporating source structure corrections to

actual observations. Progress toward this goal has been reported in [6].

References

[1] Charlot, P., Viateau, B., Baudry, A.: 1999, The Bordeaux Observatory IVS Analysis Center, International VLBI Service for Geodesy and Astrometry 1999 Annual Report, Ed. N. R. Vandenberg,

NASA/TP-1999-209243, p. 186-188.

[2] Charlot, P., Viateau, B., Baudry, A., Ma, C., Fey, A. L., Eubanks, T. M., Jacobs, C. S., Sovers,

O. J.: 2000, A Proposed Astrometric Observing Program for Densifying the ICRF in the Northern Hemisphere, IVS 2000 General Meeting Proceedings, Eds. N. R. Vandenberg and K. D. Baver,

NASA/CP-2000-209893, p. 168-172.

2000 IVS Annual Report 205
Bordeaux ObservatoryAnalysisCenter Observatoirede Bordeaux

[3] Fey, A. L., Charlot, P.: 2000, VLBA Observations of Radio Reference Frame Sources. III. Astrometric

Suitability of an Additional 225 Sources, ApJS, 128, 17-83.

[4] Meyer, U., Charlot, P., Biancale, R.: 2000, GINS: A New Multi-technique Software for VLBI Analysis,

IVS 2000 General Meeting Proceedings, Eds. N. R. Vandenberg and K. D. Baver, NASA/CP-2000-

209893, p. 324-328.

[5] Sovers, O. J., Jacobs, C. S.: 1996, Observation Model and Parameter Partials for the JPL VLBI

Parameter Estimation Software "MODEST"-1996, JPL Publication 83-39, Rev. 6, August 1996.

[6] Chariot, P.: 2000, Models for Source Structure Corrections, Proceedings of IAU Colloquium 180, Towards Models and Constants for Sub-microarcsecond Astrometry, Eds. K. J. Johnston, D. D. McCarthy,

B. J. Luzum and G. H. Kaplan, U. S. Naval Observatory, Washington, D. C., p. 29-39.

206 2000 IVS Annual Report
/

/ ,' ,,,'/IJ _"

Centro di Geodesia Spaziale (CGS)

L_ "_; , i)

4,_;

Matera CGS VLBI Analysis Center

Matera CGS VLBI Analysis Center

Roberto Lanotte, Giuseppe Bianco

Abstract

This paper reports the VLBI data analysis activities at the Space Geodesy Center (CGS) at Matera

from March 1999 through December 2000 and the contributions that the CGS intends to provide for

the future as an IVS Data Analysis Center.

1. Introduction

The VLBI data analysis activities at the CGS in the year 2000 axe mainly dominated by the

unavailability of the workstation used to process the VLBI solutions due to a power supply failure.

In spite of that some activities related to the VLBI analysis have been carried out.

2. Combination of Velocity Fields from SLR, GPS and VLBI for the Italian

Region

We combined four space geodetic solutions produced at the CGS analysis center in Matera:

1. a daily GPS network solution of the European area

2. a daily GPS precise point positioning solution that recovers single station coordinates for

some stations in the European area

3. a VLBI solution for the European area

4. a global SLR solution

Since each single-technique solution realizes its own reference frame, it is necessary to define a

common reference frame in which to perform the combined solution. We chose to transform and

combine the velocity fields within the ITRF97 reference frame by determining the time derivatives

of rotation, translation and scale parameters that transform each solution in the common frame.

For small rotations and velocities, typically on the order of a few mas and mm/yr respectively, the

approximated equations defining the roto-translations of the velocities fields are:

Xsolution -- XITRF = (d -]- _)XITRF -[- _ (1)

where X are the site cartesian coordinates (x,y,z) and X their corresponding velocities. The unknowns axe respectively the scale factor d, the three rotations and three translation time derivatives

The covariance matrix Cso_ution of each velocity solution has been propagated accordingly:

C IT RF = C solution + FTCHF (2)

where CITRF is the covariance matrix transformed in the ITRF97 reference frame, CH is the

covariance matrix of the roto-translation parameters and r is the matrix of the partials w.r.t, the

roto-translation parameters.

2000 IVS Annual Report 207
Matera CGS VLBI Analysis Center Centro di Geodesia Spaziale (CGS)

Once each velocity field was expressed in the common reference system, the combined 3-D

velocity field has been estimated in a least squares sense, minimizing the velocity residuals:

XC = (ATWA)-I ATwy (3)

Where :Kc is the combined velocity solution, A is the matrix of the partials w.r.t, the estimated

parameters and has the form:

A = (')" with I identity matrix,

i

W is the total weight matrix:

W = ".. with N_-I covarianee matrix of each single velocity solution

0 _]n 1

and

(xl) Y = " with X_ single velocity solution.

xo

More details and the results of this work can be found in Devoti et al. 2000 [1].

3. Spectral Analysis of Time Series

The estimated geodetic time series could be affected by non-tectonic signals such as: mismodeling in the data analysis models, local phenomena induced by human activities and local geophysical

or geological phenomena. It is expected that some of these phenomena have a periodical behavior

and a spectral analysis should highlight their presence. We developed some tools for the spectral

analysis of the time series. Our initial target is to recover the stationary part of a signal; this is

obtained using a wavelets approach that is able to distinguish the stationary part of the signal

from the non-stationary one. After that a least-squares procedure is used to characterize frequency,

amplitude and phase of the stationary part in the form: _, Ai cos(wit + ¢i). These tools are based

on the Lomb-Scargle periodogram that is suitable for time series with unevenly sampled data. At

the present the tools have been developed and we shall use them in the near future.

4. Contribution to IVS for 2001

The following items represent the contribution that the CGS intends to provide to the IVS for

the year 2001:

• Global analysis using all geodetic sessions to estimate TRF and EOP

• Dedicated analysis for the VLBI experiments from the EUROPE campaign

• Combination of TRF and EOP solutions available from IVS and IERS

• Comparisons of tropospheric parameters derived by VLBI and GPS

208 2000 IVS Annual Report
Centro di Geodesia Spaziale (CGS) Matera CGS VLBI Analysis Center

References

[1] R. Devoti, C. Ferraro, R. Lanotte, V. Luceri, A. Nardi, R. Pacione, P. Rutigliano, C. Sciarretta, E.

Gueguen, G. Bianco, F. Vespe: "Geophysical interpretation of geodetic deformations in the central

Mediterranean area", AGU book 2000.

2000 IVS Annual Report 209
-_ : it<. / !'_i "_ _>

CRL Analysis Center

?

+J

Kashima Space Research Center, Communications Research Laboratory

Analysis Center at Communications Research Laboratory

Ryuichi Ichikawa

Abstract

The aim of the Key Stone Project is to obtain precise relative positions of four stations using VLBI,

SLR, and GPS on a daily basis by the Communications Research Laboratory. VLBI results spanning

the last three and half years indicate that the Miura and Tateyama KSP sites are moving NNW with

respect to Kashima at velocities of 17.0 and 20.9 ram/year, respectively. For two months after June

2000, the baseline length between Kashima and Tateyama was shortened by about 5 cm caused by a dike

intrusion and co-seismic offsets between the Izu islands. We also carried out research and development

such as evaluations of tropospheric path delay and ionospheric electron content, monitoring of fluxdensity variations of radio sources using the KSP network. This report summarizes the results from

these research fields using the KSP network of CRL to the end of 2000.

1. Introduction

The KSP has been carried out around the Tokyo metropolitan area, Japan by the Communications Research Laboratory (CRL), using VLBI, SLR, and GPS. One of the main objectives of

the KSP is to monitor regional deformation and strain accumulation at the plate boundary region

of the Kanto district. The KSP is not only aimed at monitoring crustal deformation but also

utilized for research and technical development of space geodesy. It is designed to make frequent

observations possible with a minimum of human operations and to provide analyzed results as fast

as possible. In particular, its automated design allows frequent VLBI experiments. By placing

the three above-mentioned techniques close together at each site, the different and independently

obtained results can be compared. We describe some analysis results using the KSP network in

this report.

2. Analysis Results using the KSP Network

2.1. Crustal deformation

Figure la plots the estimated lengths of the baseline between Kashima and Tateyama stations

using VLBI. This figure shows gradual improvements in VLBI data quality which are evident

based oil the scattering of plots and their formal errors. The results after September 30, 1997 are

remarkable, reflecting the extended duration of each experiment.

Figure lb shows the observed horizontal site velocities (millimeters per year) using VLBI and

GPS at three KSP sites (Koganei, Miura, and Tateyama) relative to Kashima from January 1997

to June 2000. These VLBI measurements span the last three and half years and indicate that

the Miura and Tateyama sites are moving with respect to Kashima at velocities of 17.0 and

20.9 mm/year toward the NNW, respectively. The velocities moving toward NNW at Miura and

Tateyama suggest the effect of the subducting Philippine Sea plate beneath northern Honshu along

the Sagami Trough.

Figures la and 2a show extraordinary drifts in both VLBI and GPS measurements after the end

of June 2000, namely the baseline length between Kashima and Tateyama is shortened by about

5 cm in two months. Accumulated displacement at KSP sites toward north-east are presented in

210 2000 IVS Annual Report
Kashima Space Research Center, Communications Research Laboratory CRL Analysis Center

figure 2b. Similar displacement at four GPS sites (Katsuura, Kyonan, Miura, and Tateyama) of

GEONET by Geographical Survey Institute (GSI) are also shown in the figure.

............... , ......

139 140 141

PH km

0 50 100

139 140 141

Figure 1. (a) Estimated baseline length between Kashima and Tateyama using VLBI. The formal error

of each estimation is shown by a vertical bar in both figures. The variations in baseline length are fitted

by linear lines and the best fit line is shown by straight solid lines. (b) Observed horizontal site velocities

(centimeter per year) relative to Kashima site. The velocities from VLBI and KSP GPS from January 1997

to June 2000 are shown.

Following the magma intrusion in the hu Islands (about 150 km south of Tokyo), during June

26 and 27, 2000, crater subsidence and volcanic eruptions continued in July and August at one of

the islands, Miyakejima. In addition, high seismic activity and significant crustal deformation has

continued around Miyakejima and Niijima-Kodushima since the end of June. According to the

inversion using half-infinite elastic model, the crustal deformation at Tateyama, located about 100

km north-east of Kodushima island, is caused by a dike intrusion at about 3 km depth and coseismic offsets between the islands [1]. The strike of the simulated dike is N140E, which is almost

perpendicular to the azimuth from Kodushima toward Tateyama. This geometrical configuration

can move the Tateyama site toward the north-east by the deformation due to the simulated dike.

2.2. Evaluation of tropospheric path delay

The repeatability of the baseline length of KSP VLBI measurements tends to be degraded in

summertime. A correlation analysis between measured baseline lengths and surface temperature

data was made, and it suggested that an apparent position change of the Kashima site occurred

[2].

In June 1998, we initiated a field experiment for detecting and characterizing water vapor

variations using water vapor radiometers (WVRs) at KSP Kashima site and Tsukuba. A WVR at

Tsukuba is deployed by the Meteorological Research Institute (MRI) of the Japan Meteorological

Agency (JMA). Time series of atmospheric gradients estimated by WVR slant delays at Tsukuba

and Kashima are compared.

2000 IVS Annual Report 211
CRL Analysis Center Kashima Space Research Center, Communications Research Laboratory

1oo

•

KSP

KSP

VLBI

VLBI [after 6/26t2000]

Kashima- Tateyama a

* GSI GPS

50

5/31/2000 7/1/2000 811/2000 9/t/2000 10/2/2000

TIME

139 140 141

2 2FT _ ._ -

" Kllhi ma (FIX)

_, Tateyama NA

_odujin_ .is,__ _ VLBl(Icm}

Miyakejima _ (;|_J(;_;l(IL'm)

PH

km

0 50 100

33 33

Figure 2. (a) Estimated baseline length between Kashima and Tateyama using VLBI and GPS of the

KSP network. GPS results of the GEONET by Geographical Survey Institute (GSI) are also shown. (b)

Accumulated displacements from VLBI, KSP GPS and GEONET GPS sites from July to September 2000.

In spite of relatively short distance between Tsukuba and Kashima (about 54 km) the atnlospheric gradients solutions are significantly different. This result suggests that the mesoscale

weather pattern caused large differences. We are now analyzing the output of high resolution

numerical weather prediction models in order to investigate these results more deeply.

2.3. Evaluation of ionospheric electron content

Ionospheric delay correction with GPS-based Earth ionosphere total electron content (TEC)

measurement is useful for single band VLBI application; for example, pulsar astrometry and geodetic VLBI with a single band receiver. To investigate the accuracy of GPS-based ionospheric TEC

measurement, three cases of TEC estimation methods were compared with those from dual band

VLBI observations of the Kashima-Koganei baseline [3]. The comparison study indicated the GPSbased TEC measurement can correct ionospheric delay in VLBI observations in almost the same

accuracy with S/X dual band VLBI observation. This result is encouraging to apply GPS derived

TEC to single band astrometric VLBI observation. Also realizing single band geodetic VLBI benefit at lower cost single band receiver instead of dual band receiver and more data channels can be

used for X band signal.

2.4. Monitoring flux density variations of radio sources

Compact and strong radio sources are repeatedly observed in regular geodetic VLBI experiments under the KSP [4]. The two main purposes of the KSP VLBI network are to precisely

measure relative site positions and to monitor their variations with a minimum delay of processing

time. For these purposes, time delays between signals received at two sites and their rates of

212 2000 IVS Annual Report
Kashima Space Research Center, Communications Research Laboratory CRL AnMysis Center

change axe obtained through data correlation and bandwidth synthesis processing performed in

real-time. The five years of the observed data show irregular variations in the flux densities were

detected for several radio sources using the source 2134+004 as the calibrator.

3. Staff

The staff members who are contributing to KSP Analysis Center at the CRL are listed below:

• Kondo Tetsuro, Responsible for overall operations and performance.

• Koyama Yasuhiro, Development of data analysis software.

• Ichikawa Ryuichi, Research for crustal deformation and atmospheric modeling.

• Amagai Jun, Maintenance of data analysis system.

4. Current Status and Future Plans

As of mid-September 2000, the crustal deformation around Izu islands almost decayed according

to the results from continuous GPS measurements of GEONET at the Izu islands by GSI. However,

it is very important to monitor a postseismic stage in order to understand the tectonic process of

the recent event around the islands. Thus, we made a decision to continue the KSP observations

at least for one year regularly though we had a plan to close the KSP in spring 2001.

At present, the atmospheric gradient models [5][6] are not used in the operational analysis of

the KSP VLBI. We are now modifying the VLBI analysis software to improve the accuracy of the

position determination using atmospheric gradient model.

The web server for the Analysis Center is provided by CRL. The URL address is

http://ksp.crl.go.jp/index.html

The KSP web site holds all the data obtained by the KSP VLBI network. Baseline lengths,

site positions, flux densities of observed radio sources, estimated earth orientation parameters are

available on our web site. Our analysis results of the site positions have been generated using

SINEX format.

References

[1] Kimata, F, Okuda, T, Yamaoka, K, Fujii, N, Kato, T, Nakno, S, Sakai, S, Reddy, C D, Tabei, T,

and Eguchi, Y, Crustal deformations observed in the volcano-swarm activity in the Izu Islands, central

Japan using GPS, The 2000 AGU Fall Meeting, 2000.

[2] Kondo et al., Atmospheric Gradient Effects on the Compact VLBI Network Around the Tokyo

Metropolitan Area, in preparation, 2001.

[3] Sekido M., Kondo T., Eiji K., and Imae M., Comparison of ionospheric delay obtained by GPS and

VLBI, submitted to Radio Sci., 2000.

[4] Koyama Y., Microwave flux density variations of compact radio sources monitored by real-time very

long baseline interferometry, Radio. Sci., in printing (RS2398), 2001.

[5] MacMillan, D.S., Atmospheric gradients from very long baseline interferometry observations, Geophys.

Res. Lett., 22, 1041-1044, 1995.

2000 IVS Annual Report 213
CRL Analysis Center Kashima Space Research Center, Communications Research Laboratory

[6] Chen, G. and T. A. Herring, Effects of atmospheric azimuthal asymmetry on the analysis of space

geodetic data, J. Geophys. Res., 102, 20489-20502, 1997.

214 2000 IVS Annum Report
.. 1 +

DGFI, Deutsches Geod/itisches Forschungsinstitut

55 57

DGFI Analysis Center _ _

DGFI Analysis Center Annual Report 2000

Volker Tesmer, Hansj6rg Kutterer, Hermann Drewes

Abstract

This report summarizes the activities of the DGFI Analysis Center from March 1999 to the end of

2000. The report contains planned activities for the year 2001, too.

1. Special Analysis Center Operation

The Deutsches Geod/itisches Forschungsinstitut (DGFI) is a non-governmental research institute under the auspices of the Deutsche Geod/itische Kommission (DGK). It is housed at the

Bavarian Academy of Sciences (BAdW) in Munich. DGFI is financed by the State of Bavaria.

The general task of the IVS Analysis Center at DGFI is to support and to improve the VLBI

data analysis and to generate VLBI products, in particular Earth rotation parameters (see DGFI

web serverhttp ://www.dgfi.badw. de).

2. Initial Activities

Since the beginning of IVS, DGFI has carried out following activities:

1. Modification of the OCCAM VLBI software

correction of the station coordinates due to atmospheric loading, published by H.G.

Scherneck (www.oso.chalmers.se/_hgs);

correction of thermal antenna deformation, according to Haas et al. (1999);

implementation of the new model of solid Earth tides, which will be included in the

next IERS Conventions (2000);

extension of OCCAM by a least-squares approach following the Gauss-Markov model

(in cooperation with J. BShm from the University of Technology, Vienna).

2. Analysis of all NEOS-A, CORE-A, CORE-B and IRIS-S sessions between 1997 and 1999

Systematic differences between the series were detected. The offsets between results from

different networks reach 190 mas (Tesmer and Schuh, 2000).

3. Analysis of the 58 simultaneous NEOS-A and CORE-A sessions between 1997 and 1999

Differences were found between EOP derived from the two completely independent networks

observing simultaneously, which were occasionally two times greater than their formal errors

(Tesmer and Schuh, 2000). They are very similar to those obtained by MacMillan et al.

(1999) who used the CALC/SOLVE software package.

4. Considering a-priori correlations in VLBI data analysis

Comparisons between solutions with a full variance-covariance matrix of the observables

and 'usual' solutions with the off-diagonal elements set to zero showed that taking a-priori

correlations into account yields formal errors of the results of a single session which are

greater and hence more realistic than those from an 'uncorrelated' solution. Additionally,

the repeatability of the parameters improved significantly (Schuh and Tesmer, 2000).

2000 IVS Annual Report 215
DGFI Analysis Center DGFI, Deutsches Geod_tisches Forschungsinstitut

5. Development of a Knowledge-Based System for the automation of VLBI data analysis by

SOLVE (Schwegmann and Schuh, 1999, Schwegmann and Schuh, 2000).

3. Staff

DGFI personnel involved in the IVS Analysis Center are the following (status January 2001):

Hermann Drewes, HansjSrg Kutterer and Volker Tesmer.

Changes in personnel:

In April 2000, Harald Schuh, Head of the Earth Rotation Section, left the DGFI to become a

full professor at the University of Technology Vienna. His successor is HansjSrg Kutterer, formerly

at the University of Technology Karlsruhe.

In May 2000, Wolfgang Schwegmann left the DGFI for a position at the Istituto di Radioastronomia, Bologna.

4. Plans

For 2001 the plans of DGFI Analysis Center are:

• Further improvement of OCCAM:

OCCAM will be updated to be in full agreement with the IERS Conventions (2000). The

parameterisation will be extended. All changes will be done in cooperation with the VLBI

groups of Saint-Petersburg University (O. Titov) and the University of Technology Vienna

(J. BShm).

• Contribution to the VLBI terrestrial reference frame:

It is planned to compute a terrestrial reference frame with OCCAM, accumulating normal

equations of all usable VLBI sessions from 1979 till present.

• Further investigations of offsets between EOP series which depend on the particular VLBI

network.

• hlrther investigations on the stochastical model used in VLBI data analysis.

• Investigations of subdiurnal variations of Earth orientation parameters.

• Generation of IVS products (EOP and TRF) and contribution to the IVS Working Group

on data analysis.

Due to the move of W. Schwegmann to Bologna, the work on the development of a KnowledgeBased System for the automation of VLBI data analysis will not be continued at DGFI, but at

the Istituto di Radioastronomia, Bologna.

5. References

Haas, R., Nothnagel, A., Schuh, H., Titov, O.: Explanatory Supplement to the Section "Antenna Deformation" of the IERS Conventions (1996). In: Schuh, H. (Ed): Explanatory Supplement

216 2000 IVS AnnualReport
DGFI, Deutsches Geod_tisches Forschungsinstitut DGFI Analysis Center

to the IERS Conventions (1996) Chapters 6 and 7, Deutsches Geod£tisches Forschungsinstitut Report No. 71, 26-29, 1999, http://www, dgfi. badw. de/dgf ±/DOC/report71. pd_f

MacMillan, D.S., Himwich, W.E., Thomas, C.C., Vandenberg, N.R., Bosworth, J.M., Chao, B.,

Clark, T.A., Ma, C.: CORE, High-Accuracy Earth Orientation Measurements. In: Schliiter, W.,

Hase, H. (Eds): 13th Working Meeting on European VLBI for Geodesy and Astrometry, 166-171,

Viechtach, 1999

Schuh, H.: The Rotation of the Earth Observed by VLBI. Acta Geod. Geoph. Hungarica, Vol

34(4), 421-432, 1999

Schuh, H.: Contributions of VLBI to Space Geodesy. In: Rummel, R., Drewes, H., Bosch, W.,

Hornik, H. (Eds): Proceedings of the international syposium 'Towards an Integrated Global Geodetic Observing System', Munich, Oct. 1998, Springer IAG Symposia series Vol 120, 33-40, 2000

Schuh, H.: Short-period Variations of Earth Rotation Observed by VLBI. In: Soffel M., Capitaine N. (Eds): Journ. 1999 and IX. Lohrmann-Kolloq., 'Motion of Celestial Bodies, Astrometry

and Astronomical Reference Frames', Proc., Obs. de Paris, UMR 8630, CNRS, 197-205, 2000

Schuh, H.: Geodetic Analysis Overview. In: Vandenberg, N., Baver, K. (Eds): IVS 2000 General Meeting Proceedings, NASA/CP-2000-209893, 219-229, 2000

Schuh, H., Tesmer, V.: Considering A Priori Correlations in VLBI Data Analysis. In: Vandenberg, N., Baver, K. (Eds): IVS 2000 General Meeting Proceedings, NASA/CP-2000-209893,

237-242, 2000

Schuh, H., Titov, O.: Short-period variations of the Earth rotation parameters as seen by

VLBI. In: Schliiter, W., Hase, H. (Eds): 13th Working Meeting on European VLBI for Geodesy

and Astrometry, 172-177, Viechtach, 1999

Schwegmann, W., Schuh, H.: On the Automation of the MarkIII Data Analysis System. In:

Schl/iter, W., Hase, H. (Eds): 13th Working Meeting on European VLBI for Geodesy and Astrometry, 265-272, Viechtach, 1999

Schwegmann, W., Schuh, H.: Status of IADA: an Intelligent Assistant for Data Analysis in

VLBI. In: Vandenberg, N., Baver, K. (Eds): IVS 2000 General Meeting Proceedings, NASA/CP2000-209893, 319-323, 2000

Tesmer, V., Schuh, H.: Comparison of the Results Obtained by Different VLBI Networks. In:

Tomasi, P., Mantovani, F., Perez Torres, M.(Eds): Proceedings of the 14th Working Meeting on

European VLBI for Geodesy and Astrometry, Istituto di Radioastronomia, Bologna, 7-12, 2000

2000 IVS Annual Report 217
FFI Analysis Center

6 15

Forsvarets forskningsinstitutt (FFI) (Norwegian Defence Research Establishment)

Combination of VLBI, GPS and SLR Data Analysis at FFI

Per Helge Andersen

Abstract

FFI's contribution to the IVS as an Analysis Center will focus primarily on a combined analysis at

the observation level of data from VLBI, GPS and SLR using the GEOSAT software. This report briefly

summarises the current status of analyses performed with the GEOSAT software. FFI is currently

Analysis Center for IVS and ILRS, Technology Development Center for IVS, and Combination Research

Center for IERS.

1. Introduction

Recently, a number of colocated stations with more than one observation technique have been

established. In principle, all instruments at a given colocated station move with the same velocity

and it should be possible to determine one set of coordinates and velocities for each colocated

site. In addition, a constant eccentricity vector from the reference point of the colocated station

to each of the individual phase centers of the colocated antennas is estimated using constraints in

accordance with a priori information given by the ground surveys. One set of Earth orientation

parameters (EOP) and geocenter coordinates can be estimated from all involved data types. The

present dominating error source of VLBI is the water content of the atmosphere which must be

estimated. The inclusion of SLR data, which is independent of water vapour, gives new information

which will help in the de-correlation of atmospheric and other solve-for parameters and lead to

more accurate parameter estimates. These, and many more advantages with the combination of

independent and complementary space geodetic data at the observation level, are fully accounted

for with the GEOSAT software [2] developed by FFI during the last 15 years.

2. Data Analysis

A set of VLBI data from January 1993 to September 1999 has been analyzed. This analysis will

be referred to as the VLBI-alone analysis. A second analysis referred to as the combined analysis

was performed where SLR data for Lageos I and Lageos II from the same period was combined

with the VLBI data at the observation level using exactly the same strategy as for the VLBI-alone

analysis. The two analyses were performed in arcs of 24 hours using the GEOSAT software. The

arc-results were combined into a multi-year VLBI-alone and a combined VLBI and SLR solution

using the CSRIFS software [1]. The VLBI analysis model and analysis strategy are described in

Andersen [3]. Station coordinates and velocities were estimated simultaneously with the Earth

orientation parameters.

The results show that the use of SLR data in addition to VLBI data improves the precision

of the estimated polar motion parameters from 0.2 mas to 0.1 mas, it improves the precision of

the estimated UT1 parameters from 10 to 5 microseconds, and it improves the precision of the

estimated nutation parameters from 0.2-0.3 mas to 0.15 mas. The formal precision of the nutation

parameters indicates that the precision of these parameters in principle could be improved to the

level of 0.05-0.08 mas. The analyses show that the applied VLBI and SLR models are consistent

to a few mm.

218 2000 IVS Annual Report
Forsvarets forskningsinstitutt (FFI) (Norwegian Defence Reseaxch Establishment) FFI Analysis Center

The results indicate that as long as SLR tracking of two Lageos satellites is available on a daily

basis it might be better to have, say 3-4 VLBI sessions a week, with many participating stations

rather than daily VLBI sessions with a small number of participating stations. The SLR data are

fully capable of producing high precision estimates of these parameters for days where VLBI data

axe not available. Further investigations are necessary in order to determine the consequence of

enlarging (or reducing) the periods with no VLBI data on the precision of the estimates of the

Earth orientation parameters.

It is observed from the solutions for the radio source positions that the inclusion of SLR data

can lead to changes up to 0.3 mas in the estimated source coordinates. This is not unexpected

since the two Lageos satellites used in the present analysis are physical objects in addition to the

radio sources being used for the realization of CRF. It is a general trend in the formal uncertainties

that the standard deviation in the right ascension is slightly improved with the inclusion of SLR

data while the standard deviation in declination is significantly improved in some cases by as much

as a factor of four. This will be further investigated.

The results show that for the first time VLBI and SLR tracking data have been successfully

combined at the observation level. Furthermore, it is the first time satellite tracking data successfully have been used for the direct determination of nutation parameters. Based on the analysis

and preliminary experience with the combination of VLBI, SLR and GPS data the author is convinced that the direct combination of high precision space geodetic data at the observation level

within ten years will be the primary method for the realization of terrestrial and celestial reference

frames and their interrelations.

More details of the analysis can be found in Andersen [4].

3. Prospects

In the near future GPS data for selected days will be incorporated in the analysis and combined

with the VLBI and the SLR data at the observation level.

4. Technical Staff

Table 1 lists the FFI staff involved in IVS activities.

Table 1. Staff working at the FFI AC and TDC

I Name I Background I Dedication I Agency I

I Per Helge Andersen I geodesy I 40% t FFI I

2000 IVS Annual Report 219
FFI AnalysisCenter Forsvaretsforskningsinstitutt (FFI) (NorwegianDefenceResearchEstablishment)

References

[1] Andersen, P. H. Multi-level arc combination with stochastic parameters. Journal of Geodesy (2000) 74:

531-551.

[2] Andersen, P. H. High-precision station positioning and satellite orbit determination. PhD Thesis,

NDRE/Publication 95/01094.

[3] Andersen, P. H. Combined analysis of VLBI, GPS and SLR data at the observation level. Under

preparation.

[4] Andersen, P. H. Determination of Earth orientation parameters using VLBI and SLR data combined

at the observation level. Invited paper submitted 15 May, 2000, to Journal of Geodesy for the special

issue on the theme "New methodologies for EOP combinations"

220 2000 IVS Annual Report
Geod_itisches Institut der Universit_it Bonn

2........""55576

q

GIUB/BKG Analysis Center

The GIUB/BKG VLBI Analysis Center

Axel Nothnagel, Volkmar Thorandt, Gerald Engelhardt

Abstract

This report describes the activities of the GIUB/BKG VLBI Analysis Center during the reporting

period. Data analysis activities and the development of data analysis technology are described. Past

and on-going research topics are reported. Finally, center personnel are listed.

