INTERNATIONAL VLBI SERVICE FOR GEODESY AND ASTROMETRY

]-

the

Earth

Service, a

U.S. Naval

and Goddard

Center for VLBI

Goddard Space Flight Center

Greenbelt, MD 20771 USA

August, 1999

Edited by N. R. Vandenberg NASA/TP--1999-209243
NASA Center for Aerospace Information

7121 Standard Drive

Hanover, MD 21076-1320

Price Code: A17

Available From:

National Technical Information Service

5285 Port Royal Road

SpringfieLd, VA 22161

Price Code: AIO

II
PREFAC

This volume of reports is the 1999 Annual Report of the International VLBI Service for Geodesy and

Astrometry -- IVS. The individual reports were contributed by VLBI groups in the international geodetic community who constitute the components of IVS.

The IVS 1999 Annual Report documents the work of the IVS components for the year ending March

1, 1999, the official inauguration date of IVS. As the newest of the space technique services, IVS

decided to publish this Annual Report as a reference to our organization and its components.

All of the content of this Annual Report also appears on the IVS web site at:

http://ivscc.gsfc, nasa.gov/publications/ar1999

This book and the web site are organized as follows:

• The first section of the Annual Report contains general information about IVS: its mission,

structure, and Directing Board. The Chairman's report gives a brief history of the genesis of

IVS, an overview of IVS as an organization, and a look toward the future.

• The second section comprises two brief overviews of VLBI with particular emphasis on reference frames which are fundamental to geodesy and astrometry.This material is offered with

the intention of providing brief but comprehensive overviews to those readers of the Annual

Report who are unfamiliar with the technique of VLBI and its applications to geodesy and

geodynamics.

• The next seven sections contain the heart of the Annual Report -- the reports from each IVS

component: the Coordinators, Network Stations, Operation Centers, Corretators, Data Centers,

Analysis Centers, and Technology Development Centers. These reports are dense with technical information, staff descriptions, photographs, and plans for the coming year. Each report

documents the work of the IVS component for the year preceeding the start of IVS.

• The last section provides IVS reference material: the Terms of Reference, a list of institutions

contributing to this Annual Report, the list of IVS Associate Members, a complete list of the

IVS components, and a list of acronyms.

The IVS 1999 Annual Report will be a valuable reference for information about IVS and its components. This Annual Report will serve as a baseline from which we can measure the anticipated

progress of IVS in coming years.

III

ACKNOVVLEDG MENTS

The editor would like to acknowledge the essential contributions of the following people to the

preparation of the IVS 1999 Annual Report:

• Leonid Petrov and Hayo Hase convinced me to use LaTeX as the source format for these

reports. This has made it possible to automate the production of both the printed version

and the web version.

• Leonid Petrov provided the TeX programming to produce the appearance of the printed page

and he devised the scheme for pagination of the individual reports.

• Hayo Hase provided a demonstration station report and template. His example enabled

even those unfamiliar with LaTeX to produce outstanding reports.

• Karen Bayer did the programming and wrote the scripts that processed all of the LaTeX

source flies. Her scripts produced the tables of contents, the printed reports, the HTML versions, and the institution lists. Her scripts also paginated the entire report.

• Frank Gomez located and installed the software for the latest versions of LaTeX and

LaTeX2HTML. He also provided system and web administration support throughout.

• John Hazen designed the striking cover art that captures the essence of geodetic VLBI

today, and he did the layout for the color pages of the report.

• The HTML versions of the reports were generated using the LaTeX2HTML translator Version

98.1 by Nikos Drakos, Computer Based Leaning Unit, University of Leeds, customized for

IVS by the editor.

Finally I would like to thank all of the IVS colleagues who contributed their reports to the Annual

Report. The high quality of the reports demonstrates that we have an active worldwide community with a splendid future.

Nancy Vandenberg

IVS Coordinating Center Director

Editor, 1999 Annual Report

I.I
UI
TABLE OF OON NTS

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

Acknowledgements .......................................... v

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

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

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

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

Chairman's Report ........................................................ 8

Reference Frames in VLBI ................................................. 11

Overview of VLBI .....................

................................... 13

The Celestial Reference Frame ............................................... 18

Coordination .......................................................... 23

Coordinating Center Report ................................................. 25

Analysis Coordinator Report ................................................. 27

Network Coordinator Report ................................................. 29

Technology Coordinator Report ............................................... 31

Network Stations .......................................................

Algonquin Radio Observatory ................................................ 3335

Progressat ROEN - FortalezaGeodeticStation..................................... 39

GilmoreCreek GeophysicalObservatory ......................................... 42

Goddard Geophysicaland AstronomicalObservatory................................. 46

USN0 Green Bank 20-MeterTelescope .......................................... 49

HartebeesthoekRadio Astronomy Observatory..................................... 53

Kashima 34-m Radio Telescope............................................... 57

Key Stone ProjectVLBI Stations(Kashima,Koganei,Miura,and Tateyama) ................. 62

Kokee Park GeophysicalObservatory

Matera CGS VLBI Station ........................................... 66

Medicina StationReport ................................................... 70

................................................... 74

Report from the Noto VLBI Station............................................ 77

NYAL Ny-Alesund 20-metre Antenna ......................................... 80

German AntarcticReceivingStation0'Higgins....................... " "85

Onsa[aSpace Observatory- IVS Network Station

................................... 90

Status Report of Seshan VLBI Station

Simeiz VLBI Station ....... " ......................................... 94

Svettoe Radio Astronomical Observatory ........................................ .96

........................................ _.D.[

JARE Syowa Station 11-m Antenna, Antarctica

Transportable Integrated Geodetic Observatory ................................... 105

................................... 110

Tsukuba 32-m VLBI Station ................................................ 115

Urumqi Astronomical Observatory ............................................ 119

Westford Antenna ....................................................... 122

20-m Radiotelescope at Wettzell ............................................. 126

0bservatorio Astron6mico Naciona[ ........................................... 132

Yellowknife Observatory ................................................... 136

Operation Centers ...................................................... 139

The Bonn Geodetic VLBI Operation Center ....................................... 141

CORE Operations Center ................................................... 143

The U.S. Naval Observatory VLBI Program: Operations in 1998 and 1999 .................. 147

UII
TABLE OF CONTENTS

Corretators ........................................................... 149

The Bonn Astro/Geo Mark IlIA Correlator ....................................... 151

The Haystack Observatory VLBI Correlator ....................................... 153

Key Stone Project VLBI Correlation Center ....................................... 156

Tsukuba VLBI Center ..................................................... 160

Washington Correlator .................................................... 164

167

Data Centers ......................................................... 169

BKG Data Center ............................... . .......... 170

Data Center at Communications Research Laboratory .................... 173

CDDIS Data Center Summary .......................................... 177

Matera GeoDAF Data Center ......................................... 179

Italy CNR Data Center Report ..................... 181

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

Analysis Centers ....................................................... 183

Analysis Center of Saint-Petersburg University .................................... 185

The Bordeaux Observatory IVS Analysis Center .................................... 186 189

Matera CGSVLBI Analysis Center .............................................

Special Associate Analysis Center at Communications Research Laboratory ................. 192

DGFI Analysis Center ..................................................... 196

Combination of Results at FFI - Data Analysis .................................... 198

The GIUB/BKG VLBI Analysis Center .......................................... 200

GSFCVLBI Analysis Center Annual Report ....................................... 203

Analysis and Research at the Haystack Observatory ................................ 207 209

IAA VLBI Analysis Center Report for 1998-1999 ..................... 213

Italy CNR Analysis Center Report .................... . .................... 215

JPL VLBI Group Report for 1998-1999 .................... 217

IVS Analysis Center at MA0 UNAS ............................................

Paris Observatory Analysis Center 0PAR: Report on Activities January 1998 - March 1999 ....... 220

The IVS Special Analysis Center at the 0nsala Space Observatory ....................... 228

VLBI Research Activities for Astrometry and Geodesy at Shanghai Astronomical Observatory ..... 232

Earth Orientation Analysis from the U.S. Naval Observatory VLBI Program ................. 236

•.. 241

Technology Development Centers ........................................ 243

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

Technology Development Center at CRL ........................................ 248

Combination of Results at FFI - Software Development .............................. 253

Goddard Space Flight Center IVS Technology Development Center ....................... 256

IVS Technology Development Center at Haystack Observatory .......................... 259

Institute of Applied Astronomy Technology Development Center ........................ 264 269

Institute d'Estudis EspaciaLs de Catalunya (IEEC) ..................................

The IVS Technical Development Center at the 0nsala Space Observatory ................... 272

, . • • 277

IVS Information ................................................... .279

IVS Terms of Reference .................................................. 288

IVS Components ........................................................ 292

Contributing Institutions .................................................. • 297

IVS Associate Members .................................................. 307

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

UIII
ABOUT IVS
IVS ORGANIZATION

Mission:

IVS is an international collaboration of organizations which operate or support Very Long Baseline Interferometry (VLBI) components. IVS provides a service which supports geodetic and astrometric work on reference systems, Earth science research, and

operational activities.

Objectives:

IVS is the International VLBI Service for Geodesy and

Astrometry. IVS groups geodesy and astrometry together

because they use the same observations and the same analysis gives both types of results.

IVS is a service of International Association of Geodesy (IAG).

IVS was originally established under IAG Commission VIII --

the International Coordination of Space Techniques for

Geodesy and Geodynamics (CSTG).

IVS is the third of this type of service to be established. The

first was the IGS (International GP5 Service) which has been

highly successful as a service for GPS. The second service was

the ILR5 (International Laser Ranging Service) which started in late 1998.

The objectives of IV5 are

• to provide a service to support geodetic, geophysical,

and astrometric research and operational activities;

• to promote research and development for VLBI; and

• to interact with users of VLBI products.

Comm|ssJonVlll:

CSTG

TAG Services

I k

International R

secuonm

AdvancedSpace

Technotogy

ILRS

InternationaL

Laser Ranging

Service

IVS provides data and products for the scientific community.

Some of the products are

• a terrestrial reference frame (TRF),

• the international celestial reference frame (ICRF), and

• Earth orientation paramenters (EOP),

ALl IVS data and products are archived and are pubUcally

available.

The organizations Listed on the next page contribute to IVS by

supporting one or more IVS components.

IUGG

International

Union of

and

IAG

International

Association of

Geodesy

I

I SectionV: t

Geodynandcs

TntemationaL

Astronom|cat

Division Z

Fundamental

Astronomy

Comnflsston19:

Rotation of the

Earth

IERS

lntemationat

Earth Rotation

Service

2
Structure: The goals of IVS are realized through seven types of

components. The interaction among the various

components is shown in the accompanying figure.

• Network Stations are high performance VLBI

statins that acquire data.

• Operation Centers coordinate the actvities of

a network of Network Stations.

• Cooretators process data, provide feedback to

stations, and provide processed data to analysts.

• Analysis Centers analyze data and produce

results and products.

• Data Centers distribute products to users,

and provide storage and archive functions.

• Tehnology Development Centers develop new

VLBI technology

• The Coordinating Center coordinates the

daily and long-term activities of IVS.

In the figure, the link to the International Earth

Rotation Service (IERS) indicates that the IVS is

now the VLBI Coordinating Center for IERS. The

Directing Board provides overall guidance. The

Coordinating Center and the three Coordinators

work closely together. Each Coordinator has a special relationship with the components they work

with. All of the components interact with each

other on a daily basis.

Organization Country

Centro de Radio Astronomia e AplicaqSes Espaciais

SpaceGeodynamics Laboratory

GeodeticSurveyDivision, Natural Resources

Canada Dominion Radio Astrophysical Observatory

Canadian Space Agency

Chinese Academy of Sciences

Observatoire de Paris

Observatoire de Bordeaux

Deutsches Geodatisches Forschungsinstitut

Bundesamt fti Kartographie und 6eod_isie

Geodetic Institute of the University of Bonn

Brazil

Canada

Canada

Canada

Canada

China

France

France

Istituto di Radioastronomia CNR

AgenziaSpaziate Itatiana

Germany

Germany

Germany

Italy

Italy

Geographical Survey Institute

Communications Research Laboratory

National Astronomical Observatory of Japan

Japan

Japan

Japan

Organization Country

National Institute of Polar Research Japan

Joint Institute for VLBIin Europe Netherlands

Norwegian Defence Research Establishment Norway

Norwegian Mapping Authority Norway

Astronomical Institute of St.-Petersburg University Russia

Institute of Applied Astronomy Russia

Hartebeesthoek Radio Astronomy Observatory South Africa

Institut d'Estudis Espacials de Catalunya Spain

Observatorio Astronomico NacionaI Spain

Chalmers University of Technology Swede-n

National Academy of Sciences, Kiev Ukraine

Laboratory of Radioastronomy of Crimean

Astrophysical Observatory Ukraine

NASAGoddard Space Flight Center USA

U. S. Naval Observatory USA

Jet Propulsion Laboratory USA

3
IVS COMPONENT MAP

IVS Components by Country

Brazil 1

Canada 3

China 3

France 3

Germany 8

ItMy 7

Japan 14

Netherlands 2

Norway 3

Russia 5

South Africa 1

Spain 2

Sweden 3

Ukraine 2

USA 17

_ Network Station

O Operation Center

• Correlator

• Data Center

Analysis Center

• Technology Development Center

Coordinating Center _O'Higgins

1
_lenshan

Seshen

75"

11

"Miura

anei

_'Tateyama

°15 °

-30 °

.60 _

- 15° 0° 15° 3_" 45" 60" 75" 90° 105" 1_" 1_" 150" 1_ °

.75o
IVS DIRECTING E3 3ARO

NRME:Wotfgang Schttiter

RFFILIRTION: Bundsamt fiir

Kartographieund Geod_isie,

Germany

POSiTiON:Chairman and

Networks Representative

TERM: 4 years

NRNE:Gerhard BeutLer

RVF_LmTmN: University of

Berne, Switzerland

POSITION:IAG Representative

TERM:ex officio

NRME:MarshaU Eubanks

RFFILIRTION: U.S.Nava[

Observatory,USA

POSITION: Corre[ators and

Operation Centers

Representative

TERM:4 years

NRME:Wayne Cannon

RFFILiRTION: Space Geodetic

Laboratory,Canada

POSiTiON:At LargeMember

TERM: 2 years

NAME:Ed Himwich

RFFILIRTION: NVI, Inc./Goddard

Space Flight Center, USA

POSITION: Network Coordinator

TERM:4 years

NRME:NicoteCapitaine

8FFILIRTmN:ParisObservatory,

France

POSiTiON:IAU Representative

TERM: eX OffiCiO

NRME:Tetsuro Kondo

RFFILIRTION:Communications

Research Laboratory, 3apan

POSITION: Technology

Development Centers

Representative

TERM: 2 years
m

/

NRME:Chopo Ma

RFFILIRTIDN: NASA Goddard

Space Flight Center, USA

P0Sm0N: IERS Representative

TERM:ex o.ffi'cio

NRME:PaoloTomasi

RFFILIRTION: CNR Bologna,Italy

POSITION:At LargeMember

TERM: 4 years

NRME:Shigeru Matsuzaka

RFFILmTION: Geographical

Survey Institute, Japan

P0Sm0N: Networks

Representative

TERM:4 years

NRME:Nancy Vandenberg

BFFILmIION:NVI, Inc./Goddard

Space Flight Center, USA

P0Sm0R: Coordinating Center

Director

TERM:ex offi'cio

NRME:Axe[ Nothnagel

RFF_LmT,0N:University of

Bonn, Germany

POSITION: Analysis and Data

Centers Representative

TERM:2 years

NRME:Alan Whitney

RFFJLmTmN: Haystack

Observatory, USA

PosmoN: Technology

Coordinator

TERM:2 years

7
n HAIRMAN' S REPORT

Wotfgang Schttiter

Bundesamt fiir Kartographie und Geodtisie

1. Introduction

The inauguration date for the International VLBI Service for

Geodesy and Astrometry was March 1st, 1999. A tremendous

amount of work was done by individuals for preparation of the

Terms of Reference, the Cat( for Participation and the evaluation of the proposals as well as for the initialisation of the

establishment of the IVS components.

I'm aware that the success of IVS is dependent on the support

of the individuals of the member institutions, which provide

the technology, observations, and data handling, processing

and analysis on a Long term basis. It is extremely important

to maintain the good cooperation, already developed over

many years, between institutions and individuals.

Information flow among the members and to users outside of

the IVS is vital.

We are presenting now the first Annual Report of the IVS to document from the very beginning the status of the service and to

demonstrate transparency to the applicants, scientists and

administrators to gain or to keep their confidence. All components were asked to summarize their status and to point out

their future contributions to IVS. Thanks to all for making first

Annual Report a valuable document about the IVS.

2. General Remarks

Three decades ago the space techniques played only a marginal rote in the understanding of the kinematics and dynamics of the Earth. The breakthrough came as a result of the

MERIT [Feissel, 1985] campaign and the Crustal Dynamics

Project [Smith, 1993] in the 1980s. The space techniques

demonstrated their potential for the realisation of the global reference frames ICRF and ITRF and for the determination

of Earth orientation parameters and crustal movements. Since

that time the VLBI technique played the important and primary role for monitoring of E0P and crustal motions. VLBI is

the only technique that determines the ICRF.

The requirement for continuous monitoring of E0P as well as

for continuous determination of station positions and quasar

positions was recognized as a result of MERIT. Regarding the

VLBI technique, it has been realized by performing series of

VLBI experiments.NASA/GSFC, NOAA-NGS, USNO, FGS and

other agencieshave organizedand coordinatedinternational

VLBI observations such as IRIS, NEOS, CORE, Intensive and

more with the primary objective to monitor EOP. Several series

of experiments were performed for the determination of plate

tectonics such as GLOBAL, X-ATL, N-ATL, EUROPE etc. and

many RgD-experiments to improve the technique and investigate its potential. The results have been continuously reported to the IERS, the International Earth Rotation Service

(http://hpiers.obspm.fr), which was established as a consequence of the MERIT campaign.

The VLBI community was organized within the International

Association of Geodesy (IAG) in Commission VIII--the

International Coordination of Space Techniques for Geodesy

and Geodynamics (CSTG)--as the VLBI Subcommission. CSTG

is also Subcommission B.2 in the Committee on Space

Research (COSPAR).

Over all the years the results of the VLBI technique became

basic and important products for many applications in science

and in practice. The need grew for the establishment of an

international service which would take over the responsibility for the delivery of the VLBI products on a tong term basis

and guarantee highest quality. The new service would replace

the relatively loose, historically grown commitments and

become an umbrella of the VLBI community.

3. Transition from the CSTG

Subcommission to the IVS

Encouraged by the success of the International GPS Service

(IGS), established in 1992, the president of the CSTG, Gerhard

Beufler, University of Berne, proposed in May 1997 to organize the SLR/LLR and the VLBI subcommissions of the CSTG

into comparable services. His vision was twofold: first, a service wilt guarantee much more strongly the provision of high-

[y reliable products and second, the SLR/LLR and the VLBI

techniques urgently needed more acceptance and support in

the scientific community. The coordination of the activities

within services of the SLR/LLR and VLBI communities wilt

strongly concentrate resources and increase the potential to

improve the techniques.

Thomas A. Clark,in hisfunctionas chairman ofthe CSTG VLBI

Subcommission, draftedthe Terms of Referenceforthe IVS in

October 1997. The final version was worked out by a

B
Subcommission Steering Committee whose members were

3ames Campbell (chairman), Yasuhiro Koyama, Chopo Ma,

Arthur Niell, Axel Nothnagel, rim Ray and Nancy Vandenberg.

The Terms of References were presented and approved at both

the CST6 Executive Committee and IERS Directing Board meetings in Nice/France in April 1998. The Call for Participation

was jointly released by CST6 and IERS on June 1, 1998. The

Steering Committee evaluated the proposals and accepted all

of them in October 1998.

In summary, the IVS has

30 network stations (concentrated in USA, Europe, and

Japan, deficit in the southern hemisphere),

3 operation centers (NASA-GSFC, NEOS, 6IUB),

7 correlators (IAA/Russia, 6SI/3apan, CRL/Japan,

NEOS(Washington)/USA, NASA(Haystack)/USA,

3IVE/Netheflands, BK6-MPI/6ermany),

6 data centers (fiNR/Italy, CRL/Japan, NASA-GSFC/USA,

0bserv. Paris/France, Agenzia Spaziate/ItaIy,

BKG/6ermany),

18 analysis centers (global AC to provide IVS core products; associate AC for investigations or other related

products),

9 technology centers (supporting Mark III and Mark IV,

K4 and $2 technologies),

1 coordinating center (NEOS, a cooperation of USN0

and 6SFC),

Atl together there are:

• 74 components representing 30 institutions in 15

countries

• 229 Associate Members

In November 1998, the Steering Committee, in accordance

with the Terms of Reference, released the call for nominations

for representative positions on the Directing Board (due to

December 10, 1999) and the call for proposals for the positions of the Coordinators (Analysis, Network, Technology).

The elections were carried out in the period from December

15, 1998 to January 1999 via e-mail by the Associate

Members. The Steering Committee formed the Directing Board

on the basis of the elections, the proposals for Coordinators,

and the nominations for the At Large members. The Directing

Board held its first meeting on February 11, 1999 at Wettzell,

before the 13th Working Meeting on European VLBI.

The position of the Analysis Coordinator will be fitted by

autumn 1999. The task presently is being performed by NEOS

with a team consisting of Chopo Ma (GSFC), Marshal[ Eubanks

(USN0) and Nancy Vandenberg (CC).

4. Summary of Activities

As a first step to provide the information on IVS, the IVS web

site was set up and officially announced on March 1, 1999, the

official inauguration date of IVS (http://ivscc.gsfc.nasa.gov).

For access in Europe and in Asia, the web site is mirrored at

BK6 in 6ermany and at CRL in Japan (http://www. leipzig, ifag.

de/IVS and http://ivs.crl.go.jp/mirror).

A logo contest, with entries due June 1, was announced. The

decision on the official IVS logo will be made at the next

Directing Board Meeting (July 19,1999).

A sohcitation for IVS data and analysis was released (due April

15) in order to obtain proposals from the Operation Centers

and Analysis Centers on the provision of products as observational data products (correlation results), analysis products

such as Earth Orientation Parameters (EOPs), combined analysis products to become "official" IVS products, analysis functions e.g. comparison studies or new product developments.

A call for proposals for the Analysis Coordinator was included

in the solicitation.

A Coordinators meeting was held at 6SFC on April 8, 1999. The

purpose was to discuss the activities of each Coordinator.

Particular emphasis was placed on areas where the responsibilities of the Coordinators may overlap.

Preparations for the first IVS Annual Meeting have started.

The invitation and Call for Contributions is distributed separately. The 1st IVS 6enerat Meeting will be held in K6tzting,

6ermany, close to the Fundamentalstation Wettzell in the

period from February 21 to 25, 2000.

9
5. Prospects

Among the services IGS, ILRS and IVS, the latter one is the

youngest and was established a few months ago. Obviously a

lot of work is ahead of us. The primary goal is to coordinate all

the components to a highly reliable service, which guarantees

high quality and timely products on a Long term basis.

Emphasis has to be placed on the development of standards

for the components, in order to enhance the overall data quality, quantity and reliability.

Improvements have to be considered in the network configuration. Cooperation with related communities and standardisation of the data acquisition interfaces will increase the number

of network stations and will balance their distribution.

New developments in technology will accelerate data

exchange and will allow improvements in the degree of

automatisation for the operation of stations, the correlation

and the analysis. The implementation of the MK IV correlator

will soon open up new possibilities. The Coordinators will

carry an important role.

Transparency in the IVS decisions, strong cooperation and an

open exchange of information will play key roles in guaranteeing the success of the service. CLose cooperation with the

other services--considering our common objectives--is a

requirement.

Acknowledgements

On behalf of the Directing Board I appreciate the work which

has been done for the establishment of IVS and I express my

thanks to all who have contributed to the IVS startup and to

its successful operation so far. I express explicitly my thanks

to Prof. 6erhard Beufler, who initiated the transition to the

IVS, Dr. Thomas Clark and Prof. 3ames Campbell as the chairs

of the CST6 VLBI Subcommission during the transition period

from the Subcommission to the service, Dr. Nancy Vandenberg

for the coordination of the work, and the members of the

Steering Committee that was established for the transition

period. Thanks also to all who have contributed to this report.

References

Feisset, Marline led.); MERIT-Cotes Results on Earth Rotation

and Reference Systems, Bureau International de l'Heure, Section

de (a Rotation Terrestr, 0bservatoire de Paris, ParAs 1986.

Smith, David E. led.); Contributions of Space 6eodesy to

Geodynamics, Earth Dynamics, Geodynamics Series Volume 23,

24 and 25,American 6eophysica( Union, Washington, D.C. 1993.

10
REFERENC

FRAMES IN

VLBI

Reference Frames in VLBI Overview of VLBI

Overview of VLBI

Wayne Cannon

Space Geodynamics Laboratory

1. The Importance of Reference Frames

Modern geodetic techniques are expected to provide the observational basis for the systematic

investigation of a wide range of scientific questions including, among others:

• the motions, tectonic and otherwise, of the Earth's crust on local, regional, continental, and

global scales.

• the rotational dynamics of the Earth.

In general, scientific investigations of these phenomena proceed by the precise determination

of the position vectors and their time dependence of observation locations on the Earth's surface.

These determinations are carried out to a high precision (often as high as parts in 109 to parts in

101°) by a variety of geodetic techniques over many decades. In an effort to advance our understanding of many important geophysical phenomena it is often essential that high precision data

sets, realized by various geodetic techniques and acquired at times that are decades (and eventually even centuries) apart, be merged, analyzed, and interpreted in a coherent and self-consistent

manner. In general this sort of data analysis requires the combination of vector (and possibly

tensor) quantities, directly or indirectly, derived from the geodetic measurments. In combining

high precision vector and tensor quantities it is essential that the components of the vector and

the elements of the tensor are referred to a common set of fundamental basis vectors or

a common fundamental reference frame lest the procedure yield mathematically illogical and physically meaningless results. When very high precision geodetic measurments

are being analyzed in this fashion it is essential to find a solution to the question of a common

fundamental reference frame.

In order to serve the purpose required of it in the context of modern geodesy, such a common

fundamental reference frame must:

• be realizable to a precision of the order of parts in 101°

• be reproducible to a precision of the order of parts in 101° over time scales of centuries or

longer

2. Candidate Fundamental Reference Frames

Historically fundamental geodetic reference frames (Terrestrial Reference Frames) were attached to the surface of the Earth. Such frames of reference were of course rotating and their

use in dynamical applications required a precise measurment of the rotation vector of the reference frame. This required continuous monitoring of the Earth's rotation since the rotation vector

was time varying as a result of a variety of geophysical phenomena. In the modern context the

rotational motion of the tectonic plates of the Earth, at rates of the order of 1r/2 per 10s years

1999 IVS Annual Report 13
Overview of VLBI Reference Frames in VLBI

or roughly parts in 108 per year, renders this frame unstable on the times scales of interest and

precludes the use of the Earth's surface as a candidate for such a fundamental reference frame.

The practice of successful navigation at sea also imposed a requirement for the establishment

of a fundamental reference frame on the sky. The Celestial Reference Frame was defined by the

equator, ecliptic, and pole of rotation of the Earth and was realized by the estimates of the celestial

coordinates of stars in the Milky Way Galaxy. In the modern context the rotation of the Milky

Way Galaxy at rates of the order of 27r per 3 x 108 years or roughly parts in 10s per year combined

with the chaotic proper motions of stars renders this frame unstable on the time scales of interest

and precludes the use of the Milky Way Galaxy as a candidate for such a fundamental reference

frame.

Other inadequate candidates for the definition of a fundamental reference frame include the

orbital planes of passive compact satellites such as "Lageos" or "Starlette". These objects are

buffeted by the solar wind, are perturbed by the tidal forces of the Sun and Moon, are subjected

to the gravitational accelerations of time varying harmonics of the Earth's gravity field, and are

subjected to the gravitational accelerations of unknown high order harmonics of the Earth's gravity

field.

The orbital planes of active satellites such as GPS and GLONASS axe even less suitable for

the definition of a fundamental reference frame. Active satellites suffer from all the drawbacks

of passive compact satellites and have in addition the complications of large drag effects on solar

panels, orbital maneauvers imposed by ground controllers, and angular momentum dumps imposed

by ground controllers.

The present-day solution to the definition of the fundamental reference frame has been

found by retreating from the Earth to the edges of the known Universe and adopting a cosmological

frame of reference defined by a large number (400 to 600) of "bright" quasars and Active Galactic

Nucleii (AGNs) whose relative positions on the celestial sphere are estimated by Very Long Baseline

Interferometry (VLBI) measurements with an internal precision of the order of 0.1 to 0.2 milli-arc

seconds or a few parts in 101°. This suite of cosmological objects define what is referred to as the

International Celestial Reference Frame (ICRF). The ICRF has been adopted by both the IUGG

and the IAU as constituting the fundamental reference frame for astronomy, astrophysics,

geodesy, and geophysics. The ICRF is tied to the Equatorial or Dynamical Reference Frame

defined by the Vernal Equinox and the North Celestial Pole (NCP) with high (0.2 to 1.0 milli-arc

second) precision, largely as a result of the intrinsically high precision of VLBI measurements,

but with low (100 to 200 milli-arc second) accuracy), limited largely by the uncertainties in the

location of the Equinox and NCP within the Dynamical Frame.

3. VLBI Basics

The fundamental geodetic VLBI observable, "robs also known as the signal "delay", is the differential time-of-flight, between two VLBI antennas located on the Earth's surface, of broadband

microwave "noise" signals emanating from quasars or other cosmological radio sources. This is

an observable which depends only on fundamental physics, namely a realization of the atomic

second and a clock synchronization convention.

The VLBI signal delay Tob, is measured by amplifying, downconverting in frequency, and digitally sampling, the quasar signal at each antenna site with electronic signal processing devices

whose time, frequency, and phase information is derived coherently from an on-site atomic fre14 1999 IVS Annual Report
Reference Frames in VLBI Overview of VLB!

quency standard, usually a hydrogen maser. Figure 1 shows the basic geometry of VLBI and the

equipment used.

The digitally sampled quasar signals are recorded, o.. o .

along with precise station time information, by a

broad bandwidth digital data recorder and the recorded

tapes are subsequently delivered to a special pur- ", i:

pose VLBI correlator facility for cross correlation _:'-._ " - ,

processing. Cross correlation processing of VLBI .. : ,_

data requires continual and precise compensation, be- o,:

fore nmltiplication, for the changing differential time- " "_ '

of-flight and changing differential Doppler shift im- ".."

parted to the microwave signals by the rotation of

the Earth during the entire period of coherent integration. The relative delay at which the peak of the •

cross correlation function is found yields a value of _,,0g,.M,,,,(

robs.

As in all correlation functions, the width of the

central maximum of the VLBI cross correlation func- Figure 1. VLBI Concept. Original drawing

by John Hazen, modified by Hayo Hase.

tion is inversely related to the bandwidth of the signals being cross correlated. The precision with which the value of the signal delay robs may be

measured is given by 5robs and is related to the effective bandwidth Bef f of the cross correlated

signal by

1

arobs - SNR" BeII (1)

where SNR refers to the signal-to-noise ratio observed on the interference fringes and BefI refers to

the effective bandwidth of the recorded VLBI signals. In geodetic VLBI systems it is customary

to increase the effective bandwidth of the recorded signals beyond the limitation imposed by simple

considerations of the maximum bit rate and the Nyquist Sampling Theorem by recording a number

of widely spaced, relatively narrowband, RF signal channels; separately filtered from the broadband

quasar noise signal. In this way geodetic VLBI systems function by observing the microwave analog

of optical white light interference fringes with the attendant very small tolerance on relative

delay. As a typical example we shall consider Bef f = 700 MHz, SNR = 50, and (_rob s = 28

picoseconds which corresponds to about 8 millimetres of light travel distance. Modern VLBI

systems routinely measure the signal delay robs to a few tens of picoseconds.

The VLBI signal delay measured at the correlator, "robs, while dominated by the differential

time-of-flight of the quasar microwave signal between the radio observatories, does contain other

significant contributions that require attention. In general we may express the signal delay robs as

a sum of many terms

robs = rg + Taock + rinst + rtrop + rionos + rrel + "'" (2)

where, for example

• rclock is a contribution to the signal delay arising from the mis-synchronization of the reference

clocks at each observatory

1999 IVS Annual Report 15
Overview of VLBI Reference Frames in VLBI

• 7"last is a contribution to the signal delay arising from the propagation delays through on-site

cable runs and other instrumentation

• rtrop is a contribution to the signal delay arising from the propagation delays through the

non-ionized portions of the Earth's atmosphere.

• Tionos is a contribution to the signal delay arising from the propagation delays through the

ionized portions of the Earth's atmosphere.

• TreI are special and general relativistic corrections to the classical geometric delay Tg

All of these terms, with the exception of Tret, are to be considered from a geodetic VLBI perspective

to constitute small nuisance terms corrupting the classical geometric delay r 9. The effects of all of

these terms, including rret, must be accounted for and then removed by one of several methods:

1. direct computation from known physics, (Tret)

2. direct calibration (Tinst)

3. least squares estimation by modelling, possibly with the aid of locally measured input paraaneters, (Tattoos, Tclock )

4. direct removal by physical processes (rionos)

The classical geometric delay, Tg is defined implicitly by

_g(t) = 1_. [_2(t) - _l(t + _9(t))] (3)

C

where V1 and _2 are the geocentric (or solar system barycentric) position vectors of the radio

observatories and g is a unit vector in the direction of the source of radiation as seen from the

origin of the geocentric (or solar system barycentric) frame. Repeated determinations of rg(t) by

the sequential observation, in rapid succession, of many radio sources sk, k = 1, 2, 3,... results

in a data set sufficient to overdetermine the VLBI vector baseline b = f'2 - r'l. This data set is

analyzed by standard non-linear least squares methods to yield a high precision estimate of the

VLBI vector baseline, Earth orientation parameters (precession, nutation, polar motion, UT1),

station clock errors, as well as other quantities such as radio source positions etc that pertain

to the VLBI observation technique. The Earth orientation parameters are referred to the nonrotating 1 cosmological frame of the ICRF.

The ICRF is often described (erroneously) as constituting the "best definition of an intertial

frame" for the purposes of physics and astronomy. While the ICRF is an essential aspect of the

definition of an inertial frame, this wording suggests that the ICRF can be used to define a "global

inertial frame". This is an error and is a practice that should be discouraged. A desciption of the

ICRF that is in accord with relativistic physics would require the recognition that global inertial

frames do not exist. Local inertial frames however do exist and require for their definition a "local

standard of rest" that is provided by a state of free-fall and a "standard of non-rotation" that

1The adoption by the IUGG and IAU of the ICRF defined by VLBI and the use of the ICRF to define a standard

reference frame for the geodetic application of VLBI to the measurment of Earth orientation parameters is based

on an assumption that the Universe at large is non-rotating. Our present day understanding of modem physics

persuades us that this is likely to be the case. Kurt G5del has shown that if the Universe at large is rotating then

there exist closed, time-like world lines and it would be possible to travel into one's past; a feat generally considered

impossible.

16 1999 IVS Annual Report
Reference Frames in VLBI Overview of VLBI

is provided by the ICRF. The geocenter and the solar system barycenter are both in a state of

free-fall and are both suitable origins for a local inertial frame and both are used in the reduction

of VLBI observations. The essential role of the ICRF in both cases is to provide the requisite

"standard of non-rotation" required to establish the inertial reference frame.

The present-day repeatability of vector baseline determinations by VLBI techniques, between

radio observatories equipped with state-of-the-art VLBI systems, is of the order of a few millimetres

on baselines up to several thousand kilometers. A global network of geodetic VLBI observatories

carrying out routine VLBI measurments provide an essential contribution to the definition of

the International Terrestrial Reference Frame (ITRF) defined by a number of geodetic control

points, many but not all of which, are co-located with geodetic VLBI antennas, whose positions

and velocities within the ITRF are continually monitored.

1999 IVS Annual Report 17
The Celestial Reference Frame Reference Frames in VLBI

The Celestial Reference Frame

Chopo Ma

Goddard Space Flight Center

1. Introduction

The conceptual basis of reference frames defined by extragalactic objects is straightforward:

that the universe as a whole does not rotate so very distant objects cannot have an overall rotational

motion. Experimentally, the global rotation of the universe is less than 10 -12 arcsecond/yr as

inferred from the 3K microwave background radiation. At the distance of 108 parsecs, even if

an object were moving transversely at the speed of light, its angular velocity would be less than

0.6x10 -3 arcsecond/yr, while an object moving at a physically more reasonable speed comparable

to the Sun would show a motion of 10 -6 arcsecond/yr, entirely undetectable by current technology.

Since neither systematic universal motion nor random motion at such great distance is measurable,

it is reasonable to construct a static celestial reference frame on the basis that such objects are

fixed in the sky.

2. Historical Background

The idea of using extragalactic objects to define the celestial reference frame is quite old,

having been discussed by Herschel and Laplace some two hundred years ago, even before there was

proof that such objects existed. The discovery of external galaxies and their distances in the early

20th century raised the possibility of their use as fiducial objects for the celestial reference frame.

However, their fuzzy, faint optical images made it quite difficult, and astrometry continued to use

bright stars despite the complications of significant random and systematic motions. Fortunately

observations in the radio frequencies in the 1960s revealed a class of objects that has proven to

be suitable for astrometry of the highest order, albeit with some limitations. These are quasars,

compact radio sources which are pointlike in the optical band but with large red shifts implying

cosmological distances.