1. Overview

The GIUB/BKG VLBI Analysis Center has been estabished jointly by the Bundesamt ffir

Kartographie und Geod_ie (BKG), Leipzig, and by the Geodetic Institute of the University of

Bonn (GIUB). Both institutions closely cooperate in the field of geodetic VLBI maintaining their

own analysis groups in Leipzig and Bonn. The responsibilities include data analysis and software

development.

Both groups use the Mark III/IV data analysis software CALC/SOLVE/GLOBL which originated at NASA/GSFC. At GIUB the basic SOLVE/GLOBL software has been modified extensively

to increase its computational speed and to add several new features.

2. Data Analysis Activities

At BKG the CALC9.11/f-SOLVE package is being used for routine VLBI data processing. The

software has been installed on a HP 9000/D280/1 computer (HP UX 10.20 operating system) with

about 190 GByte disc space.

The following sessions have been analysed jointly at GIUB and BKG since the beginning of

March 1999:

• Measurement of Vertical Crustal Motion in Europe by VLBI

(EUROPE sessions) (EU Project FMRX-CT960071)

Six sessions in 1999 and 7 sessions in 2000 with the stations NyAlesund, Onsala, Wettzell,

Simeiz, Madrid (DSS65), Yebes, Medicina, Matera and Noto have been processed. Effelsberg

participated once per year and the mobile unit TIGO-WTZL participated at several occasions

during its testing phase.

• Polarization tests

In order to investigate polarization impurities two regular EUROPE sessions were extended

in which several stations swapped polarization from right circular polarization (RCP) to left

circular polarization (LCP) while other stations continued to observe RCP. Fringes at all

cross-polarization scans were detected and the analysis was completed.

• International Radio Interferometric Surveying - South (IRIS-S):

Twelve sessions per year with the stations Wettzell, HartRAO, Fortaleza, Fairbanks and

Westford were processed.

• Continuous Observations of the Rotation of the Earth - O'Higgins (COREOHIG)

2000 IVS Annual Report 221
GIUB/BKG AnalysisCenter Geod_itischesInstitutderUniversit_itBonn

Nine sessions with stations HartRAO, O'Higgins, Fortaleza, Hobart, Kokee and DSS45 have

been analyzed in 1999 and 2000.

• Annual Solution for Submission to IERS

In addition to the session by session analysis one combined solution is computed cooperatively each year which comprises most of the dual frequency fixed station Mark III data

available worldwide. This solution is the basis for the annual submission to the IERS. Station

coordinates and velocities, radio source positions and Earth orientation parameters (EOP)

are estimated in one global solution. The solution types are bkgtra99 for the Terrestrial

Reference Frame and bkgira99 for the Celestial Reference Frame and the Earth orientation

parameters are available from the IVS Data Centers. Station coordinates, velocities and

covariances of the TRF solution were converted into SINEX format and submitted to the

ITRF Section of IERS as a contribution to the ITtLF2000 realization.

• Processing of correlator output

The BKG group generated calibrated databases for most of the sessions correlated at the

Bonn Astro/Geo Mark III/IV Correlator and subsequently submitted them to the IVS Data

Centers for distribution.

• IVS EOP time series

After the preprocessing of the individual VLBI sessions which includes inspection of the

residuals and procedures for outlier elimination the databases and related files are uploaded

to the incoming area of the BKG IVS Data Center and into the local data area.

The final processing of individual VLBI sessions (IRIS-S, EUROPE, COHIG, NEOS, CORE)

at BKG is the basis for producing two EOP time series regularly submitted to the IVS Data

Centers:

- bkg00001.eops generated from 2360 24h VLBI sessions between 1984 and 2000

- bkgint01.eopi generated from UT1 intensive sessions between 1999 and 2000

Table 1. Mean formal errors for 24 h sessions

Component 1984-2000 1999-2000

ffxwob

aywob

_utl

ad_

_de

0.618mas

0.641mas

33.8 #s

0.764mas

0.256mas

0.223 mas

0.213 mas

13.6 #s

0.212 mas

0.085 mas

The corresponding values for the time span from 1999 to 2000 have improved by a factor

of approximately three. The mean formal error for the intensive experiments between 1999

and 2000 is 22.0 #s. The features of the solutions are described in the respective technical

descriptions which are available in the IVS Data Centers in the directory ivsdocuments.

222 2000 IVS AnnuM Report
Geod_itisches Institut der Universit_t Bonn GIUB/BKG Analysis Center

3. Development of VLBI Data Analysis Technology

• One of the responsibilities of the GIUB analysis group is the preparation of correlator data

for export in the form of Mark III data analysis system databases for the sessions correlated

at the Bonn Astro/Geo correlator center. In most cases this task is straightforward but

sometimes it requires some extra efforts. The main reason for additional interaction is radio

frequency interference which may saturate individual channels causing some of the delay

observables to be corrupted. In this case the fringe fitting process may select the wrong

peak of the delay resolution function and produce an incorrect delay observable. However,

this fact can only be detected when a least squares solution is computed with the program

SOLVE. In a subsequent step the residuals of the SOLVE run can be used to narrow the

search window in a repeated fringe fitting process. A semi-automatic procedure for this task

is available at GIUB.

• Semi-automatic Web-presentation of data analysis results is being developed. Detailed reports of all VLBI data processed at the GIUB/BKG Analysis Center have been displayed on

the Web between 1998 and the middle of 2000. This task will be resumed when additional

man-power becomes available.

• Internal logic of the software SOLVE was updated in order to reduce overhead, to speed up

data processing and to expand the capabilities of the analysis system.

• In order to make the analysis processes more effective the BKG group developed its own

program environment around the CALC/SOLVE software automating the post interactive

part for establishing the two EOP series mentioned above.

4. Research Topics

• Determination of telescope displacements by local engineering work at Medicina

The Medicina telescope has been displaced slightly in 1996 due to track repairs. The local

surveys before and after the displacements were analysed (NOTHNAGEL AND BINNENBRUCK

2000).

• Footprint measurements at Ny/klesund

In the framework of a footprint project local measurements were carried out at Ny Alesund in

order to determine the coordinates of the antenna's VLBI reference point relative to a local

network of concrete pillars. Preliminary analysis of the measurements has occurred, and

local eccentricities between the VLBI antenna and the IGS GPS antennas will be computed

when the Norwegian Mapping Authority will have completed its GPS analysis.

• Joint least squares adjustment of GPS and VLBI observations

At DGFI a combination of space geodetic measurements at the level of observables is being

carried out. Special VLBI data preprocessing and solutions are performed at GIUB in support

of this research.

• Investigation of the feasibility of using phase delays in geodetic VLBI

An extended set of VLBI sessions has been re-analyzed for resolving phase delay ambiguities.

Conditions when ambiguities can be resolved as well as differences between group delay and

phase delay solutions were investigated.

2000 IVS Annual Report 223
GIUB/BKG Analysis Center Geod_itisches Institut der Universit_it Bonn

Correlator comparison

In order to investigate in greater detail the MK III/MK IV correlator performance, a 4-station

IRIS-S session has been correlated both at the old MK IIIa and at the new MK IV correlator.

In fact, before the definitive closing down of the MK IIIa correlator, two complete and fully

independent correlations of the same IRIS-S sessions were carried out to establish the noise

floor of the old system. First results of the comparison have been published (Mi)SKENS et

al. 2000).

5. Personnel

Table 2. Personnel at GIUB/BKG Analysus Center

Klaus BSrger GIUB I

Gerald Engelhardt BKG t

Axel Nothnagel GIUB I

Leonid Petrov GIUB ]

Christoph Steinforth GIUB t

Volkmar Thorandt BKG

Dieter Ullrich BKG

until 11/2000

until 4/2000

References

Miiskens A., K. B6rger, M. Sorgente, J. Campbell (2000): Comparison of Mk III and MK IV Correlation Using a J-station IRIS-S experiment; Proc. of the 14th Working Meeting on European

VLBI for Geodesy and Astrometry, Castel San Pietro Terme, 125-136

Nothnagel, A., B. Binnenbruck (2000): Determination of the 1996 Displacement of the Medicina

Radio Telescope by Local Surveys; Proc. of the 14th Working Mecting on European VLBI for

Geodesy and Astrometry, Castel San Pietro Terme, 61-66; available under http://giub.geod.unibonn.de/vlbi/publications

224 2000 IVS Annual Report
NASA Goddard Space Flight Center

555"770

Goddard Space Flight Center Analysis Center

GSFC VLBI Analysis Center

David Gordon, Chopo Ma, Leonid Petrov, Dan MacMillan

Abstract

This report presents the activities of the GSFC VLBI Analysis Center during the period from

March 1, 1999 through December 31, 2000. The center's primary software development, analysis and

research activities are reported, and the responsible staff members are described. Plans for 2001 are

also presented.

1. Introduction

The GSFC VLBI Analysis Center is located at NASA's Goddard Space Flight Center in Greenbelt, MD. GSFC analyzes all geodetic and astrometric VLBI sessions and submits databases to IVS

for all NASA/GSFC and USNO sessions within 24 hours or less of their correlation. The group's

main thrust is the operation and analysis of the CORE experiments and the gradual expansion

of CORE into a full time EOP monitoring program. The group processes all 24-hour sessions

from the Mark 4 correlators and submits EOP values derived from each session within 24 hours

of correlation. The group also analyzes NEOS Intensive experiments and submits the UT1 values

within 2 hours of correlator release. Additionally, GSFC periodically submits station positions and

velocities as well as source coordinates from global solutions using all available VLBI observations.

The analysis group also processes all VLBA RDV sessions using the NRAO AIPS program.

GSFC uses, maintains, develops, and distributes the Calc/Solve analysis system. The group

also engages in research and analysis activities aimed at improving the nmasurement and understanding of Earth rotation, improving VLBI analysis techniques and modeling, improving troposphere modeling, and maintaining and refining the celestial and terrestrial reference frames.

2. Activities

The primary software development activities from March 1, 1999 - Dec. 31, 2000 included:

• Program Calc was upgraded to versions 9.1 and 9.11 to add the permanent tide option and

to fix a minor error.

• F-Solve development was moved from GIUB/BKG to GSFC in April 2000, and the two

groups' Solve versions were consolidated.

• Extensive changes in programs Dbedit and Solve were made to support the processing of

data from the new Mark 4 correlators.

• Developed an automated system for data transmission between correlators, the IVS Data

Centers and the IVS Analysis Centers (programs dserver, dclient, geo_export and geo_import).

• Developed an automated system for generating EOP and submitting EOP series and

databases to IVS (program opa).

• Began bimonthly Calc/Solve system updates, in the form of an easy-installation distribution kit. Considerably increased the Calc/Solve system documentation. Currently 44

2000 IVS Annual Report 225
Goddard Space Flight Center Analysis Center NASA Goddard Space Flight Center

Calc/Solve documents are available from http://gemini.gsfc.nasa.gov/solve. (An activity

begun at GIUB/BKG and moved to GSFC in April 2000.)

• Developed software for analysis of phase calibration errors and for correction of spurious

phase cal signals. (Begun at GIUB/BKG and moved to GSFC in April 2000.)

The primary analysis activities during the period included:

• ICRF-Ext.1, the first extension of the ICRF, was produced in mid 1999 to include additional

data from July 1995 to April 1999. This solution added 59 new sources to the catalog

and introduced small modeling improvements consistent with the stated uncertainties of the

ICRF.

• Two solutions were generated as input to ITRF2000. Tile first submission, gsf1122, in the

Spring of 2000 (CALC 8.2/S-Solve) included data through the end of 1999. Based on the

discussions at the ITRF2000 workshop, a second solution, gsf2000b, was made at the end

of 2000 (CALC 9.1/F-Solve) which incorporated additional Asian stations as well as data

through October 2000.

• Began manual database submissions within 24 hours to IVS in June 1999. Upgraded to

automated submissions in October 2000.

• Began manual EOP-S weekly IVS submissions (polar motion, UT1, and nutation) in September 1999. Upgraded in October 2000 to automated submissions within 24 hours of correlator

release.

• Began NEOS-Intensive session analysis and automated EOP-I (UT1) series IVS submissions

in November 2000.

• Analysis activities were shifted from CalcS.2/S-Solve analysis to Calc9.1/F-Solve analysis in

June 2000.

• Assumed the initial analysis and data submission responsibilities for NEOS-A and NEOSIntensive experiments from the USNO in December 2000.

• Submitting all old (1979-1998) databases to IVS, approximately two-thirds completed.

The primary research activities during the period included the following:

• Investigated the precision and accuracy of daily VLBI EOP estimates. Two EOP series

derived from simultaneous CORE and NEOS sessions were compared with an IGS GPS series for the period 1997-2000. The level of bias between the VLBI networks is greater than

expected and is most likely due to an error in the underlying TRF. Based on 3-corner hat

comparisons between the two simultaneous VLBI series and the GPS series, the observed precision of polar motion (80-120 #as) from the three series is similar, although GPS is somewhat

better. Several sources of unmodeled or mismodeled station position error that contribute to

the EOP error are being examined, for example, tidal ocean loading, atmospheric pressure

loading, and hydrology loading.

• Continued investigations using meteorological data assimulation models to improve VLBI

tropospheric delay modeling. Use of a priori mean site gradients reduces systematic error in

both the CRF and the TRF. Use of a priori 6-hour gradients yields some improvement in

repeatabilities. Mapping functions based on raytracing of model profiles yield improvement

in repeatabilities.

226 2000 IVS Annual Report
NASA Goddard Space Flight Center Goddard Space Flight Center Analysis Center

• Examined signatures in corresponding VLBI and GPS baseline length and site time series. An

error budget summarizing the remaining unmodeled error was developed. Spectral analysis

indicates that there are annual and semi-annual signatures in many of the VLBI and GPS

series, but the VLBI and GPS signatures are only similar for some sites.

• Investigated the determination of high frequency tidal amplitudes from hourly EOP VLBI

estimates. Collaborated with Markus Rothacher (Technical University of Munich) to compare VLBI and GPS tidal amplitudes and to determine tidal amplitudes from a combination

of VLBI and GPS hourly series.

• Developing methods for the direct estimation of nutation expansion coefficients, precession

parameters, and high frequency EOP amplitudes and phases in a single combined solution.

Examined the differences between a combined solution versus a two-step approach, in which

a nutation time series and the nutation expansion coefficients are estimated separately, neglecting their mutual correlations.

• Estimated Love numbers for long period tides from VLBI observations.

• Investigated the feasibility of an arc-length approach for the selection of primary and secondary sources.

• Made a correlator comparison study of Mark 3 versus VLBA/AIPS processing in the RDVll

experiment. Results indicated an error source on the VLBA/AIPS side. Preparing for a

larger comparison of Mark 4 versus VLBA/AIPS in RDV22.

• Began collaboration with NRAO on astrometric analysis of the VLBA calibrator survey

experiments.

3. Staff

The GSFC analysis group is part of a larger VLBI group of civil servant and contractor personnel, led by Dr. Thomas A. Clark, which also includes a Technology Development Center, three

Network Stations, the CORE Operation Center, and the Coordinating Center. The analysis group

is composed of the following six individuals who are involved full time, or nearly so, in analysis

activities.

Dr. Chopo Ma leads the analysis group. His interests include as_rometry, the celestial and terrestrial reference frames, extension and improvement of EOP measurement, and the improvement

of analysis and modeling. He is a member of the IAU working group on the Celestial Reference

System and heads the subgroup for the maintenance and extension of the ICRS. As such he has

particular interest in improving the modeling and optimization of ICRF analysis as well as providing better information about source position variations. He is also one of the VLBI representatives

on the IERS directing board, and is responsible for generating ITRF and ICRF products for IVS

and IERS use and for improvement of consistency between them.

Dr. Dan MacMillan (NVI, Inc.) is involved in VLBI technique improvement and analysis

system software development (Solve), particularly in the area of tropospheric delay modeling. His

interests include improving the modeling of atmospheric delay gradients, deriving better mapping

functions from meteorological assimilation data, and various TRF and CRF studies. He is also

working on improving or adding modeling for atmospheric pressure loading, ocean loading, and

hydrology loading. He is also studying differences in EOP derived from different simultaneous

2000 IVS Annual Report 227
Goddard Space Flight Center Analysis Center NASA Goddaxd Space Flight Center

VLBI networks and GPS EOP in order to assess the observed accuracy and precision of the VLBI

and GPS estimates.

Dr. David Gordon (Raytheon ITSS) manages all initial data processing and analysis activities,

performs the AIPS geodetic processing of VLBA experiments, and maintains and develops program

Calc. His research interests include astrometry, global and regional tectonic motions, improving

VLBI modeling, improving VLBA/AIPS processing, correlator support, correlator comparisons,

and phase delay development.

Dr. Leonid Petrov (NVI, Inc.) moved from the GIUB/BKG analysis group to the GSFC

analysis group in April 2000. He maintains and develops the Mark 4 VLBI analysis software

Calc/Solve and the suite of programs for automated data transmission and processing. He conducts

research in the fields of optimal estimation of EOP, estimation of Love numbers, improvements in

the modeling of ocean loading, and investigation of instrumental errors in VLBI.

Ms. Karen Bayer (Raytheon ITSS) maintains and develops a wide range of software, including

the database and solution archive catalog systems, the SNOOP reporting programs, and various

analysis graphics programs. She also supports the group's web page activities, assists in generating

all types of TRF and CRF reports, generates site and velocity plots, assists in generating IVS

publications, and provides assistance to new and current users of the analysis package.

Ms. Cindy Lonigro (Raytheon ITSS) works on initial experiment preparation and data archiving and provides analysis support, web page support, and miscellaneous support.

4. Outlook

Plans for 2001 include:

• Calc/Solve: Develop source structure correction capabilities. Add the Niell isobaric mapping

function (IMF). Incorporate mapping functions derived by raytracing atmospheric profiles

and compare with the Niell IMF mapping function. Test effects of hydrology loading series

and three dimensional atmospheric pressure loading (from loading convolution method) series. Implement new schemes for estimating EOP. Update as necessary for compliance with

IERS 2000 Conventions. Modify as necessary for HPUXll.0 on an HP9000/785 workstation.

• Collaborate on the development of a new database format.

• Make a comparison study of Mark 4/Fourfit versus VLBA/AIPS correlating/fringing in the

RDV22 experiment. Also compare and study Mark 3 versus Mark 4, and K4 versus Mark 4

processing.

• Complete the astrometric analysis of the VLBA Calibrator survey experiments.

228 2000 IVS Annual Report
.; _ L / 7_F ,, /,,.i /

MIT Haystack Observatory

._5?72

Haystack Observatory Analysis Center

Analysis and Research at the Haystack Observatory

Arthur Niell, Brian Corey

Abstract

New mapping functions that incorporate easily accessible in situ atmospheric information have been

incorporated in the solvk analysis package at Haystack. For middle and high latitudes the mapping

function contribution to the vertical error budget is significantly reduced.

A study has been initiated on how to utilize VLBI to better understand the antenna characteristics

of the GPS satellites. A better model for the GPS satellite phase center will help resolve possible

discrepancies between the VLBI and GPS terrestrial reference frame scales.

1. Geodetic Research at the Haystack Observatory

The primary objectives of analysis activities at Haystack Observatory are to improve the underlying models in order to obtain better accuracy and precision and to better understand the

uncertainties that limit the space geodetic techniques. Since there are many similarities between

VLBI and GPS, it is natural to investigate both common error sources and and those that are

unique in order to obtain the best results from both techniques. This has led us to study the

atmosphere model, which can be applied to either, and the characteristics of both satellite and

receiver antennas of GPS.

Atmosphere models

Gridded global numerical weather models provide in situ meteorological information. The

geopotential heights of an isobaric surface, for example the 200 hPa surface, serve as a useful

parameter for the hydrostatic component of the mapping function [3]. The improvement relative

to the widely used NMFh [2] is shown in Figure 1 for a mid-latitude site; the scatter of the

mapping function at 5° is an indication of the error that will be introduced in the vertical. The

improvement in modeling precision, interpreted as approximate vertical error as a function of

latitude, is illustrated in Figure 2.

ALB

80! L_ o NMFh-radiosonde i_

40 o

,oo + +..

-80 _ o o ' "

-1°_2 -i992]2 -1_.4- 1_.6 1_28 1993

yc_

Figure 1. Temporal errors of hydrostatic mapping functions. The difference with respect to raytraeing of

radiosonde profiles for the IMF and NMF hydrostatic mapping functions at 5 ° elevation.

2000 IVS Annual Report 229
Haystack Observatory Analysis Center MIT Haystack Observatory

-- + IMFw [

,,', A

_,Zx A.

x -

x _ +

+ 4.'+ x +._ 4r.4++ +

x IMFh

,_ i 2 IMFw+IMFh

:- NMFh+NMFw

== HI

IE

E I

_ 5

+

O_

-81) -51) --10 -20 0 20 40 60 80

latitude

Figure 2. Vertical error induced by hydrostatic mapping functions. The approximate contribution of the

hydrostatic and wet mapping functions to the vertical error for VLBI or GPS experiments with a minimum

elevation of 5°. The dashed lines are of the form cos(2*latitude) and are intended only to guide the eye to

the expected height uncertainties for the combined hydrostatic and wet mapping function errors for IMF

azld for NMF.

The relative value of the two hydrostatic mapping functions has been tested by comparison of

the variation of the baseline lengths for the CONT94 VLBI data, assuming that they are constant

over the short period of that campaign. The standard deviation of the lengths is slightly smaller

using IMFh than using NMFh. No correction was made for atmospheric pressure loading, and,

since this effect may have a comparable contribution to the scatter, this may account for the

marginal improvement.

VLBL GPS, and the Terrestrial Reference Frame

The direction-specific instrumental delay (phase center variation) of GPS ground antennas

differs by antenna model. The Dorne-Margolin choke ring antenna has been assumed to be uniform,

but measurement of the phase pattern in anechoic chambers and by a rapid cycling among satellites

by a "robot" [4] suggest a large elevation-dependent error. For this error to be reasonable the

GPS satellites must have a compensating phase error to avoid a large discrepancy between GPS

and VLBI in the scale of the terrestrial reference frame. A joint working group composed of

representatives from the IVS, IGS, and ILRS and chaired by Brian Corey has been studying

the feasibility of using differential VLBI observations of GPS satellites and nearby extragalactic

sources to measure the phase pattern of the transmitted L1/L2 GPS signals. The aim is both to

measure the pt_ase center locations of the GPS phased array transmitters and to "map" the relative

magnitu(tes and phases of the drive voltages of the individual phased array elements. The required

accuracy on the VLBI fringe phase is < 10°, or < 5 mm in differential range, after correction for

propagation media effects, extragalactic source position uncertainty, etc.; this level of accuracy will

likely be difficult to achieve.

230 2000 IVS Annual Report
MIT Haystack Observatory Haystack Observatory Analysis Center

2. Outlook

Both of these projects will continue. For the evaluation of the atmosphere models, solvk [1]

will be updated with atmospheric pressure loading and with an improved ocean loading model.

The amount of data will be extended to cover at least a full year in order to evaluate any annual

components in the results.

Upon completion of the study to determine the feasibility of using VLBI to characterize the

GPS satellite antennas, a decision willl be made on whether to proceed, and, if the project looks

promising, funding will be sought.

References

[1] Herring, T. A., J. L. Davis, and I. I. Shapiro, Geodesy by radio interferometry: The application of

Kalman filtering to the analysis of very long baseline interferometry data, J. Geophys. Res., 95, 12,561-

12,581, 1990.

[2] Niell, A.E.: Global mapping functions for the atmosphere delay at radio wavelengths, J. Geophys. Res.,

Vol. 101, No. B2, 3227-3246, February 1996.

[3] Niell, A.E.: Improved atmospheric mapping functions for VLBI and GPS, Earth, Planets, and Space

(accepted), 2001.

[4] Wubbena, G. Schmitz, M., Menge, F., Boder, V. and Seeber, G.: Automated Absolute Field Calibration

of GPS Antennas in Real-Time, Proceedings of the ION Meeting 2000, Salt Lake City, Utah.

2000 IVS Annual Report 231
IAA Analysis Center

,,._ j ;j

,_-°.-,.., 0o- :"55 577 

f) i!

Institute of Applied Astronomy of Russian Academy of Sciences (IAA) 9 ") t,_

IAA VLBI Analysis Center Report for 2000

Zinovy Malkin, Elena Skurikhina, Maria Sokolskaya, George Krasinsky, Vadim Gubanov,

Igor Surkis, Iraida Kozlova, Yuriy Rusinov

1. Introduction

The IAA Analysis Center (IAA AC) is located at the Institute of Applied Astronomy of the

Russian Academy of Sciences. The main fields of the activity include EOP service, computation

of station and radio source coordinates, geodynamical investigations, comparison and combination

of EOP, TRF and CRF realizations, development and comparison of algorithms and software for

processing VLBI observations. IAA AC works in close cooperation with IERS and IVS.

2. Staff

Three VLBI groups of IAA contribute to IAA AC activity:

1. Lab of Space Geodesy and Earth Rotation: Dr. Zinovy Malkin (head), Elena Skurikhina,

Dr. Maria Sokolskaya. The main tasks of this group related to IVS activity are: management of

the IAA EOP Service, determination of EOP, station and radio source coordinates, comparison

and combination of VLBI, GPS, and SLR products. The group explores two program packages:

OCCAM for EOP and TRF computation, and ERA for EOP and (mainly) CRF computation.

2. Lab of Ephemeris Astronomy: Prof. George Krasinsky (head). The main IVS related

activity of this group is development of program package ERA for investigations in Earth sciences

and dynamical astronomy based on processing VLBI observations including combining VLBI, SLR,

LLR, and optical observations. In particular, determination of EOP from combination of VLBI

and SLR observations is under development.

3. Lab of New Methods in Astrometry and Geodynamics: Prof. Vadim Gubanov (head), Igor

Surkis, Iraida Kozlova, Yuriy Rusinov. The main task of this group related to IVS activity is

determination of EOP, station and source coordinates using new package QUASAR with emphasis

on investigation of stochastic parameters (EOP, troposphere, clocks).

3. Analysis Activities

3.1. EOP service

IAA EOP Service based on regular processing of SLR and VLBI observations has been operating

since 1994. Regular processing of VLBI observations started in 1996. Both operative and yearly

final EOP series are regularly contributed to both the IERS and the IVS. Accuracy of these series

is presented in Table 1. Along with EOP, station coordinates for every 24h session are computed.

In 2000 we started operative processing of the NEOS Intensives series.

In 2000 two EOP final solutions EOP(IAA)00R01 (1984-1999) obtained with OCCAM package

and EOP(IAA)00R02 (1994 1999) obtained with ERA package have been submitted to the IERS

1999 Annual Report. For all solutions the model of reduction and the method of parameter

estimation were practically analogous to those described in the IVS 1999 Annual Report.

232 2000 IVS Annual Report
Institute of Applied Astronomy of Russian Academy of Sciences (IAA) IAA Analysis Center

Table 1. Accuracy of EOP series obtained with the OCCAM package for 1999-2000.

Series (program) Xp, mas Yp, mas UT1, 0.1 ms A¢ sine, mas Ae, mas

IAAo9907 (NEOS-A+CORE) 0.19 0.15 0.09 0.13 0.15

IAAo9907 (NEOS-A) 0.14 0.14 0.07 0.12 0.14

IAAi0011 (NEOS-I) -- -- 0.22 -- --

3.2. Radio source coordinates

The computation of radio source catalogues from global processing VLBI observations using

ERA package was continued in 2000. Two catalogs of 312 radio sources have been submitted to the

IERS 1999 Annual Report. Moreover, the first version of software for comparison and combination

of catalogs is advanced. The latest radio source catalog was transformed to the ICRF system and

compared with ICRF-Ext.1. Result of comparison is presented in Figure 1.

2

1

0

-1

-2

-3

A_ cos 6, mas

, , , o

• •

-;0-;0-40-20 2; 4; 6; S_0

A 6_ mas

1

0

-1

-2

-3

-80 -60 -40 -20 0 20 40 60 80

Figure 1. Differences of radio source coordinates RSC(IAA)-ICRF-Ext.1.

A special study was performed to investigate possible dependence of radio source coordinates

on observational programs (NEOS-A - CORE-A).

3.3. Processing long time series VLBI observations

All available 24h VLBI sessions were processed to obtain session station coordinates and troposphere zenith delay time series. An example of wet troposphere delay time series is presented

in Figure 2.

GILCREEK

O.1

O

1986 1988 1990 1992 1994 1996 1998

Figure 2. Time series of wet zenith troposphere delay for station Gilmore Creek.

A series of UT1 based for period 1984-2000 has been also obtained and submitted to the IVS.

2000 IVS Annual Report 233
IAA Analysis Center Institute of Applied Astronomy of Russian Academy of Sciences (IAA)

3.4. Comparison and combination of EOP series

The basic software for comparison of EOP series is developed. This software allows us to

compute and investigate systematic differences of EOP and TRF series and related statistics. It is

in every-day use in the EOP service. Software for combining EOP series including those obtained

from different observational techniques is also advanced.

In 2000 we performed intensive study of systematic differences between EOP series and CRF

realizations obtained from NEOS-A and CORE programs with OCCAM and ERA packages. It

was found, in particular, that EOP results substantially depend on software and CRF used for

computation. The differences between EOP series contain significant systematic components.

Table 2 presents some obtained results.

Table 2. Wrms of differences between EOP series obtained from different observational programs using two

pro 7am packages and two radio source catalogues with EOP(IERS)C04 before/after removing linear trend.

Program / catalog / package

NEOS-A / IAA / ERA

NEOS-A / WGRF / ERA

NEOS-A / IAA / OCCAM

NEOS-A / WGRF / OCCAM

CORE-A / IAA / ERA

CORE-A / WGRF / ERA

CORE-A / IAA / OCCAM

CORE-A / WGRF / OCCAM

CORE-B / IAA / ERA

CORE-B / WGRF / ERA

CORE-B / IAA / OCCAM

CORE-B / WGRF / OCCAM

Xp, Iza_ ]Iv, #as UT1, 0.1 #s A¢, #as A_, /zas

323/271 287/246 170/105 570/531 254/201

273/265 268/232 140/97 550/521 206/192

219/200 202/165 103/93 328 /306 142/133

219/201 202/165 103/93 328/305 142/134

453/389 448/320 261/229 808 /619 325/252

398/361 343/306 238/214 737 /630 241/228

213/194 247/170 114/107 467 /420 180/174

204/194 219/173 124/114 489 /426 188/184

357/313 298/287 247/192 763/725 268/203

374/322 317/294 270/207 764/729 240/226

273/207 250/218 158/140 545 /521 185/170

273/208 258/225 159/141 550/526 190/176

3.5. First results of program package QUASAR

The multi-functional package QUASAR is aimed at processing observations of global VLBI

networks with the purpose of studying Earth rotation and improving coordinate systems accuracy.

The package runs under Windows 9x. Main features of the package are:

1. Flexible parameterization.

2. Different methods of parameter estimation: multi-parameter least squares (MPLS) (realized); multi-group least squares (MGLS) (realized); moving least squares filter (MLSF)

(planned); optimal Kalman filter (OKF) (realized); moving Kalman filter (MKF) (planned);

least squares collocation (LSC) (realized).

3. Multi-window control system which allows the user to select and tune the reduction model,

to correct or reject outliers, and organize input-output database control.

Package QUASAR was applied to processing NEOS-A observations for period 1997-1998. Data

were processed using LSC techniques. The accuracy of EOP determination in comparison with

234 2000 IVS Annual Report
Institute of Applied Astronomy of Russian Academy of Sciences (IAA) IAA Analysis Center

EOP(IERS)C04 series is presented in Table 3. Comparative analysis of EOP results obtained with

different estimation techniques is underway.

Table 3. Accuracy of EOP series obtained with the QUASAR package for 1997-1998.

Yp, mas UT1, 0.1 ms A¢ sine, mas

0.17 0.09 0.14

AE_ ma8

0.20

NEOS Intensives observations for 1998-2000 were processed using MPLS, OKF and LSC techniques. The most accurate estimations were obtained by MPLS with use of stochastic regularization.

Twelve sessions carried out during CONT94 experiment were processed using LSC technique

and estimates of intraday stochastic components were obtained as follows:

• wet component of zenith troposphere delay for all stations (for station Onsala result is in

good agreement with independent WVR measurements); significant horizontal gradients of

wet troposphere zenith delay were found for some stations.

• residual variations of PM and UT with reference to Ray's and Gipson's models that are

consistent within ±0.1-0.3 mas.

The same observations were used for determination of global nominal and secular Love

and Shida numbers. The following values were obtained: h(°)--0.579+0.003, l(°)=0.087+0.001,

hs=0.795+0.009,/s=0.129+0.002. Secular numbers are related to total permanent tide in the reference frame ITRF'97. Moreover, nominal Love and Shida numbers were estimated from 12 daily

sessions. These results show some instability of local number h that may be caused by insufficient

modelling of vertical motion of Earth crust.

LSC technique has been also applied to processing observations of programs IRIS (1984-1992)

and NEOS-A (1993-1999). Estimates of all stochastic parameters and their autocovariance functions were obtained. Significant instability of these functions was detected; therefore further LSC

evaluation will be carried out by use of iteration process.

4. Outlook

We plan for the coming year:

• Regular computation of combined eops and eopi series and submission of results to the IVS

Analysis Coordinator for further investigation.

• Development of algorithms and software for analysis, comparison and combination of radio

source catalogs.

• Regular computation of session station coordinates in SINEX format.

• Comparison of weekly station coordinates and troposphere delay solutions obtained from

VLBI and GPS.

• Beginning of regular submission of EOP computed from NEOS-A and NEOS-I sessions with

QUASAR package.

2000 IVS Annual Report 235
 ̧

ItalyCNR Analysis Center

Z z ooqi *' 7

5 S S 75

Istitutodi R_lio_tronomia-Bolo_a

Italy CNR Analysis Center Report

P. Tomasi

Abstract

This report summarises the work of the Italian CNR VLBI Analysis Center. It will give the

fundamental information about the structure of the center, its locations, and its activity.

1. Introduction

The Italy CNR VLBI Analysis Center is the joint effort of two Institutes of Consiglio Nazionale

delle Ricerche (CNR) to improve the quality of the geodetic VLBI results, in particular in the

European area. The two institutes are:

a) the Istituto di Radioastronomia (Institute of Radio Astronomy, IRA) located in Bologna,

where the main research activity is carried out, both in radioastronomy and geodesy;

b) the Istituto di Tecnologia Informatica Spaziale (Institute of Informatica and Technology for

Space, ITIS), located in Matera at the Center of Spatial Geodesy (of the Italian Space Agency),

where VLBI antenna, laser ranging telescope, permanent GPS receiver and PRARE antenna are

located. Also a different analysis center is located here. All these structures are properties of the

Italian Space Agency and run by Telespazio.

However the two institutes mentioned above will become quite shortly a single institute, the

"Istituto di Radioastronomia", with a section located in Matera. The new CNR's institute will

carry on the same commitment to IVS as the previous two intitutes.

The IRA have started to analyze VLBI geodetic database from 1989, using CALC/SOLVE

package at the HP1000 at the Medicina station. In the following years that software was installed

on an HP360 workstation and later on on an HP715/50 workstation. We have analyzed here

mostly databases with some European baselines, generally at least three. Most of the databases

have been reprocessed here in Bologna (using CALC and SOLVE). We are now using CALC9.1

and the November 2000 version of f-solve, for data analysis. We will soon move to the updated

version of f-solve (February 2001).

From 1997 also ITIS have installed the CALC/SOLVE software and after some tests we have

specialized the Bologna section to analyze single databases, in order to produce the final database.

The global solutions have been computed in Matera at the ITIS. In Matera we are also using f-solve

but with a previous version with respect to the one installed in Bologna.

2. Data Analysis and Results

In Bologna the main computer is HP715/80; the computer name is boira6.ira.bo.cnr.it. On it

we are now analysing single experiments (interactive solve); the global solutions are run mostly on

Matera computer.

We are continuing to work on the possibility of using tropospheric zenith path delay from GPS

in order to improve the repeatability of the VLBI geodetic results. We have inserted the wet

zenith path delay in the VLBI database as if this information was derived using a water vapour

radiometer. The tropospheric data have been collected at the Berna site of the IGS. However the

IGS data, with an hour interval, are the total tropospheric delay. For that we have subtracted

236 2000 IVS Annum Report
IstitutodiRadioastronomia-Bologna ItalyCNR AnalysisCenter

the dry delay, from the VLBI data, in order to produce the "wet" zenith delay. These data have

been inserted into the VLBI database using an updated version of DBCAL. In this new version

the Niell mapping function was implemented and also some other errors present in the program

have been corrected.

In Matera the main computer is an HP282 computer with internet name hp-j.itis.mt.cnr.it.

Also here we have installed f-solve (the center name is ITISCNR) and we are using it mostly for

global solutions in order to compute the positions and velocities of European stations.

The use of GPS tropospheric zenith path delay have produced some interesting results. On

the European database of 1998, the use of the new way of analysing VLBI data seems to produce

a better repeatability on the European baseline length (Rioja at al. 2000).

3. References

M. J. Rioja, P. Tomasi, P. Sarti, M.A. Tortes Integrating GPS zenith path-delay measurements into the VLBI analysis of geodetic observations with the European Network. - Proceedings

of the 14th Working Meeting on European VLBI for Geodesy and Astrometry. P. Tomasi et al.

editors, IRACNR 2000.

2000 IVS Annual Report 237
_./// /

IGG Analysis Center

.' ; .:(it,, d. ! _'7 _ -_

Institute of Geodesy and Geophysics / University of Technology, Vienna

Vienna IGG Special Analysis Center Annual Report 2000

Harald Schuh, Johannes B6hm, Thomas Hobiger

Abstract

A short overview about the Institute of Geodesy and Geophysics (IGG) at the Vienna University

of Technology is given and its activities as IVS Special Analysis Center are described. Topics currently

worked on and future plans are described.

1. Introduction

The Institute of Geodesy and Geophysics (IGG) at the University of Technology in Vienna,

Austria, was officially appointed as an IVS Special Analysis Center on December 4, 2000. Already

since 1999 the VLBI group at IGG has worked on the modification of the VLBI software package

OCCAM and on investigations concerning the modeling of tropospheric path delays.

2. Staff at IGG associated with the IVS Special Analysis Center

Personnel at IGG associated with the IVS Special Analysis Center in Vienna axe Harald Schuh

(Head of the Department of Advanced Geodesy) and the research assistants Johannes BShm (allocation 100%) and Thomas Hobiger (50%).

3. Special Analyses at IGG

• Modification of the VLBI software package OCCAM

Together with Oleg Titov (Astronomical Institute of St. Petersburg University) and Volker

Tesmer (Deutsches Geod/_tisches Forschungsinstitut DGFI, Munich) a group was set up in

summer 2000 to test, develop and further enhance the OCCAM software. At IGG, we

extended the classical least-squares approach of the Gauss-Markov model in OCCAM by

allowing the estimation of piecewise linear functions for the clocks, the zenith path delays

and horizontal tropospheric gradients (BShm et al., 2000).

• Modeling of tropospheric refraction

Based on the classical least-squares estimation procedure we compared tropospheric gradients determined by GPS and VLBI. Different software packages for the two techniques were

applied (OCCAM and SOLVE for VLBI, BERNESE and GIPSY for GPS). Moreover several

constraints were used for the piecewise linear functions to check their impact on the estimation of gradients. The results axe described in BShm et ai. (2000) and BShm et al. (2001)

and one example of good agreement between gradients derived by GIPSY and OCCAM is

shown in Figure 1.

4. Outlook

During the year 2001 the plans of the IVS Special Analysis Center at IGG include:

• Further development of OCCAM, e.g. the implementation of a free network solution and its

datum definition.

238 2000 IVS Annual Report
Institute of Geodesy and Geophysics / University of Technology, Vienna IGG Analysis Center

• Contributions to the IVS working group on geophysical models.

• Research on new tropospheric models which correspond to the traditional usage of mapping

functions and gradients.

• Comparisons of tropospheric parameters derived by VLBI, GPS and WVR data based on

NEOS-A, IRIS-S and EUROPE sessions.

• Contributions to special IVS projects, e.g. the pilot project 2000 by delivering EOP estimates

for 1999.

_0

-2

I I

-3 0 31 6 9 12 1=5 ll8 211 24

3

2

-2

-3 I l I

3 6 9 ll2 lj5 lj8 211 24

Figure 1. North and east gradients at Wettzell station for the VLBI session IRIS-S 136 on 15 March

1999 and simultaneous GPS measurements. For the estimation of tropospheric parameters a 3 hours' time

interval was chosen and the constraints for the gradients were set to 0.6 mm/sqrt(h). Diamonds are used

as markers for GPS (GIPSY), circles for VLBI (OCCAM). Acknowledgement: Ruediger Haas from Onsala

Space Observatory, Chalmers University of Technology, Sweden, provided the gradients obtained by GIPSY

for this comparison.

2000 IVS Annual Report 239
IGG Analysis Center Institute of Geodesy and Geophysics / University of Technology, Vienna

5. References

BShm, J., R. Haas, H. Schuh and R. Weber: Comparison of tropospheric gradients determined by

GPS and VLBI. Proceedings of the 14th Working Meeting on European VLBI for Geodesy and

Astrometry, Bologna, September 2000, ed. by P. Tomasi, F. Mantovani and M. A. Perez-Torres,

pp. 41-46, 2000.

BShm, J., H. Schuh and R. Weber: Comparison of tropospheric gradients determined by GPS

and VLBI. Submitted to 'Physics and Chemistry of the Earth', 2001.

Schuh, H., and H. Schmitz-Huebsch: Short periods in Earth rotation as seen by VLBI. Surveys in

Geophysics (in press), 2001.

Tesmer, V., and H. Schuh: Comparison of the Results Obtained by Different VLBI Networks. Proceedings of the 14th Working Meeting on European VLBI for Geodesy and Astrometry, Bologna,

September 2000, ed. by P. Tomasi, F. Mantovani and M. A. Perez-Torres, pp. 7-12, 2000.

Titov, O., and H. Schuh: Short periods in Earth rotation seen in VLBI data analysed by the

least-squares collocation method. IERS Technical Note 28, 'High frequency to subseasonai variations in Earth Rotation', Observatoire de Paris, ed. by B. Kolaczek, H. Schuh and D. Gambis, pp.

33-41, 2000.

240 2000 IVS Annual Report
ObservatoiredeParis,DANOF/UMR8630

2oozoo

Paris Observatory Analysis Center (OPAR)

Paris Observatory Analysis Center OPAR: Report on Activities,

March 1999 - December 2000

A.-M. Gontier, M. Feissel, N. Essai_/, D. Jean-Alexis, K. Le Bail

Abstract

The OPAR Analysis Center activities over March 1999 - December 2000 focused on analyses of the

time stability of the celestial reference frame. The routine analysis of the intensive and 24-hour sessions

was continued. The team was not changed, except for the help of one student (six months in 2000).

1. Activities

1.1. Stability of ICRF

The capability of the VLBI geodetic and astrometric programs to maintain stable directions

in space was evaluated [1] on the basis of time series of session-per-session source coordinates

computed at USNO using the CALC-SOLVE software [2].

The systematic and random characteristics of several hundreds of source apparent motions

were investigated in order to derive a set of qualifiers that would be helpful in selecting sources to

maintain a precise and stable celestial reference frame. We developed a selection process based on

the density of observations over 1987-1999 and on the time stability of averaged yearly coordinates.

The stability considered is that along the maximum variability direction in a source-fixed frame.

242 sources were thus selected. The rotation angles of the corresponding differential celestial

reference frames are shown on Figure 1.

The results of this selection process are compared to the current ICRF qualifiers [3], i.e. "defining", "candidate" and "other" sources, and structure index, is shown in Table 1. The following

comments can be made.

. ICRF categories. The stability test keeps practically all "defining" and "candidate" sources

that were preselected on the basis of their observational history, and most of the "others".

When considering the complete ICRF-Ext.1, one can note first that only 1/3 of the "candidate" sources were selected on the basis of long and dense observational history. In fact

we know that a number of "candidate" sources axe considered so because their time span

of observation is still too short. We also know that a number of sources were qualified as

"other" although they had a dense observational history, explaining the selection of 3/4 of

them. The selection rate of the "defining" sources is between the other two (1/2). Already

at this first level, the first part of our selection scheme (based on the observational history of

the source) provides a pre-qualification of sources which is quite different from the current

ICRF one. Once this first selection is performed, the second one, based on the internal consistency of the time series of coordinates in the direction of the maximum variability, keeps

nearly all "defining" and "candidate" sources, thus confirming their current ICRF status.

Meanwhile, 7/10 of the "other" sources are still kept. This seems to indicate that using time

series information might bring in more sources that would contribute to stabilize the celestial

reference frame.

2000 IVS Annual Report 241
Paris Observatory Analysis Center (OPAR) Observatoire de Paris, DANOF/UMR 8630

0.6

0.3

0.0

-0.3

-0.6

dA1 (mas)

1988 1992 1996 2000

0.6

0.3

0.0

-0.3

-0.6

1988 1992 1996 2000

0.3

0.0

-0.3

-0.6

dA3 (mas)

36 72 87 135 191 138

i

1988 1992 1996 2000

Figure l. Rotation angles of 12 yearly differential CRFs relative to a mean one, using 242 sources selected

on the basis of dense observational history and time stability over 1987-1999. The numbers of sources whose

coordinates were available in a given year are listed (dA3 graph). The double horizontal line corresponds

to the stated uncertainty of the ICRF axes directions (+20 #as).

Table 1. Match of the source selection with the ICRF source qualifiers. The sources are first selected on

the basis of a dense observation history, then a percentage of them is recognized as stable.

Number % All % Number %

presel, stable sources stable presel, stable

1. ICRF categories 2. Structure index

Defining 108 95% 212 49% 1 49 86%

Candidates 98 88% 294 29% 2 87 80%

Other 73 67% 102 48% 3 63 87%

4 26 85%

. The structure index for each source [4] qualifies the level of position disturbance expected

from the irregularity of the source emission structure (1 for the less disturbed, 4 for the most

disturbed). The lack of correlation between this index and our stability criterion suggests

that, for the data set used in this study, the observational and analysis errors due to other

factors tend to dominate the source structure effect.

This study also highlights the usefulness of considering the time evolution of radiosource directions, not only for internal purposes such as the ICRF quality control or applications like differential

VLBI, but also to enhance the support of VLBI to scientific research, as in the understanding of the

physical properties of the non-rigid Earth through analysis of precession and nutation observations,

or for realistic studies of source structure or microlensing effects.

In another study [5], using a set of 16 well observed radio sources (north of +20 degrees), it

was shown that reliable information can be obtained on the local motions in the sources since the

end of the 1980's, with a 0.5-year time resolution. The analysis showed that the variability of

242 2000 IVS Annual Report
Observatoire de Paris, DANOF/UMR 8630 Paris Observatory Analysis Center (OPAR)

these objects have varied spectral characteristics, that could possibly be related to diverse physical

processes taking place in the sources.

1.2. OPAR time series of source coordinates

Computation of time series of source coordinates referred to the ICRF was initiated. Preliminary results were obtained for 52 sources over 1999. Figure 2 shows the average coordinates of

37 of them, for which the 1998 coordinates could also be derived from the USNO [2] series. The

weighted standard deviations of the yearly position differences between the USNO and OPAR

analyses are 0.13 mas in R.A.cos(Dec) and 0.18 mas in Declination.

1.0

CD

E 0.5

g o o

o_O-0.5

P

.< -1.0

rr

'_ 0.5 E

0.0

C

O

= -0.5

t'-

-1.0

D

-1.5

J

0 _ _ •

!

L0

i •

O

!

t 0

• o o,_ ;%° _**,:.#" o o 'A ,o_.

q ¢. • . 0

¢

Declinations (degrees)

-40 -20 0 20 40 60 80

Figure 2. Average coordinates for 37 common sources: USNO 1998 (brown/light) and OPAR 1999

(blue/heavy)

1.3. Operational analyses

The analysis of the intensive one-baseline sessions was continued and that of the 24-hour sessions was initiated. Results were provided to IERS and IVS. The results obtained are illustrated

in Figure 3. The standard deviation of the differences of the OPAR solutions with the IERS series

C04 over 1999 is +20 #s on UT1-UTC for the intensive sessions; for the 24-hour sessions: +0.28

mas on polar motion, +12 #s on UT1-UTC and =t=0.22 mas on celestial pole offsets.

2. Prospects

Our plan is to continue developing reference frame studies and applications. Most of these

studies will contribute to the work of the IERS ICRS Product Center, with which the OPAR IVS

2000 IVS Annual Report 243
Paris Observatory Analysis Center (OPAR) Observatoire de Paris, DANOF/UMR 8630

1

0

-1

dX pole (mas)

Date (years)

1

0

-1

dUT1, 24-hr (mas)

T - • f

4 * Jt

Date {years}

, !

0.3

0.0

-0.3

dPsi*sin(Eps) (mas)

Date (years)

I I

1999.0 1999.5 2000.0

Figure 3. OPAR EOP results in 1999. Difference with EOP(IERS) C04.

Analysis center is closely associated.

1. Time series of source coordinates referred to the ICRF. These time series can be used in several research and operational applications, e.g. the astrophysical interpretation of observed

apparent motions, the accurate use of the sources in differential VLBI, the scheduling of

IVS observing sessions, the optimization of future revisions of ICRF. The time series will be

available on the ICRS-PC website (http://hpiers.obspm.fr/icrs-pc).

2. Global celestial reference frame analyses.

3. Time series of terrestrial reference frames.

References

[1] A.-M. Gontier, K. Le Bail, M. Feissel, T. M. Eubanks, 2001. Stability of the extragalactic VLBI reference

frame. AA (in press)

[2] T.M. Eubanks. Private communication

[3] International Earth Rotation Service (IERS), 1999, 1998 Annual Report, 83. Observatoire de Paris.

[4] A.L. Fey, P. Charlot, 2000, ApJS, 128, 17

[5] M. Feissel, A.-M. Gontier, T.M. Eubanks, 2000, AA, 359, RN1201

244 2000 IVS Annual Report
Onsala Space Observatory (OSO)

9 5>, ,,;-

;' Lt

Onsala Space Observatory (OSO) Analysis Center

The IVS Special Analysis Center at the Onsala Space

Observatory

Riidiger Haas, Hans-Georg Scherneck, Gunnar Elgered, Jan M. Johansson,

Lubomir P. Gradinarsky, Boris Stoew, and Sten Bergstrand

Abstract

We give a short overview on the activities of the IVS Special Analysis Center at the Onsala Space

Observatory. Current topics of analysis and research are ocean tide and atmospheric loading, crustal

deformation in Europe, atmospheric radio wave propagation, thermal deformation of VLBI radio telescopes, combining and integrating VLBI and GPS and earth rotation. Future plans are briefly described.

1. Introduction

The IVS Special Analysis Center at the Onsala Space Observatory (OSO) concentrates on a

number of particular problems which can be investigated using and developing VLBI databases

and analysis programs, and providing ancillary parameters. No routine analysis of global VLBI

data in a service sense is performed or planned at OSO for the next few years.

2. Ocean Tide Loading

The studies performed at OSO cover theoretical modelling and empirical determination of ocean

tide loading effects. New ocean tide loading coefficients based on recent ocean tide models have

been calculated and made available for a global set of VLBI stations [1]. The ocean loading web

site http://www.oso.chalmers.se/_hgs/README.html includes loading parameters computed on

the basis of the recent GOT99.2 tide model [2].

A case study for the IVS station Westford showed that the refinement of the tidal modelling at

the continental shelves leads to an improved agreement between modelled ocean tide loading and

three-dimensional ocean tide loading effects derived from the analysis of VLBI data [1].

3. Atmospheric Loading

A data base with time series of atmospheric loading predictions based on global pressure fields

has been generated for most of the VLBI databases since 1990 [1] and is available from our http

server ht t p: //www.oso.chalmers.se/,-_hgs/apload/apload.html.

4. Crustal Deformation in Europe

The pure geodetic European VLBI experiments observed since 1990 have been analysed applying the two-step analysis strategy described in [3]. Crustal motion results and the corresponding

large-scale strain-rate field in Europe have been determined [4].

2000 IVS Annual Report 245
OnsalaSpaceObservatory (OSO) Analysis Center Onsala Space Observatory (OSO)

5. Atmospheric Radio Wave Propagation

Atmospheric studies have been performed using the collocated techniques VLBI, GPS and

microwave radiometry at Onsala [5]. Simultaneous observations with these three techniques during

1993 to 1998 showed correlation coefficients for the zenith wet delay between 0.74 and 0.87 and

for the horizontal delay gradients between 0.27 and 0.51 [6]. Equivalent zenith wet delay values

derived from VLBI and GPS have also been compared to values from Numerical Weather Prediction

(NWP) models [7]. The agreement is promising with correlations at the level of 0.8.

6. Thermal Deformation of VLBI Radio Telescopes

The simple model describing the deformation of radio telescopes due to thermal influences [8]

has been used to model the effects and to compare them to the vertical height changes measured

at Onsala and Wettzell with the respective invar measurement devices (see Fig. 1).

Onsala

oE_I ®

¢- ®

-_ -2

>

¢-3

a 1996 1997 1998 1999 2000 2001

Wettzell

®

®

®

1997 1998 1999 2000 2001

Figure 1. Vertical height chmlges of the VLBI radio telescopes at Onsala and Wettzell: solid lines - measured

by the invar rod measuring systems; stars in circles - modelled with a simple model based on daily mean

temperature from the VLBI data base, thermal expansion coefficient, and the telescope dimensions.

7. Combining and Integrating VLBI and GPS

Since each space geodetic technique has specific advantages and disadvantages, the combined

and integrated use of several space geodetic techniques seems to be a useful approach. This is

especially true for investigations concerning the crustal strain-rate fields and for the determination

of absolute sea level changes. Therefore we started first investigations to combine and integrate

VLBI and GPS in Europe [9]. The continuously growing data set of daily GPS solutions since

1993 available at OSO and in particular the GPS data from the BIFROST project [10] offer an

excellent basis to continue these investigations.

246 2000 IVS Annual Report
OnsalaSpaceObservatory(OSO) OnsalaSpaceObservatory(OSO)AnalysisCenter

8. Earth Rotation

The IVS Special Analysis Center at the Onsala Space Observatory participated in the First

IVS Analysis Pilot Project and submitted an earth orientation parameter (EOP) solution obtained

from the 52 NEOS-A sessions in 1999 (see Fig. 2).

400

o,.350

>- 300

250

_-50

-45

._ -50

-55

0

-o -5

-10

L

, , , = ,

J F M A M J J A S O N D

300 I

15 ITV,TrETT[ITiTITWCTI,TTjwTItTI]!,TI,TI$It

,.300 f

>- 150ioiTT.T[]TTTIITTT, TIjT,TIETITITT, TT,!LTTITITT, TT.TI,TTITTI[T=TT +

,.. 300 II

ID 150

"O

0 T:TItTTTIItTI,TTJLTT.TTTIITT,TJT,TTtTITT, TT,IT,TTITTTIt_IT,

TllIli]1111i.Tl.l]:lj.TT]iIl+'j'[,

rI

30011 _ 150

0 IITT]TTTITIt tTTJ[JT3TTItTT,TT,TLTTIT_T[TT:TT,T[ITTTITZII:

J F M A M J J A S O N D

Figure 2. OSO's submission of earth orientation parameters derived from the 52 NEOS-A experiments in

1999 for the First IVS Analysis Pilot Project. The left column shows the earth orientation parameters

in milliarcseconds, the right column shows the respective standard deviations in microarcseconds. For

UT1-UTC (dUT1) an offset, a drift, an annual and a semi-annual term are subtracted.

9. Outlook

The TVS Special Analysis Center at the Onsala Space Observatory will continue to work on

crustal loading and deformation effects. Special focus will be ocean tide loading and atmospheric

loading but we will also work in the field of solid Earth tides. Parameter estimation and the

covariances with EOP determinations will be of main interest. Eventually we will also contribute

to IVS by submitting EOP solutions.

We will continue to analyze the European VLBI data with the aim to derive the most robust and

reliable results for crustal motion and strain-rates. Our investigations will include also combination

strategies with other space geodetic techniques like GPS, especially to achieve a more detailed view

on the strain-rate field in Europe and to investigate changes in absolute sea level. We will also

work on the geophysical interpretation of the results.

Our research concerning atmospheric properties will continue and we will use especially the

collocated space geodetic and remote sensing techniques available at the Onsala Space Observatory.

The investigations will reach from small scale structures in the atmosphere that can be detected

with the new microwave radiometer [11] to climatological studies.

2000 IVS Annual Report 247
J

fl f

Onsala Space Observatory (OSO) Analysis Center Onsala Space Observatory (OSO)

References

[1] Scherneck, H.-G., R. Haas, and A. Laudati, Ocean Loading Tides For, In, and From VLBI, In: IVS

2000 General Meeting Proceedings, N. R. Vandenberg and K. D. Baver (eds.), NASA/CP-2000-209893,

257 262, 2000.

[2] Ray, R., Global Ocean Tide Model From TOPEX/POSEIDON Altimetry: GOT99.2, NASA/TM-1999-

209478, 1999.

[3] Haas, R., and A. Nothnagel, A two-step approach to analyze European geodetic Very Long Baseline

Interferometry (VLBI) data, In: Proc. of the 13th Working Meeting on European VLBI for Geodesy

and Astrometry, W. Schl/iter and H. Hase (eds.), 108-114, 1999.

[4] Haas, R., E. Gueguen, H.-G. Scherneck, A. Nothnagel, and J. Campbell, Crustal motion results derived

from observations in the European geodetic VLBI network, Earth, Planets and Space, 52, 759-764,

2000.

[5] Gradinarsky, L. P., R. Haas, G. Elgered, and J. M. Johansson, Wet path delay and delay gradients

inferred from microwave radiometer, GPS and VLBI observations, Earth, Planets and Space, 52, 695-

698, 2000.

[6] Haas, R., L. P. Gradinarsky, G. Elgered, and J. M. Johansson, Atmospheric parameters derived from

simultaneous observations with space geodetic and remote sensing techniques at the Onsala Space

Observatory, In: IVS 2000 General Meeting Proceedings, N. R. Vandenberg and K. D. Bayer (eds.),

NASA/CP-2000-209893, 269 273, 2000.

[7] Behrend, D., L. Cucurull, J. Vii/t, and R. Haas, An inter-comparison study to estimate zenith wet

delays using VLBI, GPS and NWP models, Earth, Planets and Space, 52,691-694, 2000.

[8] Haas, R., A. Nothnagel, H. Schuh, and O. Titov, Explanatory Supplement to the Section "Antenna

Deformation" of the IERS Conventions (1996), DGFI Report 71, H. Schuh (ed.), 26-29, 1999.