3. Use of the VLBI Technique

The technique for measuring the positions of quasars and similar objects is VLBI (very long

baseline interferometry). In this application, VLBI is a geometric technique that measures directions in space with great accuracy. Schematically, using a pair of distant antennas, the difference

in the time of arrival at the two stations of signals emitted by a radio source is measured with a

precision of a few picoseconds. For a typical baseline of 5000 km, this corresponds to a fraction of

a milliarcsecond. This time difference (delay) and its first derivative (delay rate) are reconstructed

by offiine correlation of the signals (actually radio noise usually buried in the thermal noise of the

electronics) recorded at the two ends of the baseline. A key piece of equipment at the stations is

the clock used to time events. VLBI makes use of hydrogen masers with stability of a part in 1014

for both time and frequency, and the raw data are recorded digitally at rates up to 1 Gbit/sec.

18 1999 IVS Annual Report
Reference Frames in VLBI The Celestial Reference Frame

In current practice a network of up to 20 stations observes 50-80 radio sources around the sky

multiple times during a 24-hr session. Since a delay and a delay rate are generated from each pair

of stations for each time a source is observed, there can be upwards of 20,000 delay/delay rate

data points from one observing session. VLBI observations suitable for high precision astrometry

began in the late 1970s with the development of dual- frequency receivers and the Mark III VLBI

data acquisition system, and an active worldwide observing program continues.

4. Analysis

The analysis of VLBI data for astrometric and geodetic purposes requires the estimation of

source positions, station positions, nutation corrections, and parameters characterizing the behavior of the clock and atmosphere at each station as well as careful modeling of all geophysical and

astronomical effects. Each separate session provides the relative positions of the observed sources

with some uncertainty. On different days different sets of sources are observed. It is the overlap

of some common sources from one day to another that connects all the positions together.

From all the overlaps and directly measured positions come the complete set of relative positions. Repeated measurements, either directly in one day or indirectly from different days, improve

the precision of the inferred positions. Having varied combinations of baselines and sets of observed sources strengthens the overall geometry and weakens the correlations between the source

coordinates and the numerous phenomena modeled in the analysis. In particular, a mixture of

north-south and east-west baselines is needed to determine both components of source position.

Since VLBI measurements give relative positions, the orientation of the ensemble of positions,

i.e., the pole and right ascension origin, must be determined from external information. This is a

necessary step in assigning the numerical position values that define the reference frame. In practice

the intermediate results are manipulated as the usual right ascension and declination values, but

the fundamental VLBI measurements are of the arclengths between sources, the precision of which

is contained in the full covariance matrix of the set of source positions. The earliest VLBI positions

in 1971 were no better than a few arcseconds, but by the mid 1980's a few milliarcseconds had

been achieved.

Unlike stellar astrometry, which must rely on a conventional theory of precession and nutation

to transform true of date coordinates to mean coordinates of the standard epoch, VLBI astrometry

is sensitive to the errors in the standard precession/nutation model, which amount to several

milliarcseconds. To achieve the full accuracy inherent in the stability of extragalactic positions, it

is necessary to allow for corrections to the precession/nutation theory. This can be accomplished

in two ways, either by adjusting the precession constant and various nutation coefficients or by

estimating the offset between the actual pole and the modeled pole for each day of observation.

5. Genesis of the ICRF

The process of laying the conceptual foundation for the extragalactic reference frame, identifying its fiducial objects, and developing the fundamental catalog was begun at the XXth IAU

General Assembly in Baltimore in 1988 by a resolution stating "The International Astronomical

Union should adopt a celestial reference frame based upon a consistent set of coordinates for a

sufficient number of extragalactic objects when the required observational data have been successfully obtained and appropriately analyzed .... This reference frame is likely to be based, initially

1999 IVS Annual Report 19
The Celestial Reference Frame Reference Frames in VLBI

at least, exclusively upon radio astrometry."

The Working Group on Reference Systems headed by J. Hughes was established with subgroups

for time (B. Guinot), coordinate frames and origins (J. Kovalevsky), astronomical constants (T.

Fukushima), and the theory of nutation (D. McCarthy). The fundamental concepts of what is

now the ICRF (International Celestial Reference Frame) were developed by the subgroups and

extensively discussed at the IAU Colloquium 127 on Reference Systems held in Virginia Beach in

1990.

The General Theory of Relativity for space and time, the use of extragalactic radio objects,

and the continuity between the existing stellar and the anticipated extragalactic celestial reference

frames were summarized in nine recommendations adopted as a resolution by the XXIst IAU

General Assembly in Buenos Aires in 1991.

A working group under C. de Vegt was formed to select the radio sources to be used with

emphasis on the need to connect the radio and optical frames.

The XXIInd IAU General Assembly in Den Haag in 1994 adopted the list of some 600 sources

and established a new working group under L. Morrison to define the positions. This work was

done by a subgroup of VLBI and celestial reference system specialists. The resulting ICRF catalog

was adopted by the XXXIIIrd IAU General Assembly in Kyoto in 1997 and came into effect on 1

January 1998, replacing the FK5.

A Working Group for the International Celestial Reference System (ICRS) under F. Mignard

was formed to carry on the ICRF work, to extend the frame to other objects and frequencies, and

to elucidate the consequences of the ICRF.

6. Definition of the ICRF

According to the new adopted rules, the fundamental directions of the celestial reference system

will remain fixed in space; they will no longer be dependent on modeling the motion of solar system

objects. The fiducial objects will be monitored. The adopted positions may be revised when

improved information is available, but the coordinate axes will be maintained by implementing

the statistical condition that the coordinates of selected defining sources show no global rotation

from the old set of coordinates to the new realization.

The data used to determine the ICRF radio source positions included 1.6 million pairs of dualfrequency delays and rates from 1979 through the middle of 1995. The data were contributed from

several geodetic and astrometric observing programs, the vast majority of the observations coming

from the former but most of the sources coming from the latter. The design of the analysis was

intended to provide (1995) state of the art source positions, in particular to free the results from

contamination from precession/nutation errors, anomalous source behavior, geodetic noise, and

systematic atmospheric effects. Simultaneous dual-frequency observations provided the calibration

of ionospheric dispersion. Celestial pole offsets in obliquity and longitude were estimated for each

day. Positions of sources with excessive scatter or apparent motion (as determined from test

solutions) were estimated separately for each day as were station positions. An elevation limit of

6 degrees was adopted to balance the need for maximum observing geometry against the difficulty

in correctly modeling the atmosphere at low elevations. Atmospheric gradients were estimated to

remove a significant systematic effect. Both delays and rates were used to maximize the information

available and to decrease correlations.

Because of the large number and high quality of observations, the formal errors for the positions

20 1999 IVS Annual Report
Reference Frames in VLBI The Celestial Reference Frame

were exceedingly small and not a meaningful measure of uncertainty. It was necessary to consider

several other effects to assign realistic errors. One was the statistical validity of the formal errors.

Another was the cumulative influence of all modeling errors and editing decisions. Yet another was

the magnitude of specific, identifiable errors that could have distorted the results. A consideration

of all known error sources indicated that a realistic error estimate could be made by inflating the

formal errors by a factor of 1.5 followed by a root-sum-square increase of 0.25 milliarcsecond. For

the most frequently observed sources the 0.25 milliarcsecond was the dominant error.

The sources from the ICRF solution were divided after the fact into three categories:

• 212 defining sources that met a series of quality criteria;

• 294 candidate sources that failed one or more of the quality criteria, e.g., too few observations

or observing interval too short;

• and 102 "other" sources (whose positions were estimated each day).

While the distribution over the sky of the ICRF as a whole is quite uniform (see Figure 1), the

defining sources are sparser in the southern hemisphere because of a dearth of VLBI stations and

limited observing programs. The "other" sources include a number with relatively bright optical

counterparts that could be used to connect the radio and stellar frames.

The axes of the frame were aligned to the International Earth Rotation Service (IERS) realization of the ICRS with an error of 0.020 milliarcsecond. The Hipparcos catalog, which is the optical realization of the celestial reference frame, was

aligned to the ICRF, largely through VLBI observations of radio stars. The ICRF also provides the

framework for various space geodetic techniques

to measure the terrestrial positions and velocities

that constitute the terrestrial reference frame and

to monitor variations in the rotation of the Earth.

The two chief phenomena leading to random

Figure 1. Distribution of ICRF sources.

and systematic errors in the ICRF are the atmosphere and source structure. While the propagation

delay at zenith from the dry atmosphere can be accurately calibrated from local meteorological

data, the dry delay in the line of sight to the observed source is subject to modeling error. The

delay from water vapor cannot be calibrated accurately, and both delays are subject to random

temporal and spatial fluctuations that must be estimated from the VLBI or other microwave data.

7. Source Structure

The quasars are not point radiators. Source structure can cause the position to appear slightly

different depending on baseline geometry, and changes in source structure can cause apparent

movement. Detailed source maps show that intrinsic variations in structure can be quite extreme,

ranging from relatively compact naked-core objects, to compact double sources, to complex corejet objects. The situation is complicated by the fact that compact extragalactic radio sources are

known to have variable intensity and to have frequency- and time-dependent intrinsic structure.

Consequently, unknown and unmodeled source structure effects may be introduced into the reference frame. The sources can be characterized after mapping by the degree to which the delay and

1999 IVS Annual Report 21
The Celestial Reference Frame Reference Frames in VLBI

delay rate are affected by the structure over the full range of possible baseline geometries, and the

worst sources can be rejected for most astrometric purposes.

8. Future Work

As of the beginning of 1999, 800 000 more observations including 50 new sources had been

acquired by geodetic and astrometric programs since the ICRF was constructed in 1995. These

need to be integrated with the data and analysis used for the ICRF to update the original catalog.

The original ICRF analysis need not be copied exactly to incorporate new data, but the new

positions must be consistent with the ICRF at its stated level of accuracy, 0.25 milliarcsecond in

overall source positions and 0.020 milliarcsecond in orientation.

Positions will be determined for new sources, and updated positions and errors will be found

for candidate sources with additional observations. The positions and uncertainties of the defining

sources will not be changed since they are the actual realization of the ICRF, and the work to

include more recent data does not lead directly to the replacement of the existing ICRF. The

defining sources will be used in a no-net-rotation condition relative to the ICRF to assure that

positions from new analyses are aligned with the ICRF.

There are several features that distinguish the ICRF from conventional stellar catalogs that

formerly defined the celestial reference frame.

1. First, the quasars are optically faint so connection to the stellar frame is complicated.

2. Second, while the positional history of the radio sources is known, the results of future

observations cannot be predicted. Consequently, new sources must be observed to replenish

and expand the list of candidates.

3. Third, as new observations accumulate, it should be possible to move candidate sources up

or down the scale of usefulness in subsequent ICRF realizations.

The problem of position changes related to source structure variation may be solved in the

future if the application of source structure information permits the identification and use of truly

kinematically static points in the sky. Since the original VLBI delay and delay rates are accessible,

they can always be reused in improved analysis. When models and estimation techniques are

significantly improved and sufficient data are accumulated, a new ICRF can be constructed de

novo.

A detailed reference about the ICRF may be found in Ma C, Arias E F, Eubanks T M, Fey A

L, Gontier A-M, Jacobs C S, Sovers O J, Archinal B A, Charlot P 1998 The International Celestial

Reference Frame Realized by Very Long Baseline Interferometry Astron. J. 116 516-546.

22 1999 IVS Annual Report
COORDINATION

From the Terms of Reference:

Coordinating Center

The IVS Coordinating Center is responsible for coor_

dination of both the day,o-day and the long-term

activities of IVS, consistent with the directives and

policies established by the Directing Board.

Specifically, the Coordinating Center monitors, coor_

dinates, and supports the activities of the other IVS

components. The Coordinating Center works closely

with the Technology Coordinator, the Network

Coordinator, and the Analysis Coordinator to coordinate all IVS activities.

Technology Coordinator

The Technology Coordinator is responsible for coordinating the new technology activities of IVS and for

stimulating advancement of the VLBI technique.

Network Coordinator

The Network Coordinator is responsible for stimulating the maintenance of a high quality level in the station operation and data delivery.

Analysis Coordinator

The Analysis Coordinator is responsible for coordinating the analysis activities of IVS and for stimulating

VLBI product development and delivery.

NASA Goddard Space Flight Center/NVI, Inc. Coordinating Cenh:r

IVS Coordinating Center Report

Nancy Vandenberg

Abstract

This report summarizes the activities of the IVS Coordinating Center since the establishment of

IVS, and forecasts the activities planned for the coming year.

1. Coordinating Center Operation

The IVS Coordinating Center 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 main mission of the Coordinating Center is to provide communications and information

for the IVS community and the greater scientific community. The Coordinating Center coordinates

the day-to-day and long-term activities of IVS.

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

http://ivscc, gsfc. nasa. gov

2. Initial Activities

During the few months before and after the official inauguration of IVS, the Coordinating

Center supported the following IVS activities:

Feb. 11 Arranged the first IVS Directing Board meeting at Wettzell, Germany. Notes

from this meeting were published on the IVS web site.

Mar. 1 Set up the IVS web site at http://ivscc.gsfc.nasa.gov. The web site is

the primary means of providing communication and information services to

the IVS community.

Mar. 5 Set up a mail system for IVS. All mail is archived and can be read on the

web site. The address ivsmail@ivscc.gsfc.nasa.gov is used for messages of

general interest to the whole community.

Mar. 8 Announced a contest for the IVS logo, and posted the logos for viewing on

the web site.

Mar. 29 Initiated mirror sites for the IVS web site at Communications Research Laboratory in Japan and Bundesamt fiir Kartographie und Geod_ie in Germany.

The mirrors enable quicker connections for colleagues around the world.

Apr. 8 Hosted a meeting of the IVS Chair and Coordinators. Notes from this meeting were published on the IVS web site.

June Coordinated the receipt of contributions to the first IVS Annual Report.

July 19 Arranged the second IVS Directing Board meeting at Birmingham, England.

July Published the first IVS Annual Report (this volume), covering the period of

the year prior to the establishment of IVS.

1999 IVS Annual Report

25
CoordinatingCenter NASAGoddardSpaceFlightCenter/NVI, Inc.

3. Staff

The staff of the Coordinating Center is drawn from individuals who work at Goddard and

USNO. The staff and their responsibilities are:

Name

Nancy Vandenberg

Cynthia Thomas

Frank Gomez

Merri Sue Carter

Karen Baver

new hire

Title

Director

Operation

Manager

Web Manager

Web Support

Programmer

Publication

Support

Programmer

Data Technician/Programmer

Responsibilities

Web and data base design and

content, Directing Board support,

meeting support program,

publications

Master schedule, resource

management, session web pages,

meetings support, special sessions

support

Web server administration, mail

system maintenance, discussion

system maintenance, data center

support, session processing scripts,

mirror site liaison

Web site maintenance, configuration

files maintenance

Publication processing programs

Data base maintenance and

programming, site catalog inputs,

report production, product delivery

support

50%

50%

]0%

lO%

100%

1 Plans

During the period until March 1, 2000, the Coordinating Center plans to do the following:

• Work with the Canadians who will manage a web site for IVS analysis functions.

• Enhance the web site with links to IVS-coordinated observing sessions.

• Establish electronic discussion groups on topics of interest to the IVS community.

• Update the site catalog maintained by GSFC.

• Establish web access to the IVS data base of information.

• Set up configuration files for all IVS components.

• Coordinate the first IVS General Meeting, to be held in KStzting, Germany, February 21-25,

2000.

• Publish the proceedings of the first IVS General Meeting.

1999 IVS Annual Report

26
NEOS Analysis Coordinator

Analysis Coordinator Report

Marshall Eubanks, Chopo Ma, Nancy Vandenberg

Abstract

This report describes the activities of the IVS Acting Analysis Coordinator team. Activities planned

for the coming year are forecast.

1. Initial Activities

The National Earth Orientation Service (NEOS) was appointed as Acting Analysis Coordinator

at the first IVS Directing Board meeting because there had been no proposal received for this

position. NEOS is a joint activity of the U.S. Naval Observatory and NASA's Goddard Space

Flight Center for VLBI.

The authors of this report form a team that has been performing the work of Analysis Coordinator. We plan to turn over a smoothly running system when the new Analysis Coordinator is

selected.

Our first activity was to write a solicitation for IVS data products and analysis products. The

solicitation was announced on March 10 and proposals were received by April 15. The purpose of

the solicitation was to obtain the commitment of IVS components for providing data and analysis

products on an continuing, operational basis.

Next we developed a draft data and products plan that laid out a proposed disk structure

and procedures. Comments were received about the plan from various members of the IVS analysis community and changes in the data structure and the procedures were made based on the

suggestions received.

We worked with the primary IVS Data Centers OPAR (Paris), CDDIS (GSFC), and BKG

(Leipzig) to develop a script that verifies data and analysis submissions and then moves the files

into the IVS data structure. A plan was coordinated for these Data Centers to mirror each

other's holdings so that all IVS data and product files will be accessible at all three Data Centers.

We coordinated with the IVS Operation Centers to begin submitting data to the Data Centers

operationally. The Team is monitoring the flow of data and products to ensure that this new

service functions smoothly.

2. Plans

For the immediate future, we recognize that the most work needs to be done in establishing

communications between IVS Analysis Centers. We will set up an electronic discussion group to

discuss work in progress such as troposphere modeling, syles of parameterization, and so on.

Coordination with the other services is a very important activity. We will make contact with

the IGS and ILRS Analysis Coordinators and identify topics of mutual interest such as colocation

difficulties, definition of the TRF, and problems specific to each technique. We will work with the

IGS and ILRS Analysis Coordinators and with the members of the IVS teams who proposed to be

active in these topics. We will also work with the new IERS Analysis Coordinator.

1999 IVS Annual Report 27
AnalysisCoordinator NEOS

There have been informal proposals for a new data exchange and archiving format. We plan

to initiate discussions on this topic and develop a formal proposal.

We are receiving analysis products at the IVS Data Centers and several IVS Analysis Centers

have begun the work of combining the individual contributions into a single product. We encourage

this activity and we are monitoring the process. A consensus still needs to be reached about what

constitutes the official IVS products.

We plan to hold an analysis workshop to establish coordination among the many analysis

activities of IVS. The workshop will be an opportunity to exchange ideas and expertise on various

aspects of analysis techniques and results.

28 1999 IVS Annual Report
NASA Goddard Space Flight Center Network Coordinator

Network Coordinator Report

Ed Himwich

Abstract

The Network Coordinator (NC) is responsible for assuring high quality data are produced by the

Network Stations (NS). This report identifies the Network Coordinator and discusses some of the

history of efforts to assure high quality data and some of the new initiatives that will be put into place.

The NC also acts as liaison to the observational astronomical VLBI community and as an advocate for

the IVS NS with the IVS organization.

1. Network Coordinator

The initial IVS Network Coordinator (NC) is Ed Himwich. He has over 17 years experience in

many aspects of geodetic VLBI including: operations, control software development, experiment

and logistical coordination, data analysis software development, data analysis, management, and

scientific research.

Himwich works at NASA Goddard Space Flight Center. At this location he is able to work

closely with the Core Operations Center, GSFC Analysis Center, GSFC Technology Development

Center, and the IVS Coordinating Center. Being located at GSFC also provides access to a variety

of work stations, personal computers, and peripherals. In addition, an absolutely mandatory high

speed connection to the Internet is available.

2. Status of Network Coordination

There was no such position as Network Coordinator prior to March 1, 1999. However, several

people, Ed Himwich among them, were carrying on many of the functions on an informal basis.

They monitored the status of the experiments, correlation, and data analysis for problems. They

contacted station personnel to help them resolve problems or refer them to the individuals who

could help them. They visited stations to provide training, install upgrades, suggest improvements,

as well as carry feedback back to the technology development centers. They worked closely with the

European VLBI Network on Field System software and operations development. When necessary

they would act as an advocate for stations when requirements were being developed that seemed

unreasonable or problems were not getting the resources needed for their resolution.

3. Outlook

This year will be the first one of activity for the Network Coordinator (NC) as such. It

is expected that most of the work existing will continue. However, now it will be a formally

recognized activity. In addition there will be new initiatives that are carried out under the IVS

banner.

The new initiatives will include development of performance standards, monitoring operations,

Web plots, and station visits. In order to help each station achieve high quality in their data, we

plan to develop performance standards for hardware, software, and operations. These will provide

1999 IVS Annual Report 29
Network Coordinator NASA Goddard Space Flight Center

a set of specifications that the stations can use to verify that their performance is nominal. If the

performance is not nominal, the standards will provide a goal for improving performance.

The "ivs-ops" mail list, correlator reports, and analyst reports will be monitored for signs of

problems. The NC will contact the network stations (NS) to help resolve these problems. The NC

will attempt to help resolve the problem or will try to make sure the NS get in contact with people

who can. This is not really a new initiative, but now is included as part of the responsibilities of

the NC.

There will a Web based plotting system for display of ancillary data from the logs. In addition

to providing an easily accessible historical archive, this should make it easier to isolate and identify

problems.

The need for people from technology development centers to visit stations is clear. Not only

does this provide an opportunity for additional training and hardware and software "tune-ups", but

it provides an opportunity for more direct feedback to the technology development centers about

problems that have been encountered. Unfortunately because of time and money constraints it is

difficult to have all the stations visited as often as we would wish, at least once every three years.

These visits axe a resource to all the stations, not just the ones visited. In order to get as much

advantage as possible from these visits, a Web page will be developed that will chronicle the visits.

This should make it easier for other stations to benefit from new developments and insights that

come out of the visits.

Coordination of station operations between geodesy and astronomy is especially important at

stations that make both types of observations. A great deal of progress in this area has been made

by standardizing the control software used and harmonizing the use of schedules. This work will

continue. Several improvements are coming in the FS that will further unify operations and benefit

both communities. In particular mode independent parity check procedures and automated Tsys

measurements will benefit all users. The EVN continues to be one of the largest users of the FS.

We expect the geodetic community's collaboration with them on FS development to continue.

The role of NC as an advocate for the NS is not intended to displace existing channels of

communication. NS will still deal with the same people (including the NC) for schedule, operations,

and maintenance issues. However, if a NS has a problem that is not being resolved or wishes to

raise an issue at a higher level, the NC is an appropriate first contact for additional assistance.

The NC is the one person within the IVS specifically charged with looking out for the stations'

interests as a whole.

Another initiative that will be started is that each station will be asked to designate one person

to be the "Friend of Geodesy". This is intended to be in the style of the EVN's "Friend of VLBI" for

astronomy. The duties of this person will be explained more fully in the call for these designations,

but basically this person would act as the primary contact at the station for issues dealing with

geodetic VLBI.

30 1999 IVS Annual Report
MIT Haystack Observatory Technology Coordinato,

Technology Coordinator Report

Alan Whitney

Abstract

The main initial effort of the Technology Coordinator has been participation in the development of a

VLBI Standard Interface. Future plans include formation of technology study groups and compilation

of an index of VLBI technology papers.

1. VLBI Standard Interface

The primary focus of efforts for the past few months has been the development of a "VLBI

Standard Interface" (VSI) specification which will allow the transmission of data to and from

heterogeneous VLBI Data Transmission Systems (DTS). The goal is to define the interface to

be compatible with traditional recording/playback systems, 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 mechanism and deal only with the interfaces to the outside

world.

The following assumptions are being 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 in 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.

A committee consisting of representatives from technical development centers in North America, Europe, Japan and Australia is actively reviewing and expanding the draft proposal. The

effort is being fully coordinated with the international astronomical VLBI community as well,

with the goal of a unified standard interface for all VLBI activities worldwide. We hope that an

agreed standard interface definition can be reached by the end of 1999.

2. Other Activities

Other planned and ongoing activities in the technology coordination area are:

1. Formation of a few small subgroups with interests 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-mall, 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 as a prototype for this type of activity.

1999 IVS Annual Report 31
MIT Haystack Observatory

Technology Coordinator

2. Compilation of an index of published papers and memos in all of the relevant VLBI technology

axeas. Ideally, this will be a Web-based index with links to electronic versions of the referenced

material. The members of all IVS Technology Development Centers, as well as other experts

in the field, will be invited to contribute. This activity is planned to be formally initiated in

the latter half of 1999.

3. Promotion and encouragement of the inclusion of topical sessions on advanced VLBI technology at international meetings and workshops.

1999 IVS Annual Repo_ L

32
NETVVORK

STATIONS

From the Terms of Reference:

The IVS observing network consists of high

performance VLBI stations.

• Stations can be dedicated to geodesy

or have multiple uses (including astronomical observations or satellite

tracking applications).

• Stations comply with performance

standards for data quality and operational reliability 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.

Geodetic Survey Division, Natural Resources Canada Algonquin Radio Observatory

Algonquin Radio Observatory

Mario Bdrubd, Calvin Klatt

Abstract

This report gives an overview of the activities at the Algonquin Radio Observatory. It also summarizes the technical parameters and upgrades done to improve the antenna performance. Finally, the

Algonquin VLBI team is introduced.

Figure 1. Algonquin Radio Observatory 46m Antenna

1. Overview

The Algonquin Radio Observatory (ARO) is situated in Algonquin provincial park, about

250 km north of Ottawa. The 46-m telescope was built and operated by the National Research

Council (NRC) of Canada and began operations in May, 1966. At the current time the ARO is

operated by the Geodetic Survey Division of Natural Resources Canada in partnership with the

Space Geodynamics Laboratory, CRESTech.

The ARO 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 Alto and a telescope in Prince Albert,

1999 IVS Annual Report

35
Algonquin Radio Observatory Geodetic Survey Division, Natural Resources Canada

Saskatchewan was measured to be 2143 km (sigrna=20 m). The antenna participated in the

NASA CDP and DOSE programs beginning in 1984. A long term loan of a Mark III terminal from

NASA in 1989 makes it possible to participate regularly in VLBI observations in support of the

maintenance of the celestial and terrrestrial reference frames in the CORE and NEOS series. 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.

The Algonquin Radio Observatory Act protects the site from radio interference. This protection

extends to a few hundred kilometers, making Algonquin a very quiet site.

2. 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 0.634 cm steel plates surrounded by

4.6 m of steel mesh.

Foci : S and X band at prime focus. Gregorian capability with 3 m elliptical subrefiector.

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 (10 Ghz)

Azimuth speed : 24 degrees per minutes.

Elevation speed : 10 degrees per minutes.

Receiver : S and X cryogenic receiver.

VLBI equipment : Mark III with thick tape drive.

terminal.

• PCFS version : 9.3.7

• Time standard : NR Maser

$2 data acquisition and recording

• GPS receiver : Rogue

3. Antenna Improvements

In order to improve the operational performance of Algonquin, GSD undertook a major upgrade

of the antenna control system which was completed in 1997. For high precision tracking of radio

sources the original control system used a Master Equatorial (ME) system to control the 46-m

antenna. In recent years this system became unreliable and had to be replaced. In the new system

1999 IVS Annual Report

36
Geodetic Survey Division, Natural Resources Canada Algonquin Radio Observatory

the azimuth and elevation drives are directly controlled by computer. This greatly simplifies the

control system and has produced a major improvement in the reliability of the Algonquin antenna.

This antenna control system still uses the original azimuth and elevation encoders to determine

antenna position. In the next year, we are planning to upgrade them in a way that should not

affect scheduled operations.

4. Antenna Survey

The antenna is surrounded by a high stability network made of 13 concrete piers. This network

has been precisely measured four times to obtain the geodetic tie between the VLBI, the GPS and

the SLR reference points with a precision of few mm. The VLBI antenna itself requires a special

indirect survey since the reference point cannot be accessed directly.

Figure 2. Algonquin Antenna with co-located GPS Antenna

This year we are planning to re-measure the network. In addition to tying GPS and SLR to

VLBI, we will be doing a special survey to determine the antenna deformation a_s a function of

elevation angle.

1999 IVS Annual Report 37
Algonquin Radio Observatory Geodetic Survey Division, Natural Resources Canada

5. Algonquin VLBI team

The Algonquin VLBI team has a very diversified background with many years of experience

in VLBI. The team is based in Ottawa, 250 km from the Algonquin antenna. Using satellite

communication, the team can monitor the Algonquin site from its office in Ottawa. For a VLBI

experiment, three members of the team drive to the site a day in advance to check the antenna

and the VLBI equipment. At the same time they perform general maintenance of the site. All

members are experienced VLBI operators.

• Maxio B@rub6 : (50%) station programming, geodetic data analysis

• Sylvain Brazeau : (90%) electronics, cryogenic, RF, VLBI equipment

• Mike Daniels : (75%) data quality, masers, VLBI equipment, gravity

• Stephen Farley : (90%) VLBI logistics, site operations, Linux

• Calvin Klatt : (10%) VLBI data analysis, scheduling

• Jacques Lafrance : (50%) high precision survey, transportable antenna

Contractor

• Normand Servant : Site maintenance and VLBI operations

Consultants

• Doug Sparkes : Electronics engineer for antenna control system

• Don Buchan : Mechanical engineer for antenna

6. Operations 1998-1999

Algonquin Radio Observatory is involved in several international VLBI networks. We summarize below the activities in the past year.

• CORE-A 26

• NEOS 15

• CORE-B 6

• MARS 5

• CGLBI 5

• NAPS 2

38 1999 IVS Annual Report
Centro de RAdio-Astronomia e Aplica_6es Espaciais (CRAAE) ROEN - Fortaleza Geodetic Station

Progress at ROEN - Fortaleza Geodetic Station

Pierre Kaufmann, A. Macilio Pereira de Lucena, Claudio E. Tateyama

Abstract

This report present the works developed at ROEN: R,4dio-Observat6rio Espacial do Nordeste,

Eus_bio near Fortaleza, CE, Brazil, in 1998. Activities were related to observing sessions, major

maintenance items, and scientific results obtained.

1. ROEN General Information

The North-East Spatial Radio Observatory, ROEN, located at INPE facilities in Eus_bio, nearly

30 km east from Fortaleza, Cear£ State, Brazil, began operations in 1993. Geodetic VLBI and GPS

observations are carried out regularly, as contributions to international programs and networks.

ROEN is part of the Brazilian space geodesy program coordinated by CRAAE, the Center for

Radio Astronomy and Space Applications, which is a consortium between Brazilian institutions

Mackenzie, INPE, USP and UNICAMP. Construction and activities at ROEN were sponsored at

the beginning by U.S. agency NOAA and Brazilian Ministry of Science and Technology's FINEP

agency. Presently the operational staff and part of infra-structure is maintained by INPE and by

Mackenzie, the other costs of technical maintenance, part of infra-structure, are sponsored by US

agencies NASA, USNO and NOAA.

2. Technical Parameters of ROEN Facilities

The largest instrument of ROEN is the 14.2 m radio telescope, on one alt-azimuth positioner.

It is operated at S- and X-bands, using cryogenic radiometers. The system is controlled by Field

System, Version 8.27. Observations are recorded with a Mark III data acquisition system. One

Sigma-Tau hydrogen maser clock standard is operated at ROEN. One dual frequency GPS Rogue

receiver is operated continuously. The collected data are provided to the IGS center, as well to

Brazilian IBGE center. ROEN has all basic infrastructure for mechanical, electrical and electronic

maintenance of the facilities.

3. CRAAE and ROEN Staff Dedicated to Space Geodesy

The Brazilian space geodesy program, conducted by CRAAE, is coordinated by Prof. Pierre

Kaufmann, from the S_o Paulo main office, receiving scientific assistance from Dr. Claudio E.

Tateyama, and partial administrative support from Valdomiro S. Pereira and Neide Gea. Partial

technical assistance might be given by Itapetinga Radio Observatory staff, near S£o Paulo.

The ROEN station facilities and geodetic VLBI and GPS operations are managed by Eng. A.

M. P. de Lucena (CRAAE/INPE), assisted by Eng. Adeildo Sombra da Silva (CRAAE/Mackenzie), and technicians Avicena Filho (CRAAE/INPE) and Clairv£nia Maria Anast_cio da Silva

(CRAAE/Mackenzie). Partial administrative assistance is given by Onivaldo Assun_£o de Freitas

(CRAAE/INPE).

1999 IVS Annual Report 39
ROEN - Fortaleza Geodetic Station Centro de R,4dio-Astronomia e Aplica&Ses Espaciais (CRAAE)

Figure 1. The 14.2-m antenna located in Eus4bio near Fortaleza

, Status for 1998/1999

• Geodetic VLBI observations. ROEN has participated in 91 VLBI observational runs until

March 1999 on experiments NEOS-A (52), IRIS-S (12), CORE-B (11), CRF (3) and COREOHIG (3).

• Development and major maintenance. (1) Antenna positioner: replacement and repair of

large elevation gear box, mechanical alignment of elevation axis, electrical alignment including

controller card, high power amplifier, DC motors and tachometers for both axes, new pointing

model was implemented. (2) Repairing jobs on four Mark III video converters, current

monitoring of power conversion station, controller of power motor-generator group, 14 bit

tracking converter card of shaft encoder, display controller of the UPS, and spectrum analyser

unit. (3) Installed internet connection, with server, router, 64 kbs radio link via INPE

at Natal. (4) New thermal dissipation system done, in order to prevent corrosion in the

inductosyns.

• Scientific papers using ROEN:

1. Tateyama, C.E., Kingham, K.A., Kaufmann, P., Piner, B.G., de Lucena, A.M.P., Botti,

L.C.L., "Observations of BL Lacertae from the Geodetic VLBI Archive of the Washington Correlator", ApJ 500, 810, 1998.

40 1999 IVS Annual Report
Centro de Rhdio-Astronomia e Aplicaq5es Espaciais (CRAAE) ROEN - Fortaleza Geodetic Statio,

2. Tateyama, C.E., Kingham, K.A., Kaufmann, P., Piner, B.G., Botti, L.C.L., de Lucena,

A.M.P., "Observations of OJ287 from the Geodetic-VLBI Archive of the Washington

Correlator", ApJ 520, scheduled for August 1, 1999.

3. Almeida, A.A., Vilas-Boas, J.E.S., Lucena, A.M.P., Huebner, W.F., "On an Upper

Limit to the Continuum Microwave Radiation from Comet C/Hale-Bopp(1995 O1)",

Icarus, submitted, 1999.

5. Plans for 1999/2000

Plans are for keeping ROEN regular operations along the following year, with a number of

essential improvements needed. Prospects for obtaining funds to upgrade data acquisition system

to Mark IV axe expected to improve.

1999 IVS Annual Report 41
Gilmore Creek Geophysical Observatory (GCGO) National Earth Orientation Service

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.

1. GCGO at Fairbanks

Gilmore 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 on an 8,500 acre reservation that is mostly undeveloped wilderness.

Ten antennas are in operation. The GCGO telescope can be seen in Figure 1 as the last antenna

on the right in the valley. GCGO was instrumented by NASA's Crustal Dynamics Project in the

mid 1980s 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.

Figure 1. NOAA/NASA Data Acquisition and Geophysical Observatory. Fairbanks, Alaska

Table 1. Address of GCG0 near Fairbanks.

Gilmore Creek Geophysical Observatory

NOAA/NESDIS FCDAS

1300 Eisele Road

Fairbanks, AK 99712

http ://www.fcdas.noaa. gov

2. Technical Parameters of GCGO

The 26 meter telescope is hydraulic operated and controlled by a Modcomp computer system

(see Table 2). The DAT rack is a VLBA terminal and recorder (thin tape). The X/S band

1999 IVS Annual Report

42
National Earth Orientation Service Gilmore Creek Geophysical Observatory (GCGO)

Figure 2. GCGO 26-meter radio telescope, Fairbanks, Alaska. Monument number 4047. X-East Y-North.

Latitude N 64° 58' 43.81288" and Longitude E 147 ° 29' 42.18552" Height 306.418 meters

microwave receiver has a cryogenic low noise front end. VLBI Field System version 9.3.25 is

used with a PC. Hydrogen Maser NR5 is the time standard with a HP Cesium for the telescope

computer. A TAC receiver is used with a HP 5334 counter for GPS offset measurements. The

station also runs NASA/JPL Rogue receiver 8100 running software v. 3.2.32.8. UCLA maintains

the HIPAS system located in the GCGO and currently is operating an ionosonde. The Institut

Geographique National in France operates the DORIS beacon that is located near the NOAA

transmitter area.

3. Staff of the Gilmore Creek Facility, Fairbanks, Alaska

GCGO is a major NOAA data collection facility and does not have a science staff. The NOAA

Manager is Jim Budd. The site is operated by the Lockheed Technology Services Group with

Doug Ooms a.s Lockheed Project Manager and Mike Simmons as Lockheed Operational Manager.

1999 IVS Annual Report 43
Gilmore Creek Geophysical Observatory (GCGO) National Earth Orientation Service

Table 2. Technical parameters of the GCGO

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

Ts_s

SEFD(CASA)

G/T

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 J y

35.3 dB/K

8.1 - 8.9, GHz

58K

550 Jy

44.5 dB / g

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 W. Powell.

4. Status of Gilmore Creek Geophysical Observatory

Gilmore Creek continues to observe in the CORE, NEOS, and RDV experiments. Yasuhiro

Koyama arrived on site Jan/Mar to install the K4 DFC2100 for K4TIE observing. GCGO was

used for Mars Pathfinder and USNO intensive as well as fringe sessions for equipment verification

checks for other stations. The NASA/JPL Rogue receiver was replaced in June. It is now running

Y2K compliant software. The Doris beacon was reprogrammed by station staff to continue support

of precision satellite-based orbit determination. The VLBI receiver was pulled from the telescope

several times this year for dewar repair. D. Rhine, Allied-Signal, arrived on site in September for

maser preventive maintenance. PRARE satellite tracking instrument failed in June and has been

shipped to Germany for repair. Field system software development continues by Ed Himwich,

NVI, using the station's DAT racks for testing. The majority of Gilmore Creek's data loss has

been due to telescope hydraulic failures.