[9] Scherneck, H.-G., J. M. Johansson, and R. Haas, BIFROST Project: Studies of Variations of Absolute

Sea Level in Conjunction With the Postglacial Rebound of Fennoscandia, In: R. Rummel, H. Drewes,

W. Bosch, H. Hornik (eds.), Towards an Integrated Global Geodetic Observing System (IGGOS), IAG

Symposia (120), International Association for Geodesy, 241 244, Springer-Verlag, Berlin, 2000.

[10] Johansson, J. M., J. L. Davis, H.-G. Scherneck, G. A. Milne, M. Vermeer, J. X. Mitrovica, R. A.

Bennett, B. Jonsson, G. Elgered, P. E16segui, H. Koivula, M. Poutanen, R. O. RSnn/_g, and I. I.

Shapiro, Continuous GPS measurements of postglacial adjustment in Fennoscandia, 1. Geodetic results,

Journal of Geophysical Research, submitted 2000.

[11] Stoew, B., C. Rieck, and G. Elgered, First results from a new dual-channel water vapor radiometer,

In: Proc. of the 14th Working Meeting on European VLBI for Geodesy and Astrometry, P. Tomasi,

F. Mantovani and M.-A. Perez-Torres (eds.), 79-82, 2000.

248 2000 IVS Annual Report
SHAO, NAO, Chinese Academy of Sciences

/

2 oo 2c c --

i3. '

Shanghai Astronomical Observatory Analysis Center

Analysis Center Report from Shanghai Astronomical Observatory

for 1999.03--2000.12

Jinling Li, Guangli i'l,hng

Abstract

Here we summarize the activities of the astrometric and geodetic VLBI group of Shanghai Astronomical Observatory during the period from March 1999 to the end of 2000. Our activities are involved

in the coordination of the VLBI observations for Asia-Pacific Space Geodynamics (APSG) program

and several Chinese national geodetic projects, the data archives and reduction, the astrometric and

geodetic application studies of VLBI. We also describe our plans for the year 2001 and finally show our

thanks to all IVS colleagues and others giving us help.

1. Observation Coordination

Outstanding characteristics such as high precision repeatability for long baseline length measurements and providing high precision observations in the quasi-inertial deep space background,

make VLBI one of the key supporting techniques of the Asia-Pacific Space Geodynamics (APSG)

program and several Chinese national geodetic projects, for instance, the Chinese Observation Network of Crustal Movement, the Mechanism and Prediction of Continental Intensive Earthquakes.

hi January and October of 2000, our group organized in total four 24-hour Chinese national VLBI

experiments. The antennas are one fixed at Sheshan and one 3-m mobile at Kumning. In November of 1999 two international VLBI sessions were coordinated and in October of 2000 one session.

All are for the APSG program. The stations are Sheshan and Urumqi of China, Gilereek and Kokee of USA, Kashima of Japan and Hobart of Australia. These observations are important to the

studies of contemporary crustal motions within the China mainland as well as in the Asia-Pacific

region.

2. Data Archives and Reduction

The original HP C180 workstation was updated by extending the memory capacity to 260 Mb

and the hard disk to 54 Gb. The originally installed CALC8.2 was replaced by CALC9.1. The

observations were archived in personal computer disk, which is cheaper, faster and more convenient

than originally used 4-ram tape and its tape driver.

As a milestone in our group's history of data reduction, Mark III VLBI observations between

August 1979 and December 1998 were successfully analyzed in 1999. It was the first time for

our group to perform a full time span global VLBI data reduction. We compared our solution

with ITRF96, RSC (WGRF) 95 R01 and EOP (IERS) 97 C04. The three orientation angles for

the Celestial Reference Frame are not significant at the level of precision of O.lmas. Though no

significant values are found for the three deformation parameters, coordinate drifts up to 0.5mas

are identifiable for some sources in the southern hemisphere. The relative rotation angles and their

rates of change for the Terrestrial Reference Frame are not significant respectively at the precision

level of 0.2mas and O.lmas/yr. Detailed comparisons however show that the differences in the

velocity field are obvious for the eastern part of Eurasian plate and Australian plate. About Earth

2000 IVS Annual Report 249
Shanghai Astronomical Observatory Analysis Center SHAO, NAO, Chinese Academy of Sciences

Orientation Parameter series, the systematic differences and the relative drifts are not significant

respectively at the level of 0.4mas and 0.1mas/yr.

In the year 2000, our global VLBI solution was adopted as one of the three input solutions of the

latest version International Terrestrial Reference Frame (ITRF2000), which is really encouragement

to the whole group and also to the supervisors of our work unit.

3. Application Studies

3.1. Temporary crustal movement

Based on our global VLBI solution, we analyzed the motion of Sheshan VLBI station using

two different methods. One is based on the prediction of plate motion model. The other is based

on the absolute angular velocity of plate. In the first method, the VLBI measurement of Eurasia

plate motion was compared with the prediction of the plate motion model NNR-Nuvella by the

following equation,

vy - vy = T2 + -Ra D R1 y (1)

Vz NNR-NUVEL1,4 Vz VLBI T3 R2 -R1 D z VLBI

where D, T1,2,3 and R1,2,a are respectively the scaling factor, the translation and rotation parameters between tile measurement and prediction. These parameters are solved for by a least-squares

adjustment in a re-processing procedure. Only stations with post-fit residuals in horizontal velocity less than the analysis formal error (la) were finally used to contribute to the solution. Then

after the removal of the effects of systematic transformation parameters and the prediction of plate

motion model from the VLBI measurement, the motion of Sheshan station relative to the stable

part of Eurasia plate is found to be 8.4 ± 0.4mm/yr in the direction N122.4 ± 2.8°E.

In the second method, the absolute angular velocity of Eurasia plate, _(f_, ft w gt_). was solved

for from the following equation,

= fix (2)

where g and _'are the geocentric velocity and position of a station from VLBI measurement. Again,

only stations with post-fit residuals in horizontal velocities less than the analysis formal error were

used to solve for the absolute angular velocity. The motion of Sheshan station relative to the

Eurasia plate was found in this way to be 7.4 ± 0.3Inm/yr in the direction Nl17.4 ± 2.0°E. By

comparing this with that from the first method, the difference between them is obvious. However,

if we neglect the effect of the sealing factor and the translation parameters in Eq.(1), the motion

will be 7.3 ± 0.4mm/yr in the direction Nl13.5 ± 3.0°E, which becomes consistent with that from

the second method within the error budgets. Since D, T and R are independent parameters from

each other and modeling possible real systematic effects, the motion determined from the first

method should be more reliable than from the second one.

In Table 1 some results about the motion of Sheshan station relative to the Eurasia plate determined by various authors are shown for eomt)arison. From this one can only say that the motion

is eastward about 1 cm/yr. An efficient way to improve the precision of this determination would

be to improve the temporal coverage of data rather than solely the accumulation of observations.

250 2000 IVS Annual Report
SHAO, NAO, Chinese Academy of Sciences Shanghai Astronomical Observatory Analysis Center

Table 1. The motion of Sheshan station relative to Eurasia plate

Author Technique Rate Azimuth

mm/yr N°E

Heki, 1996 VLBI

Molnar & Gipson, 1996 VLBI

Zhu Wenyao et al., 1997 GPS

Zhu Wenyao et al., 1999 GPS

Yu & Kuo, 1999 GPS

This paper (based on absolutely angular motion) VLBI

This paper (based oil plate motion model) VLBI

11.1+1.2 112.1+6.2

8.0+0.5 116.5+4.1

11.2 75.7

10.8 87.3

11.2=t=1.0 112.3+6.4

7.4+0.3 117.4+-2.0

8.4+-0.4 122.4+-2.8

Tile relative motion between Eurasia and North America was also analyzed based on our global

VLBI solution. In Table 2 several determinations are listed for coinparison. Various authors

provided generally consistent results. The rotational velocity is about 0.2°/Myr with a slightly

faster rotation for the inodern space technique determination compared with the past millions of

years' geophysical records. The positions of the rotational pole and the azinmths of major semiaxis

given by various authors are obviously different from each other, so again the (:overage and amount

of observations nmst be improved.

Table 2. Angular motion between Eurasia and North America plates

Angular velocity Pole error ellipse

Author Technique Latitude Longitude w o,,_x amin A

°N °E °/Myr ° ° N°E

DeMets et al., 1994 NUVEL1A 62.4 135.8 0.21 -t-0.01 4.1 1.3 -11

Cook et al., 1986 Earthquake 71.2 132.0

Argus & Heflin, 1995 GPS 78.5 122.0 0.23 -t-0.03 4.1 2.4 -8

Larson et al., 1997 GPS 68.1 126.6 0.24 :k0.02 3.2 2.0 -30

Kogan et al, 2000 GPS 74.3 123.0 0.231+0.008 1.8 1.4 16

This paper VLBI 74.34 137.98 0.242+0.007 3.5 2.1 -9

ca: rotational velocity.

a ......... cr,,,i,_: major and minor semiaxes of the lcr error ellipse.

A: azimuth of major selniaxis re(:koned clockwise from north.

3.2. Polar motion

In a spectrum aim wavelet analysis of the VLBI determined polar motion series for the time span

from August 1979 to December 1998, it is shown that (1) during the VLBI data span the Markowitz

wobble does not appear, (2) the amplitudes of both annual and Chandler wobble show temporal

variations, with the former being more obvious than the latter within the observation period, (3)

all the signals in polar motion series are characterized by temporal variation in amplitudes, which

means that it is ahnost impossible to separate signals by a least-squares fit and (4) by applying

a low-pass filter the secular polar motion is tbund to be 2.74+-0.01 mas/yr towards 83.9+0.3 °W

longitude, which is smaller in rate and more westward in direction compared with those determined

from optical observations (Li & Wang, 2000).

3.3. Optical astrometry

hnage restoration has been shown to be a very useflfl tool for many kinds of research, such

a.s in the reduction of Hubble Space Telescope images, gamma ray data and in monitoring the

2000 IVS Annual Report 251
Shanghai Astronomical ObservatoryAnalysisCenter SHAO, NAO, Chinese Academy of Sciences

gravitational lenses of AGNs. Members of our group used image restoration to remove the influence

of tracking error in a_strometric CCD images. As shown in Fig.l, (a) is the two-dimensional

Gaussian distribution of an ideal image, (b) is the image of the standard star degraded by tracking

error in a CCD frame, ((:) shows the blended images of two nearby stars and (d) shows that after

the image restoration the two nearby stars are well separated. By applying image restoration, the

precision of the center of star image can be improved, tile images of nearby stars too (Tang et al.,

2001). The optical counterparts of 23 extragalactic radio sources, of which 13 are ill the southern

hemisphere, are observed with CCD. The positions have been determined with mean standard

errors in right ascension and declination better than 0.2 arcsec (Tang et al., 2000).

4. Plans for the Year 2001 ....'"

Most important, try our best to provide analysis products to

IVS data center quarterly. Continuously coordinate VLBI _ _..._....

experiments for Chinese national geodetic projects and for '°._.;_:. i "_

tile APSG progranL Make some analysis of the effects of _'i_ 7i_-.,-

various constraints on the global solution. Precisely deter- ,,i.... ' :

mine the positions of the optical counterparts of two dozen _' ".... ' :

extragalactic radio sources. Improve our ability in VLBI

data reduction and application studies.

Q_

Figure 1. Separating nearby images degraded by tracking error

with image restoration.

Acknowledgements We are thankful to Drs. Chopo Ma, Nancy Vandenberg, Axel Nothnagel and

all ()tiler IVS colleagues who have been giving us help to our work. Our work ha_s been supported

I)y Chinese national projects (No. 95-13-03-02, No. 970231003 ), Chinese National Natural Science

F(mndation Committee (No. 19833030), Chinese Academy of Sciences (No. KJ951-1-304), Science

and Technology Foundation of Shanghai City (No. JC14012).

References

[1] Heki K. J Geophys. Res, 1996, 101(B2): 3187--3198

[21 Molnar P, Gipson J M..! Geophys Res, 1996, 101(B1): 545 553

[3] Zhu Wenyao, Cheng Zhongyi, Jiang Guojun. /it Progress in Astronomy, 1997, 15(4): 373 376

[4] Zhu _nyao, Cheng Zhongyi, Wang Xiaoya et al.. Chinese Science Bulltin, 1999, 44(14): 1537 1540

[5] Yu S, Kuo L. Geophys Res Let, 1999, 26(7): 923 926

[6] DeMets C, Gordon R G, Argus D F et al.. Geophys Res Let, 1994, 21(20): 2191 2194

[7] Cook D B, Fujita K, MeMullen C A. J Geodyn, 1986, 6:33 51

[8] Augus D F, Heflin M B. Geophys Res Let, 1995, 22(15): 1973 1976

[9] Larson K M, Freymueller J T, Philipsen S. J Geophys Res, 1997, 102(B5): 9961 9981

[10] Kogan M G, Steblov G M, King R W, et al.. Geophys Res Let, 2000, 27(14): 2041 2044

[11] Li Jinling, Wang Guangli. Chinese Science Bulletin, 2000, 45(21): 1945-1948, Plate t

[12] Tang Z H, Wang S H, Jin W J. Astron J, 2001, 121(2), (In press)

[13] Tang Z H, Wang S H, Jin W J. Mon Not R Astron Soc, 2000, 319:717--720

252 2000 IVS Annual Report
U. S. Naval Observatory

ZOOcoo':!

USNO Analysis Center for Source Structure

USNO Analysis Center for Source Structure Report

Alan L. Fev; David A. Boboltz, Ralph A. Gaume, Kerry A. Kingham

Abstract

This report summarizes the activities of the United States Naval Observatory Analysis Center for

Source Structure from its inception in January 2000 to the end of the calendar year 2000. The report

forecasts activities planned for the year 2001.

1. Analysis Center Operation

Tile Analysis Center for Source Structure is supported and operated by the United States Naval

Observatory (USNO).

The main mission of the Analysis Center is to analyze VLBI data to extract intrinsic source

structure information for use in maintaining the International Celestial Reference Frame (ICRF).

Source structure information is provided in the form of synthesis images and source models suitable

for evaluating sources for astrometric and/or geodetic use and for long term monitoring of sources.

Research into the effects of source structure on astrometric position determination is also carried

out with emphasis on improving the long term stability of the ICRF.

The web server for the Analysis Center is provided by the USNO. The temporary address is:

http ://www. usno. navy. mil/RRFID/

The Radio Reference Frame Image Database (RRFID) web site holds infornlation on the radio

frequency intrinsic structure of most ICRF sources with declination greater than -30 degrees.

Both the raw data and processed images (with their associated source models) can be obtained

from this site. Links to the astrometric suitability of the sources, as derived by Fey & Charlot

(2000, Astrophysical Journal Supplement Series, Vol. 128, pp. 17 83 and references therein), are

also provided. A new web site devoted exclusively to the Analysis Center for Source Structure is

planned.

2. Initial Activities

In December 1999, the USNO proposed to become an IVS Analysis Center. The USNO Analysis

Center for Source Structure was accepted by the IVS a_s a Special Associate Analysis Center in

Jammry 2000.

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., t)rimarily,

radio frequency images of 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 USNO has, since mid 1996, hosted the Radio Reference Frame Image Database (RRFID),

a web accessible database of radio frequency images of most ICRF sources with declination greater

than -30 degrees. Images are available at both S band (13 cm) and X band (3.6 cm), the standard

frequencies used for VLBI astrometric and geodetic observations. Observations are taken from

both the geodetic/astrometric database and from RDV observations. The RDV experiments are

a joint collaboration between the USNO, Goddard Space Flight Center and the National Radio

2000 IVS Annual Report 253
USNO Analysis Center for Source Structure U. S. Naval Observatory

Astronomy Observatory (NRAO). During each 24 hour RDV session, about 70 ICRF sources are

observed at S/X band using the NRAO Very Long Baseline Array (VLBA) antennas together

with up to 10 additional geodetic antennas. The resulting intrinsic source structure information

provides a valuable resource for evaluating the astrometric suitability of the extragalactic sources

used to define the ICRF.

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.

3. Current Activities

Since the inception of the USNO Analysis Center, three VLBA RDV experiments have been

processed and imaged. These include the RDV07, RDV08 and RDV09 sessions. Processing of

RDV10 is under way.

The RRFID has contributed data to the structure analysis of Fey & Charlot (2000). The

resultant "Structure Index" is available from Patrick Charlot at

http ://www.observ, u-bordeaux, fr/public/radio/PCharlot/structure, html

The USNO and the Australia Telescope National Facility (ATNF) are collaborating in a VLBI

research program ill Southern Hemisphere source imaging and astrometry using USNO, ATNF

and ATNF accessible facilities. These observations are aimed specifically toward improvement of

tile ICRF in the Southern Hemisphere. Plans include strengthening the ICRF in the Southern

Hemisphere by a) increasing the reference source density with additional S/X band (2.3/8.4 GHz)

bandwidth synthesis astrometric VLBI observations, and b) VLBI imaging at 8.4 GHz of ICRF

sources south of 5 = -20 °. These observations will provide a strong tie between the Northern and

Southern Hemisphere through the overlap with common sources measured from the north. One

48 hour imaging session has been carried out and is awaiting correlation.

Several summer students contributed to the Analysis Center. Sarah Zelechosky used geodetic

VLBI observations to image 3C418, finding evidence of superluminal motion. Ginger Leonard used

RRFID data to classify ICRF sources according to the variability of their intrinsic structure.

4. Staff

The staff of the Analysis Center is drawn from individuals who work at the USNO. The staff

and their responsibilities are:

Name Responsibilities

Alan L. Fey Primary scientific contact, Web and data base design and

content, Webmaster, Web server administration, VLBA

data analysis (imaging), structure analysis

David A. Boboltz VLBA data analysis (imaging), structure analysis

Ralph A. Gaume Liaison to the ICRF Product Center of the IERS

Kerry A. Kingham Web and data base design and content, Webmaster, Web

server administration, geodetic data analysis (imaging),

Mark 4 interface to imaging software, structure analysis

254 2000 IVS Annual Report
U. S. Naval Observatory USNO Analysis Center for Source Structure

o Future Activities

The following activities are planned:

• Continue imaging of VLBA RDV experiments

• Make additional astrometric and imaging observations in the Southern Hemisphere in collaboration with ATNF partners

• Continue research into the effects of intrinsic source structure on astrometrie position determination

• Continue development of an interface between the Mark 4 correlator output and the imaging

software

• Establish a new web site devoted exclusively to the Analysis Center for Source Structure

6. Relevant Publications

Analysis Center products of relevance which are currently available can be found in the scientific

literature, e.g.:

• "VLBA Observations of Radio Reference Frame Sources. I.," Astrophysical ,Journal Supplement Series, August 1996 issue (Vol. 105, No. 2, Pages 299-330).

• "VLBA Observations of Radio Reference Frame Sources. II. Astrometric Suitability Based

on Observed Structure," Astrophysical Journal Supplement Series, July 1997 issue (Vol. 111,

No. 1, Pages 95-142).

• "The Proper Motion of 4C 39.25," Astronomical Journal, December 1997, (Vol. 114, No. 6,

Pages 2284-2291).

• "Geodetic VLBI Observations of EGRET Blazars," Astrophysical Journal November 1998,

(Vol. 507, No. 2, Pages 706-725).

• "VLBA Observations of Radio Reference Frame Sources. III. Astrometric Suitability of an

Additional 225 Sources," Astrophysical Journal Supplement Series, May 2000 (Vol. 128, No

1, Pages 17-83).

2000 IVS Annual Report 255

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Canadian VLBI Technology Development Center

Canadian VLBI Technology Development Center

i'ISyne C_m_om Calvin Klatt

Abstract

The Canadian VLBI Technology Development Center has been active in a number of areas during

the 22 month reporting period.

The $2 Geodetic VLBI program continues to make significant advances on many fronts, including development of the frequency switched $2 VLBI data acquisition system, enhancement of the $2

correlator capabilities to process frequency switched VLBI observations, utilization of a transportable

antenna and the expansion of capabilities for scheduling, data processing and analysis. A number of

experiments have been conducted using the Algonquin, _llowknife and the Canadian Transportable

VLBI Antenna (CTVA).

The next-generation, $3, VLBI system continues to be under active development at the Space

GeodynaJnics Laboratory. It is capable of 1 Gbit/sec recording with unattended record times as long

as 160 hours (depending on system configuration) using robotic tape changers.

1. Introduction

The Canadian VLBI Technology Development Center is a collaborative effort of the Space Geodynamics Laboratory of the Center for Research in Earth and Space Technology, (SGL/CRESTech),

the Geodetic Survey Division of Natural Resources Canada (GSD/NRCan) and the Dominion Radio Astrophysical Observatory (DRAO) of the Herzberg Institute for Astrophysics of the National

Research Council of Canada, (DRAO/HIA/NRC).

2. $2 VLBI Geodesy

Introduction

The Canadian $2 geodetic VLBI program is developing a complete "end-to-end" geodetic VLBI

system and operational capability. This effort involves a wide range of activities including development of the frequency switched $2 VLBI data acquisition system, enhancement of the $2 corrclator

capabilities to process frequency switched VLBI observations, utilization of a transportable antenna

and the expansion of capabilities for scheduling, data processing and analysis.

$2 VLBI Data Acquisition System (S2-DAS)

The $2 VLBI data acquisition system is being jointly developed by SGL and the GSD. The S2-

DAS is designed to accomodate up to four VLBA/MkIV-type single sideband baseband converters

(BBCs), each with a local oscillator (LO) independently frequency switchable under computer

control. The objective of the development of the S2-DAS is to enable high sensitivity group delay

measurements without appealing to a more costly parallel IF/baseband sub-system.

There are currently four $2 DASs in use. An additional three are in production: two for GSD

and one for BKG. These should be available for operational testing within the first half of 2001.

The DAS Operating System (DASOS) has seen extensive development in the past 22 months.

Much effort has gone into frequency switching with automatic gain control (1999) and automated

self tests (2000). The official release of DASOS is t)lanned to occur in April 2001.

2000 IVS Annual Report 259
Canadian VLBI Technology Development Center York University/Space Geodynamics Laboratory/CRESTech

DAS-PCFS communication requirements are being established. Development of a station wavefront clock model is also underway.

$2 VLBI Correlator

The Canadian $2 Corrclator is a six station correlator using $2 playback terminals and is

designed to handle $2 frequency switched bandwidth synthesis data. Recent activity has focussed

on the deveh)pment of post processing software to enhance system performance monitoring.

Canadian Transportable VLBI Antenna (CTVA)

The CTVA is a 3.61n radio telescope acquired to facilitate densification of the terrestrial reference fi'ame in remote regions. The antenna will be colocated with GPS elements of the Canadian

Active Control System (CACS) to provide fiducial station positions. The GSD is responsible for

CTVA system development.

Since 1997 the antenna has t)een located at DRAO near Penticton, B.C. Recent work focusses

on antenna sensitivity and system stability and reliability. Extensive testing through CGLBI ($2)

experiments has occurred. We anticipate that the antenna will be moved to a new site in 2001.

$2 Geodetic Ezperiment Scheduling, Operations and Analysis

The Canadian Geodetic VLBI program involves all aspects of Geodetic VLBI operations, from

experiment design through analysis. Anthony Searle has recently joined the GSD VLBt group. He

has taken on many scheduling and analysis tasks and has assisted with experiment operations.

The CGLBI experiment scheduling was improved as a result of the introduction of $2 support in

the SKED software. The CGLBI scheduling (and drudging) process is at)proaching full automation

through use of scripts. The analysis software was updated to f-SOLVE and we have both CALC

8.2 and 9.1 available. Minor software changes to SOLVE remain necessary for CGLBI data to

l)e analyzed. Software to create Mk3-type databases from ($2) frequency-switched experiments

(CGLBIDB) was written and has been used on a regular basis.

A number of $2 VLBI experiments have taken place in the reporting period (see below). A

significant amount of simulation work (using SKED and SOLVE) has taken place to investigate the

system performance and possible filture directions ($2 CORE?) for S2-based geodesy. An investigation into multi-beam VLBI (several small antemlas co-observing with large ones) is underway.

The GSD has produced a CGLBI website which is regularly updated to reflect experiment

activity (www.vlt)i.ca). An analysis web site was created as a contribution to the IVS. This

website documents SOLVE: f-SOLVE is documented elsewhere.

Interferometric Experiments

In the reporting period 23 developmental experiments (CG006/June 1999 through CG028/

December 2000) have been performed using the $2 VLBI system, ALGOPARK and the CTVA.

Of these, 17 were 24-hour geodetic experiments and the remainder were system tests. Yellowknife

participated in 10 of these experiments, 6 being 24-hour geodetic.

Fringes have bccn obtained in each $2 interferometric experiment. The measured baseline

length between ALGOPARK aim PENTICTN using the $2 system ha_s been repeatable within 1

cnl.

260 2000 IVS Annual Report
"fork University/Space Geod)'namics Laboratory/CRESTech Canadian VLBI Technology Development Center

65O

64.0

E 630

oo

o

04

620

o

610

600

ALGOPARK-CTVADRAO Basehne Length $2 VLgl Results

i

CGLBI Da_a

i ,

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590 I h I L L i

200 300 400 500 600 700

Days since Jan 1 lgg9

i

Figure 1. Penticton - Algonquin $2 Baseline Length Measurements

3. $3 Wide Bandwidth VLBI Data Record/Playback System Development

VLBI applications to geodesy and astrophysics can benefit fronl higher signal to noise ratio

observations. The most attractive means of achieving large factor improvements in SNR in geodetic VLBI observations is by developing wide bandwidth VLBI data record/playback/correlation

systems.

Tim Space Geodynamics Laboratory (SGL) located on the campus of York University in

Toronto, Canada is developing a family of wide bandwidth VLBI data record/playback systems

designated "$3", as a next generation follow-on to the "$2".

The $2 VLBI data record/playback system is a 128 Mbit/sec, Mostly-Off-The-Shelf (MOTS)

VLBI data record/playback system t)a_sed on an array of eight video tape transports together with

custom designed signal channel cards and a single board control computer housed in a standard

VME enclosure. The $2 is specified to operate without error correction coding at a Bit Error Rate

(BER) of the order of 10-4; however typical BER performance in the $2 is of the order of 10 -5.

The extensive use of MOTS hardware in the $2 design resulted in a tow cost, high performance,

VLBI data record/playback system of which more than 50 have been fabricated at SGL and are

now in use in a variety of radio astronomy and VLBI applications in more than a dozen countries

around the world.

The $3 VLBI data record/t)layback system is the next generation MOTS VLBI system. It has

inherited a significant amount of its architecture fl'om the $2 although the VME backplane has

been replaced with a wide bandwidth Compact PCI backplane. In addition the interface for the

$3 will be compatible with the VLBI Standard Interface (VSI) specification. The $3 is constructed

as an array of eight JVC "Digital-S" (now designated "D9") digital video tape transports, each of

which is able to record/playback VLBI data at a rate of 150 Mbit/sec, of which 128 Mbit/sec is

"user data", for an overall user data rate of 1024 Mbit/sec (1 Gbit/sec). Recent $3 system tests

2000 IVS Annual Report 261
CanadianVLBITechnology Develol)ment Center YorkUniversity/Space Geodynamics Laboratory/CRESTech

at SGL in which pseudorandom digital data was written to and read from the $3 tape transport

indicate that ttle signal to noise ratio on the $3 eye pattern is comparable to that of the $2. The

$3 is expected to provide a BER performance that is comparable to the $2.

The tape change interval for the $3 tape array is 2.5 hours at a data rate of 1024 Mbit/sec (1

Gbit/sec) with longer tape change intervals being possible when operating the $3 at reduced data

rates. Tile cost of recording media for the $3 is expected to be $150 (US) per hour at a data rate

of 1024 Mbit/sec (1 Gbit/sec).

Tile $3 VLBI data record/playback system is designed for systein upgrades based on the

recently introduced JVC High Definition TV "D9-HD" tape transport, which in the $3 context

will record/playback VLBI data at a rate of 300 Mbit/sec. The D9-HD will enable the fabrication

of the "Compact" version of the $3 system, the "$3-C", which will record/playback VLBI data at

a rate of 1024 Mbit/see (1 Gbit/sec) on a compact array of only four tape transports.

The D9-HD will also enable the fabrication of the "Extended" version of the $3 system, the

"S3-E", which will record/playback VLBI data at a rate of 2048 Mbit/see (2 Gbit/sec) on an array

of eight tape transports. Dual operation of the S3-E will provide for VLBI data record/playback

at data rates as high as 4096 Mbit/sec (4 Gbit/sec).

SGL has implemented a TiltRac robotic tape changer for the $3 family of VLBI data

record/playback systems. The tape changer is u true Commercial-Off-The-Shelf (COTS) system developed especially for use with the JVC D9 and D9-HD tape transports. The robotic tape

changer is available in single-bay, dual-bay, and triple-bay configurations. SGL ha_ implemented

a dual-bay configuration in its development system. The robotic tape changer provides the option

of long unattended operation intervals with the $3 family of VLBI data record/playback systems.

Unattended Operation (Hrs)

System Data Tape Single Double _iple

Config Rate Duration Bay Bay Bay

(Mbps) (Hrs) Robot Robot Robot

$3

$3-C

S3-E

1024 2.5 65 130

512 5 130 260

256 10 260 520

128 20 520 1040

1024 1.25 32.5 97.5 162.5

512 2.5 65 195 325

256 5 130 390 650

2048 1.25 32.5 65

1024 2.5 65 130

512 5 130 260

256 10 260 520

Dual 4096 1.25 32.5 65

S3-E 2048 2.5 65 130

1024 5 130 260

512 10 260 520

Table 1. $3 Tape Durations and Unattended Operating Times with Robotic Tape Changer

262 2000 IVS Annual Report
Kashima Space Research Center, Communications Research Laboratory Technology Development Center at CRL

Technology Development Center at CRL

Tetsuro Kondo

Abstract

Communications Research Laboratory (CRL) has led the development of the VLBI technique in

Japan and has been keeping high activities in both observations and technical developments. This

report gives a review of the Technology Development Center (TDC) at CRL and summarizes recent

activities.

1. Introduction

Communications Research Laboratory (CRL) has been leading the development of the VLBI

system in Japan since the development of the K3 VLBI system in 1979 which is compatible with

the Mark III VLBI system developed by the US group. CRL then developed the K4 VLBI system,

which facilitated ease in both operation and transportation. In October 1990, the International

Earth Rotation Service (IERS) designated the Communications Research Laboratory (CRL) and

Haystack Observatory (in the United States) as Technical Development Centers (TDC). In September 1996, the IERS directing board designated CRL as TDC again. The function of the IERS VLBI

Technical Development Center was taken over by the IVS Technology Development Center after

its establishment on March 1, 1999. Since then CRL has participated in IVS as one of its Technology Development Centers. The CRL-TDC newsletter is published biannually to inform the VLBI

community of its current activities. The newsletter is also available through the Internet at the

following URL http://www.crl.go.jp/ka/radioastro/tdc/index.html.

2. Recent Activities

2.1. Real-Time VLBI

The Keystone (KSP) real-time VLBI [1] system observed extraordinary crustal deformation of

over 2 cm/month on the Kashima-Tateyama baseline during July-August 2000 (Fig.l). It occurred

just after the volcanic eruption event at Miyake Island about 150 km south of Tokyo at the end of

June. To provide data to the Headquarters for Earthquake Research Promotion more frequently,

we changed a 24-hour session frequency from every two days to every day. Every-day observation

continued till November when the crustal deformation seemed to be well settled. During this

period we had no technical problems in real-time VLBI operation. Although it was planned to

terminate the Keystone project at the end of March, 2001, it was decided from the importance of

KSP observation to extend the term of the project for one more year with three stations, Kashima,

Koganei, and Tateyama.

This real-time VLBI technique is also used to connect a 64-m antenna at USUDA and a

34-m antenna at Kashima so as to realize a large virtual radio telescope. A test observation

was successfully carried out in December 1998, then this project was named GALAXY and has

carried out radio astronomical observations once every several months. The GALAXY has been

carried out in collaboration with the Institute of Space and Astronautical Science (ISAS), National

Astronomical Observatory (NAO), and Nippon Telegraph and Telephone Corporation (NTT)[2].

2000 IVS Annual Report 263
Technology Development Center at CRL Kashima Space Research Center, Communications Research Laboratory

#%

Figure 1. Kashima-Tateyama baseline length

change. Extraordinary crustal deformation over

2 cm/month was observed during July-August

2000.

Figure 2. PCI sampler board for tile IPVLBI system.

In the KSP real-time VLBI system, data axe transmitted through the high-speed ATM network.

However, network cost is still expensive and connection sites are still limited, so that ATM-VLBI

is not yet well generalized. We therefore aimed to develop a new real-time VLBI system using

IP (Internet protocol) technology that has already spread widely, to reduce network cost and to

expand the connection sites of network. We call this system "IP-VLBI" or "VLBI over IP", and

started the development in late 1999. We have been developing the PC-based IP-VLBI system

consisting of a PCI-bus sampler board (Fig.2) and PC software to make real-time data transmission

and reception. We also intend to carry out real-time correlation by PC software. One sampler

board has 4 video signal inputs and is designed to be able to sample each signal with a frequency of

up to 16 MHz for 1 bit A/D. The sampler board has been tested by using actual signals from radio

sources. Real-time characteristics have been evaluated by using the LAN at the Kashima Space

Research Center. So far we can confirm the sufficient performance of "coherent sampling" up to

8 MHz sampling. Although the performance of 16 MHz sampling has not yet been confirmed, it

will be checked soon. Regarding the "real-time correlation processing" by using PC software, we

can process 2 MHz sampling data in real-time at present time. An improvement in the algorithm

to make correlation processing faster is in progress[3].

2.2. Giga-bit VLBI System

The developments of the giga-bit VLBI system at the Communications Research Laboratory started in 1996. The system consists of the A/D sampler unit (TDS580D/TDS784A), the

recorder system (GBR1000), the correlator (GICO), sampler interface unit, the timing control unit

(DRA1000), and the data buffer unit (DRA2000). In 1998, first fringes were successfully detected

on the Kashima-Koganei baseline using this system.

During 1999 - 2000, four geodetic VLBI experiments were performed using the giga-bit VLBI

system. Two of them are on the Kashima-Koganei baseline and others axe on the Kashima-Gifu

baseline (about 360 km). In each experiment, observations were performed with K4 VLBI system

in parallel to compare the results. As the sampling frequency of giga-bit system (1024MHz) is

much higher than that of K4 system (16 MHz), performance of the giga-bit system is influenced by

the stability of the sampling frequency. By developing a inethod to compensate for the sampling

264 2000 IVS Annual Report
Kashima Space Research Center, Communications Research Laboratory Technology Development Center at CRL

jitter using a superimposed tone signal, data quality and estimation errors have been improved to

a level comparable to the K4 VLBI system [4].

A new compact VSI Gbps sampler, ADS-1000, has been developed. A design of ADS-1000

started to provide a simple portable Gbps sampler. Antenna front-end mounted with AD samplers

will eliminate long analog transmission in near future. Although, the current AD packages weigh

50 kg and occupy 6U in the system, the ADS-1000 weigh less than 10 kg and occupies 1/2U

(Fig.3). Sampling jitter is expected to be reduced by using a high purity-sampling signal which

is directly supplied from a PLO. As a remarkable feature, the sampler output is VSI-H (VLBI

Standard Hardware Interface) compatible. According to the endorsed document VSI-H proposal,

LVDS devices have been examined and this is CRL's first VSI-H instrument. The ADS-1000

is manufactured by DigitalLink Co.Ltd. and Venetex corporation. They are venture companies

which are distinguished by advanced digital technology [5].

Derr_st_c h Kashima

I DRAZ_

Oversea _ Domestc. C

ReaJtlme Station

Figure 3. ADS-1000, the new compact VSI Gbps sampler under test.Figure 4. Proposed Gbit VLBI system enhaJlcement

for the global baseline.

2.3. VLBI Standard Interface

CRL TDC has been contributing to the establishment of the VLBI standard interface (VSI)

with Dr. Alan R. Whitney, Technology Coordinator of IVS. We had international telephone conferences several times to discuss VSI and reached the agreed specification of VSI hardware (VSI-H).

VSI-H Vet1.0 was opened to public in August, 2000. It can be accessed through the VSI homepage

(http://dopey.haystack.edu/vsi/) or Japanese VSI homepage (http://www2.crl.go.jp/

ka/radioastro/tdc/ivs/vsi/).

We are adapting VSI-H to $2-K4 copying system and VSI-based K4 data acquisition system.

One of the motivations was the request for a $2-K4 data copying system. Antarctica VLBI data

observed in 1997-1999 and Pulsar VLBI observation data are recorded on an $2 system. These

data axe desired to be correlated with K4-type (K4, KSP) correlators because of easiness to handle

it in Japan. Also $2-K4 copier will expand the ability of organizing VLBI network observation [6].

Late 2000 supplementary budget to make upgrade of the giga-bit VLBI system was approved.

The importance of the parallel data transmission is recognized again in the VSI-H, while IT

technology promoted high-speed serial transmission by IP. All the VLBI instruments in the Gbps

system developed by CRL will adopt VSI-H. We also intend to encourage the application of the

VSI interface to a wide scientific use through the demonstration that will be made using the

2000 IVS Annual Report 265
Technology Development Center at CRL Kashima Space Research Center, Communications Research Laboratory

upgraded giga-bit VLBI system. Preliminary plan of the enhanced Gbit VLBI system is shown

in Fig.4. Upgraded Gbit data recorders are introduced and new Gbit samplers, ADS-1000 are

disposed to each station. The number of the Gbit recorders is doubled and this will increase

Gbps observation sites. As well as K4 and/or KSP system, a robot tape exchanger is being

designed for automatic observation. While the experimental correlator UWBC-GICO will continue

its operation, a new multi-baseline Gbit correlator equipped with VSI-H ports will start operation.

The correlator system of the CRL-TDC is promised to open in the other VLBI groups and new

countries. Technical supports and VSI related supplies are also planned [7].

3. Future Perspectives

CRL TDC will continue to make efforts to develop new technologies introduced in this report

and to apply them to actual observations. In particular, we will demonstrate VSI-H instruments

as soon as possible. We also continue the development of the "Internet VLBI" system which is

the succession of the current real-time VLBI technique but aims at realizing more economical

(lower running cost) and flexible connections between VLBI stations by using the Next Generation

Internet (NGI).

References

[1] Kiuchi, H., M. Imae, T. Kondo, M. Sekido, S. Hama, T. Hoshino, H. Uose, and T. Yamamoto, RealTime VLBI System Using ATM Network, IEEE Trans. Geosci. Remote Sensing, Vol.38, No.3, 1290-

1297,2000.

[2] Takahashi, Y., H. Kiuchi, A. Kaneko, S. Hama, J. Nakajima, N. Kurihara, T. Yoshino, T. Kondo,

Y. Koyama, M. Sekido, J. Amagai, K. Sebata, N. Kawaguchi, H. Kobayashi, M. Iguchi, T. Miyaji,

H. Uose, and T. Hoshino, The plan of the big virtual telescope using the high speed communications

network, Technical Development Center News CRL, No.13, 17-19, 1998.

[3] Kondo, T, Y. Koyama, M. Sekido, J. Nakajima, H. Okubo, H. Osaki, S. Nakagawa, and Y. Ichikawa,

Development of the new real-time VLBI technique using the Internet Protocol, Technical Development

Center News CRL, No.17, 22-24, 2000.

[4] Koyama, Y., J. Nakajima, M. Sekido, and T. Kondo, Geodetic VLBI experiments using giga-bit VLBI

system, Technical Development Center News CRL, No.17, 15-17, 2000.

[5] Nakajima, J., M. Sekido, and T. Suzuyama, Another giga-bit sampler prototype, nearly completion;

ADS-1000 development status, Technical Development Center News CRL, No.17, 18, 2000.

[6] Sekido, M., J. Nakajima, Y. Koyama, T. Suzuyama, and T. Kondo, Development of VSI-based $2-K4

copying system and data sampler, Technical Development Center News CRL, No.17, 19-21, 2000.

[7] Nakajima, J., Y. Koyama, M. Sekido, R. Ichikawa, and T. Kondo, Approved upgrade of the Gbit VLBI

system expansion, Technical Development Center News CRL, No.17, 25, 2000.

266 2000 IVS Annual Report
' " " 55577

5dForsvarets forskningsinstitutt (FFI) (Norwegian Defence Research Establishment) FFI Tech. Development Center

Combination of VLBI, GPS and SLR Software Development at

FFI

Per Helge Andersen

Abstract

FFI's contribution to the IVS as a Technology Development Center will focus primarily on the

development and validation of the GEOSAT software for a combined analysis at the observation level

of data from VLBI, GPS and SLR. This report briefly summarises the latest improvements of the

GEOSAT software. FFI is currently Analysis Center for IVS and ILRS, Technology Development

Center for IVS, and Combination Research Center for IERS.

1. The GEOSAT software

The advantages of the combination of independent and complementary space geodetic data at

the observation level is discussed in Andersen ([1]). The models of GEOSAT are listed in Andersen

([2]). Recent changes are described in the following.

The GEOSAT software has recently extended the analysis capability from 30 to 60 GPS stations

per day. In addition, a new procedure for the generation of a priori GPS orbits for the filter has

been implemented. A three day IGS precise orbit for each GPS satellite is used as observations for

the determination of a GEOSAT-generated GPS orbit. In this fit six orbital elements in addition to

nine solar radiation pressure (SRP) parameters are solved for. The rms of residual fit for the threeday orbital dataset is typically between 2 and 4 cm for all satellites except for 2-4 satellites where

the rms is significantly larger. The estimated orbit is used to generate a priori observation residuals

and observation partial derivatives to be used in the filter where all data types are combined. In

the 24 hour filter solution the nine-parameter SRP model are kept fixed and only the six orbital

elements and one SRP-scaling parameter and a Y-bias parameter are solved for. In this way the

one-day orbits will be based on a very realistic SRP model. However, for satellites with large rms

of orbital fit two additional stochastic velocity change parameters are solved for. Experiments

with the IGS precise orbits show that this parameterization is sufficient in order to fit a 24 hour

GEOSAT-generated GPS orbit for all satellites including the outlier satellites with an rms of 2-3

cm in each coordinate. A significant part of the 2-3 cm difference is due to the use of inconsistent

values for the EOPs. EOP values are taken from IERS and not the IGS EOP estimates to be used

with the precise IGS orbits. In conclusion, a highly sophisticated GPS orbit strategy has been

established. The use of a large number of GPS stations in combination with a moderate number

of dynamical solve-for parameters and a realistic dynamical model is expected to result in GPS

orbits with a precision level of a few cm in each coordinate.

It is a fact that the position of the effective phase center of the transmitter antenna of the

GPS satellites is not very well known. This leads to a scale inconsistency with VLBI and SLR of

approximately 2 ppb. It is therefore a standard procedure in analysis with GEOSAT to estimate

the z-coordinate of the mean position of the transmitter phase center. With GPS-data alone it is

only possible to determine the phase center position relative to the position of the phase center

of a reference satellite. Since the GPS data in our case are combined with VLBI and SLR data

absolute positions of the phase center of all satellites can be determined.

2000 IVS Annual Report 267
FFI Tech. Development Center Forsvarets forskningsinstitutt (FFI) (Norwegian Defence Research Establishment)

Another possible candidate for scale inconsistency between the different techniques is the tropospheric mapping function. In order to be consistent with VLBI and GPS the SLR data are

analyzed with the use of the dry NMF mapping function which is used for VLBI and GPS. The

signal delay in the zenith direction is however calculated using the Marini-Murray model. This

procedure is in accordance with recent recommendations given by Richard Eanes. A model for

tidal geocenter motion is implemented (Watkins and Eanes, [3]).

In GEOSAT data from the different techniques are combined in batches of one day which is

called an arc. The state vectors and complete variance-covariance matrices from the analyses of a

number of independent arcs of space geodetic data can be combined using the CSRIFS (Combined

Square Root Information Filter and Smoother) program. Four parameter levels are available and

any parameter can, at each level, either be represented as a constant or a stochastic parameter

(white noise, colored noise, or random walk). The batch length (i.e. the time interval between the

addition of noise to the SRIF array) can be made time- and parameter dependent. More details

can be found in Andersen ([1]).

2. Prospects

Two new programs in the GEOSAT system are under development. The IERS program will

transform the output from internal reference frames in GEOSAT to the external reference frames

of the IERS. Also the final combined covariance matrix of CSRIFS will be rotated. The SINEX

program will write the global solution in the SINEX format.

Statens kartverk has recently received a copy of the GEOSAT software.

The GEOSAT software will be converted to PC/LINUX in the near future.

3. Technical Staff

Table 1 lists the FFI staff involved in IVS activities.

Table 1. Staff working at the FFI AC and TDC

I Name t Background ] Dedication I Agency ]

I Per Helge Andersen I geodesy l 40% I FFI ]

References

[1] Andersen, P. H. Multi-level arc combination with stochastic parameters. Journal of Geodesy (2000) 74:

531-551.

[2] Andersen, P. H. High-precision station positioning and satellite orbit determination. PhD Thesis,

NDRE/Publication 95/01094.

[3] Watkins M., Eanes R. Observations of tidally coherent diurnal and semidiurnal variations in the geocenter. Geophysical Research Letters, Vol. 24, No. 17, 2231-2234, Sep 1, 1997.

268 2000 IVS Annual Report
NASAGoddardSpaceFlightCenter

/

l

GSFC Technology Development Center

:!

GSFC IVS Technology Development Center Report

Ed Himwich, Nancy Vandenberg, Tom Clark

Abstract

This report summarizes the activities of the GSFC IVS Technology Development Center from the

establishment of IVS to the end of 2000. The report forecasts activities planned for the year 2001.

The GSFC IVS Technology Development Center (TDC) develops station software including the Field

System (FS), scheduling software (SKED), hardware including tools for station timing and meteorology,

scheduling algorithms, operational procedures, and provides a pool of individuals to assist with station

implementation, check-out, upgrades, and training.

1. Technology Development Center Operation

The GSFC IVS Technology Development Center (TDC) develops hardware, software, algorithms, and operational procedures. It provides manpower for station visits for training and upgrades. There are other techology development areas at GSFC covered by other IVS components

such as the GSFC Analysis Center.

The current staff of the GSFC TDC consists of Tom Clark, Nancy Vandenberg, Ed Himwich,

Chuck Kodak, Raymond Gonzalez, and William Wildes.

The remainder of this report covers the status of the main areas of development that are

currently being pursued.

2. Field System

During this period two major new features were released: Y2K support and mode independent

parity checks. Y2K support was of course necessary for continued operation of the FS in the year

2000 and beyond. Mode independent parity checks removed the need for stations to change parity

check procedures for every experiment that used a different mode than the previous experiment.

In addition several new features under development during this period will be released in the

next major release, 9.5. Some of the features included are: (1) Support for K4 systems, (2) support

for sequential use of two longitudinal tape recorders, (3) better handling of default values for Mark

III/IV IF attenuators, (4) a utility "msg" for sending Ready, Start, and End messages for geodetic

sessions, (5) support for report logging maser offset data from a TAC, (6) support for NTP, (7) a

command, "ifadjust" to automate determining the IF attenuator settings for a given mode, (8) an

experimental tool for monitoring FS operation remotely, ARTS, (9) a command, "tnx" to disable

reporting of an error message that can't be fixed, and (10) an experimental program, "erchk" to

display only error messages to make it easier for the operator to keep track of them. This release

is expected in the first quarter of 2001.

In the following FS release, 9.6, several other improvements are expected; among these axe:

(1) dual head recording for Mark IV and VLBA4, (2) support for the new Mark IV firmware,

(3) onsource flagging formatted in AIPS flagging file format, (4) improved Tsys measurements

with automatically generated procedure files, frequency dependent noise diode temperatures, and

ANTTAB file format output, (5) faster set-up when the formatter set-up doesn't change between

scans. The release is expected the third quarter of 2001.

2000 IVS Annual Report 269
GSFC Technology Development Center NASA Goddard Space Flight Center

3. SKED and DRUDG

The GSFC Technology Development Center is responsible for development, maintenance, and

documentation of the SKED and DRUDG programs. These two programs operate as a pair for

preparation of the detailed observing schedule for a VLBI session and its proper execution in the

field. During 2000 SKED was enhanced to add new user interface features, the ability to write

VEX files, and K4 and $2 scheduling support. Some bugs remain to be worked out before official

release of the new SKED version. Meanwhile users are testing and using the available version.

• A Java-based user interface was added to SKED by Kristian Refinetti, a Chalmers University

engineering student on a trainee program sponsored by NVI/GSFC. The SKED catalog files

can now be accessed with a set of screens that make selection of sources, stations, observing

modes, and scheduling parameters more powerful and flexible.

• New SKED commands to generate a VEX file from the schedule file were added. The VEX

file is required as input to the Mark IV correlators. The native SKED format is still the

standard schedule file format and the VEX file is only an output format.

• Scheduling support for K4 and $2 systems was added to SKED so that geodetic schedules

could be easily generated for these recording systems. Displays of tape usage and tape speed

arc handled in the native units for each system.

4. VLBI Timing

At Goddard, we have continued to stress the development of high accuracy (,_20 nsec for each

day) GPS-based timing measurements at VLBI stations; this data is needed for several reasons:

• Correlator efficiency is improved significantly if the relative station clocks are known at the

--,50 nsec level and clock drift rates are known at levels _1:1013.

• To produce accurate UT1 measurements, station clocks need to be tied to UTC(USNO) to

a few hundred nsec.

• Discontinuities seen in timing data are an excellent diagnostic of performance problems in

hydrogen masers.

After much discussion we decided that the ideal timing system for VLBI stations would

• Run continuously, logging data between experiments,

• Be easily reproducible at all stations and be low cost,

• Produce daily timing accuracy of 20-30 nsec anywhere in the world.

Our R&D testing beginning in 1993 showed that we could meet the accuracy goal with a

particular low-cost GPS receiver (the Motorola PVT-6) and by 1995, we distributed ,,_50 timing clocks for the community - for humorous reasons, these receivers were named the TAC -

Totally Accurate Clock. The historical archives of the early TAC development are available

at ftp://aleph.gsfc.nasa.gov/GPS/totally.accurate.clock. The current software package, called

TAC32Plus is a VLBI "plug in". Some of the VLBI features are depicted in the final figure

of this report ("Recommended Clock and Timing Setup for a Mark4 VLBI Station") and include:

270 2000 IVS Annual Report
NASA Goddard Space Flight Center GSFC Technology Development Center

• Full-time logging of Time Interval Counter (TIC) data to disk in a "friendly" format,

• Automatic application of corrections for quantization dither (amounting to 104 nsec peakto-peak with the ONCORE) inherent in the GPS receivers,

• Providing smoothed TIC data to the VLBI system via a TELNET socket,

• Providing station-wide network computer synchronization using NTP,

• Access to timing data via FTP for remote maintenance and diagnostics.

• Full support for TIC+TAC+TAC32Plus system is included in the LINUX PC Field System.

Before May 2000, timing performance was limited by the U.S. Dept. of Defense through a

process called Selective Availability (SA). With SA, the atomic clock onboard each GPS satellite

was "diddled" with a pseudo-random code that spoiled the spectral purity of GPS timing signal in

the range from a few seconds to ,-,1/2 hour. With the TAC, we provided some mitigation against

SA by averaging the timing over all satellites in view, and by averaging timing over many minutes

in the time domain. With this process, the ONCORE-based TACs routinely yield timing smooth

at the 15-20 nsec level at all times from minutes to a day. After May 2nd when SA was turned off,

the short-term stability, as judged by taking the RMS noise of all samples in a 5 minute window,

improved from -_15 nsec to _5 nsec. The dominant error source suddenly became the diurnal

signature of the ionosphere, amounting to ,,_15 nsec peak-to-peak.

Data was logged during a 9 week period at the end of 2000 with an ONCORE receiver and the

data system described above logging the H-Maser at GGAO in Greenbelt. The Maser had a rate

offset of ,-_20 nsec/day (a frequency error of ,_2.4 x 10-13). On Nov.22, the drift rate was observed

to increase, which was subsequently traced to a temperature change at the H-Maser chamber. A figure demonstrating this is available at ftp://aleph.gsfc.nasa.gov/ivscc/annual_report/2OOO/oncoreggao.ps.

In late 1999, Motorola announced that they were discontinuing the ONCORE VP receiver that had been used in the TAC-2 and CNS GPS clocks. We began to work with a

software developer who had made an excellent timing receiver based on the SiRF-1 chipset.

Where the ONCORE VP shows --_4 nsec noise in the 5 minute samples, the SiRF prototype

shows ,_650 psec of noise, a factor ,,,5 better. A figure demonstrating this is available at

ftp :/ / aleph.gsfc.nasa.gov / ivscc / annual_report / 2OOO/ sirf*ggao.ps.

A paper on these receiver developments was presented at the Sept.2000 ION meeting (T.Clark,

R.Hambly and R.Abtahi "Low Cost, High Accuracy GPS Timing", Proceedings of Institute of

Navigation GPS 2000, Salt Lake City, pp.905-913 (2000)) and copies are available on http://

www.gpstime.com.

5. New Meteorological Sensors

GSFC has investigated new meteorological sensors to replace the aging standard CDP-era

sensors in use at many sites. We are planning to provide FS support for the following devices:

MET-3A Meteorological Sensor Part #1539-001 and Handar 425 Ultrasonic Wind Sensor (Model

425A/AH) both available from Paroscientific at http://www.paroscientific.com. We expect to

install these at NASA supported sites within the next year.

2000 IVS Annual Report 271
GSFC Technology Development Center NASA Goddard Space Flight Center

dlldOJ- S,NOIJ.V.LS

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272 2000 IVS Annual Report
z/ /

MIT Haystack Observatory

Z ...S2,S 7!,2

Haystack Observatory Technology Development Center

Haystack Observatory Technology Development Center

Alan Whitney

Abstract

Current work in VLBI technology at Haystack Observatory includes further development of the

Mark IV correlator system, plus a new initiative to develop a low-cost high-performance Mark V VLBI

record/playback system, that will utilize mostly commercial-off-the-shelf (COTS) technology and most

likely incorporate magnetic discs as the storage media.

1. Mark IV Correlator

Mark IV correlators have been operational at USNO, MPI, JIVE and Haystack for about a year

and have now completely replaced the Mark IIIA correlators. Haystack Observatory maintains the

software for the USNO, MPI and Haystack installations.

Before the changeover from the Mark IIIA correlators to the Mark IV correlators, extensive

cross comparison tests were done to ensure that the Mark IV results were of the highest integrity.

In fact, the first published results from the Mark IV correlators occurred less than 2 months after

the changeover from the Mark IIIA correlator.

The Mark IV correlator software has been continuously improved over the past year to include

new operational capabilities and efficiency improvements, and all Mark IV correlators are now

operating at an efficiency exceeding that of the Mark IIIA, with still more improvements to be

made. Some of the features that are now supported are:

• Processing of Mark IIIA, Mark IV and VLBA tape formats

• GUI control interface

• Simultaneous auto and cross-correlation

• Support for 1 and 2-bit samples

• Full phase-cal extraction

• Bar-code-driven tape library

• Transparent file-version control

• Full configuration specified by a set of VEX-format files

• HOPS post-correlation package

Soon to be implemented will be:

• Multiple-stream processing (multiple simultaneous independent scans)

• Faster tape synchronization

• 'Double-speed' tape playback, followed by 'qudruple-speed' tape playback

2000 IVS Annual Report 273
Haystack Observatory Technology Development Center MIT Haystack Observatory

2. Mark V VLBI Data System Development

With support from NASA, JIVE and NRAO, Haystack Observatory is now developing the

Mark V VLBI record/playback system based on the requirements for the next generation of VLBI

systems:

• Minimum of 1 Gb/sec data rate

• Economically upgradeable/expandable to ,-_ 8 Gb/sec over the coming decade

• Design based primarily on unmodified off-the-shelf subsystems and components

• Modular, easily upgradeable as better/cheaper technology becomes available

• Robust operation, low maintenance cost

• Easy transportability

• Conformance to VLBI Standard Interface (VSI) specification

• Flexibility to support electronic transfer ('e-VLBI') and computer processing of recorded

data

• Minimum of 24-hour unattended operation at 1 Gb/sec

Though this list of goals may appear idealistic, we believe they can be achieved in a system which

can be designed today, and which will evolve in the following years to even higher data rates and

additional storage capacity with minimal additional engineering effort.

2.1. Magnetic discs on the way to surpassing tape

Though both magnetic disc technology and magnetic tape technology have made great strides

over the past few years, the pace of magnetic disc development has been so great that it is very

likely that disc storage will become cheaper than magnetic tape storage by ,-_ 2004. This trend can

be clearly seen in Figure 1, where the $/GB for both disc drives and magnetic tape media (including

projections for LTO tape media, which we focused on in the original COTS concept proposal) are

plotted as a function of time. In addition are shown two 1998 projections for disc- storage costs_

one from IBM and the other from the National Storage Industry Consortium (NSIC); the latter

suggests a tape-to-disc crossover in the latter part of this decade. However, it is clear that the

cost decreases of magnetic disc storage have dramatically accelerated over the past two years, far

exceeding industry projections of only 3 years ago, and show no signs of ceasing. Current disc

industry predictions suggest that in 2004 the cost per GB will be ,-, $.30 for low-cost 'dimestore'

IDE (aka ATA) drives, but even these predictions may well prove conservative. As you can see

from Figure 1, by _ 2004-5 the cost of disc drive storage is expected to fall below that of magnetic

tape. Magnetic tape industry predictions have historically been pretty much on target and are

expected to continue to be so, provided magnetic tape can even survive in the face of magnetic

disc progress! Furthermore, note that the costs shown in Figure 1 are for complete disc drive units,

while the tape costs are for the magnetic tape media, ignoring the substantial cost of tape drives.

The reason for this happening is quite clear - the flow of money into magnetic disc development

is perhaps two orders of magnitude greater than that for magnetic tape! The disc industry sees no

apparent obstacles to the current breakneck pace of development for at least several more years.

Magnetic disc area-bit-densities on modern discs now (in early 2001) are ,,_ 15 Gb/in 2, and are

274 2000 IVS Annual Report
MIT Haystack Observatory Haystack Observatory Technology Development Center

expected to rise to at least ,,_ 100 Gb/in 2 by 2004. This is even far outstripping optical recording

technology, which appeared to have such a bright future just a few years ago but has not become

a serious competitor to magnetic discs for high-data-rate, high-density storage. We believe the

VLBI community should begin to prepare now for a changeover to magnetic discs, which is the

front-runner technology for the new Haystack Mark V system.

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Figure 1. Disc/Tape Price Comparisons

2.2. The Mark V VLBI Data System

A 'Mark V' VLBI data system based on magnetic disc technology is now being designed at

Haystack Observatory. Based on a standard PC platform with standard commercial busses and

interfaces, it will support a continuous data flow of at least 1 Gb/sec to an array of up to ,,,16

magnetic discs. The only custom hardware will be VSI-H formatter and deformatter interfaces.