Table 3. VLBI observing at Gilmore Creek between 03/01/98

Experiments assigned to GCGO - 101

Observations scheduled - 27757

Observations recorded - 27078

Efficiency - 97.55%

and 03/01/99.

1999 IVS Annual Repmt

44
National Earth Orientation Service Gilmore Creek Geophysical Observatory (GCGO)

5. Outlook

Increased observing in CORE program is scheduled. RFI studies are being completed due to

full time operation of a gold mine near the station. Plans are being made to move this observatory

to the NOAA operations building and installing a new 20 meter electric drive telescope.

References

[1j C.Ma, J.Sauber, L.Bell, T.Clark, D.Gordon, W.Himwich, and J.Ryan Measurement of Horizontal Motion in Alaska Using VLBI 1990, In: Journal of Geophysical Research, vol 95, No.B13, Pg 21991-22011,

December 10,1990

1999 IVS Annual Report 45
Goddard Geophysical and Astronomical Observatory NASA Goddaxd Space Flight Center

Goddard Geophysical and Astronomical Observatory

Rawland Cowey, Charles Kodak

Abstract

This report summarizes the technical parameters and the technical staffof the VLBI system at

GGAO. It also gives an overview of VLBI activitiesduring the previous year. The outlook liststhe

tasks planned for 1999.

1. GGAO at Goddard

The Goddard Geophysical and Astronomical Observatory consists of a radio telescope for VLBI,

several SLR sites including a 48" telescope for developmental Satellite Ranging, a GPS timing and

development lab, meteorological sensors and a H-maser clock. In addition, we are a fiducial IGS

site with several IGS 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.

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 as 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

1999 IVS Annual RepoL

46
NASA Goddard Space Flight Center Goddard Geophysical and Astronomical Observatory

Table 1. Location and addresses 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

• 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).

The technical parameters of the radio telescope are summarized in Table 2.

Table 2. Technical parameters of the radio telescope of GGAO for geodetic VLBI.

Parameter

owner and operating agency

year of construction

diameter of main reflector d

azimuth range

azimuth velocity

azimuth acceleration

elevation range

elevation velocity

elevation acceleration

GGAO-VLBI

NASA

1982

5m

0...540 °

3°/s

l°/s 2

0... 90 °

3°/s

l°/s 2

X-band 8.18 - 8.98 GHz

Cassegrain f ocus

24K

800MHz, -2dB

32.1dB/K

receiving feed

Tsys

Bandwidth

G/T

S-band 2.21 - 2.45GHz

receiving feed

Tsys

Bandwidth

G/T

primary focus

19K

240 M H z, - 2dB

21.2 dB/K

Mark IV I

thin-tape only

9.3.25

VLBI terminal type

recording media

Field System version

1999 IVS Annual Report 47
Goddard Geophysical and Astronomical Observatory NASA Goddard Space Flight Center

3. Technical Staff at GGAO

The GGAO VLBI facility gains from the experiences of the Goddard VLBI group. GGAO is a

NASA R&D and facility, operated under contract by AlliedSignal Technical Services Corporation

(ATSC).

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 Background Dedication I Company

Rawland Covey engineering technician 100% I ATSC Jay Redmond engineering technician 20% ATSC

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 the table MV3 has participated in several unscheduled experiments

for VLBI developmental purposes and various other developmental activities.

Table 4. Participation of GGAO in VLBI Experiments from February 1, 1998 to March 1, 1999.

Date

1998-02-09

1998-04-15

1998-06-24

1998-08-10

1998-09-01

1998-10-01

1998-10-06

1999-02-02

Experiment

RDV07

RDV08

RDV09

RDV10

NA279

RDV 11

NA284

NA301

5. Outlook

GGAO will continue to support both scheduled experiments and developmental activities. Our

scheduled experiments have been shifted from the RDV's to the NEOS-A throughout 1999.

The plan for 1999 consists of:

1. Continuing testing of PC-FS version 9.3.25 based on Linux kernel 2.0.

2. Testing of the Mark IV decoder prototype.

3. Continuing with research on Mark IV development.

4. Continually striving to improve the performance of the entire receive system.

48 1999 IVS Annual Report
National Radio Astronomy Observatory (NRAO) USNO Green Bank 20-meter telescope

USNO Green Bank 20-Meter Telescope

Frank Ghigo

Abstract

NRAO-Green Bank has been operating a 20-meter telescope for the USNO Earth orientation

program since 1995. This report summarizes the characteristics of the system and its activities

from 1995 to the present. One may also find information in the NRAO-Green Bank web page:

http://www.gb.nrao.edu/fgdocs/20m/GB20m.html

1. Introduction

The NRAO-Green Bank 20-meter telescope is operated by the National Radio Astronomy

Observatory (NRAO) under contract with the U.S. Naval Observatory (USNO), in support of

USNO and NASA Earth Orientation, geodetic, and astrometric VLBI programs.

The 20-meter was built by RSI and completed in late 1994. Regular operations began in

October of 1995. The delay between completion and starting regular operations happened because

its encoders were lent to KPGO for several months.

Table 1. Location of Green Bank 20-meter telescope.

I Longitude Latitude 7938°° 49' 26' 31.865" 12.661" WN

2. Description of Equipment

Similar to the geodetic antennas at KPGO (Kauai, Hawaii), and Ny/_lesund (Spitzbergen),

the 20-meter telescope features a fast slew speed of 2 degrees per second in both azimuth and

altitude axes, surface accuracy of about 0.8 mm rms, and an F/D ratio of 0.43 at prime focus.

The prime focus receiver is an NRAO-built S- and X-band dual polarization system using cooled

(15 K) HEMT amplifiers. The design is somewhat novel because the RF signals are transmitted

to the control room on optical fibers where the LO system and mixers are located. A 500 MHz

reference signal locked to a H-maser standard is sent to the receiver on an optical fiber to drive

the phase cal unit. The 500 MHz is returned to the control room where a round-trip phase

measurement is done.

Typical system temperatures are 45 K at X-band and 30 K at S-band, typical SEFDs are

700-800 Jy at X-band and 400-500 Jy at S-band.

The VLBI recording system consists of a VLBA DAR rack with 14 baseband converters (BBC)

and VLBA formatter, and a VLBA-type tape recorder. All experiments for the last two years are

recorded only on thin tape.

1999 IVS Annual Report 49
USNO Green Bank 20-meter telescope National Radio Astronomy Observatory (NRAO)

Figure 1. The USNO 20-Meter RSI telescope at Green Bank, WV

3. Technical Staff for the Green Bank 20-meter

The 20-meter project benefits from being located at a major radio astronomy observatory

because all phases of maintenance, technical support, and repairs can for the most part be done

by the local staff, who support all the telescopes at the site. Cryogenics technicians, telescope

mechanics, electronics engineers and technicians, and programmers all contribute small portions

of their time to maintenance and repairs of the 20-meter systems.

At the present time, the staff dedicated primarily to the 20-meter operations include two

full-time telescope operators (K. Lehman and G. Monk), operations supervisor (M. Chestnut),

electronic technician (W. Shank), and "friend of the telescope" (F. Ghigo).

4. Status of the Green Bank 20-meter

The 20-meter primarily supports the USNO weekly NEOS-A and daily INTensive experiments.

In the past two years, it has also observed experiments including the VLBA (RDGEO, RDV, and

RDWPS), and bi-monthly CORE-B experiments. In 1997-1998 it participated in observations of

the Mars spacecraft.

The primary experiments (NEOSA and weekday Intensives) are run with full coverage by tele1999 IVS Annual Report

50
National Radio Astronomy Observatory (NRAO) USNO Green Bank 20-meter telescope

scope operators. The other experiments (CORE-B, RDV, etc) are generally run partly unmanned.

Table 2 summarizes the usage from October 1995 through May 1999; (GLOBAL,etc: includes

Reference Frame, GBTies, GLOBALS, CRF, and GEOCAT.) Figure 2 shows total usage in graphical form.

Table 2. Hours scheduled October 1995 through May 1999

Experiments

74 1237 1296 1304 520 4631 1

] 37 400 616 659 243, 1955 I

'48 91 48 0 22 2091

6 5 3 6 2 22

NEOS-A

INTensive

NAVEX

Fringe Tests

GLOBAL, etc. 24

RDV, RDGEO, RDWPS 0

CONT96 0

CORE-B 0

MARS TOTALS i 3890

Percent Time Lost

232 22 7O 0 348

163 138 133 23 457

587 0 0 0 0

0 113 135 68 316

0 41 6 0 47

2715 2277 2313 878 8572

10.1 4.7 2.0 5.4 3.5

400

o

E

300

o 200

CO

100

0

USNO-GB 20-Meter Usage

Figure 2. Usage of the 20-meter, 1995-present.

In October 1998, the 20-meter back end electronics and the operations area was moved into a

new control building. The new building has shielded control and electronics rooms. The shielding

1999 IVS Annual Report 51
USNO Green Bank 20-meter telescope National Radio Astronomy Observatory (NRAO)

is primarily to protect the new 100-meter GBT from locally generated RFI. The ST H-maser time

standard was also relocated to the new building, where it provides reference and time signals for

all systems on the site as well as the 20-meter VLBI system.

Some major maintenance was done during May 1999: oil was changed in all gear boxes, and a

leaky oil seal on one of the azimuth motors was replaced.

5. Future Plans

Both the Green Bank and Kokee systems will be upgraded to Mark IV operations early in

2000. New Mark IV formatters and decoders will be obtained, and the recorders will be modified

for the faster data rates and for the addition of an extra head stack.

We also plan to install a Turbo Rogue GPS station at Green Bank later this year.

1999 IVS Annual Repo, t

52
Hartebeesthoek Radio Astronomy Observatory HaxtRAO

Hartebeesthoek Radio Astronomy Observatory

Ludwig Combrinck

Abstract

This report summarises the current technical parameters of the HartRAO VLBI station. It also gives

an overview of our geodetic VLBI activities during the last year and briefly describes our involvement

with other space geodesy techniques. Current and envisaged upgrading to the antenna which should

improve the performance of HartRAO as a VLBI station are discussed.

1. Geodetic VLBI at HartRAO

HartRAO is located north of Johannesburg, South Africa, in a valley of the foothills of the

Witwaters mountain range. HartRAO uses a 26 metre 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. The antenna is located in a valley which shields it from

terrestrial RFI.

2. Technical Parameters of the VLBI Telescope of HartRAO

The feed horns used for 13 cm and 3.5 cm are single polarised conical feeds. Both S and X bands

have right hand circular polarisation. The RF amplifiers are cryogenically cooled HEMTS. The

radio telescope is being upgraded, and we have recently (November 1998) replaced the hydraulic

drive with an electric drive. A project has been launched to upgrade the perforated surface panels

of the telescope to higher tolerance solid panels.

1999 IVS Annual Report 53
HartRAO Haxtebeesthoek Radio Astronomy Observatory

Table 1. Location and addresses of HartRAO.

Latitude 25.889 ° S

Longitude 27.686 ° E

Hartebeesthoek Radio Astronomy Observatory

Geodesy Programme

PO BOX 443

Krugersdorp, 1740, SOUTH AFRICA

http://_w.hartrao.ac.za/geodesy/geodesyAndex.html

The technical parameters of the radio telescope are summarised in Table 2.

Table 2. Technical parameters of the radio telescope of HartRAO for geodetic VLBI.

I Parameter HartRAO-VLBI

owner and operating agency

year of construction

radio telescope mount

receiving feed

diameter of main reflector d

focal length f

//d

surface contour of reflector

wavelength limit

pointing resolution

pointing repeatability

X-band

(standard u = 8.580GHz_ A = 0.0349m)

Tsys

SSEFD

Point source

3 dB beamwidth

S-band

(standard u = 2.280GHz_ A = 0.1316)

Tsys

HartRAO

1961

offset equatorial

Cassegrain

25.914m

10.886m

0.424

:t:2.0mm

2.5 cm

0.001 o

0.004 °

8.180 - 8.980 GHz

65K

1500 Jy

17.1 Jy/K

0.092 °

2.210 - 2.344GHz

40 K

SSEFD

Point source

3 dB beamwidth

VLBI terminal type

recording media

Field System version

attended VLBI observations

1500 Jy

9.7Jy/K

0.332 °

Mark IV

thin tape only

9.3.25

24h, mode C

1999 IVS Annual Repo_

54
Hartebeesthoek Radio Astronomy Observatory HartRAO

3. Staff Members Involved in VLBI

The Geodesy Programme draws some manpower from other programs at the observatory,

particularly for technical maintenance and operations assistance. 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% Project Leader Geodesy

Jonathan Quick Astronomy 5% Hardware/Softwaxe Astronomy

William Moralo Technical 30% Operator Geodesy

Peter Stocker Technical 10% Day Shift Operator Electronics

Ferdie Nel Technical 5% Night Shift Operator Electronics

4. Status of the HartRAO Geodetic VLBI Component

During the period of this report (1998 - March 1, 1999) HartRAO participated in several VLBI

experiments which are listed in Table 4. 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. We have a Mark IV terminal and thin tape recorder. An $2 terminal is used for

astronomical VLBI and SYOWA experiments.

Table 4. Participation of HartRAO in Geodetic VLBI experiments for the period 1998 to March 1, 1999.

Date Exp. Date Exp. Date Exp. Date Exp.

1998-01-13

1998-02-24

1998-04-07

1998-05-11

1998-06-16

1998-07-28

1998-09-08

1998-10-06

1998-12-15

1999-01-28

1999-02-09

1999-02-23

CA027

CA030

CA033

IS126

CA038

CA041

CA044

CA046

CA051

IS134

CA055

CA056

1998-01-27

1998-03-10

1998-04-13

1998-05-19

1998-06-30

1998-08-11

1998-09-22

1998-11-17

1998-12-29

1999-02-01

1999-02-11

CA028

CA031

IS125

CA036

CA039

CA042

CA045

CA049

CA052

CRF06

COHIG5

1998-01-29

1998-03-23

1998-04-21

1998-06-02

1998-07-13

1998-08-24

1998-09-28

1998-12-01

1999-01-12

1999-02-04

1999-02-15

IS122

IS124

CA034

CA037

IS128

IS129

IS130

CA050

CA053

COHIG4

CRF07

1998-02-12

1998-03-24

1998-05-05

1998-06-15

1998-07-14

1998-08-25

1998-10-05

1998-12-07

1999-01-26

1999-02-08

1999-02-18

IS123

CA032

CA035

IS127

CA040

CA043

IS131

IS133

CA054

IS135

COHIG6

1999 IVS Annual Report 55
HartRAO Hartebeesthoek Radio Astronomy Observatory

Table 5. Table of eccentricities, VLBI telescope to SLR and

Reference Coordinate A

SLR X 41.680

SLR Y -66.564

SLR Z -8.131

HRAO X 90.236

HRAO Y -132.190

HRAO Z -34.704

GPS (HRAO) reference points.

o (ram)

15.8

7.5

3.9

15.8

7.5

3.9

Table 6. Table of Geodetic reference points, ITRF96 Epoch 1997, VLBI, SLR and GPS (HRAO).

Reference Coordinate

VLBI X 5085442.780

VLBI Y 2668263.483

VLBI Z -2768697.034

GPS X 5085352.500

GPS Y 2668395.681

GPS Z -2768731.692

X

Y

Z

Cartesian (m) [a (m) [Velocity (m)

0.006 0.0007

0.005 0.0192

0.005 0.0164

0.009 0.0007

0.007 0.0192

0.006 0.0164

5085401.135 0.101 0.0007

2668330.108 0.063 0.0192

-2768688.865 0.071 0.0164

SLR

SLR

SLR

o (m)

0.0009

0.00101

0.0007

0.0009

0.00101

0.0007

0.0009

0.00101

0.0007

5. Future Plans

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 5) were determined using GPS (Combrinck & Merry 1997) and the

SLR to GPS eccentricity values are from 1998 footprint results. We are processing HRAO in a 14

station regional (IGS) network and envisage having a permanent SLR (MOBLAS 6) operational

by January 2000. This will strengthen colocation and with accurate eccentricities should tie the

independent ITRF (Table 6) 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 1999 are:

1. Upgrade of radio telescope surface.

2. Automation of dichroic.

3. Upgrade of S and X band receivers to dual polarisation.

References

[1] Combrinck W.L. and Merry, C.L. Very long baseline interferometry antenna axis offset and intersection

determination using GPS. JGR, Vol.102, NO.Bll, pages 24,741-24,743, 1997.

56 1999 IVS Annual Report
Kashima Space Research Center, Communications Research Laboratory Kashima 34-m Radio Telescope

Kashima 34-m Radio Telescope

Junichi Nakajima, Yasuhiro Koyama, Eiji Kawai

Abstract

Kashima 34-m radio telescope is a facility of the Kashima Space Research Center, Communications

Research Laboratory. The telescope is mainly used for geodetic and astronomical VLBI observations.

Brief reports of the current status and on-going projects are presented in this report.

1. Introduction

Communications Research Laboratory (CRL) constructed the Kashima 34-m telescope in 1988

[1]. Since the operation started, 11 years have passed. The telescope has been kept in a good

condition and it has joined various VLBI observations continuously. The station is located in the

Kashima Space Research Center of CRL which was founded in 1964 near the Pacific ocean. The

34-m telescope (Figure 1) is currently operated and improved by staff in the Radio Astronomy

Applications Section. The structure of the telescope below the alidade section is almost identical

to NASA DSN 34-m stations, but the equipped frequency range and other electronics are different.

Figure 1. The Kashima 34-m Radio Telescope.

1999 IVS Annual Report 57
Kashima 34-m Radio Telescope Kashima Space Research Center, Communications Research Laboratory

2. Antenna Specifications

2.1. Mechanical System

Although the Kashima 34-m telescope has an ability of the maximum slew rate of 1 degree

per second in azimuth, we reduced its speed slightly to prevent mechanical wear in several parts

of the telescope expecting to extend the life time of the telescope. The mechanical performance

and related parameters of the telescope are shown in Table 1. Annual inspections of the motors

and preparations of spare units substantially reduced unexpected troubles. Since last year, there

has been no observation failures due to mechanical troubles of the telescope. The sub-reflector

was re-furnished in 1998. Most of the parts in 5-axis positioning were renewed. Sub-reflector FRP

surface was cleaned and re-painted from metal paint layer.

Table 1. Mechanical specification and related parameters of the 34-m radio telescope.

Maximum Speed in Azimuth

Maximum Speed in Elevation

Drive Range in Azimuth

Drive Range in Elevation

Operation Wind Speed

Panel Surface Accuracy

Latitude

Longitude

Mailing Address

0.8°/see.

0.64°/see.

±27O °

7-88 °

13 m/sec.

0.17 mm (RMS)

35°57.3 t

140°39.4 l

893-1 Hirai, Kashima, Ibaraki 314-0012 Japan

2.2. Receiver System

Currently available receivers are L, C, K and S/X bands. A computer controls the receivers

and feed groups in the cassegrain secondary focus. A group of feeds is mounted on an elevator

unit called "trolley". With the trolley, selected frequency feeds and receivers are moved to the

cassegrain focus. The other receivers are retracted to lower positions. In the case of the C-band

receiver, additional sub-reflector adjustments are required because of the offset position of the

feed. For all the receivers except C-band, HEMT or FET low noise amplifiers are cooled down to

a physical temperature of around 12 K. The C-band receiver is placed in ambient temperature.

It takes from 15 minutes to 1 hour to switch observing receivers depending on which receiver

is demanded. Intermediate frequency (IF) signals from all the receivers except for the K-band

receiver are in the range of commonly used 100-600 MHz band. On the other hand, IF signal of

the K-band receiver is in the frequency range of 5-7 GHz. The IF signals are converted to optical

signals and sent to the observation room through optical fibers. The wide-band IF signal of the

K-band receiver is converted to lower frequency signals in the observation room. Recently, we are

experiencing strong interferences which are generated from artificial satellites and mobile phone

base stations, especially in L-band. As a result, the observations in the L-band are sometimes very

difficult. Current performance of the receiver systems are summarized in Table 2.

58 1999 IVS Annual Report
Kashima Space Research Center, Communications Research Laboratory Kashima 34-m Radio Telescope

Table 2. Receiver performance of the 34-m radio telescope.

Band Frequency (MHz) Tsys (K) Efficiency SEFD (Jy)

L 1350-1750 43 0.68

S 2150-2350 83 0.65

C 4600-5100 150 0.70

X 7860-8680 50 0.68

K 21900-23900 300 0.57

348

254

2.3. Hydrogen Maser Systems and Time Comparison

Two K4 type hydrogen maser systems are available at the telescope and one of them is used

for the frequency reference. The same frequency reference is used at the ll-m antenna station

of the Key Stone Project (KSP). Another Hydrogen maser system developed by a Russian group

(CHI-80) is also kept running as a backup system. To compare the station clock maintained by

the hydrogen maser system with the UTC, a GPS time receiver (AOA) and a Totally Accurate

Clock-2 unit are in operation.

2.4. VLBI Back-end System

As of March 1999, K3A (Mark IIIA compatible system developed by CRL), K4, VSOP, and

VLBA data recorder systems are available. For observations with the K4 and VSOP data recorder

systems, an automatic tape changer unit can be used for a continuous unattended operations for

more than a day. For the K4 type 2 and VSOP video converter systems which require IF signal in

the range of 500-1000MHz, an IF up converter unit is used to convert the IF signals.

3. On-going Projects

Followings are the major VLBI observation projects which are currently running at Kashima

34-m radio telescope. Schedule of the telescope is determined in the telescope operation meetings

based on the pre-determined priorities and requests from users.

K4-TIE experiments A K4 data recorder system has been shipped to the Gilmore Creek Geophysical Observatory at Fairbanks and a geodetic VLBI experiment was performed with the

station in January 1999. Four VLBI stations in the KSP VLBI network were also included

in the experiment. The main purpose of the experiment was to tie the KSP VLBI network

to a global terrestrial reference frame (ITRF). Another experiment with the same stations

and Wettzell VLBI station was performed in March 1999.

APT and APSG The Kashima 34-m radio telescope has been participating in APT (Asia Pacific

Telescope) and APSG (Asia Pacific Space Geodetic Program) VLBI experiments for geodesy

and astronomical purposes.

Pulsar VLBI Since 1997, regular observations were carried out with Kalyazin 64-m radio telescope in Russia. A K4 recorder system has been installed at the Kalyazin 64-m radio telescope. Repeated observations revealed the proper motion of a pulsar [2].

VSOP (VLBI Space Observatory Program) Under the collaboration with the Institute of

1999 IVS Annual Report 59
Kashima 34-m Radio Telescope Kashima Space Research Center, Communications Research Laboratory

Space and Astronautical Science (ISAS), Kashima 34-m telescope joined the space VLBI

experiments as a ground telescope. C-band and L-band receivers are mainly used. The

Kashima 34-m telescope has an important role especially when the Usuda 64°m telescope is

not available.

J-net (Japanese domestic astronomical VLBI network) With three other radio telescopes

in Japan which are 45-m telescope at Nobeyama, 10-m telescope at Mizusawa and 6-m

telescope at Kagoshima, VLBI observations based on qualified astronomical proposals are

performed as the J-net. The purposes of the observations are focused in astronomical studies

and most of the J-net observations are done towards K-band water maser emission regions.

Intensive monitoring observations of the burst of the Orion-KL were done in 1998.

GALAXY (Giga-bit Astronomical Large Array with cross connect) Utilizing optical networks for the KSP VLBI network and another network for the OLIVE project which is connecting 64-m telescope at Usuda and 45-m telescope at Nobeyama with the correlator facility

at Mitaka (National Astronomical Observatory: NAO), three large telescopes have been successfully connected via the Asynchronous Transfer Mode (ATM) high speed network. The

network has been established under close cooperation with the the Telecommunication Network Laboratory Group of Nippon Telegraph and Telephone Corporation (NTT). Kashima

34-m and Usuda 64-m telescopes were connected in September 1998. Nobeyama 45-m telescopes will also be connected in 1999. The first fringes between Usuda 64-m and Kashima

34-m telescopes were detected at the correlator facility for the KSP network which is located

at Koganei, Tokyo.

4. Technical Staff for the Kashima 34-m Radio Telescope

Engineering and technical staff members who are contributing to observations and operations

of the Kashima 34-m axe listed below.

• Noriyuki Kurihara, Chief of the Radio Astronomical Applications Section.

• Eiji Kawai, Responsible for operations and maintenances.

• Junichi Nakajima, Responsible for the overall performance and improvements of the 34-m

radio telescope.

• Yasuhiro Koyama, Field system and monitoring software development.

• Mamoru Seiko, Hydrogen maser systems and reference frequency signals.

• Hiroshi Okubo, Technical staff for mechanical and receiver systems.

• Hiroo Osaki, Technical staff for software and mechanical systems.

• Yuki Watababe, Engineer from Rikei Corporation.

5. Future Plans

Several mechanical modifications and preventive work are planned for the radio telescope. The

antenna system is currently controlled from software developed on a mini computer (HP1000 model

A400). The operating system of the antenna and the observation facilities are being replaced with

60 1999 IVS Annual Report
Kashima Space Research Center, Communications Research Laboratory Kashima 34-m Radio Telescope

Field System version 9 under close corporation with Goddard Space Flight Center of NASA. As

for the backend system, S-2 recording system will become available for pulsar VLBI observations

in 1999. The ambient C-band receiver will be replaced with a new HEMT amplifier packaged in

a closed cycle gas cooling system in 1999. Two Giga-bit VLBI recoeder systems and a correlator

system have been placed at the observation room of the 34-m radio telescope. Experimantal

observations are performed at the sampling rate of 1024Msps with the 1-bit sampling mode. These

systems will be used for general observations after the performance of the system is evaluated.

References

[1] Hitoshi Takaba: VLBI Antennas of the Communications Research Laboratory, J. Commun. Res. Lab.,

Vol. 38, No. 3, pp. 417-433, November 1991

[2] Mamoru Sekido, Michito Imae, Yuko Hanado, Sin'ichi Hama, Junichi Nakajima, Eiji Kawai, Yasuhiro

Koyama, Tetsuro Kondo, Noriyuki Kurihara, Mizuhiko Hosokawa, Yuri P. Ilyasov, Vasilli V. Oreshko,

and Alexander E. Rodin: Astrometric Observation of PSR0329+54, submitted to Pub. Astron. Soc.

Jpn.

1999 IVS Annual Report 61
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

Key Stone Project Network consists of four space geodetic observation sites around Tokyo, Japan.

The overview of the four sites will be described in this report.

1. Introduction

Communications Research Laboratory (CRL) has been establishing a compact space geodetic observation network around Tokyo, Japan under a project which was named as Key Stone

Project [1]. The Key Stone Project network consists of four observation sites at Koganei (Tokyo),

Kashima (Ibaraki), Miura (Kanagawa), and Tateyama (Chiba). The geographic locations of these

four sites are shown in Figure 1. Table 1 shows the latitudes, longitudes and mailing addresses of

the four sites.

/

/

36iN-

/'

/'

40i N.

30i N

35

TATEYAMA

139i E 140iE 141iE

130iE 140iE 1501E

Figure 1. Geographic locations of four Key Stone Project network sites.

At each site, observation facilities of three space geodetic techniques, Very Long Baseline

Interferometry (VLBI), Satellite Laser Ranging (SLR) and Global Positioning System (GPS), are

collocated. An 11 m diameter fully steerable cassegrain antenna for VLBI observations, an optical

telescope with an aperture of 75 cm in diameter for SLR observations, and a GPS antenna mounted

on top of a stable pillar are placed within about 100 m from each other. While the Kashima and

Koganei stations are located where research members of CRL are working, there are no dedicated

personnel at Miura and Tateyama stations. The observation system is therefore automated as

62 1999 IVS Annual Repot%
Kashima Space Research Center, Communications Research Laboratory Key Stone Project VLBI Stations

Table 1. Locations and addresses of the Key Stone Project observation sites.

Station Latitude Longitude Mail address

Koganei 35o42.6 ' 139o29.3 '

Kashima 35o57.3 ' 140039.4 '

Miura 35°12.4 _ 139°39.0 I

Tateyama 34o56.2 ' 139o50.9 '

4-2-1 Nukui-kita, Koganei, Tokyo 184-8795

893-1 Hirai, Kashima, Ibaraki 314-0012

1691 Koenbo, Hasse, Miura, Kanagawa 238-0115

1397 Kitatsuka, Inuishi, Tateyama, Chiba 294-0226

much as possible and regular VLBI observations at four stations can be performed without any

human interactions in principle [2].

Daily VLBI observations began in January 1995 with a single baseline between Koganei and

Kashima, and the full network observations with four stations began in September 1996. As of

March 1999, a four station VLBI experiment is performed once every two days with a duration

of about 24 hours. High speed Asynchronous Transfer Mode (ATM) communication network

connecting the four sites have been established under the collaboration between CRL and the

Telecommunication Network Laboratory Group of Nippon Telegraph and Telephone Corporation

(NTT). The observed and formatted signals are transferred to the correlator facility at Koganei and

processed in real-time. Observations and data analysis of VLBI measurements are fully automated

and the analysis results are produced shortly after all observations of an experiment session finished.

GPS observations at four sites began in July 1997 and the regular SLR observations began in

September 1998.

2. Technical Characteristics

The design of the antenna system at four sites are identical in design except that the Koganei

VLBI antenna has a taller pedestal than the other three sites in order to maintain clear sky view as

much as possible since the antenna is surrounded by tall woods. The antennas are 11-m diameter

cassegrain system with S-band and X-band receivers (Figure 2). The low noise amplifiers are

located at room temperature but the performance of the receivers is not so bad, as shown in

Table 2 [3].

Table 2. Performance of the antenna (Kogazmi).

S-band (7700-8600MHz) X-band (2100-2500MHz)

Aperture Efficiency 81 _ 67 %

System noise temperature 76 K 95 K

SEFD 3030 Jy 6180 Jy

Structure of the antennas is Azimuth-Elevation mount with the ranges of 0° - 540 ° in azimuth

and 5° - 88 ° in elevation. The maximum slewing speed is 3°/sec in both axes. The antenna and

other observation systems are controlled from a Unix workstation with observation control software

developed by CRL. The data acquisition system is KSP (K4) VLBI data acquisition system [4].

1999 IVS Annual Report 63
Key Stone Project VLBI Stations Kashima Space Research Center, Communications Research Laboratory

Figure 2. 11 meter VLBI antenna at Kashima. A GPS antenna is mounted on top of the pillar (right).

3. Technical Staff for the KSP VLBI stations

Technical staff members who are contributing observations and operations of the Key Stone

Project VLBI stations are listed below. In principle, no operations are necessary for the regular

VLBI observations, but the status monitoring and remote operations are performed from Koganei

station where at least one operator is on duty during the daytime period.

• Tetsuro Kondo, Responsible for overall operations and performances.

• Taizoh Yoshino, Leader of the Key Stone Project team in CRL.

• Yasuhiro Koyama, Development of operation and monitoring software.

• Ryuichi Ichikawa, Responsible for Kashima and Tateyama stations.

• Jun Amagai and Kouichi Sebata, Responsible for Koganei and Miura stations.

• Naoki Goto and Muneo Takeda, Operator at Koganei station, Space Engineering Development Co., Ltd.

4. Current Status and Future Plans

Regular VLBI observations at the data rate of 256 Mbps are currently performed once every

two days. Unfortunately, the ATM network for the Miura station will be terminated in May

1999, and the regular once-in-two-days experiments will be performed with Kashima, Koganei,

and Tateyama stations afterwards. Tape-based VLBI observations at all of four stations will be

performed instead once every six days.

The Key Stone Project ATM network was connected with the OLIVE network which is connecting Usuda (64 m antenna operated by Institute of Space and Astronautical Science) and Nobeyama

(45 m antenna operated by Nobeyama Radio Observatory). The first successful real-time VLBI

observations with the Key Stone Project VLBI stations and Usuda was performed in November

64 1999 IVS Annual Report
Kashima Space Research Center, Communications Research Laboratory Key Stone Project VLBI Station_

1998. The first successful 1 Gbps VLBI observations were also performed by using the Key Stone

Project VLBI sites at Kashima and Koganei in July 1998. Two sets of Giga-bit VLBI system which

has been in development by CRL were used and the data were correlated by using the Giga-bit

VLBI correlator system at Kashima. The Key Stone Project VLBI stations will be used for such

a technical test-bed of the new observation systems developed by CRL.

Seven geodetic VLBI experiments have been performed with the 34 m antenna station at

Kashima and the Key Stone Project VLBI stations to make a precise tie of the network to the

global terrestrial reference frame. A further tie experiment was performed in January 1999 with the

34 m antenna station at Kashima and Gilmore Creek Geophysical Observatory at Fairbanks and

such an experiment was repeated in March 1999. Experiments with Wettzell and Urumqi stations

are planned in the future to improve the accuracy of the tie. Ground survey measurements between

VLBI, GPS, and SLR reference points at four Key Stone Project observation sites were performed

in 1996, 1997, and 1998. These efforts are expected to contribute to a detailed study of the

colocation of VLBI, GPS, and SLR.

References

[1] Taizoh Yoshino: Overview of the Key Stone Project, J. Commun. Res. Lab., Vol. 46, No. 1, pp.3-6,

March 1999

[2] Yasuhiro Koyama, Takahiro Iwata, and Hiroshi Takaba: KSP VLBI System; Observation and System

Management Software, J. Commun. Res. Lab., Vol. 46, No. 1, pp.33-38, March 1999

[3] Noriyuki Kurihara, Hiroshi Takaba, Akihiro Kaneko, and Kouichi Sebata: KSP VLBI System; Antenna

and Receiver System, J. Commun. Res. Lab., Vol. 46, No. 1, pp.7-13, March 1999

[4] Hitoshi Kiuchi, Jun Amagai, Shin'ichi Hama, and Michito Imam: KSP VLBI System; KSP DataAcquisition System, J. Commun. Res. Lab., Vol. 46, No. 1, pp.25-32, March 1999

1999 IVS Annual Report 65
Kokee Park Geophysical Observatory National Earth Orientation Service

Kokee Park Geophysical Observatory

Clyde A. Cox

Abstract

This report summarises 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 up to March, 1999

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 transferered to the Crustial 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 Aug 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.

Kokee Park Geophysical Observatory is located on the Island of Kauai in the Hawaiian Islands.

Table 1. Location and Addresses of Kokee Park Geophysical

Longitude 159.665 ° W

Latitude 22.126 ° N

Kokee Park Geophysical Observatory

P.O. Box 538

Waimea, Hawaii 96796

USA

Observatory

2. Technical Parameters of the VLBI System at KPGO

The receiver is of NRAO (Green Bank) design (dual polorization 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.

1999 IVS Annual RepoL t

66
National Earth Orientation Service Kokee Park Geophysical Observatory

Figure 1. Kokee Park Geophysical Observatory 20m Antenna.

Figure 2. Kokee Park also hosts other systems; PRARE, DORIS Beacon, and IGS (Turbo-Rogue).

3. Technical Staff of the VLBI system at KPGO

The staff at Kokee Park consists of six people who are employed by AlliedSignal Technical

Services Corp. under contract to NASA for the operations and maintenance of the Observatory.

1999 IVS Annum Report 67
Kokee Park Geophysical Observatory National Earth Orientation Service

Table2.TechnicalparametersoftheradiotelescopeatKPGO.

Parameter Kokee Park

owner and operatingagency

year ofconstruction

radiotelescopesystem

receivingfeed

diameter of main reflectord

focallengthf

//d

surfacecontour ofreflector

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°Is

l°/s 2

X-band 8.1 - 8.9 GHz

(reference v = 8.4GHz 7A = 0.0357m)

Tsys

SSEFD(CASA)

G/T

S-band

(reference v = 2.3GHz_ A = 0.1304m)

40K

900 Jy

45.05 dB / K

0.406

2.2 - 2.4GHz

40K

665 Jy

35.15dB/g

0.539

VLBA

thin-tape only

9.3.17

Tsys

SSEFD(CASA)

G/T

VLBI terminal type

recording media

Field System version

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.

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 three systems are

shown in Figure 2.

68 1999 IVS Annual Report
National Earth Orientation Service Kokee Park Geophysical Observatory

5. Outlook

USNO will be upgrading the present DAR to Mark IV this calendar year.

1999 IVS Annual Report 69
Matera CGS VLBI Station Agenzia Spaziale Italiana

Matera CGS VLBI Station

Giuseppe Colucci, Domenico De1 Rosso, Francesco Vespe

Abstract

This report summarises the VLBI activitiesperformed at the Matera VLBI station.

overview of the technicalcharacteristicsof the system and some staffaddresses 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.

Figure 1. The Matera "Centro di Geodesia Spaziale" (CGS)

The "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. Next year the new Matera Laser Ranging Observatory (MLRO),

the most advanced Satellite and Lunar Laser Ranging facility in the world, will be installed at the

CGS. 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 340 experiments up to August 1998.

Besides the participation in the network programs listed above, Matera has been involved also in

some Intensive IRJS Campaigns (also during 1998) and in several astronomical experiments. In

1996 the receiver was upgraded to standard wideband and the Mark IV upgrade is now in progress

(installation during 1999 planned). The installation of the new Linux PC FS with FS 9.x is in

progress too.