Because the Mark V system is based on a standard PC platform, the data stored to discs will

also be available for local analysis by the PC or for transmission over a network for e-VLBI. The

cost of either the 1 Gb/sec Mark V recording or playback system (without discs) is expected to

be <$25K. Multi-Gb/sec systems will be constructed simply by using Mark V systems in parallel,

2000 IVS Annual Report 275
Haystack Observatory Technology Development Center MIT Haystack Observatory

though future versions of the Mark V may have standalone multi-Gb/sec capability. The Mark

V system will be explicitly based on disc drives with IDE interfaces, which axe the most costeffective consumer discs that can be procured. Furthermore, the IDE interface is so pervasive

and so successful that any successful follow-on to magnetic discs, such as (possibly) optical discs,

will almost certainly also be available with IDE interfaces, in which case they can be adapted to

the Mark V system almost seamlessly. It is important to note that the Mark V data system is

only a data recording and playback system and will require the use of a separate set of back-end

electronics (IF converters, BBC's, samplers, etc).

2.3. The 24-hour Challenge

Disc industry expectations are that in 2004 a terabyte disc will be available for ,,_ $300. The

recording of a continuous data rate of 1 Gb/sec for 24 hours will consume ,,_ 11 TB of storage, so

that an array of only ,-_ 12 such discs for a total cost of $3600 will comfortably operate unattended

at 1 Gb/sec for 24 hours. This compares to today's cost of >$20K for VLBA/Maxk IV media of

the same storage capacity.

Disc drives will be mounted in carriers, holding either single or multiple discs, made for multiple

insertion/removal cycles. When modern disc drives are powered down, they axe quite robust to

external handling forces and can be shipped easily in padded containers. Including the carriers,

the shipping weight per disc should be <,-_1.5 kg, so that the shipping weight of 12 discs containing

an aggregrate of 11 TB will be < -_18 kg.

2.4. Other Benefits of Disc-Based Mark V VLBI Data System

There are a number of other obvious benefits of magnetic discs over magnetic tape:

• Rapid random access to any data

• Essentially instant synchronization on playback into a correlator

• Self contained; expensive tape drives are not needed

• Can always buy and use the latest and cheapest 'dimestore' IDE disc drives, while still using

older ones

• The entire host platform, including the computer and interface cards, can be easily and

inexpensively upgraded as newer models become available

2.5. Mark V Development Schedule

Haystack is now beginning the development of the Mark V system based on magnetic disc

technology. Early demonstrations of feasibility may occur as early as the end of 2001, with a

deployable system ready as soon as --, 2003.

276 2000 IVS Annual Report
Institute of Applied Astronomy of Russian Academy of Sciences

2_•OOZoO "jiii) 5sg ?3

5 2--

IAA Technology Development Center

Institute of Applied Astronomy Technology Development Center

Alexander Ipatov

Abstract

IAA TDC works on the base of Radioastronomy apparatus building Section of IAA. The field of IAA

TDC includes the devices of receiving, recording and processing of radio signals on QUASAR dishes.

Now it consists of two radio telescopes (Zelenchukskaya and Svetloe), Badary under construction.

1. 1999-2000 Activities

Zelenchukskaya Station. Two years ago we planned the hard work on the new dish. Really,

we spend all time for this work. At this time the 18-21 cm, 13 cm, 6 cm, 3.5 cm and 1.35 cm

receivers are mounted on the dish. Six cryogenic machines are installed too.

Svetloe Station. On this station continues the routine work for supporting receiving equipment in working status. Measurements of the radio-telescope parameters were carried out. Performance parameters of the Svetloe Station are given in Table 1.

Table 1. Performance parameters of the Svetloe Station.

Wave band

cm

Frequency

GHz

Polarization

13 2.15-2.5 L

R

3.5 8.18-8.68 L

R

r dish sys SEFD cal

Ja

18.5 39.5 58 430 13.5

42.5 37.5 80 600 35

17 26 43 300 1.2

32 26 58 470 5.7

The investigations of pointing corrections were carried out using Field System software for

automatic pointing measurements. Pointing corrections models for wave bands 3.5 cm and 6 cm

were determined.

A new system of radiometrical recording was constructed by Prof. Koltsov's group. It is

installed on the Svetloe dish and now is being tested.

We created an experimental prototype of an automatic control system for one channel of the

receiver's complex. This system consists of:

• a personal computer;

• an interface between the computer and the receiver on a parallel channel LPT-port; this

interface was developed in the laboratory;

• programs for checking and remote control.

To this moment this system passed the laboratory tests. In future we will plan to increase the

system possibilities for the control of all 10 channels of receiving system of complex "Quasar".

Technical Staff of IAA TDC is stable and did not change.

2000 IVS Annual Report 277
IAA Technology Development Center Institute of Applied Astronomy of Russian Academy of Sciences

e Prospects

For the 2001-year we are planning:

1. To begin in Zelenchukskaya dish:

• putting into operation antenna tracking control system;

• the adjustment of reflector and feed system;

• radio telescope performance parameters measurement.

2. Test VLBI observations on baseline Zelenchukskaya-Svetloe.

278 2000 IVS Annum Report
Institutd'EstudisEspacialsdeCatalunya

200 L o°u 7

55 7q f

q

IEEC Technology Development Center

Technology Development at IEEC

Dirk Behrend, Antonio Rius

Abstract

A summary is presented of the work carried out at the Institut d'Estudis Espacials de Catalunya

(IEEC) regarding geodetic VLBI. The main activities encompass the geodetic surveillance of the DSS65

VLBI antenna at Robledo de Chavela (Madrid) and comparisons of tropospheric parameters derived

from VLBI with those from GPS, WVR and numerical weather prediction (NWP) models.

1. Past and Current Activities

In 1997 a track and wheel repair work had to be performed at the Madrid telescope (DSS65)

due to the formation of cracks in and a deformation of the concrete foundation. As for this task

the telescope had to be lifted up and put back again, it is possible that the position of the geodetic

reference point was changed. In order to monitor such a change conventional geodetic surveys

have been done with respect to the local geodetic footprint of the telescope before and after the

repair work (see e.g. [6]). Two a_tditional local surveys have been performed after the repair work at

roughly annual intervals (Table 1). Prior to the repair only one additional survey is available which

was done some 9 years before the repair. Thus, five local geodetic control surveys are available

to date. Table 1 gives a summary of the campaigns' results using the June 1997 campaign as

reference.

Table 1. Position of the DSS65 reference point derived from conventional geodetic surveys using the June

1997 campaign as origin. Error estimates are la standard deviations resulting from the least squares

adjustment procedure• The table is divided into two parts: the upper part refers to the time before and the

lower part to the time after the repair work. The repair was completed on April 30th, 1997.

Campaign North East Height

[mm] [mm] [mm]

December 1988 0.4 ± 3.0 0.3 ± 3.1 -23.2 ± 1.3

March 1997 7.0 ± 3.8 -1.5 ± 3.9 -6.0 ± 1.6

June 1997 0.0 0.0 0.0

April 1998 0.1 ± 3.1 -0.5 ± 3.2 -0.7 ± 1.6

March 1999 2.0 ± 3.2 1.6 ± 3.3 -0.3 ± 1.4

It appears that the east component was stable over the entire time span. The north component,

on the other hand, was stable after the repair, but the repair itself caused a decrease of -7.0 mm

(March 1997 to June 1997). Still, it seems that the repair re-created the initial state of December

1988. In height, an increase of 17.2 ± 1.3 mm (December 1988 to March 1997) and an uplift of

6.0 ± 1.6 mm (March 1997 to June 1997) are discernible where the latter can be attributed to the

repair work. After the repair work the height can be considered stable.

Provided that sufficient geodetic VLBI observations before and after the repair work are available, the above found displacements should also show up in the time series of these experiments in

2000 IVS Annual Report 279
IEEC Technology Development Center Institut d'Estudis Espacials de Catalunya

the form of offsets. A respective study has been done (see [7]) for three stations of the European

geodetic VLBI network including the antenna in Madrid. For this a drift rate as well as possible

offsets caused by the repair work have been modelled. The drift rates were forced to be the same

before and after the offset [7]. Offsets that did not pass a signifance test were rejected, i.e. only

jumps that are statistically significant are retained (cf. Figure 1).

20

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Figure 1. Time series of topocentric site movements for the station Robledo de Chavela (Madrid) as derived

from an analysis of European geodetic VLBI data. Only jumps that proved statistically significant are

shown.

The horizontal displacements (east and north) show a good agreement with the conventional

surveys, i.e. at the level of some millimetres the east component remained stable whereas the

north component performed a significant jump of -7 mm. With the height component, however,

an abrupt uplift caused by the repair work is not discernible. This is probably due to the short

time series available after the repair work and will hopefully be cured when more geodetic VLBI

data become available. Nonetheless, the decadal trend of +1.4 mm/y conforms with the station

height increase. Apart from investigating the site stability other activities have been done at the

Madrid site and are summarized in [8] and [2].

280 2000 IVS Annual Report
Institut d'Estudis Espacials de Catalunya IEEC Technology Development Center

At the NASA Madrid Deep Space Communications Complex (MDSCC), Spain, different microwave techniques are collocated: VLBI, GPS and WVR. These have been used in an intercomparison study for the derivation of tropospheric parameters (zenith wet delays, horizontM

delay gradients). The comparison was perf()rmed on the basis of 10 disconnected days with simultaneous observations for the years 1994 and 1995 [1]. Tile estimates of the zenith wet delay

are consistent between all three techniques. The results agree at the 1.6 cm WRMS level. Tile

horizontM gradients, on the other hand, agree at the WRMS level of 0.15 cm.

20 40 60 80 100

100 _ ' ' ' ' ' ' ' ' I , , 100

' - 80 80 _"

60 -- • 60

..c ..c:

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40 40 ,

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20 40 60 8O 100

VLBI - Zenith Wet Delay in mm

20 40 60 80 100

100 J i I I , , ! , , , i 100

80 -- _ 80

oo

ii .,,11'.

40 40

20 , I ' ' ' • 20

20 40 60 80 100

VLBI - Zenith Wet Delay in mm

Figure 2. Scatter plots of ZWD values. Left panel: VLBI vs. GPS. Time span: Dec. 6, 1996 (9.5 h).

Sampling rate: 30 rain. Right panel: VLBI vs. MM5. Time span: Dec. 6, 1996 (9.5 h). Sampling rate: 30

rain.

Furthermore, a preliminary comparison between zenith wet delays derived from VLBI, GPS,

and numerical weather prediction (NWP) models has been done. The results agree to the subcentimetre level. The correlation values obtained from a time series of two weeks amount to 0.87

(GPS vs. MM5), 0.81 (GPS vs. HIRLAM), and 0.84 (MM5 vs. HIRLAM); the bias and RMS

difference values fall within the error frames provided by the internal accuracies of the respective

methods. The VLBI data employed in the comparison cover a time span of 9.5 hours, so that the

comparison results should be considered indicative only. With correlation values of 0.78 (VLBI vs.

MM5) and 0.66 (VLBI vs. GPS) they, nevertheless, look promising. For more details see [3] and

[4].

2. Personnel

The Technology Development Center is formed by two people (Table 2): the head of the

Earth observation group and a young researcher within the frame of the Training and Mobility of

Researchers (TMR) programme of the European Community (grant FMRX-CT960071 "Measurement of Vertical Crustal Motion in Europe by VLBI"). The latter position is temporary and will

terminate at the end of September 2001.

2000 IVS Annual Report 281
IEEC Technology Development Center Institut d'Estudis Espacials de Catalunya

Table 2. Staff members of IEEC contributing to geodetic VLBI.

Name Description Allocation

Antonio Rius head of Earth observation 50%

group

Dirk Behrend temporary TMR position 50_

3. Future Plans

It is intended to continue the surveillance of the site stability of the DSS65 VLBI antenna.

Moreover, comparisons of VLBI derived atmospheric parameters with those from GPS, WVR,

radiosondes, and NWP models shall be extended.

References

[1] Behrend, D., A. Rius, R. Haas, L.P. Gradinarsky, J.M. Johansson, S.J. Keihm: Comparison of Independently Derived Atmospheric Parameters. Presented at: IUGG XXII General Assembly, Birmingham,

England, July 19-30, 1999.

[2] Behrend, D., A. Alberdi, A. Rius, J.F. Gomez, C. Garcia-Mir6, C. Calderon, J.A. Perea: MDSCC

Sation Report. In: P. Tomasi, F. Mantovani and M. Perez Torres (eds.): Proceedings of the 14th

Working Meeting on European VLBI for Geodesy and Astrometry. Castel San Pietro Terme, September

8-9, 2000, Consiglio Nazionale delle Ricerche, Istituto di Radioeustronomia, Bologna, 2000.

[31 Behrend, D., L. Cucurull, J. Vil/_, R. Haas: An Inter-comparison Study to Estimate Zenith Wet Delays

Using VLBI, GPS, and NWP Models. Earth Planets Space, Vol. 52, No. 10, pp. 691-694. 2000.

[41 Behrend, D., R. Haas, L. Cucurull, J. Vilh: ZWDs from VLBI, GPS, and NWP Models. In: P. Tomasi,

F. Mantovani and M. Perez Torres (eds.): Proceedings of the 14th Working Meeting on European VLBI

for Geodesy and Astrometry. Ca_stel San Pietro Terme, September 8-9, 2000, Consiglio Nazi(male delle

Ricerche, Istituto di Radioastronomia, Bologna, 2000.

[5] Behrend, D. and A. Rius: Reference Point Stability of the DSS65 VLBI Antenna. EOS Transactions,

AGU 1998 Fall Meeting, Vol. 79, No. 45, Supplement, p. F208, 1998.

[6] Behrend, D. and A. Rius: Geodetic Control of the Madrid DSS65 VLBI Antenna. In: W. Sctflfiter

and H. Hase (eds.): Proceedings of the 13th Working Meeting on European VLBI for Geodesy and

Astronletry. Viechtach, February 12-13, 1999, Bundesamt f(ir Kartographie und Geodesic. Wettzell,

1999.

[7] Haas. R., A. Nothnagel, D. Behrend: VLBI Determinations of Local Telescope Displacements. In: N.R.

Vandenberg and K.D. Baver (eds.): IVS 2000 General Meeting Proceedings, NASA/CP-2000-209893,

pp. 133-137, 2000.

[8] Rius, A., A. Alberdi, D. Behrend, C. Garcfa-Mir6, J.A. Perea: Radioastronomy at the NASA Madrid

Deep Space Communications Complex (MDSCC) Status Report. In: W. Schliiter and H. Hase (eds.):

Proceedings of the 13th Working Meeting on European VLBI for Geodesy and Astronmtry. Viechtach,

February 12-13, 1999, Bundesamt ffir Kartographie und GeodS_sie, V_ttzell. 1999.

282 2000 IVS Annual Report
,y//

Onsala Space Observatory (OSO)

i 7-_

OSO Technology Development Center

The IVS Technology Development Center at the Onsala Space

Observatory

Riidiger Haas, Gunnar Elgered, Bows Stoew, and Lars Pettersson

Abstract

We give a short overview of the activities at the Onsala Space Observatory in its function as an

IVS Technology Development Center. We describe the new microwave radiometer and the ongoing

development of a new S/X-band feed system for the 20-m telescope.

1. The New Microwave Radiometer at Onsala

The new microwave radiometer developed during the last couple of years at the Onsala Space

Observatory (OSO) [1], [2], [3] has been completed and first test measurements were carried out in

smnrner 2000. The new instrument is equipped with narrow beam horns and fast pointing drives.

One of its main applications is to study small scale atmospheric structures. We are looking forward

to use the two microwave radiometers at OSO collocated with GPS and VLBI for atmospheric

studies. Table 1 gives an overview on the specifications of the new instrument. Figure 1 shows

a photo of the new instrument and Figure 2 gives a schematic representation of its control and

data acquisition systems. Each of the two microwave channels is equipped with a horn antenna,

mechanical switch, ferrite switch, mixer IF amplifier, basel)and amplifier and A/D converter.

Table 1. Specifications of the new microwave radiometer developed at the Onsala Space Observatory.

Mechanical part Azimuth Elevation

Maximum pointing resolution

Achieved pointing resolution

Pointing range

Slew rates of motor drives

0.0072 ° 0.0144°

0.I° 0.05 °

0-360 ° 0 360 °

> 20°/s > 30°/s

Microwave part Channel 1 Channel 2

Centre frequency

Channel bandwidth RF

Horn beam width (E/H) plane

Side lobes (5 ° from boresight)

Calibrated load stability

A/D converter resolution

20.6 GHz 31.63 GHz

380 MHz 380 MHz

2.9°/3.4 ° 2.0°/2.3 °

-18 dB -23 dB

100 ° :t:0.01 ° C I00° +0.01 ° C

16 bit 16 bit

First successful measurements with the new instrument have been performed during the sunlmer and fall 2000 [4]. The measurements were carried out at the Esrange Space Centre near

Kiruna in northern Sweden where the instrument was collocated with one of the receiving sites in

the continuously operating Swedish GPS network.

Figure 3 shows the time series of derived wet propagation delay for the month of August 2000

and a comparison between estimates of the wet propagation delay using the GPS data and the

results inferred from the observed WVR sky brightness temperatures.

2000 IVS Annual Report 283
OSO Technology Developme m Center Onsala Space Observatory (OSO)

Figure 1. The new WVR.

RS232

.... _2......

_.._---jf __

Figure 2. Schematic representation of the control and the data

acquisition systems of the new WVR.

As expected the WVR time series contain more short term variations compared to the smooth

Kahnan filter estimates using GPS data (see Fig. 3). However, we find the white noise in the

observed brightness temperatures to be higher than expected and modifications will be made to

tile software integration algorithms.

There is a clear bias between the GPS and the WVR results (see Fig. 3). The origin of this

is unknown but we are investigating the following possible explanations: errors in the observed

brightness temperatures; error in the WVR algorithm used to calculate wet delay from [)rightness

temperatures (the algorithm used at Kiruna was (terived for the Swedish west coast); error in the

GPS estimates; error in the model used to interpolate tile ground pressure at the GPS antenna.

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i

_ t i

10 15 20 25 30

Day of August, 2000

"_10

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0 5 10 15 20

WVR wet delay at Kiruna, cm

Figure 3. Equivalent zenith wet delay derived from observations with the new WVR and from GPS measurements during August 2000 at tile Esrange Space Centre (Kiruna): a) Time series of wet delay results

from the new WVR (green/gray dots) and from GPS (thin black/blue line); b) V_t delay results from the

two methods GPS and microwave radiometry.

28:1 2000 IVS Annual Report
OnsalaSpace Observatory (OSO) OSO Technology Development Center

2. Development of a New S/X Feed System

The development of a new S- and X-band feed [5], [6] is ongoing. After the successfid re-design

of the corrugated horn that resulted in good antenna diagrams the coaxial waveguide transformer

(COWAT) was also re-designed sill(:(; its centre fr('quency was slightly off the desired value [7].

The re-designed COWAT was manufactured during 2000 with good cross-polarization isolation

(24 dB at 8.12 GHz, 38 dB at 8.62 GHz) and good return loss at X-band (-22 dB). However, with

only -8 dB for the S-band return loss it did not reach the specifications for S-band. No S-band

polarizers have been manufactured yet, so no cross-polarization data are available for S-band.

Currently a re-design of the horn throat is under consideration ill order to overcome the return

loss difficulties (see Fig. 4). The intention is to make a wider waveguide opening at S-band,

improving the return loss, 1)at without affecting the behavior at X-band. The frequency sele(:tive

surface is supposed to let S-band through, and act as a horn wall for X-band.

Horn

Upper S-band coaxial _ " _

Waveguide '_'222 _

X-band Circular Waveguide

Frequency selective

.....................................

Sur[ace Z-Axis

>-./

Lower S band Coaxial _ _ _ _

Waveguide _ _ _

Figure 4. Considered re-design of the horn throat for the new S/X-feed system.

3. Outlook

The IVS Technology Development Center at the ()nsala Space Observatory will continue with

the developinent of the new radiometer and the new S/X feed system.

W(; will concentrate our efforts on the software integration algorithms for tile new WVR in

ord('x to ilnprove its performance. We will especially investigate the reason for the obvious bias

between the radiometer results and GPS results for wet delay obtained from the measurements

at Kiruna. Extensive test measurements will be carried out at the Onsala Space Observatory

and the results for atmospheric t)aramet('xs will be conq)are(t to results from the other collocated

techniques.

The developlnent of the new S/X feed system will tbcus on the return loss difficulties. A

re-design of the horn throat will hoI)efiflly solve the prot)lems.

2000 IVS Annual Report 285
OSO Technology Development Center Onsala Space Observatory (()SO)

References

[1] Stoew, B., and C. Rieck, Dual Channel Water Vapour Radiometer Development, In: Proceedings of

the 13th \_brking Meeting oi1 European VLBI for Geodesy and Astrometry, W. Schliiter and H. Hase

(eds.), 261=264, 1999.

[2] Stoew, B., Data acquisition and software based temperature stabilization, Master's thesis, Department

of Radio and Space Science, Chalmers University of Technology, GSteborg, Sweden, 1998.

[3] Rieck, C., A pointing control system for a microwave radiometer, Master's thesis, Department of Radio

and Space Science, Chalmers University of Technology, GSteborg, Sweden, 2000.

[4] Stoew, B., C. Rieck, and G. Elgered, First results from a new dual-channel water vapor radiometer,

Ill: Proc. of the 14th Working Meeting on European VLBI for Geodesy and Astrometry, P. Tomasi,

F. Mantovani and M.-A. Perez-Torres (eds.), 79 82, 2000.

[5] Elgered, G., and R. Haas, Geodetic Very-Long-Baseline Interferometry at the Onsala Space Observatory

1996 1997, In: Proc. of the 12th Working Meeting on European VLBI for Geodesy and Astrometry,

B. R. Pettersen (ed.), 49 53, 1997.

[6] Elgered, G, P.-S. Kildal, J. Flodin, B. Hansson, L..Pettersson, S. Raffaelli, J.O. Rubios-L6pez, and

A. Tengs, A Dual Frequency Feed System for the 20 m Radio Telescope at the Onsala Space Observatory, In: Antenn 97, Proceedings of the Nordisk antennsymposium i GSteborg, 279-287, 1997.

[7] Elgered, G, R. Haas, and L. Pettersson, The IVS Technical Development Center at the Onsala

Space Observatory, In: International VLBI Service for Geodesy and Astrometry 1999 Annual Report,

NASA/TP 1999-209243, N. R. Vandenberg (ed.), 272 275, 200(}.

286 2000 IVS Annual Report
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Terms of Reference

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 ot)erate 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 ot)erationa] activities.

IVS is an official 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 ot)jectives. The primary objective of IVS is to

foster VLBI programs as a .joint service. This is acconlplished through close coordination to

provide high-quality VLBI data and products.

The second objective of IVS is to promote research and development activities in all aspects

of the geodetic and astrometric VLBI technique. This objective also supports the integration of

new components into IVS. The fl_rther education and training of VLBI participants is supported

through workshops, reports, electronic network eommctions, and other means.

The third objective of IVS is to interact with the community of users of VLBI products and to

integrate VLBI into a global Earth observing system. IVS interacts closely with the International

Earth Rotation Service (IERS) which is tasked by the, IAU and IUGG with maintaining the

international celestial and terrestrial reference fi'ames and with monitoring Earth rotation.

To meet 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 de,livery methods to ensure suitable product quality

and timeliness. IVS closely coordinates its activities with the astronoinieal community because of

the dual use of many VLBI facilities and technologies for both astronomy and astronletry/geodesy.

IVS accepts observing prot)osals for research and operational programs that conform to the

IVS objectives.

1.3. Data Products

VLBI data products contribute uniquely to these important determinations:

• definition and maintenance of the celestial reference frame

• monitoring universal time (UT1) and length of day (LOD)

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

These results are the foundation of inany s(:ientific and practical applications requiring the use

of an accurate inertial reference frame, such as high-precision navigation and l)ositioning. IVS

2000 IVS Annual Report 289
TermsofReference

provides, through the collaborative efforts of its components, a variety of significant VLBI data

products with differing applications, timeliness, detail, and temporal resolution, such as:

• all components of Earth orientation parameters at regular intervals

• terrestrial reference frame

• VLBI data in appropriate formats

• VLBI results in appropriate formats

• local site ties to reference points

• high-accuracy station timing data

• surface meteorology, tropospheric and ionospheric measurements

All VLBI data products are archived in IVS Data Centers and are publicly available.

1.4. Research

The VLBI data products are used for research in many related areas of geodesy, geophysics,

and astrometry, such as:

• UT1 and polar motion excitation (over periods of hours to decades)

• solid Earth interior research (mantle rheology, anelasticity, libration, core modes, nutation/precession)

• 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 vertical (scale) component

• climate studies

To support these activities, there are ongoing research efforts whose purpose is to improve and

extend the VLBI technique in such areas as:

• improvements in data acquisition and correlation

• refined data analysis techniques

• spacecraft tracking (Earth-orbiting and interplanetary)

• combination of VLBI data and results with other techniques

2. Permanent Components

IVS acquires VLBI data, correlates the data, analyzes the data to produce geodetic, astrometric,

and other results, and archives and publicizes data products. IVS accomplishes its goals through

the types of permanent components described in this section. IVS will accept proposals at any

time for a permanent component. Such proposals will be reviewed by the Directing Board. The

seven types of IVS permanent components are:

• Network Stations

290 2000 IVS Annual Report
Terms of Reference

• Operation Centers

• Correlators

• Analysis Centers

• Data Centers

• Technology Development Centers

• Coordinating Center

IVS acquires VLBI data, correlates the data, analyzes the data to produce geodetic and astrometric results, and archives and publicizes data products. IVS accomplishes its goals through the

operational components described below.

2.1. Network Stations

The IVS observing network consists of high performance VLBI stations.

• Stations can be dedicated to geodesy or have nmltiple uses (inchding astronomical observations or satellite tracking applications).

• Stations colnply with performance standards for data quality and operational reliability set

up by the Directing Board.

• VLBI data acquisition sessions are conducted by groups of Network Stations that are distributed either globally or over a geographical region.

2.2. Operation Centers

The IVS Operation Centers coordinate the routine operations of one or more networks. ()peration Center activities include:

• plalming network observing programs,

• establishing operating plans and procedures for the stations in the network,

• supporting the network stations in improving their performance,

• making correlator time available at an IVS Correlator,

• generating the detailed observing schedules for use in data acquisition sessions by IVS Network Stations,

• posting the observing schedule to an IVS Data Center for distribution and to the Coordinating Center for archiving.

IVS Operation Centers follow guidelines from the Coordinating Center for timeliness and schedule

file formats. Operation Centers cooperate with the Coordinating Center in order to define:

• the annual master observing schedule,

• the use of antenna time,

• tape availability and shipping,

• the use of other community resources.

2000 IVS Annual Report 291
Terms of Reference

2.3. Correlators

The IVS Correlators process raw VLBI data and station log files following a data acquisition

session. Their other tasks are to:

• provide immediate feedback to the Network Stations about problems that are apparent in

the data,

• jointly maintain the geodetic/astrometric community's tape pool,

• make processed data available to the Analysis Centers,

• regularly compare processing techniques, models, and outputs to ensure that data from

different Correlators are identical.

2.4. Analysis Centers

The IVS (:()ordinates VLBI data analysis to provide high-quality products for its users. The

analyses are performed by Analysis Centers and by Associate Analysis Centers.

Analysis Centers are committed to produce series of Earth Orientation Parameters (EOP) or

series of individual EOP components, without interruption and at a specified time lag to meet IVS

requirements. In addition, Analysis Centers produce station coordinates and source positions in

regular intervals.

The 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 Analysis Center

makes fl'om IVS recommendations are properly documented. Analysis Centers provide timely

feedback about station performance. In addition to these regular services, 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 crealion of high-quality products and their timely archiving and distribution. Any deviations

that an Associate Analysis Center makes from IVS recommendations are properly documented.

2.5. Data Centers

The IVS Data Centers are repositories for VLBI observing schedules, station log files, and data

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.

• Data Centers work ch)sely with the Coordinating Center and with the Analysis Centers to

ensure that all the information and data re(tuircd by IVS components are quickly and reliably

available.

Data Centers provide the following functions:

292 2000 IVS Almual Report
Terms of Reference

• receive and archive schedule files from Operation Centers,

• receive and archive log files and ancillary data files fronl tile Network Stations,

• receive and archive data products from tile Analysis Centers,

• 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. They may be engaged in hardware and/or software technology development, or evolve new

approaches that will improve the VLBI technique and enhance compatibility with different data

acquisition terminals. They will:

• design new hardware,

• investigate new equipment,

• develop new software for operations, processing or analysis,

• generate new information systems,

• develop, test, and document prototypes of new equipment or software,

• assist with deployment, installation, and training for any new approved technology.

• After dissemination of the new hardware or software, the centers may continue to provide

maintenance and updating functions.

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 all IVS activities.

The primary flmctions of the Coordinating Center are to:

• coordinate observing programs approved by the Directing Board,

• maintain the master schedule of observing sessions, coordinating the schedule with astronomical observing programs and with IVS networks,

• foster communications among all components of the IVS,

• define the best use of community resources,

• develop standards for IVS components,

• provide training in VLBI techniques,

• organize workshops and meetings, including an annual IVS technical meeting,

• produce and publish reports of activities of IVS components,

2000 IVS Annual Report 293
Terms of Reference

• maintain the IVS information system and archive all documents, standards, specifications,

manuals, reports, and publications,

• provide liaison with the IERS, IAG, IAU, and other organizations,

• provide the Secretariat of the Directing Board.

3. Coordinators

Specific IVS activities for technology, network data quality, and data products 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 Networks 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 operation 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

t)erformance,

The Network Coordinator works closely with the geodetic and astronomical communities who

are using the same network stations for observations. The Coordinator takes a leading role in

ensuring the visibility and representation of the Networks.

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 analysis software documentation,

• participates in comparisons of results ti'om different space geodetic techniques,

• monitors Analysis Centers' products for high quality results and for adherence to IVS standards and IERS Conventions,

• ensures that analysis products from all Analysis Centers are archived and available for the

scientific community, and

• forms the official products of IVS, as decided by the IVS Directing Board, using a suitable

combinatiou of the analysis results submitted by the Analysis Centers.

294 2000 IVS Annual Report
Terms of Reference

The Analysis Coordinator works closely with the geodetic and astronomical communities who

are using some of the same analysis methods and software. The Analysis Coordinator plays a

leadership role in the development of methods for distribution of VLBI products so that the

products reach the widest possible base of users in a timely manner. The coordinator promotes the

use of VLBI products to the broader scientific community and interacts with tile IVS Coordinating

Center and with the IERS.

3.3. Technology Coordinator

The IVS Technology Coordinator is selected by the Directing Board from responses to an

open solicitation to tile IVS Technology Development Centers. The Technology Coordinator is

responsible for coordinating the new technology activities of IVS and for stimulating advancement

of the VLBI technique. The Technology Coordinator performs the following functions:

• maintains cognizance of all current VLBI technologies and ongoing development

• coordinates development of new technology among various IVS components

• helps pronmlgate new technologies to the geodetic/astrometrie community

• strives to ensure the highest degree of global compatibility of VLBI data acquisition systems

The Technology Coordinator works closely with the astronomical community because of the

many parallels between the technology development required for both groups.

4. Directing Board

4.1. Roles and Responsibilities

The Directing Board determines policies, adopts standards, and approves the scientific and

operational goals for IVS. The Directing Board exercises general oversight of the activities of IVS

including modifications to tile organization that are deelned appropriate and necessary to maintain

efficiency and reliability.

A specific function of the Board is to set scientific goals for the IVS ot)serving program. The

Board will establish procedures for external research programs and will review any proposals thus

received.

Tile Board may determine appropriate actions to ensure the quality of the IVS produ(:ts and

that the IVS components maintain the adopted standards.

4.2. Membership

The Directing Board consists of appointed members who serve ex officio, members elected by

the Directing Board, and members elected by the IVS components. The members are:

Apt)ointed melnbers ex officio:

•IAG representative

• IAU ret)resentative

• IERS representative

• Coordinating Center Director

2000 IVS Annual Report 295
Terms of Reference

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, tile IERS Directing Board designates a representative to the IVS Directing Board. This

arrangement is to assure full cooperation between the two services.

Selected by Directing Board upon review of proposals from IVS Member Organizations:

• T(,chnology, Network, and Analysis Coordinators (3 total)

Elected by Directing Board upon recommendation from the Coordinating Center (see below):

• Memt)ers at large (2)

Elected by IVS Components (see below):

• Correlators and Operation Centers representative (1)

• Analysis and Data Centers representative (1)

• Networks representatives (2)

• Technology Development Centers representative (1)

Total number: 14

The four appointed members are considered ex officio and are not subject to institutional

restrictions. The five members of the Directing Board who are elected by IVS Permanent Comt)onents must each be a meml)er of a different IVS Member Organization. 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 as possible. All elected members

serve staggered tbur-year terms once renewable.

A 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 for the remainder of the original term.

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 three months notice before resigning.

4.3. Elections

Election of Board nlembers by 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 noininations 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 l)e 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 possibility of reelection for one additional term. The chair is the official

representative of IVS to external organizations.

296 2000 IVS Annual Report
Terms of Reference

4.5. Decisions

Most decisions by the Board are made by consensus or by simple majority vote of the members

present. In case of a tie, the chair shall vote but otherwise does not vote. 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 change any of the members

elected by the Directing Board before the normal term expires.

4.6. Meetings

The 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. The reviews should be done every four

years.

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 Correspondents.

5.3. Associate Members

Individuals associated with organizations that support an IVS component may become IVS

Associate Members. Associate Members are generally invited to attend non-executive sessions of

the Directing Board meetings with voice but without vote. 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 on a mailing list maintained by the Coordinating

Center. They do not actively participate in IVS but 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 General Secretary

• President of IAG Section II - Advanced Space Technology

• President of IAG Section V - Geodynamics

• President of IAU Division I - Fundamental Astronomy

2000 IVS Annual Report 297
Terms of Reference

• President of IAU Commission 19 - Rotation of the Earth

• President of IAU Commission 8 - Positional Astronomy

• President of IAU Commission 31 - Time

• President of IAU Commission 40 - Radio Astronomy

• President of URSI Commission J - Radio Astronomy

Individuals axe accepted as IVS Corresponding Members upon request to the Coordinating Center.

298 2000 IVS Annual Report
Members

IVS Member Organizations

(alphabetized by country)

Organization

Vienna University of Technology

Centro de Reldio Astronomia e Aplica_Ses Espaciais

Space Geodynamics Laboratory

Geodetic Survey Division, Natural Resources Canada

Dominion Radio Astrophysical Observatory

Canadian Space Agency

Chinese Academy of Sciences

Observatoire de Paris

Observatoire de Bordeaux

Deutsches Geod_itisches Forschungsinstitut

Bundesamt ffir Kartographie und Geod_ie

Geodetic Institute of the University of Bonn

Istituto di Radioastronomia CNR

Agenzia Spaziale Italiana

Geographical Survey Institute

Communications Research Laboratory

National Astronomical Observatory of Japan

National Institute of Polar Research

Norwegian Defence Research Establishment

Norwegian Mapping Authority

Astronomical Institute of St.-Petersburg University

Institute of Applied Astronomy

Hartebeesthoek Radio Astronomy Observatory

Institut d'Estudis Espacials de Catalunya

Instituto Geogr&¢ico Nacional

Chalmers University of Technology

Country

Austria

Brazil

Canada

Canada

Canada

Canada

China

France

France

Germany

Germany

Germany

Italy

Italy

Japan

Japan

Japan

Japan

Norway

Norway

Russia

Russia

South Africa

Spain

Spain

Sweden

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

2000 IVS Annual Report 299
Affiliates

IVS Affiliated Organizations

Organization Country

Australian National University Australia

University of New Brunswick Canada

Max-Planck-Institut fiir Radioastronomie Germany

Satellite Geodetic Observatory Hungary

Joint Institute for VLBI in Europe (JIVE) Netherlands

Westerbork Observatory Netherlands

National Radio Astronomy Observatory USA

300 2000 IVS Annual Report
Associate Members

IVS Associate Members

Name

Akiyama,

Tadayuki

Amagai, Jun

Andersen, Per

Helge

Arias, Felicitas

Baudry, Alain

Bauernfeind,

Erhard

Bayer, Karen

Beck, Norman

Behrend, Dirk

Bergman, Per

Berube, Mario

Bianco,

Giuseppe

Institution

Geographical Survey Institute

Communications Research

Laboratory

Norwegian Defence Research

Establishment

Facultad de Ciencias

Astronomicas y Geofisicas, Univ.

Nac. De La Plata

Observatoire de Bordeaux

For schungseinrichtung

Satellitengeodaesie de

Technischen Universitaet

Muenchen

Raytheon/Goddard Space Flight

Center

Geodetic Survey Division,

Natural Resources Canada

Institut d'Estudis Espacials de

Catalunya

Onsala Space Observatory

Geodetic Survey Division,

Natural Resources Canada

Agenzia Spaziale Italiana

Country

Japan

Japan

Norway

Argentina

France

Germany

USA

Canada

Spain

Sweden

Canada

Italy

E-mail

vlbi@gaos.gsi-mc.go.jp

amagai_crl.go.jp

per-helge.andersen@ffi.no

felicita@fcaglp.fcaglp.unlp.edu.ar

baudry@observ.u-bordeaux.fr

bauernfeind@wettzell.ifag.de

kdb@leo.gsfc.nasa.gov

norman.beck@geocan.nrcan.gc.ca

behrend@ieec.fcr.es

bergman@oso.chalmers.se

mario@gdim.geod.nrcan.gc.ca

bianco@asi.it

Boboltz, David U.S. Naval Observatory USA dboboltz@usno.navy.mil

Boehm, Technical University of Vienna Austria jboehm_luna.tuwien.ac.at

Johannes

Bolotin, Sergei bolotin_mao.kiev.ua

Boyer, William

National Academy of Sciences,

Kiev

NASA Goddard Space Flight

Center

Ukraine

USA wboyer@gemini.gsfc.nasa.gov

Booth, Roy Onsala Space Observatory Sweden roy@oso.chalmers.se

Bosworth, John NASA Goddard Space Flight USA jmb@ltpmail.gsfc.nasa.gov

Center

Bougeard, Observatoire de Paris France bougeard@hpvlbi.obspm.fr

Mireille

Brazeau, Geodetic Survey Division, Canada brazeau@geod.nrcan.gc.ca

Sylvain Natural Resources Canada

Buretta, Tom MIT Haystack Observatory USA tburetta_haystack.mit.edu

Buttaccio, Salvo Istituto di Radioastronomia Italy buttaccio@ira.noto.cnr.it

CNR

2000 IVS Annual Report 301
Associate Members

Name Institution

Campbell, Geodetic Institute of the

James University of Bonn

Cannon, Wayne Space Geodynamics Laboratory

H.

Cappallo, Roger

Carlson, Brent

Carter, Merri

Sue

Caskey, Steve

Chao, Benjamin

Chariot, Patrick

Chestnut, Pete

MIT Haystack Observatory

Dominion Radio Astrophysical

Observatory

Country E-mail

Germany

Canada

USA

Canada

campbell@sn_geod_l.geod.unibonn.de

wayne_sgl.crestech.ca

rcappallo@haystack.mit.edu

bcarlson@drao.nrc.ca

U. S. Naval Observatory USA msc@usno01.usno.navy.mil

Lockheed Martin USA steese@icefog.gcgo.nasa.gov

NASA Goddard Space Flight USA chao@denali.gsfc.nasa.gov

Center

Observatoire de Bordeaux France charlot@observ.u-bordeaux.fr

National Radio Astronomy

Observatory, Green Bank

Clark, Thomas NASA Goddard Space Flight

A. Center

Colomer, Instituto Geografico Nacional

Francisco

Colucci, Telespazio SpA

Giuseppe

USA

Combrinck,

Ludwig

pehestnu@nrao.edu

South

Africa

Hartebeesthoek Radio

Astronomy Observatory

USA clark_tomcat.gsfc.nasa.gov

Spain colomer@oan.es

Italy colucci_asi.it

ludwig@bootes.hartrao.ac.za

Corey, Brian MIT Haystack Observatory USA bcorey@haystack.mit.edu

Onsala Space Observatory Sweden fredrikc@oso.chalmers.se

Honeywell Technology Solutions

Incorporated

Corneliusson,

Fredrik

Covey, Rawland

Cox, Clyde Honeywell Technology Solutions

Incorporated

USA

de-Vicente,

Pablo

USA

mv3_cddis.gsfc.nasa.gov

kokee@pele.kpgo.hawaii.edu

Daniels, Mike Geodetic Survey Division,

Natural Resources Canada

Instituto Geografico Nacional

Honeywell Technology Solutions

Incorporated

Telespazio SpA

Diegel, Irv

del Rosso,

Domenico

Dewdney, Peter

Digre, Helge

Doi, Koichiro

Canada mike.daniels@gdim.geod.nrcan.gc._

Spain vicente@cay.oan.es

USA irv.diegel@honeywell-tsi.com

Italy

Dominion Radio Astrophysical Canada

Observatory

Norwegian Mapping Authority Norway

National Institute of Polar Japan

Research

domenico_delrosso@telespazio.it

ped@drao.nrc.ca

helge@gdiv.statkart.no

doi@nipr.ac.jp

302 2000 IVS Annual Report
Associate Members

Name Institution Country E-mail

Dong, Yousuo China

Drewes,

Hermann

Dube, Maurice

Elgered, Gunnar

Engen, Bjorn

Chinese Academy of Sciences

Joint Laboratory for Radio

Astronomy

Deutsches Geodaetisches

Forschungsinstitut

Raytheon/Goddard Space Flight

Center

Onsala Space Observatory

Norwegian Mapping Authority

Germany

USA

Sweden

Norway

uao@public.wl.xj.cn

drewes@dgfi.badw-muenchen.de

dube@cddis.gsfc.nasa.gov

kge@oso.chalmers.se

bjorne@gdiv.statkart.no

Essaifi, Najat Observatoire de Paris France essalfi@hpvlbi.obspm.fr

Far]ey, Stephen Geodetic Survey Division, Canada farley@geod.nrcan.gc.ca

Natural Resources Canada

Feil, Georg Space Geodynamics Laboratory Canada georg@sgl.crestech.ca

Feissel, Martine Observatoire de Paris France feissel@obspm.fr

Fey, Alan U.S. Naval Observatory USA afey@alf.usno.navy.mil

Finkelstein, Institute of Applied Astronomy Russia amf@quasar.ipa.nw.ru

Andrey

Frolov, Vladimir Institute of Applied Astronomy Russia fvn@isida.ipa.rssi.ru

Fhjita, Communications Research Japan mfujita@crl.go.jp

Masaharu Laboratory

Fukuzaki, Geographical Survey Institute Japan vlbi_gaos.gsi-mc.go.jp

Yoshihiro

Furuya, Masato Communications Research Japan mf@crl.go.jp

Laboratory

Gambis, Daniel Observatoire de Paris France gambis@obspm.fr

Gaume, Ralph U.S. Naval Observatory USA rgaume@usno.navy.mil

Ghigo, Frank National Radio Astronomy USA fghigo@nrao.edu

Observatory, Green Bank

Gomez, Frank Raytheon/Goddard Space Flight USA fgg@gemini.gsfc.nasa.gov

Center

Gomez- Instituto Geografico Nacional Spain gomez@oan.es

Gonzalez,

Jesus

Gontier, Observatoire de Paris France gontier@obspm.fr

Anne-Marie

Gonzalez, Ray NVI, Inc./Goddard Space Flight USA rgonzale@gemini.gsfc.nasa.gov

Center

Gordon, David Raytheon/Goddard Space Flight USA dgg@leo.gsfc.nasa.gov

Center

Grachev, Valery Institute of Applied Astronomy Russia gratch@isida.ipa.rssi.ru

Gradinarsky, Onsala Space Observatory Sweden lbg@oso.chalmers.se

Lubomir

Gubanov, Institute of Applied Astronomy Russia gubanov@quasar.ipa.nw.ru

Vadim

2000 IVS Annual Report 303
AssociateMembers

Name Institution Country E-mail

Gueguen, IstitutodiRadioastronomia Italy gueguen@hp-j.itis.mt.cnr.it

Erwan CNR

Haas,Ruediger OnsalaSpaceObservatory Sweden haas@oso.chalmers.se

Hammargren, OnsalaSpaceObservatory Sweden roger@oso.chaJmers.se

Roger

Hanssen, Rune NorwegianMappingAuthority Norway rune.hanssen@gdiv.statkart.no

I.

Harms,Matt Honeywell TechnologySolutions USA kokee@pele.kpgo.hawaii.edu

Incorporated

Hase,Hayo Bundesamt fuerKartographie Germany hase@wettzell.ifag.de

undGeodaesie

Himwich,Ed NVI,Inc./GoddardSpaceFlight USA weh@vega.gsfc.nasa.gov

Center

Hinteregger, MIT Haystack Observatory USA hhinteregger@haystack.mit.edu

Hans

Hobiger, Technical University of Vienna Austria thobiger@luna.tuwien.ac.at

Thomas

Holland, David Norwegian Mapping Authority Norway david@gdiv.statkart.no

Hori, Hiroshi Geographical Survey Institute Japan vlbi@gaos.gsi-mc.go.jp

Huang, Xinyong Shanghai Observatory, Chinese China xhuang@center.shao.ac.cn

Academy of Sciences

Ichikawa, Communications Research Japan richi@crl.go.jp

Ryuichi Laboratory

Ipatov, Institute of Applied Astronomy Russia ipatov@ipa.rssi.ru

Alexander

Ipatova, Irina Institute of Applied Astronomy Russia ipatova@isida.ipa.rssi.ru

Jacobs, Chris Jet Propulsion Laboratory USA chris.jacobs@jpl.nasa.gov

Jenson, George Geodetic Survey Division, Canada xgeop@ssimicro.conl

Natural Resources Canada

Johansson, Onsala Space Observatory Sweden kaj@oso.chahncrs.se

Karl-Ake

Johansson, Jan Onsala Space Observatory Sweden jmj@oso.chahn(,rs.s(_

M.

Johansson, Lars Onsala Space Observatory Sweden leb@oso.chahners.s(,

E.B.

Johnston, U.S. Naval Observatory USA kjj@astro.usno.nav.v.mi[

Kenneth

Josties, Jerry U.S. Naval Observatory USA jos(_casa.usno.navy.mil

Kaneko, Akihiro Communications Research Japan kazmko@crl.go.jp

Laboratory

Kaufmann, Centro de Radio Astronomia e Brazil kaufmaml__usp.l)r

Pierre Aplicacoes Espaciais

Kawai, Eiji Communications Research Japan kawa@crl.go.jp

Laboratory

304 2000 IVS Annual Report
AssociateMembers

Name Institution Country E-mail

Kaydanovsky, InstituteofAppliedAstronomy Russia kmn@isida.ipa.rssi.ru

Michael

Kennard,Ruth Raytheon/GoddardSpaceFlight USA kennard@cddis.gsfc.nasa.gov

Center

Kilger, Richard Forschungseinrichtung Germany kilger @wettzell.ifag.de

Satellitengeodaesie de

Technischen Universitaet

Muenchen

Kim, Kelly Honeywell Technology Solutions USA kokee@pele.kpgo.hawaii.edu

Incorporated

Kingharn, Kerry U.S. Naval Observatory USA kakQcygx3.usno.navy.mil

Kiuchi, Hitoshi Communications Research Japan kiuchi@crl.go.jp

Laboratory

Klatt, Calvin Geodetic Survey Division, Canada klatt@geod.emr.ca

Natural Resources Canada

Kobayashi, Geographical Survey Institute Japan vlbi@gaos.gsi-mc.go.jp

Kyoko

Kodak, Charles Honeywell Technology Solutions USA charles.kodak@honeywell-tsi.com

A. Incorporated

Koltsov, Nikolay Institute of Applied Astronomy Russia nec@isida.ipa.rssi.ru

Kondo, Tetsuro Communications Research Japan kondo@crl.go.jp

Laboratory

Korkin, Edward Institute of Applied Astronomy Russia korkin@isida.ipa.rssi.ru

Koyama, Communications Research Japan koyama@crl.go.jp

Yasuhiro Laboratory

Kozlova, Ixaida Institute of Applied Astronomy Russia via@quasar.ipa.nw.ru

Krasinsky, Institute of Applied Astronomy Russia kra@quasar.ipa.nw.ru

George

Kronschnabl, Bundesamt fuer Kartographie Germany kron@wettzell.ifag.de

Gerhard und Geodaesie

Kurihara, Communications Research Japan kurihara@crl.go.jp

Noriyuki Laboratory

Kurihara, Geographical Survey Institute Japan vlbi@gaos.gsi-mc.go.jp

Shinobu

Kutterer, Deutsches Geodaetisches Germany kutterer@dgfi.badwHansjeorg Forschungsinstitut muenchen.de

LaFrance, Geodetic Survey Division, Canada lafrance@geod.emr.ca

Jacques Natural Resources Canada

Lanotte, Telespazio SpA Italy lanotte@hp835.mt.asi.it

Roberto

Li, Suqin Chinese Academy of Sciences China uao@public.wl.xj.cn

Joint Laboratory for Radio

Astronomy

Li, Jinling Shanghai Observatory, Chinese China jll@center.shao.ac.cn

Academy of Sciences

2000 IVS Annual Report 305
Associate Members

Name

Liang, Shiguang

Liu, Xiang

Lizin, Igor

Lonigro,

Cynthia

Lonsdale, Colin

Lucena, Antonio

Macilio

Luzum, Brian

Ma, Chopo

Institution

Shanghai Observatory, Chinese

Academy of Sciences

Chinese Academy of Sciences

Joint Laboratory for Radio

Astronomy

Institute of Applied Astronomy

Raytheon/Goddard Space Flight

Center

MIT Haystack Observatory

Centro de Radio Astronomia e

Aplicacoes Espaciais

Country

China

E-mail

sgliang@center.shao.ac.cn

China uao@public.wl.xj.cn

Russia lizin@isida.ipa.rssi.ru

USA cal@gemini.gsfc.nasa.gov

USA clonsdale@haystack.mit.edu

Brazil

U. S. Naval Observatory USA

NASA Goddard Space Flight USA

Center

Maccaferri, Istituto di Radioastronomia Italy

Giuseppe CNR

MacMillan, Dan NVI, Inc./Goddard Space Flight USA

Center

McCarthy,

Dennis

macilio@roen.inpe.br

bjl@maia.usno.navy.mil

cma@virgo.gsfc.nasa.gov

beppe@ira.bo.cnr.it

dsm@leo.gsfc.nasa.gov

Malkin, Zinovy Institute of Applied Astronomy Russia malkin@quasar.ipa.nw.ru

Mamat, Rizwan Chinese Academy of Sciences China uao@public.wl.xj.cn

Joint Laboratory for Radio

Astronomy

Manabe, Seiji National Astronomical Japan manabe@gprx.miz.nao.ac.jp

Observatory of Japan

Mantovani, Istituto di Radioastronomia Italy fmantovani@astbol.bo.cnr.it

Franco CNR

Mardyshkin, Institute of Applied Astronomy Russia vvm@isida.ipa.rssi.ru

Vyacheslav

Martin, Jim U.S. Naval Observatory USA jom@cygx3.usno.navy.mil

Matsuzaka, Geographical Survey Institute Japan vlbi@gaos.gsi-mc.go.jp

Shigeru

U. S. Naval Observatory USA dmc@maia.usno.navy.mil

Michaih)v, Institute of Applied Astronomy

Andrey

Honeywell Technology Solutions

Incorporated

Geographical Survey Institute

National Academy of Sciences,

Kiev

Russia agm@isida.ipa.rssi.ru

USA kokee@pele.kpgo.hawaii.edu

Japan

Ukraine

Germany

vlbi@gaos.gsi-mc.go.jp

Geodetic Institute of the

University of Bonn

Mitchell,

Donald

Miyagawa,

Kohei

Molotaj,

Olexander

Mueskens, Arno

Nakajima, Communications Research

Junichi Laboratory

mol@aoku.freenet.kiev.ua

mueskens@mpifr-bonn.mpg.de

Japan nakaji@crl.go.jp

306 2000 IVS Annual Report
AssociateMembers

Name Institution Country E-mail

Nanni,Mauro Istitutodi Radioastronomia Italy nanni@ira.bo.cnr.it

CNR

Negusini,Monia Istitutodi Radioastronomia Italy negusini@astbol.bo.cnr.it

CNR

Nesterov, Laboratory of Radioastronomy Ukraine nesterov@crao.crimea.ua

Nikolay of Crimean Astrophysical

Observatory

Newby, Paul Space Geodynamics Laboratory Canada paul@sghcrestech.ca

Nicolson, Hartebeesthoek Radio South george@bootes.hartrao.ac.za

George Astronomy Observatory Africa

Niell, Arthur MIT Haystack Observatory USA aniell@haystack.mit.edu

Nikitin, Pavel Laboratory of Radioastronomy

of Crimean Astrophysical

Observatory

Novikov,

Alexander

Nilsson, Bjorn Onsala Space Observatory

Noll, Carey NASA Goddard Space Flight

Center

Nothnagel, Axel Geodetic Institute of the

University of Bonn

Space Geodynamics Laboratory

Petrachenko,

William

Ukraine nikitin@crao.crimea.ua

Sweden bin@oso.chalmers.se

USA noll@cddis.gsfc.nasa.gov

Germany nothnagel@uni-bonn.de

Canada sasha@sgl.crestech.ca

Geodetic Survey Division,

Natural Resources Canada

Okamoto, Communications Research Japan okamoto@crl.go.jp

Ken'ichi Laboratory

Onogaki, Geographical Survey Institute Japan vlbi@gaos.gsi-mc.go.jp

Michiko

Orfei, Sandro Istituto di Radioastronomia Italy orfei@astbol.bo.cnr.it

CNR

Outhwaite, Bill Geodetic Survey Division, Canada xgeop@ssimicro.com

Natural Resources Canada

Parsley, Stephen Joint Institute for VLBI in Netherlands parsley@jive.nfra.nl

Europe

Canada billp@cass.drao.nrc.ca

Petrov, Leonid

Plag,

Hans-Peter

NVI, Inc./Goddard Space Flight USA

Center

pet@leo.gsfc.nasa.gov

Pettersson, Lars Onsala Space Observatory Sweden larsp@oso.chalmers.se

Norwegian Mapping Authority Norway plag@gdiv.statkar t.no

Quick, Jonathan Hartebeesthoek Radio South jon@bootes.hartrao.ac.za

Astronomy Observatory Africa

2000 IVS Annual Report 307

Shanghai Observatory, Chinese

Academy of Sciences

Poirier, Michael MIT Haystack Observatory

Popelar, Josef Geodetic Survey Division,

Natural Resources Canada

Qian, Zhihan

USA mpoirier@haystack.mit.edu

Canada popelar@geod.emr.ca

China qzh@center.shao.ac.cn
AssociateMembers

Name Institution Country

Rahimov,Ismail InstituteofAppliedAstronomy Russia

Ray,Jim U.S.NavalObservatory USA

Reinhold,

Andreas

Bundesamt fuerKartographie

undGeodaesie

Rekkedal,Svein NorwegianMappingAuthority

Rioja,Maria Istitutodi Radioastronomia

CNR

Rius,Antonio Institutd'EstudisEspacialsde

Catalunya

Rot tmann, Geodetic Institute of the

Izabela University of Bonn

Rusinov, Yuriy Institute of Applied Astronomy

Salnikov,

Alexander

Institute of Applied Astronomy

Germany

E-mail

iar@ipa.rssi.ru

NVI, Inc./Goddard Space Flight

Center

jimr @maia.usno.navy.mil

ar@leipzig.ifag.de

Norway sveinr@gdiv.statkart.no

Italy rioja@ira.bo.cnr.it

Spain rius@ieec.fcr.es

Germany owsianik@mpifr-bonn.mpg.de

Russia rusinov@quasar.ipa.nw.ru

Russia salnikov@isida.ipa.rssi.ru

Sarti, Pierguido Istituto di Radioastronomia Italy psarti@astbol.bo.cnr.it

CNR

Schatz, Forschungseinrichtung Germany schatz@wettzell.ifag.de

Rainmnd Satellitengeodaesie de

Technischen Universitaet

Muenchen

Scherneck, Onsala Space Observatory Sweden hgs@oso.chalmers.se

Hans-Georg

Schlueter, Bundesamt fuer Kartographie Germany SchlueterQwettzell.ifag.de

Wolfgang und Geodaesie

Schuh, Harald Technical University of Vienna Austria hschuh@luna.tuwien.ac.at

Schupler, Bruce Honeywell Technology Solutions USA bruce.schupler@honeywellIncorporated tsi.com

Schwarz, Walter Bundesamt fuer Kartographie Germany schwarz@wettzell.ifag.de

und Geodaesie

Schwegmann, Deutsches Geodaetisches Germany schwegma@bek.badwWolf gang Forschungsinstitut muenchen.de

Sciarretta, Telespazio SpA Italy cecilia@asi.it

Cecilia

Sebata, Kouichi Conmmnications Research Japan sebaQcrl.go.jp

Laboratory

Sekido, Mamoru Communications Research Japan sekido@crl.go.jp

Laboratory

Shaffer, David USA dbs@gemini.gsfc.nasa.gov

Shao, Minghui Chinese Academy of Sciences China

Joint Laboratory for Radio

Astronomy

Shiba, Kousei Geographical Survey Institute Japan

Shibuya, Kazuo National Institute of Polar Japan

Research

uao@public.wl.xj.cn

vlbi@gaos.gsi-mc.go.jp

shibuya@nipr.ac.jp

308 2000 IVS Annual Report
Associate Members

Name

Shu,Fengchun

Skurikhina,

Elena

Smolentsev,

Sergey

Smythe,Dan

Sokolskaya,

Mariya

Sousa,Don

Sovers,Ojars

Stanghellini,

Carlo

Steinforth,

Christoph

Steppe,Alan

Stoew,Borys

Stotsky,

Alexander

Strand,Rich

Institution

Shanghai Observatory, Chinese

AcademyofSciences

InstituteofAppliedAstronomy

InstituteofAppliedAstronomy

MIT HaystackObservatory

InstituteofAppliedAstronomy

MIT HaystackObservatory

RemoteSensingAnalysisInc.