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). The receivers were

70 1999 IVS Annual Report
Agenzia Spaziale Italiana Matera CGS VLBI Station

installed at Cagliari, Medicina, Noto, Genova and Venezia. Currently the IGFN is included in the

IGS global network. All the GPS stations are managed by CGS and the data 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 9.3.23.

Table 1. Matera VLBI Antenna Technical Specifications

Input frequencies S-band 2210 MHz to 2450 MHz

X-band 8180 MHz to 8980 MHz

Noise temperature S-band <20 K

at dewar flange X-band <20 K

IF output frequencies S-band 190 MHz to 430 MHz

X-band 100 MHz to 900 MHz

IF Output Power with 300 K S-band 0.0 dBm to +8.0 dBm

at the input flange X-band 0.0 dBm to +8.0 dBm

Gain compression S-band <1 dB at +8 dBm output level

X-band <1 dB at +8 dBm output level

Image rejection S-band >45 dB within the IF passband

X-band >45 dB within the IF passband

Inter modulation products S-band

X-band

At least 30 dB below each of

2 carriers at an IF output

level of 0 dBm per carrier

At least 30 dB below each of

2 carriers at an IF output

level of 0 dBm per carrier

Tsys S-Band 55 K

X-Band 65 K

SSEFD S-Band 800 Jy

X-Band 900 Jy

1999 IVS Annual Report 71
Matera CGS VLBI Station Agenzia Spaziale Italiana

3. Staff

The list of the VLBI staff members of Matera VLBI station is provided in Table 2.

Table 2.

Agency

Ylatera VLBI staff m

Activity

_mbers

I Nam e E-Mail

Dr. Giuseppe Bianco ASI CGS Director bianco_asi.it

Dr. Francesco Vespe ASI CGS Geodesy vespe@asi.it

Manager

Domenico Del Rosso Telespazio Operations domenico_delrosso@telespazio.it

Manager

Luciano Garramone Telespazio Station Engeneer garramone@asi.it

Giuseppe Colucci Telespazio VLBI contact colucci@asi.it

4. Status

The Matera station is involved in CORE-A and EUROPE experiments. During 1998 Matera

performed also NEOS-A, INTENSIVE and some astronomical experiments coordinated by EVN.

Figure 2 shows the summary of acquisition up to March 1999 in terms of hours of acquisition.

1200,0

1000.0

800.0

600.0

400.0

20(I.0

0.0

(') since May (") up to March

Figure 2. Summary of acquisition from May 1990 to March 1999

72 1999 IVS Annual Report
Agenzia Spaziale Italiana Matera CGS VLBI Station

5. Outlook

During the second half of the 1999, the system will be upgraded to Mark IV and thin tape

operation by MIT Haystack.

References

[1] G.Colucci, D.Del Rosso, L.Garramone: "Matera VLBI Station Report on the Operational and Performance Evaluation Activities from January to December 1998", available on-line at this address:

http://geodaf.mt.asi.it/GDHTL/matera.html

1999 IVS Annual Report 73
Medicina Station Istituto di Radioastronomia, Bologna, Italy

Medicina Station Report

Allesandro Orfei, Franco Mantovani

1. Introduction

The Medicina 32-m dish is an alt-az antenna run by the Istituto di Radioastronomia di Bologna

del Consiglio Nazionale delle Ricerche. The radiotelescope is located about 30 km east of Bologna,

Italy. It is part of the European VLBI Network. Details on the telescope characteristics and

equipments can be found at the EVN Home Page (http://www.nfra.nl/evn/).

In the last couple of years, the main goal at the Medicina Station was to get the telescope agile

in changing the observing frequency. Achieving this goal will greatly increase the observational

efficiency of the telescope. Moreover it will make the operation of changing the receivers more safe

and it makes this task independent of weather conditions.

The first part of the project has been completed and the new subreflector is fully in operation.

The increased flexibility in changing frequency, together with the facility of recording both thick

and thin tapes implemented at all the European VLBI Network (EVN) stations has immediately

produced an increase in the number of geodetic VLBI observations to which the Medicina Station

will take part in 1999.

2. Medicina Station Report

In the following we list the main upgrading in both hardware and software done at the Medicina

Station.

2.1. Tape Recording

a) The thin tape capability has been installed at the station with good results.

b) A problem due to the sliding of thin tapes has been solved by adopting a new capstan with

deeper grooves.

c) The write head has been replaced at the end of 1998, since it wore out. The new one is of the

old Metrum type. The read head is also on its way to die. The new ordered head, made by Spin

Physics, will have two triple cap heads mounted.

2.2. Computer Control

a) A new version of the remote control programme for the S/X receiver has been implemented.

It allows monitoring of the receiver status (cryogenic temperature, vacuum pressure and so on) in

real time.

b) To serve different types of observational projects, the computers facilities have been reorganized.

Three computers are now available:

- A computer runs the Field System. It can be used to prepare schedules and procedures. The

Field System version implemented is 9.3. This machine is connected to the server of the computer

74 1999 IVS Annual Report
Istituto di Radioastronomia, Bologna, Italy Medicina Station

centre in Bologna.

- A computer with the Windows NT operating system serves equipment like the polarimetre

and the antenna levelmeters. Moreover, it acquires the GPS-Formatter clock offsets data, it keeps

under control the receivers and it drives the movements of the secondary mirror.

- A computer with either Linux or Windows 95 operating systems is used as a general purpose

machine and for data acquisition during spectroscopic observations making use of the autocorrelator, etc.

2.3. Upgrading of the Telescope

There are two projects for upgrading the telescope. The first is the completion of the frequency

agility project. The second aims to a better efficiency at higher frequencies.

a) In order to complete the frequency agility project for the Medicina dish we are planning to place

in the secondary focus room a series of receivers which covers the frequencies between 4.3 GHz and

48 GHz. The electromagnetic design of the eight-feed system is ready and the parameters to design

the mechanical support for the receivers are now available. The design of the electronics part of

the eight receivers is also at a good stage. The priority is to build the 6 cm and the 5 cm receivers

first, to fulfill the EVN requirements about the observing bands which should be available at any

station.

b) A project is going on for the implementation on the telescope of an active surface to compensate

the loss in efficiency due to gravity deformation of the primary mirror of the parabolic antenna.

After a series of tests with the prototype of a mechanical actuator, calculations have been made

to figure out the parameters for an "actuators network" which will keep under control the full

surface of the dish. In the meantime we are looking for a proper electronics to be used and for

an engineering phase of the linear actuator. Furthermore, the cost of more accurate panels for

the dish and of the actuators itself have been assessed. A system of this kind, together with new

panels of enhanced precision surface, will increase very much the antenna efficiency at frequencies

up to 43 GHz.

3. Geodetic Observations

The geodetic experiments run by the Medicina Station in 1998 have been 18 (6 EUROPE, 6

CORE and 6 VLBA).

Three experiments "Mars Pathfinder VLBI", designed for the determination of the Martian

Precession Constants, of the relativistic precession of the perihelion of Mars to a few parts per

thousand, of the Martian Length of Day to about 1 millisecond, were run on the following dates:

07 Jul MARS-15 (04:00 - 16:00 UT)

14 Aug MARS-16 (03:00 - 15:00 UT)

04 Sep MARS-17 (03:00 - 16:00 UT)

Since the Station has fulfilled the requirements to be a 'CORE' (Continuous Observations of the

Rotation of the Earth) Station (namely: a) flexible and automatic frequency change; b) Mark IV

terminal; c) TAC for station timing system; d) daily GPS acquisition), it will take part in the

"CORE" projects. Moreover, during the present year 1999, the Station will continue to observe

the EUROPE and VLBA experiments. The 38 scheduled projects are listed in Table 2. The list

1999 IVS Annual Report 75
Medicina Station Istituto di Radioastronomia, Bologna, Italy

contains 20 experiments more than in 1998, which represents an increase of more than 100% in

observing time allowed for geodetic VLBI.

Tab. 2 - List of Geodetic VLBI observations in 1999

DATE EXPERIMENT DATE EXPERIMENT

12-JAN CORE-A053 29-JUN CORE-A065

13-JAN CORE-B401 13-JUL CORE-A066

26-JAN CORF_A054 15-JUL CORE-B404

01-FEB EUROPE-47 27-JUL CORE-A067

09-FEB CORE-A055 02-AUG VLBA17

08-MAR VLBA13 10-AUG CORE-A068

09-MAR CORE-A057 12-AUG CORE-B405

23-MAR CORE-A058 16-AUG EUROPE-50

24-MAR CORE-B402 24-AUG CORE-A069

06-APR CORE-A059 07-SEP CORE-A070

15-APR VLBA14 05-OCT CORE-A072

20-APR CORE-A060 ll-OCT EUROPE-51

26-APR EUROPE-48 19-OCT CORF__A073

04-MAY CORE-A061 02-NOV CORE-A074

05-MAY CORE-B403 13-DEC EUROPE-52

10-MAY VLBA15 14-DEC CORE-A077

18-MAY CORE-A062 16-DEC CORE-B406

21-JUN VLBA16 20-DEC VLBA18

28-JUN EUROPE-49 28-DEC CORE-A078

76 1999 Ivs Annual Report
Istituto di Radioastronomia del CNR, Stazione VLBI di Noto Noto VLBI station

Report from the Noto VLBI Station

G. Tuccari, C. Stanghellini

Abstract

An upgrade of the Noto 32 m antenna is under way. We describe the main points related to a recent

past.

Figure 1. The Noto antenna

1. The Noto VLBI Station

The Noto VLBI station is an alt-az 32 m antenna belonging, as its twin in Medicina, to the

"Istituto di Radioastronomia del C.N.R." and is a part of the European VLBI Network (EVN). It

is located close to the baroque town of Noto at a latitude of 36.9 °.

The staff is composed of: Carla Buemi, Salvo Buttaccio, Corrado Contavalle, Paolo Leto,

Gaetano Nicotra, Leonardo Nicotra, Carlo Nocita, Luigi Papaleo, Carlo Stanghellini, Corrado

Trigilio, Gino Tuccari, Grazia Umana.

Gino Tuccari is responsible for the technical aspects and the hardware set up of the geodetic

experiments, while Carlo Stanghellini is responsible for the schedule, the pre-observation and

1999 IVS Annual Report 77
Noto VLBI station Istituto di Radioastronomia del CNR, Stazione VLBI di Noto

post-observation performance checks. Corrado Trigilio is the scheduler and should be contacted

to arrange any change in the dates of the observations, or to request the Noto antenna for new

experiments.

All the staff contribute as operators and/or in the set up of the system during geodetic experiments.

2. The New Subreflector

During the summer of 1998 the new automatic subreflector positioning system has been

mounted and successfully tested. The system, similarly to Medicina, allows now to switch between the secondary mirror and the primary focus receiver in a few minutes. The new equipment

avoids the risk to loose geo-experiments due to bad weather conditions and the related difficulty

to set the receiver.

3. A New Primary Focus Receiver System

The new primary focus receiver system is under construction and is expected to be operating

at the end of 1999. It includes the 2.5, 3.6, 13, 18, 21 cm, and the 250-1000 MHz bands. It

represents the second phase of the frequency agility program in Noto. The third phase will get the

0.7, 1.3, 6 cm bands operative in the secondary focus, switching in few seconds through subreflector

movement. Regarding the S/X receiver the present and planned system features are:

Table 1. Present and Future S/X Receiver Characteristics

X band present

Polarization:

frequency range:

cryogenic

Tsys

right

8.1-8.5 GHz

no

130 K

future

left and right

8.1-8.9 GHz (wide band)

yes

35 K

S band present future

Polarization:

frequency range:

cryogenic

Tsys

right

2.10-2.36 GHz GHz

no

140 K

left and right

2.10-2.36 GHz

yes

35 K

Both right/right or left/left polarization in the S/X band will be available.

4. A New 12 GHz Receiver for Holography

A new 12 GHz receiver has been added in the primary focus box, able to work phase-locked

with H-maser. It is mainly oriented to holography of the main dish. Indeed the efficiency at

22 GHz has increased only a little with respect to the past, due to the use of a new subreflector

mirror (rms 0.12 ram), making the surface error determination mandatory. Recent measurements

show a deviation from the ideal parabolic shape with a mean rms of about 1.6 mm. Actions to

78 1999 IVS Annum Report
Istituto di Radioastronomia del CNR, Stazione VLBI di Noto Noto VLBI station

correct the surface are under evaluation.

5. New Software

New software procedures have been created in order to automatically set the system with the

requested observing band.

6. The Mark IV Formatter

The Mark IV formatter is fully integrated in the VLBA environment and both formatters,

VLBA and Mark IV, are available. In a near future, when the appropriate Field System version

will be available, the Mark IV will be used and VLBA taken as spare. This will allow to avoid

manual hardware and software modifications to switch between recording modes.

7. Geodetic Observations

In 1998 Noto took part in 12 geodetic VLBI experiments, namely five CORE-B, five Europe, one

NEOS and the BF43A experiment. In 1999 six CORE-B, six Europe and one CRF experiments

have been scheduled. It is worth to mention that Noto is deeply involved in the VSOP (plus

ground based telescopes which make use of the Canadian $2 recording terminal) survey of compact

extragalactic radio sources.

1999 IVS Annual Report 79
Ny-Alesund 20-Metre Antenna Geodetic Institute, Norwegian Mapping Authority

NYAL Ny-/klesund 20-metre Antenna

Helge G. Digre, Svein Rekkedal, David C. Holland, Rune I. Hanssen, Hans-Peter Plag

Abstract

The 20-m VLBI antenna at the space-geodetic observatory at Ny-/_lesund contributes to the IVS

as a network station. In the report period (April 1998 - March 1999), the site has operated and

participated in experiments at a normal level. Several maintenance and repair activities were required

and changes in station staff have occured.

1. Introduction

The space-geodetic observatory at Ny-/_lesund is a multi-parameter observing site located at

the west coast of Spitsbergen, the main island of Svalbard. For a more detailed description of the

geodynamic setting and other observational activities at the observatory, see e.g. [1].

Figure 1. The VLBI antenna at Ny-/_lesund. View is approximately from south-west to north-east. The

20-m radio telescope is located on a small plateau approximately 1.5 km west of the village of Ny-/_lesund at

about 45 m above sea level. The small green house seen in the middle of the picture is the control building

of the airport, with part of the runway visible in the rightmost corner of the picture. The two black pillars

to the right of the airport building and in the right lower corner are well-isolated pillars of the local control

network. Photo taken in July 1998.

The VLBI station at Ny-/_lesund was established as a result of a cooperation between NASA,

NOAA and Norwegian Mapping Agency. Mechanically, the antenna is an azimuth/elevation which

is produced by Radiation System Incorporated, now Comsat, and it is almost identical to the

80 1999 IVS Annual Report
Geodetic Institute, Norwegian Mapping Authority Ny-Alesund 20-Metre Antenna

antennas at Green Bank and Kokee (see Figures I and 2). The antenna was assembled the summers

1993 and 1994 and first regular experiment was carried out in the autumn of 1994. The station

has been operational since 1st of January 1995.

The VLBI technique is one of several observations carried out at the space-geodetic observatory

at Ny-Alesund. Briefly, we will mention: GPS, GLONASS, PRARE, absolute gravity measurements, Earth tide gravity and tide gage. The different measurements are tied together by means

of an accurate control network. This network is extended to the local surrounding (30-50 km) to

keep track of eventual local deformation

Figure 2. The VLBI antenna and the control building at Ny-/_lesund. View is approximately from west to

east. The building in front is the control building of the space-geodetic observatory. Weather condition is

dense fog banks (behind the antenna), which is quite common in summer. Photo taken in July 1998.

Table 1. Main site parameters of NYAL

Location: Ny-Alesund, Svalbard, Norway.

Latitude and longitude: 78.9 N, 11.9 E

Operated by: Statens kartverk (Norwegian Mapping Authority)

Contribution to IVS: VLBA/RDV, CORE-B, VLBI-Europe, NEOS

2. Technical Parameters of the VLBI Antenna in Ny-/klesund

The antenna in Ny-Alesund is of similar type to the ones at Green Bank and Kokee Park The

technical parameters of the antenna in Ny-/_lesund are summarized in Table 2.

1999 IVS Annual Report 81
Ny-/_lesund 20-Metre Antenna Geodetic Institute, Norwegian Mapping Authority

Table 2. Technical parameters of the VLBI

Parameter

owner and operating agency

year of construction

radio telescope system

receiving feed

diameter of main reflector d

focal length f

azimuth range

azimuth velocity

azimuth acceleration

elevation range

elevation velocity

elevation acceleration

_.ntenna at NYAL.

Ny-Alesund

NMA

1993-1994

Az-E1

primary focus

20m

8.58m

0... 540 °

2°/s

l°/s 2

1... 90°

2°/8

l°/s 2

X-band 8.1

(reference y = 8.4GHz_ )_= 0.0357m)

Tsus

S8_FD(CYGNUS- A)

S-band

(reference u = 2.3GHz, _ = 0.1304m)

Tsys

SSEFD(CYGNUS- A)

VLBI terminal type

recording media

Field System version

- 8.9 GHz

55K

750 Jy

2.2 - 2.4GHz

35K

1300 Jy

Mark IV

thin-tape only

9.8.23

3. Staff Related to the Space-geodetic Observatory in Ny-/_lesund

Until summer 1998, the permanent station staff at the observatory has been three persons.

In addition, there are two persons at the Geodetic Institute in Honefoss directly involved in the

operation of the observatory. The "permanent" staff are employed on a yearly basis, with a

possibility to continue for two additional one year periods. In 1998, a rotation group was set up

from the staff at the main institute in Honefoss. The members of the rotation group have contracts

for three years. Each member spends three months in Ny-/_lesund at a time and totally 9 months

over the contract period. Thus, the number of staff at Ny-/_lesund is effectively increased to four.

The names of the staff members in the report period are given in Table 3.

4. Status of the VLBI Antenna in Ny-/_lesund

The operation of the station at Ny/_lesund over the report period has been stable. We have

had some failures, but these have been mainly due to normal wear and tear.

Mark IV rack: Some work has been done on the Mark IV rack. All the IC sockets on the

communication chips on the MAT boards have been changed due to intermittent failures in the

1999 IVS Annual Repro t

82
Geodetic Institute, Norwegian Mapping Authority Ny-/_lesund 20-Metre Antenna

Table 3. Staff related to the operation of the VLBI in Ny-Alesund.

H0nefoss:

Section Manager:

Group leader:

Ny-Alesund:

Station manager:

up to 30 April 1999

since 01 May 1999

Permanent staff:

Rotation group:

Rune I. Hanssen

Svein Rckkedal

Leif Morten Tangen

Helge G. Digre

David C. Holland

Roar Kihle

Kari Buset

Bente R. Andreassen

Kjetil Ringen

Tom Pettersen

communication with the VCs. This work has made things much more reliable, and now this fault

rarely occurs. We used good quality gold plated turned pin sockets to replace the original type.

Tape drive: There have been problems with parity errors due to variation of the tape position,

which changed with speed and direction. The idler roller was replaced, and solved this problem. We

observed that the surface of the old roller was pitted and rough on about 20% of its circumference.

Field System: We are running FS 9.8.23 with the additional software for logging the weather

station data during experiments. The Field System with the integrated weather station has worked

well, except that the wind sensor mast broke during a violent storm. It has now been replaced

with a stronger mast and guying system.

Antenna: We have had failures of the Peltier elements in the receiver heating/cooling system.

These devices seem to have a finite life and usually break when the weather is bad (making the

replacement more difficult).

We have also experienced problems with our azimuth encoder during colder periods (below

-25 C). To improve the reliability, a heated, insulated box has been built to prevent water vapour

condensing in the optics.

General: We have now a modern "cherry picker" to replace our elderly International Harvester

model. This has made maintenance of the antenna much easier as it is considerably more portable.

Other relevant activities: In 1998, additional geodetic benchmarks have been established in an

area with a north-south extension of 30 km and an east-west extension of 50 km. These points

enlarge the existing control network consisting of an inner network of 50 by 400 m and some

additional points within 5 km of the observatory. The new points were occupied in September

1998 in a five day GPS campaign.

5. Outlook

The maser will have its scheduled bi-annual maintenance check 3 - 10 June 1999. It will be

performed by AlliedSignal, Donald A. Rhine.

The azimuth gear boxes have leaking oil seals. They have to be changed during the summer

1999 IVS Annual Report 83
Ny-_lesund20-MetreAntenna GeodeticInstitute, NorwegianMappingAuthority

season. The oil leak has interfered with the azimuth brake systems. The brakes have to be repaired

during the summer. The heating elements for the brakes are also defectiv and have to be changed.

Besides the particpation of the VLBI antenna in scheduled experiments, it should be mentioned

here that the complete control network will measured in a GPS campaign in August 1999. The

VLBI antenna will be surveyed in August in cooperation with three scientists from Italy and Spain

(under the lead of Paolo Tomasi).

We are planning to participate in CORE-3, which will considerably increase the number of

experiments per year.

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 ffir Kartographie und Geod_sie, Frankfurt, 65-77.

84 1999 IVS Annual Report
Bundesamt fiir Kartographie und Geod_ie German Antarctic Receiving Station O'Higgins

German Antarctic Receiving Station O'Higgins

Andreas Reinhold

Abstract

This report gives an overview about the technical parameters and the organizing structure of the

German Antarctic Receiving Station O'Higgins. It shows the activities since 1992 and gives an outlook

about the developments to a Mark IV station during the next years.

1. The GARS O'Higgins at the Antarctic Peninsula

The antenna of the German Antarctic Receiving Station (GARS) O'Higgins is jointly used by

DLR (German Aerospace Center) for SAR Data Acquisition of different remote sensing satellites

(in priority ERS1 and ERS2) and by BKG (Bundesamt ffir Kartographie und Geod_ie - formerly

IfAG, Institute for Applied Geodesy) for international VLBI experiments. The DLR - as owner of

the station - is also responsible for management, infrastructure and logistics. The responsibility

for all geodetic observations is in the hands of BKG.

The GARS is located at the site of Chilean Base General Bernardo O'Higgins (Antarctic

Peninsula) and was founded in 1989. The antenna and the subsystems were installed in southern

summer 1990/91 and the first VLBI experiments were carried out in January 1992. With that

O'Higgins was the first VLBI station in operation in Antarctica.

The receiving system is used in campaigns, generally in two campaigns of six to 10 weeks each

per year. During the previous campaigns three to seven VLBI sessions were planned per campaign

and realised in general.

Figure 1. Geodetic Observatory O'Higgins - Antarctica : INMARSAT antennas at the station roof, PRARE

Ground Unit (preliminary mounted in 1995), radome with GPS Turbo Rogue antenna and ERS/VLBI

antenna. (October 1995)

In addition to the VLBI equipment other geodetic systems are available at O'Higgins (Figure 1).

1999 IVS Annual Report 85
German Antarctic Receiving Station O'Higgins Bundesamt fiir Kartographie und Geod_sie

Since February 1995 a Turbo Rogue GPS receiver has been permanently working at the station.

An underwater tide gauge sensor was installed at the same time and since February 1996 a PRARE

ground unit is in communication with the remote sensing satellite ERS2 for precise orbit tracking.

2. Technical Parameters of the VLBI Equipment at O'Higgins

The main instrument of the technical equipment at O'Higgins station is the 9 m antenna

(Figure 2) used for both remote sensing satellite data acquisition (DLR) and geodetic VLBI (BKG).

The construction of the antenna is laid out to resist wind speeds up to 300 km/h. The antenna

system is solidly founded on a site free of ice on bedrock.

Figure 2. The 9 m-antenna at GARS O'Higgins in operation mode (1997).

The technical parameters of the radio telescope are summarised in Table 2. When the German

station O'Higgins is unmanned the equipment is in sleeping mode. It takes about seven to ten

days to restart the equipment at the beginning of a VLBI campaign. The organization structure

is given in Table 1.

3. Technical Staff Working at O'Higgins Station

Table 3 lists the staff which is working during VLBI campaigns in Antarctica and is preparing

the VLBI bursts for O'Higgins. There exists a close cooperation and support by the staff of the

Fundamental Station Wettzell in case of technical problems or for further technical developments.

86 1999 IVS Annual Report
Bundesamt fiir Kartographie und Geod_isie German Antarctic Receiving Station O'Higgins

Table 1. Location and addresses of GARS VLBI antenna at O'Higgins

Longitude 57.90 ° W

Latitude 63.32 ° S

Bundesamt ffir Kartographie und Geod_ie

Aui3enstelle Leipzig

Karl-Rothe-Stratle 10-14

D-04105 Leipzig, GERMANY

during campaigns:

German Antarctic Receiving Station O'Higgins

VLBI team

Base General Bernardo O'Higgins

Territorio Antartico Chileno, CHILE

ar@leipzig, ifag. de rw@leipzig, ifag. de

4. Status of the VLBI Equipment

Since 1992 the VLBI equipment at O'Higgins has been involved in 44 internationally scheduled

VLBI experiments for determination of a southern hemisphere reference system, Earth orientation

parameters, crustal dynamics and coordinates of southern hemisphere quasars together with 11

other VLBI stations.

After an interruption of continuous observation in 1998 the last VLBI burst at O'Higgins took

place in January/February 1999. This campaign was not totally successful due to some technical

problems. The problems - for example leaky helium supply (dewar) - are caused mainly on by

the extreme climate conditions in this part of the world. The complicated logistical possibilities

prevented a short term repair. Only one of seven planned VLBI experiments could be realized

(COHIG 5) with results.

The next burst at O'Higgins is in preparation for October/November 1999. All the necessary

spare parts are available to repair the cooling system.

The station time system has been controlled by a Cesium until now. During the next campaign

it will be replaced by a Totally Accurate Clock (TAC).

5. Outlook

VLBI at O'Higgins depends very closely on a stable hardware configuration because it is not

a permanently used station. But it is an important station in this part of the world with a small

number of permanent stations. The importance of O'Higgins as a reference station will increase

when TIGO will be taken outside of Germany (to the Southern Hemisphere).

It is planned to develop O'Higgins as a station with Mark IV/VLBA equipment. The time

table is as follows:

• obtaining of a VLBA/Mark IV suitable DAR (3rd-4th quarter 1999)

• test of O'Higgins-Mark IV/VLBA modules inside new DAR at Wettzell - with equivalent

TIGO modules (lst quarter 2000)

• obtaining new FS computer, update FS 9.xxx and Linux at Wettzell (lst quarter 2000)

1999 IVS Annual Report 87
Germa.n Antarctic Receiving Station O'Higgins Bundesamt fiir Kartographie und Geod_ie

Table 2. Technical parameters of the radio telescope at O'Higgins for geodetic VLBI

Parameter

owner

operating agency

year of construction

radio telescope system

receiving feed

diameter of main reflector d

focal length f

I/d

surface contour of reflector

azimuth range

azimuth velocity

azimuth acceleration

elevation range

elevation velocity

elevation acceleration

O'Higgins-VLBI

DLR

BKG

1990/91

Cassegrain

primary focus

9m

3.6 m

0.4

+ 0.25 mm RMS

-290 °... + 290 °

ll°/s

7°/s 2

0... 90 °

5°/s

5°/s 2

X-band 8.0 ... 8.6 GHz

Tsys 65 K

SSEF D 6300 Jy

G/T 31.1 dB/K

S-band 2.0 ... 2.4 GHz

Tsys 93 K

SSEFD 12500 Jy

G/T 21.4 dB/K

VLBI terminal type

recording media

Field System version

attended VLBI observations

VLBA

VLBA-recorder

normal tapes

8.21

24 h during campiagns

mode C

Table 3. Staff working at O'Higsins VLBI project

I Name Background Dedication Agency

Andreas Reinhold geodesy 75% BKG

ReinerWojdziak computer science 20% BKG

• joint tuning of DAR, FS and ACU as a complete system at Wettzell (2nd quarter 2000)

• fringe test, test experiment at Wettzell (2nd-3rd quarter 2000)

• shipment of the Mark IV equipment to O'Higgins (3rd-4th quarter 2000)

• removal of head assembly from recorder at O'Higgins, shipment for thin tape upgrade to

88 1999 IVS Annual Report
Bundesamt fiir Kartographie und Geod_ie German Antarctic Receiving Station O'Higgin,,:

Haystack (4th quarter 2000)

• upgrade to Mark IV, installation of thin tape assembly and FS 9.xxx and system test at

O'Higgins (lst quarter 2001)

Campaigns at O'Higgins are planned for 10/11 1999; 01/02 2000; southern spring 2000 and

southern summer 2000/2001.

1999 IVS Annual Report 89
OnsalaSpace Observatory (OSO) Onsala Space Observatory

Onsala Space Observatory - IVS Network Station

Riidiger Haas, Gunnar Elgered, Hans-Georg Scherneck

Abstract

We give a short overview of Onsala Space Observatory (0S0) in it's function as IVS Network Station.

Current status and plans for the future axe described.

1. General Information

Onsala Space Observatory (OSO) is the Swedish National Facility for Radio Astronomy and

connected with the Department of l_dio and Space Science at Chalmers University of Technology.

It is located 30 km south-west of Gothenburg at the Swedish west coast. The site is located on

the Eurasian plate in the southern part of the Fennoscandian uplift area.

/

Figure 1: Location of Onsala Space Observatory (OSO) at the Swedish west-coast in

the southern part of the Fennoscandian uplift area.

Figure 2: The 20 m radio telescope at Onsala enclosed

inside the radome. Note the Onsala water vapor radiometer (WVR) and the GPS antenna of the Onsala

IGS permanent station on the left hand and right hand

side, respectively.

Table 1. Address and location of Onsala Space Observatory (OSO).

Onsala Space Observatory (OSO) I Longitude 11.93 ° E SE-439 92 Onsala, SWEDEN Latitude 57.40 ° N

t. +46-31-772-5500, f. +46-31-772-5590, http ://www. oso. chalmers, se

1999 IVS Annual Report

90
OnsalaSpace Observatory Onsala Space Observatory (OSO)

2. Technical Description of the Geodetic VLBI Equipment at Onsala

The 20 m radio telescope at Ousala used for geodetic VLBI was constructed in 1975/76. It is

an az-el mounted telescope enclosed inside a radome and is equipped with a secondary receiving

feed system. The slewing speeds are 2.4°/s and 1.0°/s in azimuth and elevation, respectively. The

system equivalent flux density values in X- and S-band are 2450 and 3200 Jy, respectively. Onsala

uses a Mark-IV data acquisition terminal and since May 1998 triple-cap heads are installed at

the recorder unit which enables thin and thick tape operation. There are two hydrogen masers at

Onsala, one Oscilloquartz EFOS-7 and one Kvartz CH1-75 [1].

The stability of the antenna tower is monitored by permanent measurements of vertical height

and temperature of the concrete tower [2]. Inside the concrete wall of the tower are 16 temperature

sensors at different height levels and azimuth directions. The temperature measurements started

in December 1994. Besides this there is an invar rod mounted at the top of the tower which allows

measurement of relative vertical height changes. Figure 3 shows the Ousala invar and temperature

measurement devices and approximately 2 years of measurements of temperature and vertical

height.

J_4

/A

/A

/A

/A

/A

,/A

/'.t

.,rj

f/

fJ

fJ

J /

f]

.I J

f J

.r J

JJ

r j

fJ

fJ

rA

fJ

,¢-j

fJ

me] pl,l+ bolled_

*+®+o,,+r=+I

ound,_o, J

ndtmllv© posilio_

Rsor fixed to

ground.

onlmdn I llbe

vertienl motion

[oVf Ihe end of the

1._uvar rod

i"F

i°I +o , I

-Io- i L i + + L i l i

2oo 31oo ,KI0 |00 41KI 700 I00 llXl 'I000 1100 t2@o

0 llnllumkll moll Jllal+llly I. tl_

2

:,t '°f i-,

200 :1130 8OO $0o I042 7O0 100 I00 10 11

Dl)l_Umb4w lll+m+ Jaaully I, IDI_

Figure 3: The stability measurement devices

at the Onsala 20 m telescope. The top graphs

show approximately 2 years of data from measurements of temperature (upper plot) and

vertical motion (lower plot). The temperature shown is the mean temperature of all 16

temperature sensors inside the concrete wall.

There is a water vapor radiometer (WVR) located close to the 20 m radio telescope (see Figure

2). The instrument is used continuously for studies of atmospheric properties.

1999 IVS Annual Report 91
Onsala Space Observatory (OSO) Onsala Space Observatory

Since 1997 Onsala is also equipped with a Micro Rain Radar (MRR) in order to infer the rain

rate and liquid water in the atmospheric boundary layer, and to access the quality of the WVR

data.

3. Current Status of Onsala Space Observatory

The pioneering participation in geodetic VLBI of the Onsala Space Observatory dates back to

1968 [3]. In 1998/99 0SO participates in three geodetic VLBI series, the EURO, CORE-B and

RDV series with 6 experiments per year each. Figure 4 gives an overview of the geodetic VLBI

experiments per year observed and Table 2 lists the geodetic VLBI experiments between March

1998 and March 1999 involving the Onsala Space Observatory.

2000

1999

1998

1997

1996

1995

1994

1993

1992

1991

1990

1989

1988

1987

1986

1985

1984

1983

1982

1981

1980

1979

,i,J,l,l,l,lh{hl,Jj_,_,l.l,l,l,_,l,],t,

10 20 30 40

Number of experiments per year

Table 2: Geodetic VLBI experiments involving Onsala Space Observatory between March 1998 and March 1999.

Exper. Date Remark

CB107 980311

CB108 980408

RDV08 980415

EURO42 980420

CB109 980520

EURO43 980622

RDV09 980624

CBll0 980701

RDV10 980810

EURO44 980817

CBlll 980826

RDV11 981001

EURO45 981012

CBll2 981104

EURO46 981214

RDV12 981221

EURO47 990201

50% data lost,

tracks overwritten

50% data lost,

tracks overwritten

antenna pointing

problems

inch-worm motor

failure

inch-worm motor

failure

Figure 4: Geodetic experiments per year involving

the Onsala Space Observatory since 1980.

Currently a new S/X-feed system is completed at Onsala to replace the old one using two

seperate feed horns for the two frequencies. The new one consists of a dual frequency corrugated

horn and a two reflector feed system [2]. Most of the system is completed, some remaining parts

will be finished in the near future [4].

92 1999 IVS Annual Report
Onsala Space Observatory Onsala Space Observatory (OSO)

4. Staff at Onsala Associated with the IVS Network Station

The staff at Onsala associated with the IVS Network Station is: Per Bergman (telescope scientist), Sten Bergstrand (Ph.D. student) Roy Booth (scientist, director), Rune Bystr6m (engineer),

Fredrik Corneliusson (technician), Gunnar Elgered (scientist), Lubomir Gradinarsky (Ph.D. student), R/idiger Haas (scientist), Roger Hammaxgren (technician), Karl-/_ke Johansson (engineer),

Lars E.B. Johansson (telescope scientist), BiSrn Nilsson (engineer), Hans-Georg Scherneck (scientist), and Borys Stoew (Ph.D. student). (The corresponding e-mail addresses and telephone

numbers can be found on the Onsala web page.)

5. Outlook

After installation of the new S/X-feed system we plan to join the CORE-A VLBI experiments

on a bi-weekly basis replacing our involvment in the CORE-B experiments. We will continue to

participate in the European observation series.

During the summer of 1999 we plan to do a remeasurement of the Onsala local footprint to

check the stability of our site. This will include measurements with a GPS antenna mounted in

the VLBI telescope in an effort to try to establish a new type of tie between the two observational

methods.

References

[1] Elgered, G., and R. Haas, Geodetic Very-Long-Baseline Interferometry at the Onsala Space Observatory 1996-1997, In: Proceedings of the 12th Wbrking Meeting on European VLBI for Geodesy and

Astrometry, held at H0nefoss, Norway, September 12-13, 1997, edited by B. R. Pettersen, Statens

Kartverk, pp. 49 53, 1997

[2] Elgered, G., and R. Haas, Geodetic Very-Long-Baseline Interferometry at the Onsala Space Observatory 1997 1998, In: Proceedings of the 13th Working Meeting on European VLBI for Geodesy and

Astrometry, held at Viechtach, February 12-13, 1999, edited by W. Schlii! _r and H. Hase, Bundesamt

f/ir Kartographie und Geodesic, Wettzell, pp. 60-64, 1999

[3] Scherneck, H.-G., G. Elgered, J. M Johansson, and B. O. RSnn/_ng, S[,:_ce geodetic activities at the

Onsala Space Observatory: 25 years in service of plate tectonics, Phys. Chem. Earth, Vol. 23, No. 7-8,

pp.811-823, 1998

[4] Elgered, G., R. Haas, and L. Pettersson, The IVS Technicnology Dev¢-!opment Center at the Onsala

Space Observatory (this volume)

1999 IVS Annual Report 93
Shanghai Astronomical Observatory National Astronomical Observatory, Chinese Academy of Sciences

Status Report of Seshan VLBI Station

Hong Xiaoyu, Liang Shiguang, Qian Zhihan

Abstract

This report summarizes the status of the Seshan VLBI Station.

1. Introduction

The Seshan VLBI Station for astrophysical, astrometric and geodetic applications which is

located near Sheshan Town about 30 km far way from the downtown of Shanghai was established

in 1987 and is operated by Shanghai Astronomical Observatory (SHAO), Chinese Academy of

Sciences (CAS). The first S/X dual band astrometric and geodetic VLBI experiment was carried

out in April, 1988. At present, it is a member of the EVN, APT and IVS. Recently, Seshan station

also is one of observational bases of the National Astronomical Observatory which was formed in

this year.

2. Facilities

The Seshan station is equipped with a 25 m radiotelescope with the capability of S/X dual band

observations. A cryogenic receiver with noise temperature of 15 K is used for X-band. The SEFD is

700 Jy at X-band. The upgrade of the extension of the bandwidth from 400 MHz to 800 MHz for Xband receiver is being performed. The SEFD is 2000 Jy for S-band and the higher SEFD is caused

by higher noise temperatures of both receiver and antenna. A room temperature receiver with noise

temperature of about 50 K is used for S-band. The 25 m antenna was adopted with a waveguide

system and it is not good for lower frequency observations, such as 2.2 GHz. The improvement

for S-band is under consideration. There also are L-, C- and K-band receivers available at Seshan

station which are mainly used for astronomical VLBI and single dish observations.

There are both VLBA Data Acquisition Terminal with 14 BBCs and Canadian Recording

Terminal at Seshan station. The upgrade from VLBA to Mark IV in cooperation with JIVE is

under way and it is expected that the completion of the Mark IV upgrade will be in the first half

of 2000.

Two hydrogen masers manufactured by SHAO are used as a frequency standard for VLBI

observations. The stability of the SHAO masers is about 10-14 with the time scale of 100-1000

sec.

3. Personnel

The main staff members at Seshan VLBI Station are listed as follows:

1999 IVS Annual Report

94
National Astronomical Observatory, Chinese Academy of Sciences Shanghai Astronomical Observatory

Hong Xiaoyu Research Professor and Chief Scientist

Liang Shiguang Research Professor and Chief Engineer

Yu Zhiyao Research Professor

Qian Zhihan Research Professor

Huang Xinyong Senior Engineer

Wei Wenren Senior Engineer

Xue Zhuhe Senior Engineer

The email accounts for the station are: seshan@center.shao.ac.cn; vlbish@online.sh.cn.

4. Future Plans

In general, it will take one day or more for the frequency switch, especially, the switch between

S/X band and C- or K-band. The improvement of the frequency switch is difficult, but it is being

considered.

The upgrade of the data acquisition terminal from VLBA to Mark IV and the extension of the

bandwidth for X-band receiver is under way mentioned above. It will be completed in the first

half of 2000, we expect.

The improvement for S-band is also under consideration. The upgrade of the receiver from room

temperature to cryogenic is no technical problem, but budget limitation. The main problems

are that the upgrade of the antenna with waveguide system and S/X dual band feed is not so

convenient. We are still trying to find a good way to do the improvement.

1999 IVS Annual Report 95
Simeiz VLBI Station Laboratory of Radio Astronomy of Crimean Astrophysical Observatory

Simeiz VLBI Station

N. Nesterov, A. Volvach

Abstract

This report summarizes the technical parameters of the "SIMEIZ" VLBI station. It also gives an

overview about the VLBI activities during 5 years. Horizontal station velocity was determined and

estimates its accuracy are obtained.

1. General Information

The Laboratory of Radioastronomy of the Crimean Astrophysical Observatory (CrAO) with

its 22-m radio telescope is located near Simeiz 25 km to the west of Yalta.

Figure 1. Simeiz VLBI station

The 22-meter radio telescope is situated on the banks of Blue Gulf of Black Sea in South part

of Crimea peninsula. It was constructed in 1965 and participated in the first VLBI observations

in 1969 in cooperation with USA.

96 1999 IVS Annual Report
Laboratory of Radio Astronomy of Crimean Astrophysical Observatory Simeiz VLBI Station

RT-22 operation is supported by control system, consisting of two encoders with accuracy

about 3 arcsec (rms), personal computer, CAMAC, quartz time standard, electric engines and

other needed equipment and software. The fast RT-22 movement is supported by 2 engines with

20 kW power each, they are used for rapid change of the pointing or to move RT-22 from one

source to another. 2 kW engines are used for tracking of the source.

Table 1 shows the antenna parameters.

Table 1. The antenna parameters of the Simeiz station.

Diameter D, m

Surface tolerance, mm (root mean square)

Wavelength limit, mm

Feed System

Focal length F, m

Focal ratio F/D

Effective focal length for Cassegraln system, m

Mounting

Pointing accuracy, arc sec.

Maximum rotation rate, degree/sec

Maximum tracking rate, arcsec/sec

Working range in Azimuth, degrees (0 to South)

in Elevation, degrees

22

0.25

2

Cassegrain system or primary focus

9.525

0.43

134.5

Azimuth-Elevation

10

1.5

150

-270 - 4-270

0 - 85

The Laboratory provides observing facilities for astronomers from international community

and for its own staff:

a) Very Long Baseline Interferometry (both astrophysical and geodetic projects);

b) multi wavelength monitoring of Active Galactic Nuclei (AGN) in millimeter domain;

c) solar and stellar activity investigations at mm-dm wavelengths;

d) molecular lines observations at mm wavelengths.

2. Status

VLBI observations at the radio telescope were started in 1969 using the Mark I system and

Rubidium standard. Further the antenna was included in the global VLBI network for the study of

astrophysical objects. The observations were carried out by CrAO and Institute of Space Research

at 1.35, 2.8, 6, 18, 49 and 92 cm. The Simeiz station was equipped with MARK-2 system and

hydrogen maser frequency standard with stability 10 -14 .

In June of 1994 the Simeiz station was equipped with terminal Mark IIIA supplied by NASA

GSFC with low noise receiver of S/X bands supplied by Institute of Applied Astronomy. That gave

the possibility to start fundamental geodetic study and to continue astrophysical VLBI observations

with higher sensitivity. Table 2 shows the system parameters of the Simeiz station. Table 3 shows

the station activity in 1994-1998.

Hydrogen maser standard at the station had unsatisfactory performance during 1996-1997.

Moreover, the electric power was switched off at station often for two or more hours. These two

factors resulted in degradation of quality of the data. New maser standard was installed at the

1999 IVS Annual Report 97
Simeiz VLBI Station Laboratory of Radio Astronomy of Crimean Astrophysical Observatory

Table 2. The system parameters of the Simeiz station.

IF, GHz 10.3 ,0.6 11.6 12.315"0 /8"4'22 '

A, crn /92 /49 [18 ]13 /6 3-611.3 /

Tsys, K I 150 I 120 I 1201 80 I 150 (30) 60 I 80

Table 3. Simeiz antenna activity.

IYeaxs 1994 1995 1996 199711998 1

Number of GEO experiment 18 18 / 7 I 4 12

Number of ASTRO experiment I 4 I 31 / 8 I 25 10

station in 1998. Time standard and Mark III formatter were supplied by power using UPS device.

The observations in 1998 showed that data quality became much better.

3. Analysis

Determination of vertical position during this interval is unreliable while precision of horizontal

coordinates of the station was quite satisfactory. Horizontal station velocity and its accuracy was

determined using 4.5 years of data. The position of the station at 1997.0 are:

X -- 3785231.073 4- 0.004_7 = 5.5 * 10 -1° 4- 0.2 * 10-l°

y = 2551207.417 4- 0.003 I2 = 4.9 * 10 -1° 4- 0.1 * 10 -1°

Z = 4439796.362 4- 0.006Z = 2.3 * 10 -1° 4- 0.2 * 10 -l°

The final proccesing of the data was made by Leonid Petrov from the Geodaetische Institut in

Bonn.

Table 4 shows the residual velocities with respect to Eurasian plate.

Table 4. Residual velocities respect to Eurasian plate.

Stations

CRIMEA

EFLSBERG

MATERA

DSS65

MEDICINA

NYALES20

ONSALA60

SESHAN25

WETTZELL

Up(mm/yr)

3.9 4- 4.5

-0.3 4- 0.6

0.8 4- 0.5

2.2 4- 1.2

-2.8 4- 0.5

2.0 4- 1.0

3.0 4- 0.3

0.9 4- 3.7

-0.1 4- 0.3

East (mm/yr)

1.5 4- 1.0

0.5 4- 0.2

1.1 4-0.2

0.1 4- 0.2

1.8 4- 0.2

0.0 4- 0.2

-0.9 4- 0.2

0.74-2.1

-0.1 4- 0.1

North(mm/yr) Corr I D ]

1.9 4- 0.9 0.09

-0.4 4- 0.2 0.01 • i

4.7 4- O.2 0.53

0.1 4- 0.3 -0.27 • I

2.1 4- 0.2 0.26 i J

0.0 4- 0.2 0.00

-0.7 4- 0.2 -0.22

-4.4 4- 2.4 -0.60

0.2 4- 0.2 0.12 I

RMS difference of horizontal velocity over defining stations: 0.3 mm/yr. Stations DSS65,

EFLSBERG, NYALES20, WETTZELL define plate rotation. Station WETTZELL defines vertical

reference.

1999 IVS Annual Report

98
Laboratory of Radio Astronomy of Crimean Astrophysical Observatory Simeiz VLBI Statio.

Figure 2 shows the field of residual velocities with respect to Eurasian plate. Four and one-half

years of geodetic VLBI observation at the station Simeiz allow us to conclude that the station

moves at azimuth 39 ° + 22 ° with respect to a Eurasian plate with velocity 2.4 ± 1.0 mm/yr where

the uncertainty is the estimate of accuracy. Vertical motion is not yet reliably detected.

4. Outlook

New operational system LINUX and Field System were prepared for use with our hardware.

1999 IVS Annual Report 99
Simeiz VLBI Station Laboratory of Radio Astronomy of Crimean Astrophysical Observatory

Figure 2. Field of residual velocities with respect to Eurasian plate

,%

,ONSALA60

EFLSBERG

WETTZELL :RIMEA

MEDI-CINA b

DSS65

2 mm/yr

• denotes a defining station

• denotes a free station

1999 IVS Annual RepoI t

100
Institute of Applied Astronomy of Russian Academy of Sciences Svetloe Radio Astronomical Observatory

Svetloe Radio Astronomical Observatory

Sergey Smolentsey, Ismail Rachimoy

Abstract

This report provides information about Svetloe network station: general information, facilities,

staff, present status and outlook.

1. General Information

Svetloe Radio Astronomical Observatory was founded by Institute of Applied Astronomy (IAA)

as first Station of Russian VLBI network QUASAR. Sponsoring organization of this project is

Russian Academy of Sciences (RAS). The site for the Observatory was chosen to be Svetloe village

located at the Karelian neck nearly 100 km north from St. Petersburg. The basic instruments

of the observatory are 32-m radio telescope and technical systems provided realization of VLBI

observations.

Svetloe Observatory participated in several regional and global geodetic projects: GIG'91,

BSL'93, DOSE'93, DOSE'94, BSL'97, IGEX'98 and is a EUREF permanent station. Its coordinates are defined in ITRF96 and ITRF97 reference frames.

Table 1. Svetloe Observatory location and address.

Longitude 29047 ` E

Latitude 60°32' N

Svetloe Observatory

Leningrad region, Priozerski district,

188833 Russia

http://www.ipa.rssi, ru

2. Technical and Scientific Information

The Svetloe station equipment includes the following main components: 32 m radio telescope,

equipped with low noise receivers, frequency and time keeping systems with H-masers, local geodetic network, SLR pad, GPS Trimble 4000 SST receiver and GLONASS A724M receiver, data

acquisition system, recording terminal, control computers, local computer network and technical

service systems. Local geodetic network is adjusted with accuracy 2-3 mm. Characteristics of the

radio telescope and other main components of the station are presented in Tables 2-5.

Frequency and Time Keeping System of Svetloe network station consist of Frequency and Time

Standard ensemble, complete set of lock VHF local oscillators and picosecond pulses generators.

Frequency and Time Standard ensemble includes four active hydrogen masers CH1-80 developed

in Russia. Frequency stability of these masers is presented in Table 6. Frequency and Time

calibrations are provided by phase and frequency comparators, passive hydrogen masers CH1-76

1999 IVS Annual Report 101
Svetloe Radio Astronomical Observatory Institute of Applied Astronomy of Russian Academy of Sciences

used as mobile clock, TV calibration facility, GPS and GLONASS receivers. Local VHF oscillators

are locked by reference 5 MHz or 100 MHz signal and provide 10-20 mW power output signals

at frequencies 1.26, 2.02, 8.08, 4.5, 22.12 GHz. Picosecond pulse generators utilize the 5 MHz

output from frequency standard to produce short duration (about 50 ps) pulses at 1 MHz rate for

receivers and down converter phase calibration.

Table 2. Technical parameters of the radio telescope.

Year of construction 1998

Mount AZEL

Azimuth range :t:270 (from south)

Elevation range from -5 ° to 90 °

Maximum azimuth

- velocity

- tracking velocity

- acceleration

Maximum elevation

- velocity

- tracking velocity

- acceleration

1.5°/s,

1.5t/s,

0.2°/s 2

0.8°/s,

1.0'/s,

0.2° / s _

Pointing accuracy better than 10Ir

Configuration Cassegrain

(with asymmetrical subreflector)

Main reflector diameter 32 m

Subreflector diameter 4 m

Focal length 11.4 m

Main reflector shape quasi-paraboloid

Subreflector shape quasi-hyperboloid

Surface tolerance of main reflector • 0.5 mm

Frequency capability 1.4-22 GHz

Coordinates of axis intersection 60°31t56".44 N (Transferred from GPS

(ITRF 96) 29°46_54".97 E mark 12350M001)

H = 86.6 m

Table 3. Parameters of receivers.

Wave band Frequency range Input noise temperature

18-21 cm 1.38-1.72 GHz 22 K

13 cm 2.15-2.5 GHz 18 K

6 cm 4.6-5.1 GHz 10 K

3.5 cm 8.2-8.7 GHz 17 K

(8.9 GHz under testing)

1.35 cm 22.2-22.7 GHz 90 K

102 1999 IVS Annual Report
Institute of Applied Astronomy of Russian Academy of Sciences Svetloe Radio Astronomical Observatory

Table 4. Data acquisition system and recording terminal characteristics.

Frequency band 100-600 MHz

Frequency tuning step 10 KHz

Number of down converters 4

Band pass of channels 0.25, 2, 8, 16 MHz

Using of clipping levels 2, 3 or 4

Recording terminal S2-RT

Format of output data $2 or Mark III

Table 5. Control computers.

Telescope control computer Pentium II 350

Field system computer Pentium 100

Operation system Linux

Field system version 9.3.25

Additional information: both passive and active hydrogen masers CH1-76 and CH1-80 have

been designed and manufactured by KVARZ Institute of Electronic Measurements, Nizhny Novgorod, Russia.

Table 6. Frequency stability of the CH1-80 H-maser.

Sample time interval

1 second

10 seconds

100 seconds

1000 seconds

(Allan variance) 1/2

3.10 -13

3- 10-14

1 • 10 -14

5.10 -15

3. Technical Staff

About 30 persons of IAA are involved in VLBI activity at the Svetloe Observatory. Leading

persons are listed in Table 7.

4. Present Status of Svetloe Observatory

The construction of the radio telescope at Svetloe was finished in 1998. The main parameters

of the radio telescope on 6 cm band (antenna efficiency SEFD) were measured. The tracking

system was adjusted with pointing accuracy less than 10". First testing spectral observations of

OH masers in R and L circular polarization were carried out. Preliminary VLBI observations had

been made on the baseline Svetloe - Bear Lakes in December 1998.

1999 IVS Annual Report 103
Svetloe Radio Astronomical Observatory Institute of Applied Astronomy of Russian Academy of Sciences

Table 7. Leading person of Svetloe Observatory involved in VLBI activity.

Name Position Role Telephone

+7-(812)-

E-mail

Prof. Nikolai Chef the Laboratory Data acquisition 235-33-16 nec@ipa.rssi.ru

Kottsov Signals Conversion terminal

and Registration

Dr. Vyacheslav Senior Scientific Receivers 230-64-96 vvm@ipa.rssi.ru

Mardyshkin Researcher,

Mr. Andrey Scientific FS software 230-64-96 agm@ipa.rssi.ru

Michailov Researcher

Mr. Alexander Scientific Frequency and Time 230-74-16 smolen@ipa.rssi.ru

Vytnov Researcher Keeping System

Mr. Eugenie Senior Scientific H-masers 230-74-16 smolen@ipa.rssi.ru

Zhukov Researcher

Mr. Sergey Junior Scientific Stations software 230-64-96 ipatov@ipa.rssi.ru

Syrovoy Researcher Radio telescope

control system

Vladimir Chief Engineer of the Technical support 312-36-28 iar@ipa.rssi.ru

Taxasov Svetloe Observatory

1 Outlook

We plan for the near future:

• Final adjustment of all radio telescope systems;

• Measurement of the radio telescope parameters on 13.5/3.5 and 1.35 cm waves;

• Test VLBI observations on 13.5/3.5 cm wave under Field System control;

• Installation of Mark IV data acquisition system in cooperation with NASA;

• Installation of Turbo Rogue GPS receiver in cooperation with OSO.

104 1999 IVS Annum Report
National Institute of Polar Research JARE Syowa Station ll-m antenna

JARE Syowa Station ll-m Antenna, Antarctica

Kazuo Shibuya, Koichiro Doi

Abstract

Syowa Station is located at 69.0 deg S and 39.6 deg E on East Ongul Island, Antarctica. The

Japanese Antarctic Research Expedition (JARE), which is coordinated by the National Institute of

Polar Research (NIPR), operates the ll-m S/X band paraboloid antenna for VLBI, and for receiving

data from the EXOS-D and the ERS-2 satellites. Brief reports on current status and on-going project

of VLBI observations are presented.

1. Introduction

The National Institute of Polar Research (NIPR) constructed an S/X band ll-m paraboloid

antenna at Syowa Staton, Antarctica in 1989 [1]. Although its main purpose was to receive data

from the EXOS-D "AKEBONO" satellite and the MOS-1 "MOMO" satellite, it was designed to

be capable of making geodetic VLBI observations. At an initial stage, there was no dedicated

back-end system nor stable frequency standards, but a test VLBI observation was made between

Syowa, Tidbinbilla and Kashima in 1990 by JARE-30, using a temporary receiver system and

a Cesium frequency standard, in close collaboration with the Communications Research Laboratory (CRL). This experiment resulted in a successful baseline determination with Syowa Station

[2]. After a long pause of eight years, integration of the permanent receiver/back-end system and

hydrogen maser system was made by JARE-39 at the end of December 1997. For the three expeditions from JARE-39 through JARE-41, regular (quasi-seasonal) geodetic VLBI observations were

made/planned among the University of Tasmania 26 m antenna at Hobart and the Hartebeesthoek

Radio Astronomy Observatory (HartRAO) 26 m antenna, and the first regular experiment (named

SYW981 experiment) was made in February 1998. Because JARE members change every year after one-year wintering, the ll-m telescope (Figure 1) was operated and maintained by the staff

who participated in JARE from the National Astronomical Observatory (NAO; JARE-39) and

from the Geographical Survey Institute (GSI; JARE-40).

2. Antenna Specifications

2.1. Mechanical System

The Syowa ll-m telescope has an ability of the maximum slew rate of 10 degree per second in

azimuth within the range from -270 degree to 270 degree, but we operate it under 6 degree per

second speed to prevent mechanical wear. The maximum slew rate in elevation is 6 degree per

second within the range from 0 degree to 180 degree. As the telescope is covered with a 17 m

radius radome, it can endure 60 m/s blizzards, and weathering/corrosion of the antenna panels

was found to be insignificant by the inspection made in 1997. Although rare, some part of radome

is likely to be covered with snow (especially in September), which decreases the signal strength.

The mechanical performance and related parameters of the telescope are summarized in Table 1.

Regular inspections of the driving motors and preparations of spare units by the JARE winterover member from the manufacturer (NEC Corporation) substantially reduce unexpected troubles,

1999 IVS Annual Report 105
JARE Syowa Station ll-m antenna National Institute of Polar Research

Figure 1. Syowa Station and the antenna radome.

but accidental power failure of the facility caused several damages to the electrical units/boards

previously.

Table 1. Specification of the Syowa ll-m antenna.

Maximum Speed in Azimuth

Maximum Speed in Elevation

Drive Range in Azimuth

Drive Range in Elevation

Pointing Accuracy

Verticality of Azimuth axis

Endurance Wind Speed

Panel Surface Accuracy

Latitude

Longitude

10 °/see.

6 °/see.

+27O °

0-180 o

within 0.02 ° rms.

within 0.004 °

60 m/see.

applicable to 22GHz experiment

-69°00.4 I

39°35.21

106 1999 IVS Annual Report
National Institute of Polar Research JARE Syowa Station ll-m antenna

2.2. Receiver System

Currently available receivers are S and X bands. The LNAs are not cooled; the system noise

temperature for X-band is estimated as around 186 K for the average of 7700-8600 MHz, while

that for S-band is estimated as around 91 K for the average of 2100-2500 MHz. According to the

source on/off test of ORI-A, aperture efficiency of X-band is obtained as 48%, while that of S-band

is obtained as at worst 50%. Thus SEFDs are 11230 and 5300 for the X and S bands, respectively.

The receiver characteristics are summarized in Table 2.

Table 2. Receiver performance ofthe Syowa ll-mantenna.

Band Frequency (MHz) Tsys (K) Efficiency SEFD (Jy)

S 2200-2320 91 0.50 5300

X 7860-8600 186 0.48 11230

2.3. Hydrogen Maser Systems and Time Comparison

Two hydrogen maser systems (Anritsu RH401A) were installed at the site and one of them is

used for the frequency reference. Cable length between the hydrogen maser and the receiver unit

is 150-160 m. The frequency standard system is also equipped with a Cesium frequency standard

(HP8508A), and is synchronized to UTC by using a GPS time receiver.

2.4. VLBI Back-end System

The VLBI back-end system basically adopted at Syowa Station is called K4-TCU (Timing

Control Unit) system. Three PCs are used, where the first one is used for VLBI field system

(FS9 compatible), the second one is used for pointing control and the third is used for delay

calibrations. At present, there are no on-line meteorological sensors, and editing of the log-file

from the information by the JARE meteorological observatory is necessary. As a back-up field

system, Syowa has a Mark III type field system (called GAOS by GSI). The sampling/recording

specification is summarized in Table 3.

Table 3. Sampling/recording specification of the Syowa 11-m VLBI antenna.

Bandwidth

Sampling rate

Sampling bit

Channels

Recording rate

X band

S band

2 MHz or 4 MHz

4 Mbits/s or 8 Mbits/s

1 bit

16

64 Mbits/s or 128 Mbits/s

6 ch, 2217 - 2302 MHz

8 ch, 8210 - 8570 MHz

1999 IVS Annual Report 107
JARE Syowa Station 11-m a_tenna National Institute of Polar Research

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", NIPR made an agreement with the Australian VLBI group

and HartRAO to do 48-hour geodetic VLBI observations four times a year for the three expeditions

(JARE-39 through -41). Four observations (SYW981, SYW982, SYW983, SYW984) were made

in 1998. As the correlator processing of the Syowa data basically depends on the Mitaka VSOP

correlator of NAO, and as the hybrid correlation of the $2-K4 data is still in a development stage,

baseline solutions for the above experiments are not obtained yet [3]. However, the SYW984

experiment showed clear fringes for any combination of the station pairs, and configuration of the

Syowa VLBI system was proved to be adequate for the intercontinental geodetic VLBI observations.

JARE is rather flexible concerning programs on station geophysics, and participation in the other

international VLBI programs (CRF07 and COHIG-6) was realized in February 1999. The D1 tape

recorded data were tried to be copied on a Mark III tape, but time stamps were found to have

many bit errors, and copying is not completed yet.

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, Antenna maintenance staff of JARE-39.

• Yoshihiro Fukuzaki (from GSI), Chief operator of JARE-40 (Feb. 1999 - Jan. 2000).

• Takeshi Ino, Antenna maintenance staff of JARE-40.

• Koichiro Doi (tbd), Chief operator of JARE-41 (Feb. 2000 - Jan. 2001).

• Seiji Takao (tbd), Antenna maintenance staff of JARE-41.

As there are few staffs at NIPR, Antarctic VLBI is accomplished by a consortium with NAO, GSI,

CRL and NIPR staffs; the principal scientists are listed as authors of [3].

5. Concluding Remark

Syowa Station is located on a firm bedrock area without sedimentary layer and is situated in a

geographically important position for global geodynamics. Colocation observations using DORIS,

GPS, PRARE, STS-1 seismometer and pressure- sensor sea-level meter are continuing, e.g. [4].

We have a proposal to continue VLBI for the coming five-year JARE project (JARE-42 through

JARE-46).

References

[1] Hirasawa, T., Ejiri, M., Inada, T., Ohashi, S., Endo, K., Kuzuya, R, Okamoto, H., Nagao, T., Sato, S.

and Chiba, M. (1990): Multipurpose satellite data receiving system, NEC Technical Note, Vol. 43, No.

4, 73-94 (in Japanese).

108 1999 IVS Annual Report
National Institute of Polar Research JARE Syowa Station ll-m antenna

[2] Kurihara, N., Ejiri, M., Takahashi, Y., Kondo, T., Koyama, Y., Jauncey, D. L. and Reynolds, J. E.

(1995): The results of the first Antarctic VLBI experiments with Syowa Station in Antarctica, Antarctic

Science.

[3] 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.

[4] Shibuya, K. (1995): VLBI programs in the Japanese Antarctic Research Expedition and the role of

Syowa Station as an observatory for global geodesy in Antarctica, in Proceedings of the fourth AsiaPacific Telescope (APT) Workshop, 46-51, ed. by E. A. King, Australia Telescope National Facility,

Sydney, Australia.

1999 IVS Annual Report 109
Transportable Integrated Geodetic Observatory Bundesamt fiir Kartographie und Geod_isie

Transportable Integrated Geodetic Observatory

Hayo Hase

Abstract

This report summarises the technical parameters and the technical staff of the VLBI module of the

transportable fundamental station TIGO. It also gives an overview about the VLBI activities during

its test period at Wettzell. The outlook lists the outstanding tasks to improve the performance before

TIGO will be used at a remote site abroad.

1. TIGO at Wettzell

The Transportable Integrated Geodetic Observatory consists of a radio telescope for VLBI,

an optical telescope for SLR, a GPS array of four GPS permanent receivers, a super-conducting

gravimeter, a broad spectrum seismometer, meteorological sensors and an ensemble of atomic

clocks. TIGO is still located at the site of the Fundamentalstation Wettzell, since arrangements

have to be setup for hosting the entire system and some technical problems need to be fixed before

its first operation abroad.

Figure 1. TIGO VLBI module at Wettzell. The 6m-offset radio telescope can be setup within a week by

two persons. The operations room is in the air-conditioned container in the background.

Wettzell is located in the Bavarian Forest in the south-east of Germany.

2. Technical Parameters of the VLBI module of TIGO

The largest instrument of TIGO is the radio telescope for VLBI. The design criteria were

110 1999 IVS Annual Report
Bundesamt fiir Kartographie und Geod_isie Transportable Integrated Geodetic Observatory

Table 1. Location and addresses of TIGO at Wettzell.

Longitude 12.88 ° E

Latitude 49.14 ° N

Bundesamt fiir Kartographie und Geod£sie

Projekt TIGO

Sackenrieder Stra/_e 25

D-93444 KStzting, GERMANY

http://www.wettzell.ifag.de

• transportability in 12.20-m standard containers and maximisation of the dish size,

• setup of the radio telescope with muscle power within three days,

• optimisation for the constance of signal-path length under various elevations.

The technical parameters of the radio telescope are summarised in Table 2.

3. Technical Staff of the VLBI Module of TIGO

The TIGO VLBI module gains from the experiences of the staff from the 20-m radio telescope.

For the use of TIGO at a remote site additional operators and engineers for the maintenance will

be necessary.

Table 3 lists the TIGO station staff which are involved in the VLBI module.

4. Status of the TIGO VLBI Module

TIGO participated in several VLBI experiments which are listed in Table 4. Initially a linear

polarisation in S-band reduced the SNR to about 50% of the expected one. After the discovery of

two broken connectors no fringes indicated a wrong polarisation as delivered by the feed company.

Since May 1998 the S-band polarisation is right-hand circular. The performance in X-band is

better than specified, in S-band the specifications have not been reached yet. Some improvements

are on the agenda for 1999.

TIGO owns the world's first VLBA4 terminal. However the Mark IV formatter is a prototype

and the Mark IV decoder is still under development. Both components are expected to be replaced

by the final one during 1999.

TIGO was used in several experiments with an offset reference frequency of the H-maser.

Usually the reference frequency is 5 MHz. The offset at TIGO was -0.1 Hz to the 5 MHz. This

enabled the short baseline determinations between the Wettzell and TIGO radio telescopes. The

analysis was done by Leonid Petrov, GIUB, who checked his phase-delay routines with it [1]. The

very high accuracy of the phase-delay solution was about =h0.2 mm which cannot be increased due

to mechanical limits of the radio telescope (surface, bearings).

TIGO's cable wrap showed some problems in the azimuth part. The limited space due to its

transportability did not leave enough room for about 30 cables. This problem should be solved

by introducing four hybrid cables, which have been made specially for TIGO. The installation is

planned for spring 1999.

1999 IVS Annual Report 111
Transportable Integrated Geodetic Observatory Bundesamt flit Kartographie und Geod_isie

Table 2. Technical parameters of the radio telescope of TIGO for geodetic VLBI.

Parameter TIGO-VLBI

owner and operating agency

year of construction

radio telescope system

receiving feed

diameter of main reflector d

focal length f

//d

surface contour of reflector

azimuth range

azimuth velocity

azimuth acceleration

elevation range

elevation velocity

elevation acceleration

X-band

'reference u = 8.4GHz, )_= 0.0357m)

Tsys

SSEFD(CASA)

G/T

_7

S-band

(reference u = 2.3GHz, A = 0.1304m)

Tsys

SSEED(CASA)

G/T

VLBI terminal type

recording media

Field System version

unattended VLBI observations

BKG

1995

offset

primary focus

6m

2.18m

0.3629

+0.2ram

0... 540 °

6°/s

l°/s 2

0... 90 °

3°/s

l°/s 2

8.1 - 8.9 GHz

65K

7700 Jy

35.5dB/g

0.824

2.2 - 2.4GHz

85K

12000 Jy

22.3 dB/g

0.692

VLBA4

thin tape only

9.3.207

24h, mode C

Table 3. Staff working at the TIGO VLBI module at Wettzell.

Name I Background Dedication Agency

Hayo Hase geodesy 100% BKG

Olaf Lang electrical engineering 30% BKG

Armin BSer electrical engineering 10% BKG

5. Outlook

It is envisaged that TIGO has reached a status for its abroad mission to define new fundamental

points in the southern hemisphere.

1999 IVS Annual Report

112
Bundesamt fiir Kartographie und Geod_isie Transportable Integrated Geodetic Observatory

Table 4. Participation of TIGO in VLBI Experiments from the beginn___inguntil March 1, 1999.

Date _ Experiment -[ Remarks

1997-11-12

1997-12-08

1998-02-03

1998-02-10

1998-03-17

1998-03-24

1998-03-31

1998-04-07

1998-04-14

1998-04-21

1998-04-28

1998-05-05

1998-05-19

1998-06-22

1998-07-20

1998-08-17

1998-10-12

1998-12-14

1999-02-01

1999-02-04

1999-02-23

1999-02-25

_ingetest(Tg-Eb-On)

EUROP_40

EUROPE-41

NA254

NA255

NA256

NA257

NA258

NA259

NA260

NA261

NA262

NA264

EUROPE-43

SBI98A

EUROPE-44

EUROPE-45

EUROPE-46

EUROPE-47

WZTIE-1

NA304

WZ4TS

successful, but weak S-band

first 24h experiment

reference frequency offset

reference frequency offset

fixing linear polarisation in S-band

no fringes

S-band RHC polarisation correct

reference frequency offset

reference frequency offset

lost due to GPS-time offset in Turbo-Rogue

reference frequency offset

reference frequency offset

reference frequency offset

reference frequency offset

An Announcement of Opportunity for possible hosting countries will introduce TIGO to foreign

institutions. A decision on the first destination should be reached within 1999. Outside Germany

TIGO should be used regularly within the CORE project at a new site in the ITRF.

Several tasks must be done at Wettzell beforehand. The agenda for 1999 consists of:

1. Test PC-FS version 9.3.207 based on the Linux kernel 2.0.

2. Test the Mark IV decoder prototype.

3. Replace cables in the TIGO azimuth cable wrap.

4. Improve S-band performance.

• Make and install a low-loss cable in front of the receiver input.

• Investigate spillover of 6-m reflector.

• Replace S-band LNA.

• Replace dewar.

5. Integration of the Totally Accurate Clock into the VLBA4 system.

6. Install databases for meteorological data.

1999 IVS Annual Report 113
Transportable Integrated Geodetic Observatory Bundesamt fiir Kartographie und Geod_ie

References

[1] Hase, H., Petrov, L.: The First Campaign of Observations with the VLBI-Module of TIGO, In: Proceedings of the 13th Working Meeting on European VLBI for Geodesy and Astrometry, held at Viechtach, February 12-13, 1999, edited by W. Schliiter and H. Haze, Bundesamt ffir Kartographie und

Geodgsie, Wettzell, 1999

1999 IVS Annual Report

114
Geographical Survey Institute, JAPAN Tsukuba 32-m VLBI Station

Tsukuba 32-m VLBI Station

Misao Ishihara, Keizou Nemoto, Masao Iwata, Kousei Shiba, Kazuhiro Takashima,

Shigeru Matsuzaka

Abstract

This report summarizes the specification of our VLBI systems and the members of the Geographical

Survey Institute (GSI) VLBI section. We present our history of VLBI activities and the status. Firstly,

CSI developed three mobile VLBI systems and had repeated observations with CRL. On the other hand,

as GSI installed 1000 permanent GPS stations all over Japan (GEONET), our VLBI strategy has been

shifted from domestic mobile experiments to permanent stations and international experiments. Last

year GSI constructed a domestic VLBI network with five permanent stations. A main station of

our network is Tsukuba 32-m VLBI station (Fig 1). The station also becomes a key station in the

international VLBI networks.

1. GSI VLBI site

Our purposes of VLBI activities are the following.

1. Constructing a new geodetic reference frame referred to ITRF94.

2. Simultaneous and continuous monitoring of relative movement of the plates surrounding

Japan.

3. Contribution to global environmental preservation and investigations into the geophysical

phenomena by joining the International Geodetic VLBI Network.

4. Establishment of a terrestrial reference frame to improve the accuracy of positioning by space

geodetic survey techniques.

GSI operates the domestic VLBI network with five stations (Shintotsukawa, Kashima, Tsukuba,

Chichijima, Aira) in order to achieve these purposes. GSI also operates 959 GPS stations

(GEONET: GPS Earth Observation Network). To connect both networks we carried out a colocation survey by GPS and by total station at each VLBI station. The measured precision was

-1-5 mm for horizontal component and +2 cm for vertical component. We have a plan of colocation

between VLBI and GPS network aiming at the higher precision (:t:1 mm).

2. Specification of GSI VLBI systems

GSI has a domestic VLBI network with five stations. The recording system of the network is

K4 system. The specification of GSI's five VLBI systems are presented in Table 1.

Diameters of the antennas are 26 m (Kashima), 3.8 m (Shintotsukawa) and 10 m (Chichijima

and Aira). Antenna mount type is non-shifted AZ-EL mount. Receivers are designed for S-band

and X-band. Recording system is K4 developed by Communications Research Laboratory (CRL).

Recording rate was 64 Mbps. The recorded tape was processed with K4 correlator at Tsukuba

VLBI Center.

1999 IVS Annual Report 115
Tsukuba 32-m VLBI Station Geographical Survey Institute, JAPAN

Figure 1. Tsukuba 32m VLBI antenna.

Table 1. Technical parameters of the radio telescopes of GSI.

Parameter

year of construction

radio telescope

(S-band)

Mount

diameter of main ref.

surface contour of ref.

Tsukuba

Recorder

Controller

1998

cassegrain

Az-E1

32m

=t=0.5mm

Kashima

Mark IV, K4

FS9, GAOS

1968

cassegrain

Az-E1

26m

Chichijima

VLBA, K4 I FS9, GAOS

1997

cassegrain

prime forcus

Az-E1

10.26m

:hO.5mm

Aira

1997

cassegrain

prime forcus

Az-E1

10.26m

+0.5ram

Shintotsukawa

azimuth velocity 3°/s 1°/s 3°/s 3 °/s

elevation velocity 3 °/s 1°/s 3 °/s 3 °/s 1°/s

X-band GHz 7.78 - 8.98 8.05 - 8.55 7.78 - 8.98 7.78 - 8.98 8.18 - 8.98

S-band GHz 2.12 - 2.52 2.20 - 2.40 2.12 - 2.52 2.12 - 2.52 2.21 - 2.45

K4 K4 K4

GAOS GAOS GAOS

1995

cassegrain

prime forcus

Az-E1

3.8m

+0.5mm

2.9°/s

3. Technical Staff of the VLBI group at GSI

Table 2 lists the VLBI staff at GSI.

4. History of VLBI at GSI

The first system was a mobile system with a 5-m diameter antenna. In 1984, GSI had the first

VLBI experiment with Kashima VLBI station of Communications Research Laboratory. Since

1986, GSI participated in a project named "VLBI Experiment for Geodetic Application" (VEGA)

116 1999 IVS Annual Report
Geographical Survey Institute, JAPAN Tsukuba 32-m VLBI Station

Table 2. Staff working at GSI VLBI section.

Name Position Jobs

Shigeru MATSUZAKA IVS Networks Representative

Misao ISHIHARA VLBI leader

Keizo NEMOTO Colocation chief Colocation, H-maser, Operation

Masao IWATA Correlation chief Correlation, Operation

Kousei SHIBA Operation chief Experiments Coordination, Operation

Kazuhiro TAKASHIMA Analysis chief Baseline Analysis, Operation

Shinobu KURIHARA Operator Baseline Analysis, Operation

Michiko ONOGAKI Operator Antenna maint., Operation

Kyoko KOBAYASHI Assistant Correlation, Operation

using the mobile system. The purposes of the VEGA project were the detection of crustal deformation, accuracy improvement of the Japanese precise geodetic network, and contribution to

determination of GPS satellite orbits.