Istitutodi Radioastronomia

CNR

Geodetic Institute of the

University of Bonn

Jet Propulsion Laboratory

Onsala Space Observatory

Institute of Applied Astronomy

Lockheed Martin

Country

China

Russia

Russia

USA

Russia

USA

USA

Italy

Germany

USA

Sweden

Russia

USA

E-mail

sea@quasar.ipa.nw.ru

smolen@isida.ipa.rssi.ru

dsmythe_haystack.mit.edu

smy@quasar.ipa.nw.ru

dsousa@haystack.mit.edu

ojs@logos.jpl.nasa.gov

stanghellini@ira.noto.cnr.it

steinfor@picasso.geod, unibonn .de

as@logos.jpl.nasa.gov

boris@oso.chalmers.se

stotskii@isida.ipa.rssi.ru

steese@icefog.gcgo.nasa.gov

Surkis, Igor Institute of Applied Astronomy Russia surkis@quasar.ipa.nw.ru

Takahashi, Communications Research Japan takahashi@crl.go.jp

Yukio Laboratory

Takashima, Geographical Survey Institute Japan vlbi@gaos.gsi-mc.go.jp

Kazuhiro

Tamura, National Astronomical Japan tamura@miz.nao.ac.jp

Yoshiaki Observatory of Japan

Tangen, Leif Norwegian Mapping Authority Norway leifm@gdiv.statkart.no

Morten

Tateyama, Centro de Radio Astronomia e Brazil tat eyama@usp.br

Claudio E. Aplicacoes Espaciais

Tesmer, Volker Deutsches Geodaetisehes Germany tesmer@dgfi.badw-muenchen.de

Forschungsinstitut

Thomas, NVI, Inc./Goddard Space Flight USA cet@gemini.gsfc.n_sa.gov

Cynthia Center

Thorandt, Bundesamt fuer Kartographie Germany vt@leipzig.ifag.de

Volkmar und Geodaesie

Thornton, U.S. Naval Observatory USA blt@casa.usno.navy.mil

Bruce

Titov, Oleg A. Astronomical Institute of Russia olegtitov@mail.ru

St.-Petersburg University

Titus, Mike MIT Haystack Observatory USA mtitus@haystack.mit.edu

Tomasi, Paolo Istituto di Radioastronomia Italy tomasi@ira.bo.cnr.it

CNR

2000 lvs Annual Report 309
AssociateMembers

Name Institution Country E-mail

Torres,Miguel Istitutodi Radioastronomia Italy torres@ira.bo.cnr.it

CNR

Trigilio, Istituto di Radioastronomia Italy trigilio@ira.noto.cnr.it

Corrado CNR

Tuccari, Gino Istituto di Radioastronomia Italy tuccari@ira.noto.cnr.it

CNR

Ullrich, Dieter Bundesamt fuer Kartographie Germany dul@leipzig.ifag.de

und Geodaesie

van Langevelde, Joint Institute for VLBI in Netherlands huib@jive.nfra.nl

Huib Europe

Vandenberg, NVI, Inc./Goddard Space Flight USA nrv@gemini.gsfc.nasa.gov

Nancy Center

Venturi, Tiziana Istituto di Radioastronomia Italy tventuri@ira.bo.cnr.it

CNR

Vespe, Agenzia Spaziale Italiana Italy vespe@asi.it

Francesco

Vityazev, Astronomical Institute of Russia venvi_aispbu.spb.su

Venianlin V. St.-Petersburg University

Volvach, Laboratory of Radioastronomy Ukraine volvach@crao.crimea.ua

Alexandr of Crimean Astrophysical

Observatory

Vytnov, Institute of Applied Astronomy Russia vytnov_isida.ipa.rssi.ru

Alexander

Wang, Guangli Shanghai Observatory, Chinese China wgl_center.shao.ac.cn

Academy of Sciences

Wang, Weixia Chinese Academy of Sciences China uao_public.wl.xj.cn

Joint Laboratory for Radio

Astronomy

Wang, Na Chinese Academy of Sciences China uao@public.wl.xj.cn

Joint Laboratory for Radio

Astronomy

Wei, W_nren Shanghai Observatory, Chinese China wwr_center.shao.ac.cn

Academy of Sciences

Whitney, Alan MIT Haystack Observatory USA awhitney@haystack.mit.edu

Wildes, W.T. NASA Goddard Space Flight USA wtw@wildbill.gsfc.nasa.gov

Center

Wojdziak, Bundesamt fuer Kartographie Germany rw@leipzig.ifag.de

Reiner und Geodaesie

Xue, Zhouhe Shanghai Observatory, Chinese China zhxue_center.shao.ac.cn

Academy of Sciences

Yang, Zhigen Shanghai Observatory, Chinese China

Academy of Sciences

Yatskiv, National Academy of Sciences, Ukraine yatskiv_mao.kiev.ua

I Yaroslav Kiev

Ye, Shuhua Shanghai Observatory, Chinese China ysh_center.shao.ac.cn

Academy of Sciences

310 2000 IVS Annual Report
Associate Members

Name Institution Country E-mail

Yoshino, Taizoh Communications Research Japan yosh@crl.go.jp

Laboratory

Yusup, Aili Chinese Academy of Sciences China uao@public.wl.xj.cn

Joint Laboratory for Radio

Astronomy

Zeitlhoefler, Forschungseinrichtung Germany zeitlhoefler @wettzell.ifag.de

Reinhard Satellitengeodaesie de

Technischen Universitaet

Muenchen

Zen, Yong Chinese Academy of Sciences China uao@public.wl.xj.cn

Joint Laboratory for Radio

Astronomy

Zernecke, Forschungseinricht ung Germany zernecke@wettzell.ifag.de

Rudolf Satellitengeodaesie de

Technischen Universitaet

Muenchen

Zhang, Ali Chinese Academy of Sciences China uao@public.wl.xj.cn

Joint Laboratory for Radio

Astronomy

Zhang, Hongbo Chinese Academy of Sciences China uao@public.wl.xj.cn

Joint Laboratory for Radio

Astronomy

Zhang, Jin Chinese Academy of Sciences China uao@public.wl.xj.cn

Joint Laboratory for Radio

Astronomy

Zhou, Ruixian Shanghai Observatory, Chinese China zrx@center.shao.ac.cn

Academy of Sciences

2000 IVS Annual Report 311
IVSComponents

IVS Permanent Components

(listed by types, within types alphabetical by component name)

Network Stations

Component Name Sponsoring Organization Country

Algonquin Radio Observatory Geodetic Survey Division, Natural Canada

Resources Canada

Fortaleza, Radio Observatorio Espacialdo Centro de R_dio Astronomia e Aplica_Ses Brazil

Nordes (ROEN) Espacials

Gilmore Creek Geophysical Observatory National Earth Orientation Service USA

Goddard Geophysical and Astronomical NASA Goddard Space Flight Center USA

Observatory

National Radio Astronomy Observatory, U.S. Naval Observatory USA

Green Bank

Hartebeesthoek Radio Astronomy Hartebeesthoek Radio Astronomy South Africa

Observatory Observatory

Kashima 34m antenna Communications Research Laboratory Japan

Key Stone Project Koganei 1lm antenna Communications Research Laboratory Japan

Key Stone Project Kashima 11m antenna Communications Research Laboratory Japan

Key Stone Project Miura llm antenna Communications Research Laboratory Japan

Key Stone Project Tateyama 1lm antenna Communications Research Laboratory Japan

Kokee Park Geophysical Observatory National Earth Orientation Service USA

Matera Agenzia Spaziale Italiana Italy

Medicina (Italy) Istituto di Radioastronomia CNR Italy

Mizusawa National Astronomical Observatory of Japan

Japan

Noto (Sicily) Istituto di Radioastronomia CNR Italy

Ny/_lesund Geodetic Observatory Norwegian Mapping Authority Norway

ERS/VLBI Station O'Higgins Bundesamt fiir Kartographie und Geod_ie Germany

Onsala Space Observatory Chalmers University of Technology Sweden

Seshan Shanghai Observatory, Chinese Academy China

of Sciences

Simeiz Laboratory of Radioastronomy of Crimean Ukraine

Astrophysical Observatory

Svetloe Radio Astronomy Observatory Institute of Applied Astronomy Russia

JARE Syowa llm antenna National Institute of Polar Research Japan

Transportable Integrated Geodetic Bundesamt fiir Kartographie und Geodiisie Germany

Observatory (TIGO)

312 2000 IVS Annual Report
IVSComponents

TsukubaVLBIStation Geographical SurveyInstitute Japan

NanshanVLBIStationof Urumqi ShanghaiObservatory, ChineseAcademy China

Astronomical Observatory(UAO) ofSciences

WestfordAntenna,HaystackObservatory NASAGoddardSpaceFlightCenter USA

Fundamentalstation Wettzell Bundesamt fiir Kartographieund Germany

Geod/isieandForschungseinrichtung

Satellitengeod_iedeTechnischen

Universit/itMiinchen

ObservatorioAstron6micoNacional- InstitutoGeograficoNacional Spain

Yebes

YellowknifeGeophysical Observatory GeodeticSurveyDivision,Natural Canada

ResourcesCanada

Operation Centers

ComponentName SponsoringOrganization Country

GeodeticInstituteBonn Geod_tisches InstitutderUniversit_itBonn Germany

CORE Operation Center NASA Goddard Space Flight Center USA

NEOS Operation Center National Earth Orientation Service USA

Correlators

Component Name Sponsoring Organization Country

Astro/Geo Correlator at the Bundesamt fiir Kartographie und Germany

Max-Planck-Institute for Radio Astronomy Geod_ie and Geod_itisches Institut der

Universit_t Bonn

Communications Research Laboratory Communications Research Laboratory Japan

MIT Haystack Observatory Correlator NASA Goddard Space Flight Center USA

Institute of Applied Astronomy Correlator Institute of Applied Astronomy Russia

Tsukuba VLBI Center Geographical Survey Institute Japan

Washington Correlator National Earth Orientation Service USA

2000 IVS Annual Report 313
IVS Components

Data Centers

Component Name Sponsoring Organization Country

BKG, Leipzig Bundesamt fiir Kartographie und Geod_isie Germany

Communications Research Laboratory Communications Research Laboratory Japan

Crustal Dynamics Data Information NASA Goddard Space Flight Center USA

System (CDDIS)

GeoDAF Agenzia Spaziale Italiana Italy

Italy CNR Istituto di Radioastronomia CNR Italy

Observatoire de Paris Observatoire de Paris France

Analysis Centers

Component Name Sponsoring Organization Country

Astronomical Institute of St.-Petersburg Astronomical Institute of St.-Petersburg Russia

University University

Bordeaux Observatory Observatoire de Bordeaux France

Centro di Geodesia Spaziale (CGS) Agenzia Spaziale Italiana Italy

Communications Research Laboratory Communications Research Laboratory Japan

DGFI Deutsches Geod/itisches Forschungsinstitut Germany

Forsvarets forskningsinstitutt (FFI) Norwegian Defence Research Norway

Establishment

GIUB-BKG Analysis Center Geod/itisches Institut der Universitgt Germany

Bonn and Bundesamt f/ir Kartographie

und Geodgsie

Goddard Space Flight Center NASA Goddard Space Flight Center USA

Haystack Observatory NASA Goddard Space Flight Center USA

Institute of Applied Astronomy Analysis Institute of Applied Astronomy Russia

Center

Institute of Geodesy and Geophysics Institute of Geodesy and Austria

Analysis Center Geophysics/University of Technology,

Vienna

Italy CNR Istituto di Radioastronomia CNR Italy

Jet Propulsion Laboratory Jet Propulsion Laboratory USA

Main Astronomical Observatory National Academy of Sciences, Kiev Ukraine

NAOJ National Astronomical Observatory of Japan

Japan

Observatoire de Paris Observatoire de Paris France

Onsala Space Observatory Chalmers University of Technology Sweden

314 2000 IVS Annual Report
IVS Components

Shanghai Observatory Shanghai Observatory, Chinese Academy China

of Sciences

U. S. Naval Observatory U.S. Naval Observatory USA

USNO Analysis Center for Source U.S. Naval Observatory USA

Structure

Technology Development Centers

Component Name Sponsoring Organization Country

Canadian VLBI Technology Development Space Geodynamics Laboratory, Geodetic Canada

Center Survey Division, Dominion Radio

Astrophysical Observatory, Canadian

Space Agency

Communications Research Laboratory Communications Research Laboratory Japan

Forsvarets forskningsinstitutt (FFI) Norwegian Defence Research Norway

Establishment

Goddard Space Flight Center NASA Goddard Space Flight Center USA

MIT Haystack Observatory National Earth Orientation Service USA

Institute of Applied Astronomy Institute of Applied Astronomy Russia

Technology Development Center

Institut d'Estudis Espacials de Catalunya Institut d'Estudis Espacials de Catalunya Spain

Onsala Space Observatory Chalmers University of Technology Sweden

2000 IVS Annual Report 315
ContributingInstitutions

Addresses of Institutions Contributing to this Report

(listed alphabetically by country)

Institute of Geodesy and Geophysics / University of Technology, Vienna

Gusshausstrasse 27-29 1040 Vienna

Austria

http://luna.tuwien.ac.at

Centro de R£dio Astronomia e Aplica_Ses Espaciais, CRAAE (Mackenzie, INPE, USP, UNICAMP)

CRAAE

Instituto Presbiteriano Mackenzie

Rua da Consolax;fi_) 896

01302-907 S_o Paulo

SP

Brazil

http://www.craae.mackenzie.br

R_dio Observat6rio Espacial do Nordeste, ROEN

Rua jos6 Hlp61ito S/N

Bairro Tupuifi

61760-000 Eus6bio

CE

Brazil

http://www.roen.inpe.br

Geodetic Survey Division, Natural Resources Canada

615 Booth St. Ottawa

Ontario

Canada K1A 0E9

http://www.geod.nrcan.gc.ca

York University/Space Geodynamics Laboratory/CRESTech

4850 Keele St.

Floor 1 North York

Ontario

Canada M3J 3K1

http://www.sgl.crestech.ca

Shanghai Astronomical Observatory, National Astronomical Observatory, Chinese Academy of Sciences

80 Nandan Road

Shanghai 200030

P. R. China

http://center.shao.ac.cn

316 2000 IVS Annual Report
ContributingInstitutions

UrumqiAstronomical Observatory

SouthBeijingRoad40

sub-5

Urumqi

830011Xinjiang

P.R. China

http://www.xjb.ac.cn/

ObservatoiredeBordeaux

2ruedel'ObservatoireBP89

33270Floirac

France

http://www.observ.u-bordeaux.fr

ObservatoiredeParis,DANOF/UMR8630

61avenuedel'Observatoire

75014Paris

France

http://www.obspm.fr

Bundesamt ffir KartographieundGeod_ie

Karl Rothe-StraBe10-14

D-04105Leipzig

Germany

http://www.leipzig.ifag.de

Bundesamt fiir KartographieundGeod_ie,FundmentalstationWettzell

Sackenrieder Strafle25

D-93444KStzting

Germany

http://www.wettzell.ifag.de

DGFI,DeutschesGeod_itisches Forschungsinstitut

Marstallplatz8

80539Mfinchen

Germany

http://www.dgfi.badw.de

Forschungseinrichtung Satellitengeod/isie derTechnischenUniversit/_tMiinchen,Wettzell

Sackenrieder Strat]e25

D-93444KStzting

Germany

http://www.wettzell.ifag.de

Geod_.tisches IntitutderUniversit/itBonn

Nussallee17

D-53115Bonn

Germany

http://giub.geod.uni-bonn.de/vlbi

2000IVSAnnual Report 317
ContributingInstitutions

Max-Planck-Institute for Radioastronomy

Auf dem Hiigel 69

53121 Bonn

Germany

http://www.mpifr-bonn.mpg.de

Agenzia Spaziale Italiana

Centro di Geodesia Spaziale

C.P. Aperta

Ctr.da Terlecchia

75100 Matera

Italy

http://www.asi.it

Istituto di Radioastronomia, Bologna

Via P. Gobetti 101

40129 Bologna

Italy

http://www.ira.bo.cnr.it

Istituto di Radioastronomia, Stazione di Medicina

C.P. 14

40060 Villafontana

Bologna

Italy

http://www.ira.bo.cnr.it

Istituto di Radioastronomia del CNR, Stazione VLBI di Noto

C.P. 141

1-96017 Noto SR

Italy

http://www.ira.noto.cnr.it

Communications Research Laboratory

4-2-1 Nukuikita-machi

Musashikoganei

Tokyo 184-0015

Japan

http://ksp.crl.go.jp/index.html

Geographical Survey Institute

Kitasato 1 Tsukuba

Ibaraki Japan

http: //vldb.gsi.go.j p/sokuchi/vlbi/

Kashima Space Research Center, Communications Research Laboratory

893-1 Hirai

Kashima

Ibaraki 314-0012 Japan

http://www.crl.go.jp/ka/index.html

318 2000 IVS Annual Report
ContributingInstitutions

National Institute of Polar Research

1-9-10

Kaga

Itabashi-ku Tokyo 173-8515 Japan

http://www.nipr.ac.jp/welcome.html

Forsvarets forskningsinstitutt (FFI) (Norwegian Defence Research Establishment)

FFI/E

Box 25

2007 Kjeller

Norway

Geodetic Institute, Norwegian Mapping Authority

Kartverksveien

Hcnefoss

Norway

http://www.statkart.no

Astronomical Institute of Saint-Petersburg University

Bibliotechnaya sq.

2 Petrodvoretz St.-Petersburg 198504

Russia

http://www.astro.pu.ru

Institute of Applied Astronomy of Russian Academy of Sciences

Zhdanovskaya street 8

St. Petersburg

Russia

197110

http://www.ipa.nw.ru

Hartebeesthoek Radio Astronomy Observatory (HartRAO)

PO Box 443

Krugersdorp

1740

South Africa

http://www.hartrao.ac.za

Institut d'Estudis Espacials de Catalunya

Edif. Nexus

Gran Capit_n 2-4

08034 Barcelona

Spain

http://ieec.fcr.es

Observatorio Astron6mico Nacional

Apartado 1143

E-28800 Alcahl de Henares

Spain

http://www.oan.es/

2000 IVS Annual Report 319
Contributing Institutions

Onsala Space Observatory (OSO)

SE-439 92 Onsala

Sweden

http://www.oso.chalmers.se

Laboratory of Radio Astronomy of Crimean Astrophysical Observatory

334247 Yalta

Katsively

RT-22 Crimea

Ukraine

http://giud.geod.uni-bonn.de/vlbi/stations/rt22.html

Gilmore Creek Geophysical Observatory

NOAA/NESDIS CDA Station

GCGO/VLBI

1300 Eisele Rd.

Fairbanks, Alaska 99712

USA

http: //www.fcdas.noaa.gov

MIT Haystack Observatory

Off Route 40

Westford, MA 01886

USA

http://www.haystack.mit.edu

NASA Goddard Space Flight Center

Codes 920.1 and 926

Greenbelt, MD 20771

USA

http://lupus.gsfc.nasa.gov

Kokee Park Geophysical Observatory

Kokee State Park

P.O. Box 538

Walmea, Hawaii 96798

USA

U.S. Naval Observatory

3450 Massachusetts Ave. NW

Washington, D.C. 20392

USA

http://www.usno.navy.mil

320 2000 IVS Annual Report
List of Acronyms

List of Acronyms

AGU

AIPS

APSG

APT

ARIES

ARO

ASI

ATNF

BIPM

BKG

CAS

CDDIS

CDP

CGLBI

CGS

CNR

CORE

COTS

CRAAE

CRF

CRL

CTVA

DAR

DAS

DAT

DGFI

DLR

DOMES

DORIS

DRAO

DSN

EOP

ESA

ESO

EU

EVN

FFI

FGS

FITS

FS

FTP

American Geophysical Union

Astronomical Image Processing System

Asia-Pacific Space Geodynamics Project

Asia Pacific Telescope

Astronomical Radio Interferometric Earth Surveying program

Algonquin Radio Observatory (Canada)

Agenzia Spaziale Italiana (Italian Space Agency)

Australia Telescope National Facility (Australia)

Bureau International des Poids et Measures (France)

Bundesamt fiir Kartographie und Geod/isie (Germany)

Chinese Academy of Sciences (China)

Crustal Dynamics Data Information System (USA)

Crustal Dynamics Project (USA)

Canadian Geodetic Long Baseline Interferometry (Canada)

Centro di Geodesia Spaziale (Italy)

Consiglio Nazionale delle Ricerche (Italy)

Continuous Observations of the Rotation of the Earth

Commercial-Off-The-Shelf

Center for Radio Astronomy and Space Applications (Brazil)

Celestial Reference Frame

Communications Research Laboratory (Japan)

Canadian Transportable VLBI Antenna (Canada)

Data Acquisition Rack

Data Acquisition System

Data Acquisition Terminal OR Digital Audio Tape

Deutsches Geod_tisches ForschungsInstitut (Germany)

Deutsche Forschungsanstalt ffir Luft - und Raumfahrt (Germany)

Directory Of MERIT Sites

Doppler Orbitography by Radiopositioning Integrated on Satellite

Dominion Radio Astrophysical Observatory (Canada)

Deep Space Network

Earth Orientation Parameters

European Space Agency

European Southern Observatory

European Union

European VLBI Network

Forsvarets ForskningsInstitutt (Norwegian Defence Research Establishment) (Norway)

Forschungsgruppe Satellitengeod_ie (Germany)

Flexible Image Transport System

Field System

File Transfer Protocol

2000 IVS Annual Report 321
List of Acronyms

GALAXY

GAPE

GARNET

GAPS

GCGO

GEMSTONE

GEX

GGAO

GIPSY

GIUB

GLONASS

GLORIA

GPS

GRGS

GSD

GSFC

GSI

GUI

GeoDAF

HartRAO

HTSI

IAA

IAG

IAU

ICRF

ICPS

IEEC

IEPS

IGG

IGGOS

IGM

IGN

IGS

ILPS

IMF

INPE

IRA

IRIS

ISAS

ITIS

ITRF

ITSS

IUGG

IVS

JADE

Giga-bit Astronomical Large Array with cross connect (Japan)

Great Alaska and Pacific Experiment

GSI Advanced Radiotelescope NETwork (Japan)

German Antarctic Receiving Station (Antarctica)

Gilmore Creek Geophysical Observatory (USA)

GEodetic Measurements by the colocation of Space Technique ON Earth (Japan)

Giga-bit VLBI system performance check EXperiments

Goddard Geophysical and Astronomical Observatory (USA)

GPS Inferred Positioning SYstem

Geodetic Institute of the University of Bonn (Germany)

GLObal NAvigation Satellite System

GLObal Radio Interferometry Analysis

Global Positioning System

Groupe de Recherches de Gdoddsie Spatiale (France)

Geodetic Survey Division of Natural Resources Canada (Canada)

Goddard Space Flight Center (USA)

Geographical Survey Institute (Japan)

Graphical User Interface

Geodetical Data Archive Facility (Italy)

Hartebeesthoek Radio Astronomy Observatory (South Africa)

Honeywell Technology Solutions Incorporated (USA)

Institute of Applied Astronomy (Russia)

International Association of Geodesy

International Astronomical Union

International Celestial Reference Frame

International Celestial Reference System

Institut d'Estudis Espacials de Catalunya (Spain)

International Earth Rotation Service

Institute of Geodesy and Geophysics (Austria)

Integrated Global Geodetic Observing System

Instituto Geogrkfico Militar (Chile)

Instituto Geogr£fico Nacional (Spain)

International GPS Service

International Laser Ranging Service

Isobaric Mapping Function

Instituto Nacional de Pesquisas Espacials (Brazil)

Istituto di RadioAstronomia (Italy)

International Radio Interferometric Surveying

Institute of Space and Astronautical Sciences (Japan)

Istituto di Tecnologia Informatica Spaziale (Italy)

International Terrestrial Reference Frame

(Raytheon) Information Technology and Science Services (USA)

International Union of Geodesy and Geophysics

International VLBI Service for Geodesy and Astrometry

JApanese Dynamic Earth observation by VLBI (Japan)

322 2000IVS AnnualReport
List of Acronyms

JARE

JIVE

JMA

JPL

KPGO

KSP

LNA

MERIT

MIT

MLRO

MPI

MPIfR

MRI

MTLRS

NAO

NASA

NEOS

NGS

NIPR

NMA

NMF

NOAA

NRAO

NRCan

NVI

OAN

OPAR

OSO

PRARE

RAS

ROEN

SEFD

SGL

SHAO

SINEX

SLR

SPBU

STDN

SWT

TAC

TIGO

TMR

ToR

TRF

UAO

Japanese Antarctic Research Expedition (Japan)

Joint Institute for VLBI in Europe (Netherlands)

Japan Meteorological Agency (Japan)

Jet Propulsion Laboratory (USA)

Kokee Park Geophysical Observatory (USA)

Key Stone Project (Japan)

Low Noise Amplifier

Monitoring of Earth Rotation and Intercomparison of Techniques

Massachusetts Institute of Technology (USA)

Matera Laser Ranging Observatory (Italy)

Max-Planck-Institute (Germany)

Max-Planck-Institute for Radioastronomy (Germany)

Meteorological Research Institute of JMA (Japan)

Modular Transportable Laser Ranging System

National Astronomical Observatory (China, also Japan)

National Aeronautics and Space Administration (USA)

National Earth Orientation Service (USA)

National Geodetic Survey (USA)

National Institute of Polar Research (Japan)

Norwegian Mapping Authority (Norway)

Niell Mapping Function

National Oceanic and Atmospheric Administration (USA)

National Radio Astronomy Observatory (USA)

Natural Resources Canada (Canada)

NVI, Inc. (USA)

Observatorio Astron6mico Nacional (Spain)

PARis Observatory (France)

Onsala Space Observatory (Sweden)

Precision RAnge and Range-rate Experiment

Russian Academy of Sciences (Russia)

R,4dio-Observat6rio Espacial do Nordeste (Brazil)

System Equivalent Flux Density

Space Geodynamics Laboratory (Canada)

SHanghai Astronomical Observatory (China)

Solution INdependent EXchange format

Satellite Laser Ranging

Saint-PetersBurg University (Russia)

Satellite Tracking Data Network

SW Technology (USA)

Totally Accurate Clock

Transportable Integrated Geodetic Observatory (Germany)

Training and Mobility of Researchers program of the European Community

IVS Terms of Reference

Terrestrial Reference Frame

Urumqi Astronomical Observatory (China)

2000 IVS Annual Report 323
List of Acronyms

URSI

USNO

UT1

UTC

VERA

VEX

VLBA

VLBI

VSI

VSOP

WACO

WGRF

WRMS

WVR

WWW

International Radio Science Union

U. S. Naval Observatory (USA)

Universal Time

Coordinated Universal Time

VLBI Exploration of Radio Astrometry

VLBI EXperiment Language

Very Long Baseline Array (USA)

Very Long Baseline Interferometry

VLBI Standard Interface

VLBI Space Observatory Program

WAshington COrrelator (USA)

Working Group on Reference Frames

Weighted RMS

Water Vapor Radiometer

World Wide Web

2000 IVS Annual Report 32


REPORT DOCUMENTATION PAGE 1 Form A_proved OMB No. 0704-0188

Public reporting burden for Ihis collection of information is estimated to average 1hour per response, including the time for reviewing inslructions,searching existing data sources,

gathering and maintaining the data needed, and completingand reviewing the collectionOfinformation, Send comments regarding this burden estimate or any other aspect o1this

collection of information, including suggestions for reducing this burden, to Washington Headquarlers Services, Directorate for Information Operations and Reports, 1215 Jefferson

Davis Highway, Suite 1204, Arlington. VA 22202-4302, and to the Office of Management and Budget, Paperwork Reduction Proiect (0704-0188), Washington, OC 20503.

1. AGENCYUSEONLY(Leaveb/ank) [ 2. REPORTDATEApril 2001 [ 3. REPORTTYPECOVEREDTechnical ANDDATESPaper

4. TITLE AND SUBTITLE 5. FUNDING NUMBERS

International VLBI Service for Geodesy and Astrometry--

2000 Annual Report

6. AUTHOR(S)

N.R. Vandenberg and K.D. Baver, Editors

7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS (ES)

Laboratory for Terrestrial Physics

Space Geodesy Networks and Sensor Calibration Office

Goddard Space Flight Center

Greenbelt, Maryland 20771

9. SPONSORING / MONITORING AGENCY NAME(S) AND ADDRESS (ES)

National Aeronautics and Space Administration

Washington, DC 20546-0001

920.3

8. PEFORMING ORGANIZATION

REPORT NUMBER

2001-01284-0

10. SPONSORING/MONITORING

AGENCY REPORT NUMBER

2001--TP-209979

11.SUPPLEMENTARY NOTES

12a. DISTRIBUTION I AVAILABILITY STATEMENT 12b. DISTRIBUTION CODE

Unclassified-Unlimited

Subject Category: 42

Report available from the NASA Center for AeroSpace Information,

7121 Standard Drive, Hanover, MD 21076-1320. (301) 621-0390.

13. ABSTRACT (Maximum 200 words)

This volume of reports is the 2000 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 who constitute the components of IVS. The 2000 Annual Report

documents the work of these IVS components over the period March 1, 1999, through December 3 l,

2000. The reports document changes, activities, and progress of the IVS. The entire contents of this

Annual Report also appear on the IVS web site at http://ivscc.gsfc.nasa.gov/publications/ar2000.

14. SUBJECT TERMS

Geodesy, astrometry, VLBI, geophysics, Earth orientation, very long baseline interferometry,

interferometry, radio astronomy, geodynamics, reference frames, terrestrial reference frame,

celestial reference frame, length of day, Earth system science, Earth rotation.

17. SECURITY CLASSIFICATION 18. SECURITY CLASSIFICATION 19. SECURITY CLASSIFICATION

OF REPORT OF THIS PAGE OF ABSTRACT

Unclassified Unclassified Unclassified

NSN 7540-01-280-5500

15. NUMBER OF PAGES

324

16. PRICE CODE

20. LIMITATION OF ABSTRAC f

UL

Standard Form 298 (Rev. 2-89)


r _

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n

w_ -