From 1986 to 1994, GSI repeated mobile VLBI experiments at eight sites in Japan. By comparing with the survey results in 1987 and 1989, GSI succeeded in detecting a velocity of the Philippine

plate relative to Kashima of 3.7 cm per year. This plate motion is asserted to be the main force of

earthquakes in the Tokai area. The main station of these mobile VLBI experiments was Kashima

station (26 m). GSI developed three mobile systems. Diameters of these antennas were 5 m, 2.4 m

(with CRL) and 3.8 m. In t992, the ownership of Kashima VLBI station (26 m) was transferred

from CRL to GSI. In 1992, GSI started international VLBI experiments participating in the DOSE

project with Kashima VLBI station.

//

"s_ntot sukawa

j/

! iTsukub_;t

Kashima

iChichijimai

Figure 2. GSI domestic VLBI network.

Distributions of these stations are shown in Fig. 2. Baseline lengths between each station

are about 1000 km. Shintotsukawa and Kashima are on the North American plate, Chichijima

1999 IVS Annual Report 117
Tsukuba 32-m VLBI Station Geographical Survey Institute, JAPAN

is on the Philippine Sea Plate, Aira is on the Eurasian plate. Baseline analysis was done with

CALC/SOLVE. After February 1997, GSI had periodical (seasonal) experiments. Standard deviations of baseline length are 6 mm with Shintotsukawa and 4 mm with others in each experiment.

5. Outlook

GSI finished constructing Tsukuba VLBI station (32 m) on 26th March 1998 and had the first

(official) experiment in June 1998. We introduced some ideas to guarantee the high performance of

Tsukuba VLBI antenna. The back panels and ventilation system keeps the shape of the antenna

surface from deforming caused by temperature change. The antenna structure is covered with

sunshade panels. GPS antenna is settled on the top of the VLBI antenna for colocation. Helium

cooling system is installed for X band receiver. The front-end and back-end are connected with

optical transmission devices to improve the SNR. Back-end room is shielded from radio noise

and H-maser room is shielded from electromagnetic noise. Mark IV and K4 type recording are

available. GSI also is developing a dubbing machine from K4 to Mark IV. IGS station (TSKB) is

close by the 32 m antenna (300 m). Colocation at Tsukuba will be achieved at mm-level.

References

[1] Ogi, S.,: Status Report of Geographical Survey Institute Japan, In: Proceedings of the 13th Working

Meeting on European VLBI for Geodesy and Astrometry, held at Viechtach, February 12-13, 1999,

edited by W. Schliiter and H. Hase, Bundesamt fiir Kartographie und Geod_ie, Wettzell, 1999

[2] Ogi, S., Y. Fukuzaki, M. Iwata, K. Shiba, M. Yazawa, K. Takashima, and K. Nagata: Comparison of

the time variation with GSI VLBI Domestic Experiments and Daily GPS Measurements, held at the

Communications Research Laboratory, Koganei, Tokyo, January 25-28, 1999

118 1999 IVS Annual Report
National Astronomical Observatory, Chinese Academy of Sciences Urumqi Astronomical Observatoiy

Urumqi Astronomical Observatory

Liu Xiang, Zhang Jin

Abstract

This report summarises the technical parameters and the technical staff of the VLBI station of

Urumqi Astronomical Observatory. It also gives an overview about the VLBI activities during last

year at Urumqi.

1. The VLBI station of UAO

Urumqi Astronomical Observatory (UAO) consists of a radio telescope for VLBI, an optical

telescope, a GPS station and a telescope for solar observing. UAO is located at the site of the

Capital of Xinjiang Provice of China, while the 2- m radio telescope is located at Nanshan Mt.

Since the beginning of 1999, UAO has been affiliated with National Astronomical Observatories,

Chinese Academy of Sciences.

Figure 1. 25m telescope at Nanshan Mt.

2. Technical Parameters of the VLBI station of UAO

The largest instrument of UAO is the radio telescope for VLBI. Tables 1 and 2 list the parameters for the antenna and receivers.

1999 IVS Annual Report 119
Urumqi Astronomical Observatory National Astronomical Observatory, Chinese Academy of Sciences

Table 1. UAO Antenna Parameters

Diameter

Working range

Maximum speed

Maximun acceleration

Pointing error

RFI

Location

25m

AZ +/- 270 ° , EL 4- 89°

1°second for AZ, 0.5 for EL

0.5°second for AZ, 0.25 for EL

15" (rms)

There are interferences at 92cm and 18cm bands.

The antenna is sited about 60 km away from the host unit in Urumqi.

Band

1.3 cm

3.6 cm

6 cm

13 cm

18 cm

30 cm

92 cm

Table 2. !

Frequency range

22100-24000 MHz

8200-8600

4750-5150

2150-2450

1450-1750

underconstruction

317-337

JAO Receiver

LO

22000MHz

8080

4620

2020

1500

?arameters

Pol.

LCP

RCP

LCP

RCP

LCP+RCP

LCP+RCP

Tsys

170K

35

30

180

85

9O

SEIfD

2580Jy

290

276

2440

1394

1265

Back-end systems include Mark IIIA, Mark II, K4.

Timing system: two H-masers with stability 10 -14. A GPS (TAC) receiver is installed.

3. Technical Staff of the VLBI station of UAO

Table 3 lists the UAO staff members.

4. Status of the VLBI station

The station is a formal member of EVN, a member of NASA CORE project and China APSG

project. It is also a member of APT and Russia LFVN.

For S/X band, the system has contributed much observing time to NASA these years. The

performance sounds good, except for the phase-cals and the delay measuring system. Another

problem is that the FS has not been connected to control the antenna.

The observations were made for CB307-CB312 of NASA, total time is 144 hours, and 48 hours

observation for APSG-3 and APSG-4 project of China (S/X band).

The observations were made for 15 projects of EVN at L-band, C-band and K-band, total time

is 121 hours. The observations were made for LFVN project of Russia, the sum of time is 144 hours

(at 92 cm and 18 cm, Mark II mode). Four hours observation was made for Shanghai correlator

test. CORE-B501 of NASA was observed in Jan. 1999. EVN session-1 also was conducted in

February this year.

VLBI technical activity: a new head of the tape recorder was installed. Aili Yusup worked in

Haystack three months for a new S/X band receiver. Zhang Hongbo worked in Jodrell Bank three

1999 IVS Annual Repo,

120
National Astronomical Observatory, Chinese Academy of Sciences Urumqi Astronomical Observatory

Prof. Zhang Jin

Zhang Hongbo

Liu Xiang

Wang Na

Aili, Yusup

Shao Minhui

Wang Weixia

Dong Yousuo

Zen Yong

Rizwan Mamat

Aili. E

Jarken. Y

Bao Xinming

Wang Huaxiang

Ma Xuelian

Chen Maozheng

Yang Wenj un

Table 3. UA0 Technical Staff

chief scientist and general engineer

vice general engineer

the head of vlbi operation group.

responsible for single dish observation.

engineer, vice general engineer.

engineer, responsible for H-maser.

engineer, responsible for receivers.

engineer, responsible for operation.

engineer, responsible for the antenna.

engineer, responsible for Mark IIIA, Mark II and K4.

staff of the operation group.

staff of the operation group.

staff of the operation group.

staff of the operation

staff of the operation

staff of the operation

staff of the operation

group.

group.

group.

group.

months for Urumqi Mark IV upgrade. A team of 39th institute of China worked at the station

half month for the antenna adjustment including main reflector, sub-reflector and pointing. The

efficiency of the antenna has raised about 10%. The K-and and L-band are also adjusted.

The plate motion parameters of Urumqi station can be found in NASA Web. Astrophysical

VLBI results which the station used can be seen in literature. The single dish observing facilities

axe undergoing to be established for pulsar timing and H20 maser observing.

5. Outlook

Mark IV upgrade will be done at the end of 1999 or early 2000. A new S/X band receiver could

be installed in this year. A new FS computer will arrive at the station and a connection will be

made so as to control the antenna by FS in 1999. It is planed that 30 cm band system could be

founded in 1999 according to TOG proposal of EVN. A dual polarized cooling receiver system of

L-band is planed to be built in this year in order to fit pulsar timing and VLBI request.

1999 IVS Annual Report 121
MIT Haystack Observatory

Westford Antenna

Westford Antenna

Michael Poirier

Abstract

Technical information is provided about the antenna and VLBI equipment at the Westford site of

Haystack Observatory.

1. Westford Antenna at Haystack Observatory

Since 1981 the Westford antenna has been one of the primary geodetic VLBI sites in the world.

Located _--45 miles northwest of Boston, Massachusetts, the antenna is part of the MIT Haystack

Observatory complex.

Figure 1. Aerial view of Westford site. The VLBI antenna is inside the radome. The WES2 GPS antenna

is on top of the tower in the upper left corner of the photograph.

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.

1999 IVS Annual Report

122
MIT Haystack Observatory Westford Antenna

Table 1. Location and addresses of Westford antenna.

Longitude 71.49 ° W

Latitude 42.61 ° N

Height above m.s.1. 116 m

MIT Haystack Observatory

Off Route 40

Westford, MA 01886-1299 U.S.A.

http ://www.haystack, mit. edu

2. Technical Parameters of the Westford Antenna and Equipment

The technical parameters of the Westford antenna, which is shown in Figure 2, are summarized

in Table 2.

Figure 2. Wide-angle view of Westford antenna inside the radome. The VLBI S/X receiver is located at

the prime focus. The subreflector in front of the receiver is installed when observing with the TAL receiver

(see Section 4), which is located at the Cassegrain focus.

The antenna is enclosed in a 28-meter-diameter, air-inflated radome made of 1.2-mm-thick,

Teflon-coated fiberglass - see Figure 3. When the radome is wet, system temperatures increase by

10-20 K at X-band and by a smaller amount at S-band.

The major components of the VLBI data acquisition system are a Mark IV electronics rack, a

Mark IV tape drive, which is used for recording thin tapes only, and a Pentium-class PC running

PC Field System version 9.3.25. The primary frequency and time standard is the NR-3 hydrogen

1999 IVS Annual Report 123
MIT Haystack Observatory

Westford Antenna

Table 2. Technical parameters of he Westford antenna for geodetic VLBI.

Parameter

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

Tsys at zenith

aperture efficiency

SEFD at zenith

West ford

symmetric paraboloid

18.3 meters

aluminum honeycomb

primary focus

5.5 meters

elevation over azimuth

electric (DC) motors

90 ° - 470 °

4 ° _ 87 °

3 o S -1

2° S -I

X-band system S-band system

8180-8980 GHz 2210-2450 GHz

50-55 K

0.40

1400 Jy

70-75 K

0.55

1400 Jy

Figure 3. Westford site at night, with radome illuminated from inside.

maser. A TAC GPS receiver provides independent timing information.

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 axe available from the IGS and cignet archives.

1999 IVS Annual Report

124
MIT Haystack Observatory Westford Antenna

3. Westford Staff

The personnel associated with the VLBI program at Westford and their primary responsibilities

are:

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

4. Status of the Westford Antenna

Westford participates regularly in the CORE-A, CORE-B, IRIS-S and RD-VLBA series of

geodetic experiments, as well as in occasional NEOS experiments, fringe tests, and various ad hoc

experiments. In the year ending 1999 March 1, Westford participated in a total of fifty-one 24-hour

geodetic experiments.

Upgrades to the antenna and VLBI systems over the last two years include:

• replacement of the original antenna controls with a system based on programmable logic

controllers

• replacement of the 1970s-vintage analog servo with a digital servo system

• conversion of the Mark IIIA electronics rack and recorder to Mark IV

• replacement of the HP-1000 E-series computer used to point the antenna with a Pentiumclass PC that also runs the PC Field System.

The only significant equipment failure during the past year occurred in the cryogenic helium

compressor; AlliedSignal shipped a replacement quickly. Roughly twice a year the receiver LNA

warms up due to contamination in the cold head, which must then be purged.

Use of the Westford antenna is shared with the Terrestrial Air Link (TAL) Program operated

by the MIT Lincoln Laboratory. In this project Westford serves as the receiving end on a 42-

km-long terrestrial air link designed to study atmospheric effects on the propagation of wideband

communications signals at 20 GHz.

5. Outlook

With the advent of the Mark IV correlators and more intensive observing in the CORE program,

we anticipate being able to increase by a modest amount the number of geodetic experiments

observed annually at Westford.

Two more upgrades to the antenna systems are planned for the coming year: (1) addition of

a second drive motor with clutch assembly to each axis, to improve fine movement control, and

(2) replacement of the 17-bit position encoder on each axis by a 19-bit, LED-based encoder, to

provide improved pointing accuracy and to reduce maintenance costs.

1999 IVS Annual Report 125
2lNm Radiotelescope at Wettzell Bundesamt fiir Kartographie und Geod_isie

20-m Radiotelescope at Wettzell

R. Kilger

Abstract

This report summarizes some general information of the 20-m radio telescope, the main design and

technical criteria and introduces the working staff of the antenna. Additionally it gives an overview of

the VLBI observing activities through the present lifetime of the antenna.

1. General Information

The 20-m radio telescope in Wettzell was designed in the years 1980/81 as a project of

the former "Sonderforschungsbereich 78 Satellitengeodsie", hosted at the Technical University

Munich; the antenna was constructed in 1982/83 in cooperation with the German companies

MAN/VERTEX (VERTEX is former KRUPP). The telescope is an essential part of the Fundamental Station Wettzell, which is operated by the Bundesamt fiir Kaxtographie und Geod_sie

(BKG) together with the Forschungseinrichtung Satellitengeod_ie (FESG) of the Technical University of Munich (Figure 1).

Figure 1. The 20m-radiotelescope and its operation building at Wettzell.

The antenna was designed for geodetic applications and is dedicated 100% to geodetic VLBI

observations. It is a "turning head" antenna with a cassegrain geometry; azimuth-, elevation- and

boresight-axis intersect to the highest, technically possible precision within one single point, which

is the reference point of the antenna.

1999 IVS Annual Repolt

126
Bundesamt fiir Kartographie und Geod_isie 20-m Radiotelescope at Wettzetl

. Main Design and Technical Criteria

Geometry of the antenna:

- General Concept: "Turning Head", Cassegrain geometry with coaxial

adjusted main- and sub-reflector.

- Main reflector: Mathematical rotational paraboloid, diameter

orthogonal aperture area

focal length

- Subrefiector: Mathematical rotational hyperboloid, fixed mounted, diameter

Kinematic Data of the antenna:

- Azimuth axis angle of movement

velocity

acceleration

- Elevation axis angle of movement

velocity

acceleration

Surface Tolerances:

- total error of main reflector

- total error of sub reflector

20m

314.2m 2

9.0m

2, 7m

+270 ° from South

+ 3°/sec

+ l.5° / sec 2

0... 90 °

+l.5°/sec

+ l.5° / sec 2

±0.35ram rms

±0.02ram rms

Further Instrumentation:

• Feedhorn

In 1983 the 20-m radio telscope in Wettzell had been equipped with a dual frequency S/X-band

feedhorn of JPL design used for the big 64m-telescopes of DSN, modified to the actual geometry

of our 20-m antenna in Wettzell. This feedhorn had been operated more than 12 years with great

success until R&D observations enlarged the IF frequency span for geodetic VLBI observations:

X-band from 360 to 720 MHz and

S-band from 85 to 125 MHz.

Since July 1996 Wettzell operates with a new feedhorn manufactured by VERTEX, which was

designed according to the enlarged IF frequency span. Due to the fact that Wettzell is a station

nearly exclusively dedicated to geodetic VLBI observations, it has implemented only this feedhorn

and cannot observe different frequencies in the radio spectrum.

• Receiver

Wettzell started its VLBI observations with an uncooled S-X-receiver with parametric amplifiers on loan from Goddard Space Flight Center. These were used until 1986 and then were

replaced by a helium cooled S/X receiver in Haystack standard design for geodetic application. To

have the first preamplifiers in S/X-band as close to the feedhorn as possible and to improve the

accessibility of the helium cooled dewar the dewar is mounted directly at the output of the X-band

waveguide.

• Data Aquisition

1999 IVS Annual Report 127
20-m Radiotelescope at Wettzell Bundesamt ffir Kartographie und Geod_isie

Wettzell has a standard VLBI data aquisition terminal with:

- Standard IF Distributor including IF3 module,

- Mark IV Formatter,

- Mark III Decoder,

- 16 Videoconverters upgraded to Mark IV,

- Delay Calibrator (antenna + ground unit)

- TTY Distributor,

- 5 MHz Distributor,

- A rack mounted oscilloscope to monitor phasecal signal permanently and

- Power supply units.

• Tape Units

Wettzell has two Honeywell tape recorder units (Model 96); both have been upgraded for thin

tape usage by MPIfR. One unit is still Mark IIIA standard, one unit has been upgraded to Mark IV

standard by Haystack Observatory. All operations are done in Mark IV standard since Feb 26,

1999.

• K4

The 20-m radio telescope in Wettzell has a long history of VLBI observations with Japan; they

were partly recorded in Mark III, partly in K4 recording technique. Here the data are recorded on

D1 cassettes instead of magnetic inch tapes. Presently Wettzell has on loan from CRL, Koganei:

VLBI Interface Unit DFC 2100 and

Digital Instrumentation Recorder DIR 1000.

It is planned to purchase these units in the near future.

• Field System

Wettzell runs its VLBI observations presently - May 1999 - with Field System, version 9.3.25.

The Japanese K4 equipment can be operated by a K4 version of Field System, version 9.3.120.

This K4 version was developed and installed in Wettzell by Ed Himwich.

• Additional Equipment

A measuring system to determine the relative height of the reference point of the antenna

(intersection of Az-, El- and boresight-axis) and the ground is installed inside the 20-m radio

telescope. An Invar wire is spanned closely from the reference point of the antenna to the ground;

the relative height is taken by an inductive sensor. Since May 1999 the data "relheight" are logged

in all log files in "postob" in every observed scan.

Additionally as an integral part of the 20-m telescope a water vapour radiometer is operated;

it was designed and built at the ETH-Zrich (Switzerland) by Beat Brki.

• Overall Performance of the Antenna

The overall performance of the antenna can be demonstrated with the three characteristic

values:

System Temperature, TSYS (K),

Overall Antenna Efficiency, ETA (-) and

System Equivalent Flux Density, SEFD (K).

128 1999 IVS Annual Report
Bundesamt fiir Kartographie und Geod_ie 20-m Radiotelescope at VVettzel]

All values are a function of

- observed frequency,

elevation angle,

weather conditions.

The diagrams show these three values for X/S-band and the expected design values over the

IF frequency (MHz); the values were observed at elevation 60 ° and fine weather conditions (Fig.

2, 3).

TSYS[K],Eta[%]

140

SEFD[Jy]

120

1O0

80

6O

4O

2O

I

....... "...... I _TSYS[K] -I-ETA[%] _SEFD[Jy]

• ' I 4- TSYSau= -_- EThaua "]((- SEFDaus

! i ; ! ! ! i !

i ! ! ! ! ! : : :

..... : : : i0

100 200 300 400 500 600 700 800 900 1.000

1.400

1.200

1.000

800

60O

400

200

Figure 2. Antenna parameters for X-band at

Wettzell.

TSys[K], Eta[%] SEFD[Jy]

14l i _- TSYSau, -t- ETAau$ -)K- S EFDau,

_i/,_i_?/_i!',il  ̧!i:i _,!!iil '_!iii_:i:ii _ii'ii!_!i!_i!,ill !Tiii,_ii

100

8O

160 180200 220 240 260 280 300 320 340 360 380 400

1.400

1.200

1.000

800

600

400

200

Figure 3. Antenna parameters for S-band at

Wettzell.

3. VLBI Observing Activities

The 20-m radio telescope in Wettzell is dedicated 100% to geodetic VLBI-observations; all

observations are made in X/S-band only. The observations started in late 1983. A summary of all

VLBI observations from 1983 until 1998 is given in Table 1.

Since the beginning NEOS-A is a project with very high priority at Wettzell. In the early days

this session had still the synonym POLARIS and partner telescopes were Westford, (old) Fort

Davis and Richmond (Florida)• This session has the aim to determine with the highest possible

precision the coordinates of the rotational pole of the Earth X (marcsec), Y (marcsec) and AUT1

(#see), as well as the coefficients of nutation and precession. This is the aim of CORE as well;

therefore NEOS-A will be integrated into CORE as CORE-2. Meanwhile Wettzell comes close

to one thousand NEOS-A sessions and is the telescope with the highest number of performed

1999 IVS Annual Report 129
20-m Radiotelescope at Wettzel| Bundesamt fiir Kartographie und Geod_isie

observations within the NEOS-A project. Wettzell started from its very beginning in April 1984

together with Westford, now with Green Bank, the INTENSIVE sessions. The interferometer is

an East-West baseline with about one Earth radius long baseline, being very sensitive to changes

in A UT1 - UTC. The session gains from the fact, that both INTENSIVE antennas participate

in NEOS-A as well. Therefore the coordinates of the two telescopes and of the observed quasars

do not need to be determined by observations; they can be interpolated from NEOS-A sessions.

INTENSIVE observations are done every weekday.

Wettzell was part of the observing program IRIS-S from the beginning, a monthly VLBI session

including Hartebeesthoek; it is also part of the network EUROPE since its start in 1988.

Additionally Wettzell was involved in the CDP-program of Goddard Space Flight Center (POLAR, X-ASIA, X-ATL, N.ATL, E.ATL (later EUROPE), GLOBAL, R&D, ...).

To some extent Wettzell participates in EVN or special X/S-sessions of MPIfR or astronomical

VLBI sessions of universities, whenever there was a possibility.

In near future Wettzell will take part in CORE-2 and CORE-3 within CORE.

Wettzell has often a Japanese K4 data recording system on loan controlled by a K4 Field

System since 1999; Wettzell performed with Japanese partners

special VLBI time transfer sessions,

additional AUT1 -- UTC observations to support parallel AUT1 -- UTC measurements

with Westford-Greenbank or

- just to support a better geodetic link between European and Asian VLBI stations.

4. Technical Staff of Wettzell

Wettzell benefits from the knowledge and experience of the team:

Bauernfeind, Erhard

Bielmeier, Ewald

Kilger, Richard

Kronschnabl, Gerhard

Schatz, Raimund

Schwarz, Walter

Zeitlhfler, Reinhard

Zernecke, Rudolf

The staff performs

mechanical engineer

electro technician

mechanical engineer

electronic engineer

software engineer

electronic engineer

electronic engineer

geodetic engineer

TU-Munich 100%

TU-Munich 100%

TU-Munich 100%

BKG 100%

TU-Munich 100%

BKG 100%

TU-Munich 100%

TU-Munich 100%

all the VLBI observations, sometimes assisted by trained students,

the service of the whole hardware (mechanical, electric/electronical) and software,

upgrade of the observing system,

looking for technical problems and bugs and trying to fix them.

130 1999 IVS Annual Report
Bundesamt fiir Kartographie und Geodfisie 20-m Radiotelescope at Wettzell

. _ _

+ _

9<,

_,_°<<° : _,'_ _Z._ :=_

1999 IVS Annual Report 131
Observatorio AstronSmico Nacional - Yebes Observatorio Astron6mico Nacional

Observatorio Astron6mico Nacional

Francisco Colomer

Abstract

This report describes the OAF facilities as a network station in IVS. The 14 meter radiotelescope

at Yebes participates regularly in the geodetic VLBI campaigns (EUROPE and CORE). The institute

staff is also involved in technical development and geodetic research.

1. The OAF Facilities

The Observatorio AstronSmico Nacional (OAF) of Spain operates a 14 meter radiotelescope at

Yebes (Guadalajara, Spain). 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 radiotelescope that will be available for geodetic VLBI observations

in the next few years.

\

Figure 1. The 13.7 meter radiotelescope of OAF at Yebes (Guadalajara, Spain).

132

1999 IVS Annual Report
Observatorio Astron6mico Nacional Observatorio Astron6mico Nacional - Yebes

Table 1. OAN location and addresses.

Institute Headquarters:

Observatorio Astron6mico Nacional

Physical address

Mail address Apaxtado 1143

E-28800 Alcal_ de Henaxes

Campus Universitario

Ctra. N-II, km 33.6

E-28871 Alcalg de Henares

http :I/www. oan. esl

Yebes radiotelescope:

Centro Astron6mico de Yebes

Physical address Mail address

Cerro de la Palera s/n Apartado 148

E-19041 Yebes E-19080 Guadalajara

Longitude (WGS84) 3° 5' 21!'893 W

Latitude 40 ° 31' 26!'968 N

Height 980.946 m

2. Description of the Station

The main instrument at OAN is the radio telescope [1], used for VLBI. The technical parameters

of the radio telescope axe summarised in Tables 2 to 4. The instrument is equipped with a dual

frequency receiver (S and X bands) used in geodetic VLBI experiments, and also a Q band receiver

(41 to 49 GHz) used for astronomical observations. The radio telescope is controlled by two

computers (HP1000 and HP2100), that run independently of (but syncronised with) the Field

System PC.

Table 2. Technical parameters of the Yebes telescope for geodetic VLBI.

owner and operating agency

year of construction

radio telescope system

receiving feed

diameter of main reflector d

focal length f

f/d

diameter of geodetic subreflector ds

focal length fs

excentricity e

f/d of equivalent paraboloid

azimuth range

azimuth velocity

elevation range

elevation velocity

OAN (IGN, ?.iFOM)

1976

altazimutal

cassegrain focus

13.72 m

5.080 m

0.37026

2.2 m

3.547 m

1.557

1.7m

-358... 358 °

l°/s

4... 89 °

l°/s

1999 IVS Annual Report 133
Observatorio Astron6mico National - Yebes Observatorio Astron6mico National

Table 3. Receivers used in geodetic VLBI at the Yebes telesco

Receiver

Frequency range (GHz)

Tsys

SSEFD

Polarization

X-band

8.13 - 8.63

77K

3300 Jy

0.47

RCP

S-band

2.21 - 2.35

87K

3800 Jy

0.38

RCP

)e.

Table 4. Characteristics of the VLBI equipment.

VLBI terminal type

recording media

Telescope control computer

VLBI system computer

Operating system

Field System version

VLBA4 (Mark IV formatter,

VLBA-G rack and VLBA recorder)

thick and thin tape, 1" wide

HP1000 + HP2100

Pentium II/350

Debian 2.0r4 (kernel 2.0.34)

9.3.25 and 9.3.207

-GPS receiver

Meteorological station I 6 channel TrueTime SEAC-300 XL-DC-602

The engineers at the OAN laboratories have been involved in the design and construction of

low noise HEMT microwave amplifiers at cryogenic temperatures since 1985. These are used at

the Yebes telescope, and in other European radio astronomy observatories (e.g. IRAM, Bordeaux,

Meudon in France; INPE in Brazil). These amplifiers have been used as well for atmospheric

research (Ozone concentration) by other European research projects, like PRONAOS (France)

and EMCOR (European Minor Constituent Radiometer, European Union).

3. OAN Staff Working in VLBI

Table 5 lists the OAN staff which are involved in the VLBI studies, some of which can be found

at the telescope (CAY) address. The associated members of IVS are indicated with an asterisk.

Table 5. Staff in the OAN VLBI group (Email: vlbi@oan.es).

Name

Jesfis Gomez-Gonzalez

Alberto Barcia

Francisco Colomer*

Pablo de Vicente*

Isaac L6pez-Fern£ndez

Ma.ria Rioia*

Background

Astronomer

Engineer

Astronomer

Astronomer

Engineer

Astronomer

Role

Director

Chief engineer

VLBI coordinator

Technical responsible

Technical support

Geodesy researcher

Dedicatxon

25%

25%

75%

50%

30%

100%

Aouress

OAN

CAY

OAN

CAY

CAY

OAN

1999 IVS Annual Report

134
Observatorio Astron6mico Nacional Observatorio Astron6mico Nacional - Yebes

4. Status of the Geodetic VLBI Activities at OAN

The OAN radio telescope at Yebes has participated in several geodetic VLBI experiments since

1995. The campaigns were performed with partial success, due to a failure of the formatter in the

VLBI DAR which prevented the participation of the station in any interferometric observations

since the end of 1997. The module was substituted by a Mark IV formatter ill February 1999,

when successful observations were resumed.

The main contribution of OAN to IVS is the realization of geodetic VLBI observations in the

EUROPE and CORE projects. The institute also participates in the European VLBI Network

(EVN) for astronomy, taking part in its logistics and carrying out technical development.

Recently, geodetic studies making use of VLBI and GPS data are being performed by OAN staff.

These investigations intend to accurately measure the vertical component of the interferometer

baselines.

5. Outlook

The OAN radio telescope at Yebes has resumed operations after the faulty VLBA formatter

has been replaced by a new Mark IV one. The station participates regularly in the campaigns for

the EUROPEand CORE projects.

The construction of a new 40 meter radiotelescope at Yebes has started. This telescope will

operate at S/X bands. It is expected to be operational in the next few years.

References

[1] Barcia, A., Bujarrabal, V., G6mez-Gonz£1ez, J., Martfn-Pintado, J., Planesas, P.: First spectroscopic

observations with the 14-m radio telescope at the Centro Astronomico de Yebes - SiO masers in evolved

stars. Astronomy and Astrophysics, vol. 142, p. L9, 1985.

1999 IVS Annual Report 135
Yellowknife Observatory Geodetic Survey Division, Natural Resources Canada

Yellowknife Observatory

Mario B_rub_, Calvin Klatt

Abstract

This report gives an overview of the activities at the Yellowknife Observatory. It also summarizes

the technical poxmmeters and presents the Yellowknife VLBI team.

Figure 1. Yellowknife Geophysical Observatory 9 m VLBI Antenna

1. Overview

The Yellowknife VLBI antenna is a 9 meter diameter antenna which has had a very storied

past. Formerly the "MV-I" mobile antenna, it 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.

136 1999 IVS Annual Report
Geodetic Survey Division, Natural Resources Canada Yellowknife Observatory

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.

2. General Specifications

• Latitude : 62.48 North

• Longitude : 114.48 West

• Reflector : 9 m

• Receiver : S and X cryogenic

• Azimuth speed : 40 degrees per minute

• Elevation speed : 40 degress per minute

• PCFS version : 9.3.23

• VLBI equipment : Mark III and thick tape drive

• Time standard : NR Maser

• GPS receiver : Rogue

3. Antenna Improvements

Since being installed in Yellowknife, the 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.

Last summer there were difficulties with the antenna brakes getting stuck moments before the

beginning of an experiment. This problem was addressed, and in the near future the Algonquin

team will be travelling to Yellowknife to perform a complete check up of the antenna and the VLBI

equipment. In addition, the old antenna control unit will be replaced with one similar to that at

Algonquin.

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.

A repeat survey is planned to be conducted this year.

5. Yellowknife VLBI Team

The VLBI team in Yellowknife are working for the Geophysical Observatory of the Geological

Survey of Canada. Their main work is the operate and maintain the seismic array. For the last

few years, the VLBI team has included only two people to take care of the equipment and perform

the experiments.

1999 IVS Annual Report 137
Yellowknife Observatory

Geodetic Survey Division, Natural Resources Canada

e

• George Jensen : (25%) electronics equipment

• William Outhwaite : (25%) VLBI logistics, site survey.

Operations 1998-1999

Last year Yellowknife was involved in five CORE-B experiments.

1999 IVS Annual Repot t

138
OPERATION

CENTERS

From the Terms of Reference:

The IVS Operation Centers coordinate the routine

operations of one or more networks Operation

Center activities include:

• planning network observing programs,

• establishing operating plans and proce

dures for the stations in the network

• supporting the network stations in improv

ing their performance

• making correlator time available at an IVS

Correlator,

• generating the detailed observing sched

ules 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

Geodiitisches Institut der Universit_t Bonn Operation Center at the Geodetic Institute Bonn

The Bonn Geodetic VLBI Operation Center

A. Nothnage!

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)

Twelve Sessions per year with the stations Wettzell, HartRAO, Fortaleza, Fairbanks and

Westford.

• Continuous Observations of the Rotation of the Earth - O'Higgins (COREOHIG)

with stations HartRAO, O'Higgins, Fortaleza, Hobart, Kokee and DSS45 plus one session

also including the Japanese Antarctic station Syowa.

• Measurement of Vertical Crustal Motion in Europe by VLBI (EURO)

(EU Project FMRX-CT960071)

Six sessions per year with the stations Ny/_lesund, Onsala, Wettzell, Simeiz, Madrid (DSS65),

Yebes, Medicina, Matera and Noto. Effelsberg and TIGO-WTZL participated occasionally.

_,._ / I#" _ __ ,_

Figure 1. European VLBI network

• Phase delay and polarization test

with a subset of European stations (appended to two EURO sessions)

1999 IVS Annual Report 141
Operation Center at the Geodetic Institute Bonn Geod_itisches Institut der Universitiit Bonn

• Wettzell local ties (WTIES)

Two sessions between Wettzell 20-m telescope and TIGO-WTZL which are about 59 m apart

The operational tasks mainly consisted of preparing the detailed observing schedules for all

sessions listed above. In addition, the dates and technical setups for the last two projects had to

be organized while the dates for the first three series were fixed by the IVS CC. The schedules are

prepared with the SKED software on HP-UX platforms.

One of the critical items which affects the preparation of the EURO sessions is radio frequency

interference from televison transmitters at Matera. At this site the receiver is saturated at some

of the S-band frequency channels and bandwidth synthesis, therefore, can be performed only with

a subset of the usual series of channels. This reduction in channels has adverse effects degrading

the signal-to-noise ratio and often corrupting the delay observables. Therefore, new frequency

sequences had to be investigated on several occasions. Recently, the interference frequencies have

remained relatively stable and the current setup permits undisturbed observations at all frequency

sub-bands.

Arno Miiskens takes care of the IRIS-S and the CORE-OHIG sessions while Axel Nothnagel is

responsible for the EURO project.

142

1999 IVS Annum Repro t
NASA Goddard Space Flight Center CORE Operations Cente_

CORE Operations Center

Cynthia Thomas, Nancy Vandenberg

Abstract

This report gives an overall view of the CORE program at Goddaxd Space Flight Center (GSFC). It

summarises the different CORE sessions and gives information about the technical staff. 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 1997-2001.

The goal of the CORE program is to generate an Earth rotation data set of unprecedented time

resolution and accuracy for Earth science and global change research. The program will continue

to 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 CORE program is 3.5 #s for UT1 and

100 #as in pole position. The full CORE program has the potential for a typical precision of I #s

in UT1 and 25 #as in pole position, for daily sessions with a 5-station network. These values are

three times better than those measured weekly with the NEOS network and could be available

daily.

The breakthrough in the availability of continuous, high accuracy Earth rotation data is possible

due to the Mark IV technology that will become available in late 1999. Improved sensitivity in

the Mark IV data acquisition system together with the high playback efficiency of the Mark IV

correlator are both necessary to produce the proposed data.

CORE experiments were run with four basic network configurations: CORE-A, CORE-B1,

CORE-B2, 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 COREA sessions are simultaneous with NEOS sessions and CORE-B and NEOS sessions are on sequential

days during both 1998 and 1999.

2. CORE Sessions During March 1998 to March 1999

This section displays the purpose of the CORE-A and CORE-B sessions and lists other programs used by CORE.

• CORE-A: These experiments validate the CORE concept of measuring EOP continuously

using different networks. Comparisons of the EOP results from simultaneous sessions in

1997 and 1998 have shown fairly good agreement, but there are some puzzling systematic

differences. It is hoped that additional data to be obtained during 1999 will contribute to

understanding this data set.

1999 IVS Annual Report 143
CORE Operations Center NASA Goddaxd Space Flight Center

The network for CORE-A included Fairbanks, HartRAO, Hobart, Algonquin, Matera and

Westford during 1998. Medicina was added to the network during the first quarter of 1999.

Tsukuba will be added to the network starting the second quarter of 1999.

. CORF__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.

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, CORE-B and NEOS networks

show that there are systematic differences in EOP. There are statistically significant mean offsets

of 147 #as, 85 #as, 3.7 #s between X, Y, and UT1 estimates, respectively, from the CORE-A and

NEOS networks. Between NEOS and CORE-B, the UT1 difference of 10.6 #s is significant. The

source of these differences is under active investigation.

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. For most sessions, observed uncertainties are 20-50% greater than EOP

uncertainties from simulations using scheduled observations and uncertainties. The observed uncertainties are generally less than the minimal goal of 100/_as for PM and 3.5 ps for UT1.

4. The CORE Family

Figure 1 shows a subset of the CORE family after a Wednesday staff meeting where we come

together to discuss the various activities that have taken place during the week and the upcoming

events.

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

Although the CORE observing program for 1999 is proceeding according to plan, the Mark IV

correlator plan has changed. The correlator should be available on the planned schedule with Mark

III capabilities, but it will not have many Mark IV capabilities until later this year. The Mark IV

correlator capabilities that we need for the next step in the evolution of the CORE program are

fan-out and increased processing efficiency.

Since the CORE-3 sessions, originally scheduled to start in July, require these capabilities, we

delayed the start of CORE-3 until at least the fourth quarter of 1999. The start-up of CORE-3

in October will depend on the correlator capabilities and the performance of the new correlator

during its shakedown period.

The start of the CORE-3 sessions will be the beginning of the true CORE program, recording

1999 IVS Annual Repol_t

144
NASA Goddard Space Flight Center CORE Operations Center

Figure 1. The CORE Operations Center Family listed from left to right starting with the back row: R.

Gonzalez, C. Ma, B. Boyer, D. MacMillan, E. Himwich, B. Schupler, W. Wildes, D. Gordon, K. Refinetti,

C. Kodak, K. Baver, N. Vandenberg, T. Clark, and C. Thomas. Please note that all of the CORE family

members are not pictured.

Table 1. Key Technical Staff of the CORE Operations Center

Name Responsibility Agency

Tom Buretta Haystack

Brian Corey

Irv Deigel

Frank Gomez

David Gordon

Ed Himwich

Chuck Kodak

Cindy Lonigro

Dan MacMillan

David Shalfer

Dan Smythe

Cynthia Thomas

Nancy Vandenberg

William Wildes

Recorder and electronics maintenance

Analysis Haystack

Maser maintenance ATSC

Software engineer for the Web site Raytheon/STX

Analysis Raytheon/STX

Network Coordinator for CORE stations NVI, Inc./GSFC

Receiver maintenance ATSC

Analysis Raytheon/STX

Analysis NVI, Inc./GSFC

Sources and antenna parameter maintenance Radiometrics/NVI, Inc.

Tape recorder maintenance Haystack

Coordinate master observing schedule and NVI, Inc./GSFC

prepare CORE experiments observing schedules

Organizer of CORE program and sked man- NVI, Inc./GSFC

ager

Procurement of materials necessary for CORE GSFC/NASA

operations

1999 IVS Annual Report 145
CORE Operations Center NASA Goddard Space Flight Center

in high sensitivity Mark IV modes. The tentative CORE evolution plan for the next few years is

summarized in Table 2.

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

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!

Start Date Experiment Name

1-Oct-1999 CORE-3 weekly

1-Jan-2000 CORF__4 bi-weekly

1-Jul-2000 COI__,- 1 bi-weekly

1-Jan-2001 CORF_,-4 weekly

¢ 2. Planne_ CORE Evq

Avg Days per Week

2.5

3.0

3.5

4.0

lution

Notes

NEOS is on day 2

Discontinue CORE-A

Reduce to two CORF__B networks

COKF_,-B networks as needed

References

[1] Clark, T.: CORE White Paper, June 2, 1997

146

1999 IVS Annual Repo, t
U.S. Naval Observatory NEOS Operation Center at USNO

The U.S. Naval Observatory VLBI Program: Operations in 1998

and 1999

T.M. Eubanks, B.A. Archinal, F.J. Josties, J.R. Ray

Abstract

As part of its participation in the National Earth Orientation Service (NEOS) the U.S. Naval

Observatory (USNO) operates a program in Very Long Baseline Interferometry (VLBI) data acquisition

and analysis to monitor changes in the orientation of the Earth on a regular basis. This reports provides

details both of recent NEOS VLBI operations and intensive operations.

1. VLBI Operations

Current NEOS operations consist 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 currently includes the

VLBI stations at Gilmore Creek (Alaska), Kokee Park (Hawaii), Wettzell (Germany), Fortaleza

(Brazil), Ny-Alesund (Norway), Algonquin Park (Canada), and Green Bank (West Virginia), although at most six stations observe in any one observing session. Nominal operations divide the

NEOS since NEOS-A-193 on January 7th, 1997, into "even" NEOS and "odd" NEOS sessions on

alternate weeks. (These names arise from the parity of the sequential numbers of these sessions.)

The Kokee Park, Wettzell, Fortaleza, and Green Bank stations nominally participate in all NEOS

sessions, while Ny-Alesund participates in the even sessions, and Gilmore Creek participates in the

odd sessions, as does Algonquin Park on a roughly once per month basis. The principal reason for

this division is to enable the scheduling of simultaneous CORE-A sessions by the NASA Goddard

VLBI group, which are always scheduled during even NEOS sessions. All NEOS sessions are routinely processed in time for the next IERS Bulletin A on the following Thursday. The databases

from these sessions are freely shared with the VLBI community and are contributed fro the IVS

data centers as soon as they axe processed.

The NEOS VLBI data axe correlated at the Washington Correlator, which is located at the

U.S. Naval Observatory and run by the NEOS. After correlation, fringe fitting, and the removal

of any remaining bandwidth synthesis delay ambiguities, data from all available multiple baseline

VLBI sessions are used in a series of weighted least-squares solutions to define a USNO VLBI

reference frame and to estimate the Earth orientation within that reference frame. An empirically

adjusted station velocity model is used in order to adequately model the tectonic motion of the

stations over the 20 years of available data, and antenna axis offsets are also adjusted. Details of

previous VLBI operations at the USNO are given in the IERS Annual Report for 1997 [1].

2. UT1 Intensive Operations

The USNO has operational responsibility for the IRIS / NEOS UT1 Intensive Series. These

short-duration single-baseline observations axe being continued using the same scheduling and

observing procedures as before to ensure continuity with previous results. A nominal intensive

session during 1998 and 1999 involved 20 delay observations conducted on the Green Bank NRAO20

1999 IVS Annual Report 147
NEOS Operation Center at USNO U.S. Naval Observatory

to Wettzell baseline. These observations are conducted at the same sidereal time each day, except

during the NEOS 24-hour sessions and on Sunday. Starting in 1996, roughly every two months

the sidereal time of the intensives is shifted to keep their solar times between 1400 and 1800 UTC.

Sunday intensives are not presently observed due to budget restraints; however, two intensives

are observed on Saturday. The second Saturday intensive uses the schedule intended for the next

intensive series, four hours later in sidereal time, in order to provide a set of overlapping, nearly

simultaneous, intensives for each pair of intensive schedules. All of the Intensive data is reduced

rapidly, typically within four to seven days of the time of acquisition of data, and the NEOS/IRIS

UT1 Intensive files produced by the USNO now extend back to 1984 in one homogeneous solution.

References

[1] The USNO Annual Report for 1997 is obtainable from

ftp://casa.usno.navy.mil/navnet/iers_report•97 .

1999 IVS Annual Repo_ t

148
CORRELATORS

From the Terms of Reference:

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.

Geod_tisches Institut der Universitiit Bonn Bonn Astro/Geo Correlator

The Bonn Astro/Geo Mark IIIA Correlator

Axe1 Nothnagel, Arno MiJskens, Mauro Sorgente

The Bonn Astro/Geo Correlator is located at the Max-Planck-Institute for Radio Astronomy,

Auf dem Hiigel 69, D-53121 Bonn, Germany. The Bonn Astro/Geo Correlator is a joint activity

of the Max-Planck-Institute for Radio Astronomy, Bonn, of the Bundesamt fiir Kartographie und

Geod_ie, Frankfurt a.M., and of the Geodetic Institute of the University of Bonn sharing the

responsibilities for acquisition, maintenance and operation.

Currently, geodetic correlations are scheduled for 40% of the operation time and 60% are used

for astronomical experiments. The routine correlation tasks, mainly starting computer programs

and changing tapes, are performed by up to four under-graduate students providing on average

about 50 hours of operational geodetic correlations per week. Arno Miiskens and Mauro Sorgente

set up the necessary computer files, do fringe search and supervise the students. They are also

responsible for additional more sophistcated correlation tasks which require more knowledge and

experience.

Figure 1. Bonn Correlator: Tape Drive Section

The following projects have been correlated at the Bonn correlator during the last year:

• International Radio Interferometric Surveying - South (IRIS-S)

Twelve Sessions per year with the stations Wettzell, HartRAO, Fortaleza, Fairbanks and

Westford

• Continuous Observations of the Rotation of the Earth - O'Higgins (COREOHIG)

with stations HartRAO, O'Higgins, Fortaleza, Hobart, Kokee and DSS45 plus one session

also including the Japanese Antarctic station Syowa

• Measurement of Vertical Crustal Motion in Europe by VLBI (EURO)

(EU Project FMRX-CT960071)

1999 IVS Annual Report 151
Bonn Astro/Geo Correlator Geod/itisches Institut der Universit/_t Bonn

Six sessions per year with the stations Ny._lesund, Onsala, Wettzell, Simeiz, Madrid (DSS65),

Yebes, Medicina, Matera and Noto. Effelsberg and TIGO-WTZL participated occasionally.

• Phase delay and polarization test

with a subset of European stations (appended to 2 EURO sessions)

• Wettzell local ties (WTIES)

Two sessions between Wettzelt 20-m telescope and TIGO-WTZL which are about 59 m apart

The Bonn Astro/Geo Mark III Correlator is a shared correlator consisting of two blocks of

correlator modules for 6 • 14 tracks and 12 • 14 tracks permitting simultaneous correlation in

mode C of 3 and 12 baselines, respectively. However, only 10 baselines are correlated routinely

in one pass of the 12-crate correlator due to organizational and data flow limitations. The threebaseline correlator is only used for fringe search and sessions which need only a limited number

of correlator crates. The data flow and hardware are controlled by HP1000F and HP1000-A900

computers. Eight Metrum/Honeywell playback drives may be switched between correlator units

for efficient use of ressources. The correlator output is temporarily stored on HP1000F system

disks for subsequent transfer to a HP9000-7xx HP-UX computer for fringe fitting, archiving, and

export.

_J

Figure 2. Bonn Correlator: Correlator Modules

After their release and degaussing the Mark IIIA tapes are sent back to the observatories for

further recordings. At present two types of tapes are in use, regular tapes and extra thin tapes

with double recording capacity. In order to keep the wear of the recording magnetic heads low,

only one type of tape should be used at a station throughout. However, there is a shortage of thin

tapes causing a large discrepancy between tapes requested by the observatories and those being

sent to the Bonn correlator. The lack of thin tapes requires additional transportation of tapes

from the US correlators to observatories to compensate for the regional imbalance of thin tape

supplies. Additional thin tape purchases by BKG are urgently envisaged.

Within the next year the current Mark IIIA correlator will be replaced by a Mark IV correlator for nine stations. The existing playback tape drives have already been upgraded with Mark

IV/VLBA style control electronics (32 tracks) and thin tape capability. The infrastructure for the

new correlator is being completed and the delivery of the correlator modules is expected soon.

152 1999 IVS Annual Report
MIT Haystack Observatory Haystack Observatory Correlator

The Haystack Observatory VLBI Correlator

Mike Titus, Brian Corey, Arthur Niell

Abstract

The Haystack Observatory VLBI Correlator supports the IVS by processing approximately 25

geodetic experiments per year. In the coming year the Mark IV correlator will become operational.

This will permit increased geodetic VLBI observing time by allowing higher correlator throughput.

1. Introduction

The Haystack Observatory Mark IIIA VLBI correlator [1], 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 as a development system for testing new correlation modes and hardware improvements

and for diagnosing correlator problems encountered either at Haystack or at one of the identical

correlators 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.

2. Correlator Operations

The Mark IIIA correlator at Haystack is designed to process simultaneously up to eight stations

and 10 baselines with 14 single-sideband frequency channels each. Due to the competing hardware

demands from the Mark IV correlator [2] development in the past year the available equipment

of the operational correlator has had to be reduced somewhat. Currently eight baselines can be

correlated from among six stations. The six tape drives are a mixture of Mark IIIA and Mark IV.

The correlator configured for seven stations is shown in Figure 1.

Approximately 90% of the correlator time allocated to the IVS is used for setup and production

processing of CORE experiments. The remaining 10% is used for such tasks as correlating fringe

checks to test station performance after field equipment changes, testing Mark IV formatters for

field certification, processing comparison tests between the Mark IIIA and Mark IV correlators,

testing headstacks for viability in field use, and correlating other geodesy-related observations,

such as the Mars Global Surveyor and Pathfinder astrometry experiments.

Over the past year 20 CORE B sessions and ten special experiments were processed at the

Haystack Mark IIIA correlator.

3. Staff

The following Haystack personnel are involved with correlator activities.

Peter Bolis - correlator maintenance

Tom Buretta - playback drive maintenance

1999 IVS Annual Report 153
Haystar:k Observatory Correlator MIT Haystack Observatory

Figure 1. The Mark IIIA Correlator at Haystack Observatory.

Dr. Roger Cappallo - correlator models and control software

Dr. Brian Corey - experiment correlation oversight; station evaluation; technique development

David Fields - playback drive maintenance

Ellen Lautenschlager - correlator operator

Dr. Colin Lonsdale - correlator post-processing software

Glenn Millson - correlator operator

Ed Nesman - correlator maintenance

Dr. Arthur 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

Dr. Alan Whitney - correlator architect for Mark III, IIIA, and IV

4. Outlook

We expect to continue the current mode of operation for most of 1999. During the latter

part of the year we will make the transition to processing on the new Mark IV correlator. This

transition will be the most significant since the introduction of the Mark III system in the early

1980s. We expect a prolonged adjustment period since practically every aspect of operations will

change. Although this transition will likely result in reduced efficiency initially, we expect it will

provide an opportunity to re-evaluate procedures which will improve the quality and level of service

provided to the community in the longer term.

References

[1] Whitney, A. R.: Capabilities and Performance of the upgraded Mark III Correlator System, IAU, The

Earth's Rotation and Reference Frames for Geodesy and Geodynamics, 429-437, 1988.

[2] Whitney, A. R.: The Mark IV VLBI Data-Acquisition and Correlation System, In: Developments

154 1999 IVS Annual Report
MIT Haystack Observatory Haystack Observatory Correlator

in Astrometry and Their Impact on Astrophysics and Geodynamics, edited by I.I. Meuller and B.

Kolaczek 151-157, 1994.

1999 IVS Annual Report 155
Key Stone Project VLBI Correlation Center Communications Research Laboratory

Key Stone Project VLBI Correlation Center

Mamoru Sekido, Yasuhiro Koyama

Abstract

Communications Research Laboratory has developed two sets of correlator systems at Koganei,

Tokyo for the Key Stone Project. One is for tape-based VLBI observations and the other is for realtime VLBI observations. The overview of the correlator systems will be described in this report.

1. Introduction

Communications Research Laboratory (CRL) has been doing regular geodetic VLBI experiments to monitor crustal deformation around Tokyo metropolitan area. The project was named as

Key Stone Project (KSP) [1] and the correlator facilities have been developed at Koganei, Tokyo

for the project. Two modes of VLBI observations are possible, one is a tape-based VLBI mode [2]

and the other is a real-time VLBI mode [3]. The tape-based VLBI observation mode uses ID-1

standard cassette type magnetic tapes to record observed data. In the real-time VLBI observation mode, observation stations and correlator system are connected via high speed Asynchronous

Transfer Mode (ATM) network which has been established under collaboration with the Nippon

Telegraph and Telephone Corporation (NTT). Technical details of each system are described in

Section 2.

The KSP VLBI correlation system is supposed to be routinely operated by persons who are not

familiar with VLBI data processing. Therefore, a man-machine interface with GUI was developed

for easy operations of the system. Since an operator is on duty only in daytime, the system is

designed so that 24 hours of continuous correlation processing magnetic tapes can be performed

without the help of an operator once the process is started. The developments of the real-time

VLBI correlation system advanced the automation further. In principle, once the real-time correlation processing software (RKATS) is run, the software selects the schedule file of the day and

performs correlation processing continuously without any human operations for unlimited days.

At the same time, bandwidth synthesis procedures run to process correlator output data. After

all the observations in an experiment are finished, Mark III database files are created and the data

analysis processes are executed automatically. After all the required procedures are finished for an

experiment, the correlator system starts to wait for the next schedule to be executed [4].

Although the KSP correlation system is designed for regular operations with the KSP VLBI

stations, the system can also process general VLBI experiment data recorded in the K4 data

format. In fact, several kinds of international VLBI experiments have been processed with the KSP

tape-based VLBI correlator system. In addition, the real-time VLBI experiments with Nobeyama

(Nobeyama Radio Observatory) and Usuda (Institute of Space and Aeronautical Science) have

already been successful with optically linked ATM network as described in section 4.

156 1999 IVS Annual Report
Communications Research Laboratory Key Stone Project VLBI Correlation CenteJ

Table 1. Hardware Components of tape-based KSP correlation system

Device name Functions

Correlator Correlation processing, correlator model calculation.

DIR-1000

DFC-2200

DMS-24

Correlation Controller

Workstation

Data play back unit of K4 cassette type magnetic tape.

Data output for correlator and synchronization of data stream.

Automatic tape changer; 24 ID-1 cassette tapes can be mounted.

Controls correlation processing hardware.

Provides GUI environments for operators and management of

the correlation processing, bandwidth synthesis, and generation

of the Mark-III database files.

2. Technical Characteristics

2.1. The KSP Tape-based VLBI Correlation System

The KSP VLBI correlation system is capable of processing six baselines between four stations

simultaneously. The appearance of the correlation system is shown in Figure 1.

Figure 1. The KSP tape-based VLBI correlation system at Koganei, Tokyo. The left two racks are automatic tape changer (DMS-24). The right three racks contains correlators, output interfaces, and correlation

controller.

The system consists of six sets of single baseline correlators, automatic tape changer units

(DMS-24), K4/KSP data recorders (DIR-1000), output interface units (DFC-2200), a correlation

controller and a host workstation. Function of each hardware is summarized in Table 1.

Two correlator hardware systems are identical which is developed over VME based digital

signal processors. The technical parameters of the correlator system are shown in Table 2.

The correlation process control software (KATS) runs on HP-UX host workstation and provides

GUI environment for operation of correlation processing [5]. The correlation processing, bandwidth

synthesis procedure, and Mark III database creation are performed just by using mouse clicks and

1999 IVS Annual Report 157
Key Stone Project VLBI Correlation Center Communications Research Laboratory

Table 2. Parameters of the KSP correlator system.

Total data rate

Number of Channels 16

Number of lags per channel 32

Control Bus GPIB

Data Output Method Ethernet (NFS)

64 Mbps, 128 Mbps, 256 Mbps

several key strokes on the GUI. Then schedule file and log files can be obtained through the

network.

2.2. The KSP Real-time VLBI Correlation System

The KSP real-time VLBI system uses the ATM network over 2.4 Gbps optical fiber instead

of magnetic tapes for data transportation. The advantages of the real-time VLBI system axe

summarized as follows.

1. Fully automated VLBI correlation processing can be realized.

2. Since correlation process is done simultaneously with observation, it is possible to monitor

the fringes at real-time.

3. Results of the data analysis can be placed in publicly accessible area in less than one hour

after the end of experiment.

The real-time VLBI correlation system also has the capability of processing six baselines between four stations. Two correlator systems are identical. Instead of data recorders (DIR-1000),

automatic tape changer units (DMS-24), and output interface units (DFC-2200) which are used in

the tape-based system, ATM receivers and ATM VLBI interfaces have been used in the real-time

VLBI system.

3. Technical Staff for the KSP VLBI Correlation Center

Technical staff members who axe contributing 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.

• Mamoru Sekido, Development of correlation processing software.

• Jun Amagai and Kouichi Sebata, Responsible for management of correlation center.

• Naoki Goto and Muneo Takeda, Operator at the correlation center, Space Engineering Development Co., Ltd.

4. Current Status and Future Plans

The KSP real-time correlation system has been used for regular real-time geodetic VLBI experiments once every two days. Unfortunately the KSP Miura station will be unlinked from the KSP

1999 IVS Annual Report

158
Communications Research Laboratory Key Stone Project VLBI Correlation Center

ATM network in May 1999. From that time, regular real-time VLBI experiment will be performed

among the three KSP stations, and tape-based 24 hours VLBI experiments including the Miura

station will be performed once every six days.

The tape-based KSP correlation system has been used for processing of several kinds of international VLBI experiments. One of them is colocation aimed experiments which include Kashima

34 m antenna and several foreign stations besides the KSP observation stations.

The Key Stone Project ATM network was connected with Kashima 34 m antenna, Usuda 64 m

antenna (operated by Institute of Space and Astronautical Science) and Nobeyama 45 m antenna

(operated by Nobeyama Radio Observatory). By using these networks, astronomical radio source

survey programs have been performed occasionally when geodetic regular VLBI experiments are

not scheduled. The observed data are transferred to Koganei KSP correlation facilities and are

processed with the KSP real-time VLBI system.

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. Commun. Res. Lab., Vol. 46, No. 1, pp.47-53, March 1999

[3] 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

[4] Mamoru Sekido, Tetsuro Kondo, and Hitoshi Kiuchi: KSP VLBI System; Real-Time Correlation Processing Control Software, J. Commun. Res. Lab., Vol. 46, No. 1, pp.91-96, March 1999

[5] 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

1999 IVS Annual Report 159
Tsukuba VLBI Center Geographical Survey Institute

Tsukuba VLBI Center

Misao Ishihara, Keizou Nemoto, Masao Iwata, Kousei Shiba, Kazuhiro Takashima,

Shigeru Matsuzaka

Abstract

This report summarizes the technical parameters and the technical staff of the Geographical Survey

Institute (GSI) VLBI section. We present our history of VLBI activities and the status. In 1998 GSI

opened Tsukuba VLBI Center as an operation, correlation and analysis center. GSI installed a new

correlator system for three stations - three baselines. The correlator unit and the software which controls

the each unit have been developed as a KSP correlator in Communication Research Laboratory (CRL).

1. GSI VLBI Correlators

GSI has two different correlator systems. One is OKIVLBC-9100 (NAOCO) which was installed

in March 1993. The correlator was developed in National Astronomical Observatory (NAO) and

was made by Oki Corp. Ltd. The strong points of the correlator axe the equipment for K4 system,

128Mbps maximum process speed, maximum 8192 lag windows and portable equipment. GSI

installed it as one baseline correlator.

Another is the CRC-9403 which was installed in March 1997 for multiple baseline to cope with

the expansion of the domestic VLBI network. GSI was also equipped with the latest hardware and

software for automatic correlation from the point of labor saving.

Figure 1. The K4 correlater at Tsukuba VLBI center

160

1999 IVS Annual Report
Geographical Survey Institute Tsukuba VLBI Cente.

2. Specification of GSI K4 Correlator

GSI has a K4 correlator for multi-baseline correlation. The specification of GSI's K4 correlator

are presented.

1. The equipment of correlation process : CRC-9403-CR2

• 3 stations and 3 baselines

• process maximum speed at 512 Mbps

2. The equipment of data input : CRC-9403-DT2, Sony-DFC-2200

• Devidable for CRC-9403-CR2 from K4 Digital Recorder

• Automatic synchronization with each channel data

3. System controller : CRC-9511-CNT1

• Function of automatic correlation process

4. Computer : HP9000/D370

• OS : HP-UX10.2

• CPU : PA-RISC, PA-8000

• main memory : 1,024 MB

• cash memory : 256 MB

• internal HDD : 10 GB

• external HDD : 400 GB RAID5

5. Application : Kety KUS880419

• Support "automatic control" mode

6. Monitor for recording data : CRC-9703-MON1

• Fourier transform for output data by FFT

• number of FFT point : 128 - 16,384 points

• calculation accuracy : 8 bits fixed-point

3. Technical Staff of the VLBI group at GSI

Table 1 lists the VLBI staff at GSI.

4. Status of GSI Correlator

We process the geodetic observation data which are recorded in the domestic permanent sites

(Tsukuba, Kashima, Shintotsukawa, Aira and Chichijima) using the GSI correlator. We also

process the antarctic observation data of Syowa station for the detection of fringe.

1999 IVS Annual Report 161
TsukubaVLBICenter Geographical Survey Institute

Table 1. Staff working at VLBI section at GSI

Name Position

Shigeru MATSUZAKA IVS Networks Representative

Misao ISHIHARA VLBI leader

Keizo NEMOTO Colocation chief

Masao IWATA Correlation chief

Jobs

H-meser, operation

Correlation, operation

Kousei SHIBA Operation chief

Kazuhiro TAKASHIMA Analysis chief Baseline Analysis, operation

Shinobu KURIHARA Operator Baseline Analysis, operation

Michiko ONOGAKI Operator antenna malnt., operation

Kvoko KOBAYASHI Assistant correlation, operation

Coordination Experiments, operation

Figure 2. GSI VLBI Center is located on the second floor in the building

5. Outlook

GSI has a plan to analyze the five domestic permanent station data and the mobile station

data for geodesy. GSI also will process the data for the Syowa station. In 1999, Tsukuba VLBI

station will participate in Tsukuba-Wettzell Intensive experiments for UT1. These data will be

correlated by GSI K4 correlator because K4 recording system will be used for the experiments.

References

[1] Ogi, S.,: Status Report of Geographical Survey Institute Japan, In: Proceedings of the 13th Working

Meeting on European VLBI for Geodesy and Astrometry, held at Viechtach, February 12-13, 1999,

edited by W. Schliiter and H. Hase, Bundesamt fiir Kartographie und Geod/isie, Wettzell, 1999

1999 IVS Annual Report

162
Geographical Survey Institute Tsukuba VLBI Center

[2] Ogi, S., Y. Fukuzaki, M. Iwata, K. Shiba, M. Yazawa, K. Takashima, and K. Nagata: Comparison of

the time variation with GSI VLBI Domestic Experiments and Daily GPS Measurements, held at the

Communications Research Laboratory, Koganei, Tokyo, January 25-28, 1999

1999 IVS Annual Report 163
U.S. Naval Observatory

Washington Correlator

Washington Correlator

James O. Martin

Abstract

The report summarizes the work of the Washington Correlator for the year ending March, 1999.

The Washington Correlator is dedicated to processing geodetic VLBI for the purpose of providing data

for Earth orientation parameters, the radio reference frame, the terrestial reference frame and related

information.

1. Introduction

The Washington Correlator (WACO) is located at 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. The Washington Correlator

is dedicated to processing geodetic VLBI, spending at least 90 percent of its time in that role.

All of the weekly NEOS-A sessions and daily intensives are processed at WACO, as are most of

the bi-weekly CORE-A sessions. The remaining time is spent on reference frame sessions and

a few astrometry experiments. WACO currently utilizes a Mark IIIA correlator designed and

built by Haystack Observatory that has been operating continuously at USNO since 1986. We

anticipate replacement of the existing correlator with the Mark IV correlator in the coming year

with concomitant increase in throughput.

2. Correlator Operations

The Washington Correlator, in its present configuration, is shown in Figure 1. With six playback units and 10 crates (14 modules each), it can process up to six stations and 10 (Mark III

mode C) baselines at one time. Larger sessions can be accommodated by processing in several

passes. WACO also has the capability of splitting the correlator into two systems that can process

two sessions at one time, although that capability has not been used during the last year. During

the reporting period, four of the playback units at WACO were Mark IV upgrades and two were

older style Mark IIIA units. Five playbacks can process thin tape, but only the four Mark IV

drives can accommodate high density (56 kbit/inch) recordings.

NEOS-A processing is given priority at WACO. The weekly sessions and intensives are processed

as soon as the tapes arrive with all of the participating stations shipping their tapes via express

delivery services. The weekly sessions (5-6 stations) are exported 7-8 days after the observation

ends and the intensives (two stations) in 2-5 days. The CORE-A sessions, which are processed in

the remaining time and use conventional shipping, are prepassed as soon as all tapes have arrived,

but axe exported with a lag of at least a month. Reference frame sessions are processed on overtime

and weekend shifts. The operational budget provides for a basic 80 hours of processing per week

with provision for additional 56 hours of overtime if required. During the reported period the

Washington Correlator operated to capacity and now carries a backlog of at least one month.

1999 IVS Annual Report

164
U.S. Naval Observatory Washington Correlator

Figure 1. The Washington Mark IIIA Correlator

3. Washington Correlator Staff

The Washington Correlator is under the management and scientific direction of the Earth

Orientation Department of the U.S. Naval Observatory. USNO personnel are responsible for

oversight of scheduling and processing at WACO including: set-ups, data evaluation, exporting,

archiving, correlator testing, software and hardware maintenance, and development efforts as well

as contacts with the VLBI community.

The daily operation of the correlator is carried out by a private contractor, AMSC, which

supplies a contract manager and correlator operators.

Dr. Kerry Kingham (USNO) - VLBI Correlator Project Scientist, responsible for scientific

integrity of correlated date, hardware and software maintenance and upgrades.

James O. Martin (USNO) - VLBI Correlator Project Manager, responsible for process scheduling and evaluation of data. Oversees session set-ups, and prepasses. Evaluates station performance.

Bruce Thornton (AMSC) - Operations Manager, responsible for correlator operator scheduling,

daily operations, tape shipping.

Harvis Macon (AMSC) - Correlator operator, NEOS-A set-ups.

Valerie Bockarie (AMSC) - Correlator Operator

Michelle Diaz (AMSC) - Correlator Operator

Steven Springer (AMSC) - Correlator operator

Bosun Balogun (AMSC) - Tape librarian

1999 IVS Annual Report 165
Washington Correlator U.S. Naval Observatory

4. Status of the Washington Correlator

The Washington Correlator was fully loaded and operated at capacity up to 136 hours per

week, during the reporting period. Currently, four drives are thin tape/high density; four drives

have mode A capability, two have only mode C. The four Mark IV drives have excellent playback

characteristics, the two Mark IIIA drives are less sensitive and are subject to higher error rates.

All ten correlator crates are fully operational. The correlator is controlled by the original (now 15

year old) HP1000 computer but all correlator output is handled by a UNIX workstation (CygX3)

utilizing the Haystack Operational Postprocessing Software System (HOPS). This permits efficient

data evaluation, exporting and archiving on a system that will easily integrate into the new Mark IV

correlator system.

The replacement Mark IV correlator was expected at the end of 1998 but delivery was delayed

because of development problems with the station units. As a result, sessions that would have

been correlated at WACO, using the higher capacity of the Mark IV correlator, had to be canceled.

The delayed delivery of the Mark IV correlator has also postponed plans to reduce the backlog of

sessions waiting correlation.

5. Outlook

Plans for the coming year at the Washington Correlator are highly dependent on the final

development and delivery of the Mark IV correlator. The correlator crates and boards axe now

in place at WACO but no further progress can be made until the problems with the station units

can be resolved. When the Mark IV correlator is fully operational at WACO, hopefully before the

end of 1999, we will use the increased capacity to reduce the backlog and process an expanded

IVS observing program. The new correlator is expected to operate at double speed and will be

able to process all 15 baselines on a six-station session. Within two years we anticipate adding

two more playback units at which time we will be able to process all 28 baselines at once or divide

the correlator to process as many as four difference sessions at once. Until then, the Mark IIIA

correlator will continue to operate. In any event, before the fall of 1999, WACO should have all

six drives upgraded to Mark IV, with mode A, thin tape, high density capability.

1999 IVS Annual Repol_t

166
DATA CENTERS

Data

From the Terms of Reference:

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 closely with the

Coordinating Center and with the Analysis

Centers to ensure that all the information and

data required by IVS components are quickly

and reliably available

Centers provide the following functions:

receive and archive schedule files from

Operation Centers,

• receive and archive log files and ancillary data

files from the Network Stations,

• receive and archive data products from the

Analysis Centers,

• provide access and public availability to IVS

data products for all users.

Bundesamt fiir Kartographie und Geod/isie BKG Data Cent_

BKG Data Center

Volkmar Thorandt

1. Technical Description

available VLBI data:

covered span of time:

3450 X-Band databases

3300 superfiles

September 1976 - March 1999

2. Staff Members

background responsibility

Volkmax Thorandt

Dieter Ullrich

Reiner Wojdziak

3. Current Status

mathematics

cartography

computer science

group leader

data analysis

data flow, web design

Technical Equipment for VLBI purposes

• HP 9000/755 (HP UNIX 9.01)

• SP 9000/D280/1 (HP UNIX 10.20)

• HP 9000/735 CONVEX (HP UNIX 9.03), eight processors

• disc space: 35 GBytes

• jukebox: 18 GBytes

• internet rate: 128 KBit/sec

4. Outlook

• set up of the IVS data structure

• input area for analysis centers

• public access to the IVS data

• mirroring of the data centers CDDISA and OPAR

• mirroring of the IVS website (http://www.leipzig.ifag.de/IVS/)

• upgrade of the available disc space

• increase of internet rate (2 MBit/sec)

1999 IVS Annual Report 169
Data Center at CRL Kashima Space Research Center, Communications Research Laboratory

Data Center at Communications Research Laboratory

Yasuhiro Koyama

Abstract

bhmctions of the IVS Data Center at Communications Research Laboratory is integrated in the Key

Stone Project VLBI data analysis system. Databases and analysis results of the Key Stone Project

VLBI experiments are archived and disseminated to researchers from the data server.

1. Introduction

As a data center of the IVS, Communications Research Laboratory (CRL) holds and archives

data obtained from the geodetic VLBI experiments organized by CRL. Major parts of the data

are from the Key Stone Project VLBI experiments [1] but other regional and international VLBI

experiments are also included. The analysis results of the experiments performed before October

1992 were summarized in a data analysis report published by CRL [2]. The VLBI experiments

with the Key Stone Project VLBI stations began in August 1.994 and the analysis results and

databases are archived and disseminated to interested users over the network.

2. Data Products

The first Key Stone Project VLBI experiment was performed in August 1994, and the almost

daily experiments began in January 1995. At the beginning of the daily observations, duration of

the experiments was about six hours. The duration of the experiments was increased to about 23.5

hours to improve the quality of the results in September 1997. At the same time, the frequency of

the experiments was decreased from daily to alternate days, instead. Table 1 and Figure 1 show

how the number of experiments and valid number of observed delay for each year. Number of

experiments was decreased in 1998 but the number of observations was increased substantially.

Table 1. Number of experiments and observed delay used in the data analysis as of March 1, 1999.

Year Number of Number of

experiments valid observed delays

1994 2 261

1995 172 15837

1996 344 66005

1997 306 287452

1998 183 473864

1991 29 81780

Total 1036 925199

1999 IVS Annual Repot L

170
Kashima Space Research Center, Communications Research Laboratory Data Center at CRI,

350

3OO

250

2OO

150

100

50

0

Number of experiments

5O00OO

40O0O0

300000

Number of observed delay

1OO0O(

0

1994 1995 1996 1997 1998 1999 1994 1995 1996 1997 1998 1999

Figure 1. Number of experiments and observed delay used in the data analysis as of March 1, 1999.

3. Technical Staff for the KSP VLBI Data Center

Technical staff members who are contributing data analysis at the CRL are listed below. In

principle, no operations are necessary for the regular VLBI observations of the Key Stone Project

VLBI network.

• Tetsuro Kondo, Responsible for overall operations and performance.

• Yasuhiro Koyama, Development of various software.

• Jun Amagai and Kouichi Sebata, Maintenance of data server system.

• Naoki Goto and Muneo Takeda, Operator at Koganei station, Space Engineering Development Co., Ltd.

4. Current Status and Future Plans

CRL is also maintaining a mirror site of the WWW homepage for IVS. Those who are geographically close to Japan are encouraged to access the mirror site at http://ivs, crZ. go. j p/mirror/.

The analysis results and detailed explanations of the Key Stone Project are available at

http://ksp, crl.go, jp/. From the site, the rapid estimates of the Earth's rotation parameters

and the variation of the flux densities of the observed sources in the term of correlated amplitudes

are also available. At present, the analysis results are described in a format defined by CRL, but

the use of the SINEX (Solution Independent Exchange) format is currently planned as of March

1999.

References

[1] Taizoh Yoshino: Overview of the Key Stone Project, J. Commun. Res. Lab., Vol. 46, No. 1, pp.3-6,

March 1999

1999 IVS Annual Report 171
Data Center at CRL Kashima Space Research Center, Communications Research Laboratory

[2] Tetsuro Kondo, Jun Amagal, Yasuhiro Koyama, and Kosuke Heki: Data analysis of geodetic VLBI

organized by the Communications Research Laboratory, October 1992

[3] Yasuhiro Koyama, Noriyuki Kurihara, Tetsuro Kondo, Mamoru Sekido, Yukio Takahashi, Hitoshi Kiuchi, and Kosuke Heki: Automated geodetic Very Long Baseline Interferometry observation and data

analysis system, Earth Planets and Space, Vol. 50, pp.709-722, 1998

[4] Yasuhiro Koyama, Kosuke Heki, and Yukio Takahashi: KSP VLBI System; Data Analysis Software, J.

Commun. Res. Lab., Vol. 46, No. 1, pp.77-81, 1999

172 1999 IVS Annual Report
NASA Goddard Space Flight Center Crustal Dynamics Data Information System (CDDIS)

CDDIS Data Center Summary

Carey Noll

Abstract

This report summaries the current and future plans of the Crustal Dynamics Data Information

System (CDDIS) with respect to the International VLBI Service for Geodesy and Astrometry (IVS).

Included 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 new 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 NASA's Space Geodesy Program (SGP) and the Solid

Earth and Natural Hazards (SENH) activity. 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 submit 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, laser ranging, VLBI, and DORIS

data are stored on-line for remote access. Information 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 for 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 public via anonymous ftp

access.

1999 IVS Annual Report 173
Crustal Dynamics Data Information System (CDDIS) NASA Goddard Space Flight Center

3.1. Computer Architecture

The CDDIS is operational on a dedicated Digital Equipment Corporation (DEC) 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's Goddard Space Flight Center (GSFC) and is accessible to users 24 hours per

day, seven days per week.

3.2. Staffing

Currently, all CDDIS activities are supported by a staff consisting of one NASA civil service

employee and three contractor employees as shown in Table 1 below.

Na,tne

Ms. Carey Noll

Dr. Maurice Dube

Ms. Ruth Kennard

Ms. Laurie Batchelor

Table 1. CDDIS Staff

Position

CDDIS Manager

Head, CDDIS contractor staff and senior programmer

Request coordinator

Data technician

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 the IVS archiving requirements.

The IVS data center content and structure is shown in Table 2 below. In brief, an incoming

data area has been established on the CDDIS host computer, cddisa.gsfc.nasa.gov. Operation

and Analysis Centers deposit data files and analyzed results using specified file names. Automated

archiving routines, currently in development and testing by GSFC VLBI staff, peruse the directory

and migrate any new data to appropriate directories in the public disk area. These routines migrate

the data based on the file name as described in Table 2. Index files in the main subdirectories

under/vlbi are updated to reflect data archived in the filesystem. Furthermore, mirroring software

has been installed on the CDDIS host computer, as well as at the other primary IVS Data Centers,

to facilitate equalization of data and product holdings among these data centers. Figures 1 and 2

illustrate the flow of data and products within 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

been established to house analysis products from the individual IVS Analysis Centers as well as

the official combined IVS products. A documents disk area contains format, software, and other

descriptive files.

174 1999 IVS Annual Report
NASA Goddard Space Flight Center Crustal Dynamics Data Information System (CDDIS)

Table 2. IVS Data and Product Directory Structure

Directory I Description

Data Directories

vlbi/ivsdata/ db / yyyy

vlbi /ivsdata/ngs / yyyy

vlbi/ivsdata/aux/yyyy/ssssss

VLBI data base files for year yyyy

VLBI data files in NGS card image format for year

YYYY

Auxillaxy files for year yyyy and session ssssss; these

files include: log files, wx files, cable files, schedule

files, correlator notes

Product Directories

vlbi/ivsproducts/crf

vlbi/ivsproducts/eopi

vlbi/ivsproducts/eops

vlbi/ivsproducts/trf

CRF solutions

EOP-I solutions

EOP-S solutions

TRF solutions

Other Directories

vlbi/ivscontrol IVS control files (master schedule, etc.)

vlbi/ivsdocuments IVS document files (solution descriptions, etc.)

Schedule file

ssss sss.skd

and

Noles file

I I Data

rn Oe_er 1 I 1⁄21

IVS

Key; Ocorr_,onent OPr°°es_°rotSCript II-'l FiIe date

Figure 1. The flow of data and log files from various IVS components to the IVS data centers (Draft).

5. Future Plans

Much of the coming months will be devoted to developing and testing of the software for

automated archiving and mirroring between data centers. Although CDDIS staff is not responsible

1999 IVS Annual Report 175
Crustal Dynamic-q Data Information System (CDDIS) NASA Goddard Space Flight Center

Figure 2.

(Draft).

ivsincoming

anna

at

Data

Center

J

Analysis Center

I

data base or I

NGS card file I

;L

Key: Oc0mpcnent ivs _{"_Pr°(_SSor _ri_ Ir_ I d_, Fileor _._,_

The flow of data within the IVS data centers and flow of products to the IVS data centers

for this development, we will work closely with the IVS coordinating center staff to ensure that

our system is an active and successful participant in the IVS archiving effort.

1999 IVS Annual Repui t

176
Agenzia Spaziale Italiana Matera GeoDAF Data Center

Matera GeoDAF Data Center

Giuseppe Colucci, Domenico De1 Rosso, F_ancesco Vespe

Abstract

This report describes the Matera GeoDAF activities and characteristics. At the moment, this Data

Center is focused on GPS data and analysis products archive and distribution, but the system was

designed to manage VLBI analysis products and data too.

1. General

GeoDAF (Geodetical Data Archive Facility) is located at the Italian Space Agency "Centro di

Geodesia Spaziale" (CGS) near Matera, a small town in the South of Italy. At the same location

a SLR system (SAO-1), a VLBI Station and a GPS receiver are operated. CGS also controls and

manages the Italian GPS Network. In order to archive and distribute these RINEX GPS data

and the analysis solutions performed by CGS Analysis Group, the GeoDAF facility was set up in

1985. It was designed to manage SLR and VLBI data too, even if these features were never fully

exploited. All these activities are managed on behalf of ASI, by Telespazio S.p.A.

2. Technical/Scientific

GeoDAF is hosted on a HP/G40 server running HP-UX 10.01 (controllare con Maria) and

NCSA 1.5.2a HTTPD Web Server. A set of CGI scripts was developed to interface the archive

to the users and to manage the file requests for off-line data. The disk data storage capacity is

10 Gb, for off-line storage, DAT, EXABYTE, CD-R AND 9-TRACK TAPE axe available also. Fig

1 shows the GPS data flow for the full system.

3. Staff

The list of the GeoDAF staff is provided in Table 1.

Table 1. Matera GeoDAF staff members

Agency [Activity E-Mail Name

Dr. Giuseppe Bianco ASI CGS Director bianco@asi.it

Dr. Francesco Vespe ASI CGS Geodesy vespe@asi.it

Manager

Domenico Del Rosso Telespazio Operations domenico_delrosso@telespazio.it

Manager

Giuseppe Colucci Telespazio GeoDAF contact colucci@asi.it

1999 IVS Annual Report 177
Matera GeoDAF Data Center Agenzia Spaziale Italiana

Cagliari

T.Rogue

Genova Trimble

Noto

Trimble

Venezia

T.Rogue

Medicina

T.Rogue

TELEPHONE

MODEM

(RAW FILES)

m i

,o Lain pedusa,.._,.__

' Tri bl

' m e ,,

"............... l Bohano Leica

Win95

PC

(PENT.M)

ETHERNET

LAN

(_x F:LES)

DIRECT CABLE

Matera

T.Rogue

rGeoDAFFTP and Web

Server

(HP-G40HP-UX 10)

T T

Cosenza Trimble I1 Perugia Ashtech

T

I Padova Trimble

T

I Trimble Torino

Figure 1. The Matera GeoDAF Data Center

INTERNET

FFP

IFAG

USERS

IHTERNET

FrP & WEB

I Prato

i [ Trimble

Vallo

Leica /

4. Status

The access to GeoDAF services is provided by ANONYMOUS FTP and by Web interface.

Currently the GPS data files axe available on-line ready to transfer for six months and then they

axe put off-line on DATs. To obtain these off-line data files, users can simply send e-mails to the

GeoDAF user interface account (web@geodaf.mt.asi.it). Also an automated data request system

was set up, but this method is not managed by the system at this moment. GeoDAF is completely

free, but the users axe encouraged to "register" themselves by an on-line Web managed form. Up

to June 1998 the registered users axe 230, mainly from Italy and other European countries.

5. Outlook

The following upgrade activities are planned in order to improve the performance of GeoDAF:

* apache web server instead NCSA (no longer under development)

* new web pages look and optimization

* increase disk storage capacity (eventually)

* increase Internet connection (eventually)

* test of the SLR and VLBI data management features

1999 IVS Annual Report

178
Istituto di Radioastronomia-Bologna Italy CNR Data Center

Italy CNR Data Center Report

P. Tomasi, M. Rioja, E. Gueguen

Abstract

This report summarizes the situation of the Italian CNI:t VLBI data center. It will give the fundamental information about the structure of the center, its locations, and its activity.

1. Introduction

The Italy CNR VLBI data center is the 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 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 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.

The IRA has started to store VLBI geodetic databases from 1989 but the databases archived

here are mostly concerned with data including European antennas, starting from 1987. In particular most of the databases presented here have VLBI data with at least three European antennas.

From 1997 also ITIS started to store the VLBI databases with the same selection effect, but

during 1998 we start to define different task at the different sites. We would like to mention

that even ITIS is at the same site as the Italian Space Agency Center for spatial geodesy, that is

different institution and this data center is different from ASI data center or GEODAF. We are

discussing merging in order to avoid duplication, but up to now the two data centers are separate.

We have specialized the Bologna part to store and analyze single databases, in order to produce

a final database, that can be stored in a different format (superfile) and used in global solution.

This second part is mostly done in Matera at the ITIS.

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 disk as well. The complete list of

directories where databases are stored is the following:

1 = /datal/mk3/datal

2 -- /datal/mk3/data2

4 --/data/dbasel

6 --/data5/dbase5

5 =/data4/dbase4

7 =/data7/dbase7

8 =/data8/dbase8

9 --/data9/dbase9

1999 IVS Annual Report 179
Italy CNR Data Center Istituto di Radioastronomia-Bologna

The username for accessing the database at the moment is geo. Password can be asked by

sending a mail to tomasi@ira.bo.cnr.it. In the near future the database will be accessed by web.

During 1998 we have also started to work on the possibility of using tropospheric zenith path

delay from GPS in order to improve the repeatability of the VLBI geodetic results. For that we

have produced, for all the EUROPE databases of 1998, a different copy of the database, with this

GPS data stored in the VLBI database as coming from the water vapor radiometer. Also these

databases are available on request.

In Matera the main computer is an HP282 computer with internet name hp-j.itis.mt.cnr.it.

The database are stored in different directories and the full list will follow:

1 = /datal/mk3/datal

2 = /datal/mk3/data2

6 =/data5/dbase5

5 =/data4/dbase4

7 =/data8/dbase8

8 =/datal0/dbasel0

9 = /datal3/dbasel3

10 =/datal4/dbasel4

The super file are stored in two different directories:

/data2/super

/datal0/superl0

and the list of superfiles is stored in the file /datal/solvefiles/SUPCAT. The data can be

accessed using the username geo, and the password can be asked to tomasi@ira.bo.cnr.it.

For the moment all the data are stored on magnetic disk, but we are planning to move the

whole catalog of database to optical disk. The area available on a juke box (already installed in

Matera) will be of 80 Gb on line.

1999 IVS Annual Report

180
Observatoire de Paris, DANOF/UMP_ 8630 Paris Observatory (OPAR) Data Center

Paris Observatory (OPAR) Data Center

Najat EssaYfi

1. OPAR Data Center Functions

The Paris Observatory (OPAR) provides a Data Center for the International VLBI Service for

Geodesy and Astrometry (IVS). The purpose is to store files (data and analysis files) from IVS

components and to make them available to the community as soon as they are submitted.

The functions of OPAR Data Center are to:

• receive and archive schedule files from the operational centers,

• receive and archive log files and ancillary data files from the network stations,

• receive and archive data products from the analysis centers,

• provide access and public availability to IVS products for all users.

All these activities will be made in close collaboration with CDDISA and BKG Data Centers.

2. Staff Members

Staff members who are contributing to OPAR Analysis and Data Center for IVS are listed

below:

• Anne-Marie Gontier, responsible for GLORIA analysis software.

• Martine Feissel, scientific developments.

• Najat Essa_fi, responsible for computer science.

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 Gb disc storage for VLBI activities.

The OPAR server is accessible 24 hours per day, seven days per week through Internet connection with 2 Mbit/s rate.

4. Future Plans

• Activities with others Data Centers:

The OPAR Data Center will synchronize its activities whith the CDDISA and BKG Data

Centers to make all IVS products available as soon as new information arrive.

1999 IVS Annual Report 181
Paris Observatory (OPAR) Data Center Observatoire de Paris, DANOF/UMR 8630

• FTP and WWW access :

Users can reach the IVS products by using the TCP/IP protocol. Both World Wide Web

(WWW) and File Transfert Protocol (FTP) will be available. Access to this server will be

free for users require to get data. Authorized access is needed for IVS component to put

data; username and password would be given on request.

FTP access:

WWW site :

ivsopar.obspm.fr

username : anonymous

password : your e-mail

cd vlbi (directory of IVS produts)

http://ivsopar.obspm.fr/ivs

• Structure :

The directory structure of IVS products will be:

vlbi/

ivscontrol/

ivsdata/

ivsdocuments/ :

ivsproduts/

Directory for VLBI activities

Files giving detailed information about directory structure

and file name conventions

Directory for VLBI observations

(auxilliaxy files, Calc Data Bases and NGS Card files)

Directory for VLBI documents

Directory for VLBI products

(Earth rotation parameters, Celestial and Terrestrial Frame)

• Enhancement on the hardware :

The disc space will be increased with regards to IVS products.

5. Contact Information

To obtain username and password or more information about OPAR Data Center the contact

address is given below:

Najat Essa'ffi

Observatoire de PARIS

61, Avenue de l'Observatoire

75014 Paris - FRANCE

Phone : 33 1 40 51 22 33

Fax: 33 140512291

E-mail : essaifi@hpvlbi.obspm.fr

1999 IVS Annual Report

182
ANALYSIS

CENTERS

From the Terms of Reference:

The Analysis Centers receive and process

VLBI data from one or more IVS Data

Centers and are committed to produce the

core products, without interruption, and at

a specified time lag to meet IVS requirements. The IVS core products, at a minimum, consist of Earth orientation parameters, station coordinates, and source coor_

dinates. 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_luality products and

their timely archiving and distribution. Any

deviations that an Analysis Center makes

from IVS recommendations are properly

documented. Analysis Centers provide timely feedback about station performance.

IVS Analysis Centers satisfy the following

standards:

• Analysis is performed using VLBI

software packages that adhere to

IVS recommendations.

• Centers perform software development and produce documentation.

They periodically compare their products.

• Centers adhere to IERS Conventions.

Any exceptions are documented.

Astronomical Institute of Saint-Petersburg University Analysis Center of Saint-Petersburg University

Analysis Center of Saint-Petersburg University

Oleg Titov

Abstract

This report summarises the information about current and future activity of analysis center of

Saint-Petersburg University.

1. Analysis Center of Saint-Petersburg University

Analysis Center is located in Astronomical Institute of Saint-Petersburg University. This time

the analysis center makes an analysis of NEOS-Intensives VLBI sessions for IERS as well as IVS

(see part 4).

2. Technical Information

To estimate the UT1-UTC values we make a least squares analysis of the two-hour sessions

using OCCAM 3.4 software. Wet delay for reference VLBI station; wet delay, clock offset and

clock rate for other stations are regularly estimated. All reductional calculations axe in accordance

with IERS Conventions 1996. Niell's mapping function is applied for wet delay estimation. We

download gzipped VLBI data file in Mark III format from USNO database.

3. Technical Staff of the Saint-Petersburg University Analysis Center

V.Vityazev - Director of Astronomical Institute of Saint-Petersburg University, PhD. General

coordination and support of the activity at the Astronomical Institute.

O.Titov - associate professor of Saint-Petersburg University, PhD. Current processing of VLBI

data.

4. Status of the Saint-Petersburg University Analysis Center

Analysis Center operates for quick analysis of two-hours VLBI sessions (NEOS-Intensives).

UT1-UTC values axe estimated and submitted to USNO and Paris Observatory biweekly. IERS

takes the results for preparation of Bulletins A and B.

5. Outlook

We are going for next year:

a. to process the regular weekly NEOS-A VLBI sessions.

b. to make weekly comparison and combination of Intensive Series EOP.

c. to provide a documentation about OCCAM software. OCCAM software to be upgrade using

the recent recommendations of scientific groups collected since 1996 year.

d. to participate in comparison of high-frequency EOP variations from different space geodetic

techniques.

1999 IVS Annual Report 185
Bordeaux Observatory Analysis Center Observatoire de Bordeaux

The Bordeaux Observatory IVS Analysis Center

P. Charlot, B. Viateau, A. Baudry

Abstract

This report gives an overview about VLBI activities in Bordeaux during the past year. It also

presents the expected contribution of Bordeaux Observatory to IVS and lists the staff involved in

the IVS Analysis Center work. Future plans include the development of a new astrometric observing

program on the European VLBI Network (EVN) for densifying the International Celestial Reference

Frame (ICRF).

1. VLBI in Bordeaux

Bordeaux Observatory (Fig. 1) is located in the southwest of France (about 600 km from Paris)

near the mouth of the Garonne river. It is funded by the University of Bordeaux and the CNRS

(National Center for Scientific Research).

The Observatory comprises four scientific groups specialized in radioastronomy, astrometry,

planetology, and solar research. The radioastronomy group has long been involved in VLBI observations of active galactic nuclei and maser sources for astrophysical objectives. VLBI astrometry

and geodesy is a new activity set up during the past year as a cooperation between the astrometry

and radioastronomy groups.

Observatoire de Bordeaux

2, rue de l'Observatoire

BP 89

33270 Floirac, FRANCE

http://www, observ, u-bordeaux, fr

Figure 1. Aerial view and address of Bordeaux Observatory.

186

1999 IVS Annual Repo_-L
Observatoire de Bordeaux Bordeaux Observatory Analysis Center

2. Expected Contribution to IVS

Our major scientific interest is the celestial reference frame, especially the maintenance and

extension of the International Celestial Reference Frame (ICRF). We expect to contribute to this

area in the form of:

• Observational data:

Our goal is to develop an observing program dedicated to astrometry on the European VLBI

Network (EVN) in cooperation with the IAU sub-group in charge of the maintenance and

extension of the ICRF. The subsequent data will be submitted to IVS as data products.

• Celestial frame analyses:

Our initial plan is to analyze only the data from the expected EVN experiments. Depending

on the available support later on, we may develop larger solutions, including additional data

from other observing programs, and provide time series of source positions. The aim is to

study the ICRF source position stability and the physical phenomena that can affect this

stability (e.g. source structure variations).

VLBI analyses will be conducted with the MODEST software, developed and maintained by

the Jet Propulsion Laboratory [1].

3. Scientific Staff

VLBI in Bordeaux benefits from experience of researchers with background in both astrometry

and radioastronomy. Table 1 lists the staff participating in the IVS Analysis Center work.

Table 1. Staff involved in the IVS Analysis Center work.

Name Background Position

Patrick Charlot astrometry, radioastronomy permanent

Bruno Viateau astrometry post-doc

Alain Baudry radioastronomy permament

4. Overview of Recent Activities

During the past year, astrometric VLBI activities in Bordeaux have focused on the following

technical and scientific matters:

• Installation and test of the MODEST software on various computer platforms (HP, Sun,

DEC/Unix, DEC/VMS):

These tests have been carried out during a visit of O. J. Sovers (Jet Propulsion Laboratory)

at Bordeaux Observatory in the fall of 1998. They revealed a few non-portable features in the

MODEST code. These are being corrected, so the MODEST code should be fully portable

in the near future.

1999 IVS Annual Report 187
Bordeaux Observatory Analysis Center Observatoire de Bordeaux

• ICRF source classification based on observed structure:

Tile work previously carried out in collaboration with A. L. Fey (U.S. Naval Observatory) [2]

has been pursued further for 225 additional sources. As with the previous work, the sources

have been separated into four classes according to the magnitude of the expected source

structure effects on astrometric bandwidth synthesis delay observations. This classification

now covers 392 ICRF sources, and is complete for about 90% of the ICRF sources north of

-20 ° declination [3].

• Study of the optimal use of the EVN for astrometric observations:

Discussions have been initiated about the possible use of the EVN (and JIVE correlator)

to supplement the existing astrometric programs ongoing with the VLBA and the DSN for

maintaining and extending the ICRF. These concluded that the EVN would be useful for

densifying the ICRF, especially towards weaker sources. A subsequent proposal for observing

150 new sources, each source re-observed three times, has been submitted to the EVN.

5. Outlook

Starting next fall, we will have improved computer facilities with a new faster Unix workstation

(Compaq DS20/EV6). The MODEST software will be installed on this new workstation along

with the NASA SKED program, while the Goddard data base system will stay on our old HP

workstation.

If approved by the EVN Program Committee, we expect the initial experiment of the proposed

EVN observing program to be carried out within a year. This experiment will be designed to

provide first-epoch observations of 50 new sources. Time will be devoted to refine the source

selection strategy before scheduling.

References

[l] 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.

[2] Fey, A. L., Charlot, P.: 1997, VLBA Observations of Radio Reference Frame Sources. II. Astrometric

Suitability Based on Observed Structure, ApJS, 111, 95-142.

[3] Charlot, P., Fey, A. L.: 1999, A Classification of ICRF Sources Based on Observed Structure for Ultraprecise VLBI Astrometry and Geodesy, Proceedings of the 13 th Working Meeting on European VLBI

for Geodesy and Astrometry, Viechtach, February 12-13, 1999, edited by W. Schlfiter and H. Hase,

Bundesamt fiir Kartographie und Geod_ie, Wettzell, p. 217-223.

1999 IVS Annual Repozt

188
Agenzia Spaziale Italiana (ASI) Matera CGS VLBI Analysis Center

Matera CGS VLBI Analysis Center

Roberto Lanotte

Abstract

This paper summarizes the present status of the VLBI data analysis activities at the Space Geodesy

Center (CGS) of Matera and the contributions that the CGS intends to provide as an IVS Data Analysis

Center. The center born in 1983 as an SLR station grew in the years including in its facilities a VLBI

and a fixed GPS station. It is operated by Telespazio on behalf of the Italian Space Agency (ASI) and

is providing not just high quality data but also data analysis support.

1. Intoduction

The Matera VLBI station became operational at the Space Geodesy Center (CGS) of the

Italian Space Agency (ASI) in May 1990. Since then it is active in the framework of the most

important international programs [3]. VLBI data analysis activities are performed at CGS for a

better understanding of the tectonic motions with specific regards to the European area. The CGS,

operated by Telespazio on behalf of ASI, provides full scientific and operational support using the

three main space geodetic techniques: VLBI, SLR and GPS. The CGS intends to participate in

the IVS as an Analysis Center for:

- Terrestrial Reference Frame analysis products

- Comparison of TRF analysis products and production of a single TRF

- Comparison of results from different space geodetic techniques.

For the VLBI analysis we use the CALC/f-SOLVE software on an HP725 workstation.

2. TRF Analysis Products

Analysis of the EUROPE campaign is performed at the CGS since 1992 and its results are

regularly presented at the working meetings on European VLBI for Geodesy and Astrometry [2].

Our products from this analysis are station coordinates and velocities. Generally we perform, using

CALC/f-SOLVE, a "standard" two-step analysis procedure; the first is an "arc solution" which

provides the time series of the parameters under investigation, the second solution is a "global

solution" where parameters are estimated using all sessions. For this analysis we will provide a

solution every year using all data acquired within this campaign.

Also global geodetic VLBI solutions have been carried out and for this kind of analysis we

intend to provide solutions, without any particular time schedule, using as many data as possible

to determine TRF, CRF and EOP.

3. Comparison of TRF

For the combination of individual TRF products we intend to use the following procedure:

We assume that the individual TRF are provided in SINEX format.

1999 IVS Annual Report 189
Matera CGS VLBI Analysis Center Agenzia Spaziale Italiana (ASI)

Constraints introduced in the solution will be removed for each TRF.

- Application of minimal internal constraints adjustment will be performed on each TRF.

- Combination of all TRFs will be done evaluating a 14 parameters transformation (scale factor,

translations, rotations and their time derivatives) using the IERS ITRF as reference frame.

This step will produce a unique TRF.

Initially we can provide the combined TRF for the end of 1999. After that date combination

will be performed every six months.

Comparison of the TRFs will be performed estimating a 14-parameter transformation between

the single TRF and a ITRF that can be the IERS one or that produced by IVS. Feedback to the

Analysis Center will be provided in terms of differences between the single TRF and the ITRF.

4. Comparison of Results from Different Space Geodetic Techniques

The space geodetic data analysis activities in the fields of GPS, SLR and VLBI usually carried

out at the CGS make the comparison and combination of the results one of our natural objectives.

The kind of compared geodetic parameters depend on the particular solution (global, regional).

Results from the analysis of the EUROPE campaign have been extensively compared to those

from our SLR and GPS solutions for co-located sites [2]. Results from a worldwide VLBI solution

have been compared to SLR global solutions and to ITRF to verify the consistency of different

reference systems [1], in terms of rototraslations/scale parameters, of empirical Eulerian poles,

where possible, and in terms of Fourier coefficients for the EOPs.

Comparison of results concern:

• Comparison of baseline time series, after removal of the eccentricity vectors among the techniques.

• Evaluation of the 14-parameter transformation between the TRF determined by each technique and the ITRF.

• Determination of the Eulerian poles for each technique and comparison with those coming

out from the ITRF.

5. Staff at CGS contributing to the IVS Analysis Center

- Dr. Giuseppe Bianco, Responsible for CGS, ASI (primary scientific/technical contact)

Dr. Francesco Vespe, Responsible for CGS geodesy activities, ASI (administrative contact)

Dr. Cecilia Sciarretta, Responsible for scientific activities, Telespazio

Dr. Roberto Lanotte, Geodynamics scientist, Telespazio.

References

[1] Bianco, G., R. Devoti, M. Fermi, C. Ferraro, R. Lanotte, V. Luceri, R. Pacione, P. Rutigliano, C. Sciarretta and F. Vespe: Comparison of Space Geodetic Data Analysis Results at the CGS. In: Proceedings

of the 12th Working Meeting on European VLBI for Geodesy and Astrometry, held at Honefoss, Norway, September 12-13, 1997, edited by Bjorn R. Pettersen, Stantens Kartverk Geodesidivisjonen, ISBN

82-90408-41-2, pp. 74-85, 1997

1999 IVS Annual Repot t

190
Agenzia Spaziale Italiana (ASI) Matera CGS "LBI Analysis Center

[2] Lanotte, R., C. Ferraro, A. Nardi, C. Sciarretta and F. Vespe: The CGS VLBI EUR98 Geodetic

Solution and Comparison with the CGS GPS Results. In: Proceedings of the 13th Working Meeting

on European VLBI for Geodesy and Astrometry, held at Viechtach, February 12 13, 1999, edited by

W. Schliiter and H. Hase, Bundesamt fiir Kartographie und Geodiisie, Wettzell, pp. 101-107, 1999

[3] Colucci, G., D. Del Rosso and F. Vespe: Matera CGS VLBI Station. In this Annual Report.

1999 IVS Annual Report 191
Analysis Center at CRL Kashlma Space Research Center, Communications Research Laboratory

Special Associate Analysis Center at Communications Research

Laboratory

Yasuhiro Koyama

Abstract

Communications Research Laboratory is performing data analysis on the Key Stone Project VLBI

experiments which axe currently performed once every two days. The data analysis procedures are

fully automated and the results are placed in the publicly accessible area via Internet. Geodetic VLBI

experiments which have been organized by the laboratory are also analyzed. These activities are

summarized in this report.

1. Introduction

Communications Research Laboratory (CRL) has organized various geodetic VLBI experiments

in Japan and with foreign network stations. The analysis results of the experiments performed

before October 1992 were summarized in a data analysis report published by CRL [1]. The VLBI

experiments with the Key Stone Project VLBI stations began in August 1994 [2] and the analysis

of the Key Stone Project VLBI data is the major activity as the special associate analysis center

at present.

2. Data Analysis Software and Hardware Systems

For the data analysis of the Key Stone Project VLBI observation data, Mark III database files

are created by using software developed at CRL and database handler library routines developed by

Goddard Space Flight Center (GSFC) of National Aeronautics and Space Administration (NASA).

The theoretical delay and delay rates are calculated by CALC version 8.1 (NASA/GSFC), and

the least squares parameter estimations are performed by VLBEST (CRL) [3] [4]. Editing of bad

data points and ambiguities are applied by MRKOBS (CRL) and REMAMB (CRL) respectively.

The final results are processed and placed in a publicly accessible area via Internet in appropriate

data formats. All the processes from the generation of the database files to the publication of the

final results are fully automated and no human operations are required.

3. Data Analysis

In the data analysis, site coordinates of the ll-m antenna station at Kashima axe fixed to

the a-priori position in the ITRF96 which was defined by International Earth Rotation Service

(IERS). The site coordinates of the other three stations are estimated along with the clock offset

and atmospheric zenith delay at the time intervals of 1.5 and 3.0 hours, respectively. The apriori coordinates of the 11-m antenna station at Kashima is derived from the results of seven

tie VLBI experiments with the 34-m antenna station at Kashima. Positions of the observed radio

sources are fixed to the RSC(WGRF)95R01 and the Earth rotation parameters are fixed to the

EOP(IERS)97C04 data set, both of them are defined and maintained by IERS. Every time when

the Earth rotation parameters are updated in an e-mail bulletin from IERS, the content of the

1999 IVS Annual Repmt

192
Kashima Space Research Center, Communications Research Laboratory Analysis Center at CRL

bulletin is processed and the affected databases are reanalyzed automatically.

Estimated site positions of the Koganei station are shown in the Figure 1 as an example.

The precision of the estimates have been gradually improved. The major improvements were

achieved by better temperature control of the receiver system and the use of higher data rate

(256 Mbps) for the observations since June 1999 [5]. These results can be accessed at the URL of

http ://ksp. crl. go. jp/obsdata, html.

E

E

O

O

O

tD

O

O

vi

Eastward Component

J

Rate : 0.12 ± 0.10 (mm/year)

ReducedChi-square: 3.29

Weighted RMS : 3.10 (mm)

.... i ......... , J , , , , , , ..... t ........... J ........

1995 1996 1997 1998

O

O

O

g

v

Northward Component

Rate : -8.06:1:0.09 (rnrrgyear)

Reduced Chi-square : 3.02

Weighted RMS : 2.88 (mm)

.... i i i i i i i i i i i i i i i , , , , .... _ ........... L ........

1995 1996 1997 1998

O

O

O

Vertical Component I

i

Rate : -2.23 ± 0.51 (mm/year)

Reduced Chi-square : 3.12

Weighted RMS : 15.29 (mm)

.... i i i i i i i i i i i i i i

1995 1996 1997 1998

Figure 1. Estimated site positions of the Koganei station.

In addition to the regular data analysis described above, wobble parameters of the Earth's

rotation pole position and the time difference between coordinated universal time and the universal

1999 IVS Annual Report 193
Analysis Center at CRL Kashima Space Research Center, Communications Research Laboratory

time (UT1-UTC) are estimated by fixing the site coordinates of the four stations. Figure 2 shows

differences between the UT1-UTC values published by IERS in the monthly bulletins and the

estimated UT1-UTC from the Key Stone Project VLBI data, when only the UT1-UTC values are

estimated. Since the data analysis of the Key Stone Project VLBI data is performed immediately

after a set of observations are performed, the UT1-UTC estimations axe considered to have a

potential to be included in a rapid service from IVS.

O

(UT1-UTC) - (EOP97C04)

0

'7, 40 80 120 160

DOY(1998)

Figure 2. Estimated UT1-UTC values compared with the EOP90C04 data set.

4. Technical Staff for the KSP Analysis Center

Technical staff members who are contributing data analysis at the CRL are listed below. In

principle, no operations axe necessary for the regular VLBI observations of the Key Stone Project

VLBI network.

• Tetsuro Kondo, Responsible for overall operations and performance.

• Yasuhiro Koyama and Masato Furuya, Development of data analysis software.

• Ryuichi Ichikawa, Research for atmospheric modeling.

• Jun Amagai, Maintenance of data analysis system.

5. Current Status and Future Plans

As of March 1999, a replacement of the Unix workstation with a new system is on the way

and the new workstation will be used for regular data analysis of the Key Stone Project VLBI

observations. The newer version of the CALC (version 8.2) will be used on the new system.

At present, only the zenith atmospheric delay parameters are estimated and a mapping function

is used to model the elevation dependency of the atmospheric delay. Effectiveness of estimating

tropospheric gradient parameters are being evaluated at present. It is also planned to generate

the analysis results in SINEX (Solution Independent Exchange) format.

194 1999 IVS Annual Report
Kashima Space Research Center, Communications Research Laboratory Analysis Center at CR,I,

References

[1] Tetsuro Kondo, Jun Amagai, Yasuhiro Koyama, and Kosuke Heki: Data analysis of geodetic VLBI

organized by the Communications Research Laboratory, October 1992

[2] Taizoh Yoshino: Overview of the Key Stone Project, J. Commun. Res. Lab., Vol. 46, No. 1, pp.3-6,

March 1999

[3] Yasuhiro Koyama, Noriyuki Kurihara, Tetsuro Kondo, Mamoru Sekido, Yukio Takahashi, Hitoshi Kiuchi, and Kosuke Heki: Automated geodetic Very Long Baseline Interferometry observation and data

analysis system, Earth Planets and Space, Vol. 50, pp.709-722, 1998

[4] Yasuhiro Koyama, Kosuke Heki, and Yukio Takahashi: KSP VLBI System; Data Analysis Software, J.

Commun. Res. Lab., Vol. 46, No. 1, pp.77-81, 1999

[5] Tetsuro Kondo, Noriyuki Kurihara, Yasuhiro Koyama, Mamoru Sekido, Ryuichi Ichikawa, Taizoh

Yoshino, Jun Amagai, Kouichi Sebata, Masato Furuya, Yukio Takahashi, Hitoshi Kiuchi, and Akihiro Kaneko: Evaluation of repeatability of baseline lengths in the VLBI network around the Tokyo

metropolitan area, Geophys. Res. Lett., Vol. 25, pp.1047-1050, 1998

1999 IVS Annual Report 195
DGFI Analysis Center Deutsches Geod_itisches Forschungsinstitut (DGFI)

DGFI Analysis Center

Hara]d Schuh, Wolfgang Schwegmann, Volker Tesmer, Hermann Drewes

Abstract

At DGFI both the CALC/SOLVE software (installed at GIUB and accessible via inter net) and the

OCCAM package are used for VLBI data analysis, and a thourough knowledge of both software packages exists. The main activities of the DGFI VLBI group during the last year were focussed on the following tasks: artificial intelligence methods, OCCAM modifications, and comparison of CALC/SOLVE

and OCCAM

1. Application of Artificial Intelligence (AI) Methods

An important contribution to accelerate the VLBI procedure is a faster and semi-automatic

data analysis, which is in particular needed in view of the increasing amount of VLBI data to be

processed in the next years. Most of the tasks in the VLBI data analysis are very complex and

their automation requires typical knowledge-based techniques, but some tasks can be automated

by conventionally programmed algorithms within the existing software. First, a concept for the

automation of the Mark III Data Analysis System was developed.

Then, the program PWXCB, which extracts weather and cable calibration data from the log

files, was automated by extending the existing Fortran77 program code. The new program is called

XLOG. In XLOG the calibration data axe extracted from the log files and are checked with respect

to their plausibility, then wrong data are deleted. These tasks axe done automatically, but in case

of probably wrong data the analyst's attention is directed to these suspicious data. At present a

beta version of XLOG is being tested to be used for routine application. It is planned to release

version 1.0 of XLOG in Spring 1999.

Now, an intelligent assistant for support and guidance of the analyst is being developed using

the workbench BABYLON, which is based on methods of artificial intelligence. The construction

of the new system to automate the tasks done by the program SOLVE has been started, because

these tasks are very complex and require a comprehensive knowledge of the whole procedure of

data analysis. The system can also be used as a teaching-system for less experienced analysts. This

would be very helpful because there is a shortage of qualified experts and the analyst's training

takes a long time.

2. Modification of OCCAM

The OCCAM V3.4 package installed at DGFI was extended by allowing a-priori correlations

between the VLBI observables, i.e. including a full variance-covariance matrix. Empirical correlation coefficients had been computed already at the beginning of the 1990s [1], but they were

neglected so far due to missing computer capacity and power. Now, the a-priori correlation matrix

was constructed with the formerly obtained empirical correlations. They were compared with the

a-posteriori correlations between the observables which were taken from a first least squares adjustment. This allows to optimize the determination of realistic a-priori correlations which are in

fact rather high. Their consideration in the VLBI least squares fit will improve the results in par196 1999 IVS Annual Report
Deutsches Geod_tisches Forschungsinstitut (DGFI) DGFI Analysis Center

ticulax with respect to more realistic formal errors than those obtained by the present uncorrelated

approach. It is planned to do further work on that and on the models used in OCCAM.

3. Comparison of Software Packages (CALC/SOLVE and OCCAM)

At DGFI both the CALC/SOLVE software and the OCCAM package are used for VLBI data

analysis. First comparisons of the results have been done. They yield a rather good agreement

of the pattern of residuals. However, the geodetic results (baseline components, Earth orientation

parameters, ...) still show significant differences probably due to different models used in both

software packages and due to the procedures applied for editing the data and choosing the apriori weights of the observables. The comparisons will be continued in more detail. It is planned

to use databases of the IRIS-S sessions for that.

References

[1] Schuh, H. and A. Wilkin: Determination of Correlation Coefficients between VLBI Observables. Proc.

7th Meeting on European VLBI, Madrid 1989, ed. by A. Rius, CSIC/Univ. Complutense de Madrid,

pp. 79-91, 1990.

1999 IVS Annual Report 197
FFI Analysis Center Forsvarets forskningsinstitutt (FFI) (Norwegian Defence Research Establishment)

Combination of Results at FFI - Data Analysis

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

shortly summarises the current status of analyses performed with the GEOSAT software.

1. Introduction

FFI is centrally located in the Kjeller area, 30 minutes east of Oslo (near LillestrCm). Here

approximately 2400 people axe engaged in several research establishments, technical institutions,

university branches and Air Force Material Command. FFI is a state operated, civilian research

establishment reporting directly to the Ministry of Defence. The number of employees is approximately 550.

For many years FFI has performed research in space science and remote sensing using satellites.

As a part of this research FFI has developed a highly sophisticated software (GEOSAT, [2]) for

satellite orbit determination and space geodesy. With this software all types of high precision

space geodetic observations can be combined and analyzed at the observation level.

2. Status of FFI's Contribution to the IVS

FFI is presently establishing using GEOSAT a database of VLBI, GPS, and SLR observations,

residuals, partial derivatives, and arc-by-arc state vectors and covariance matrices estimated on

the basis of a combination of VLBI, GPS and SLR data at the observation level. The arc-by-arc

state vectors and complete covariance matrices will be combined into a multi-year solution using

a highly sophisticated and flexible Square-Root-Information-Filter-and-Smoother, CSRIFS ([1]),

which is a part of the GEOSAT software (GEOSAT, [2]).

Our first combined contributions to IVS and IERS will primarily be based on some selected

high-quality datasets. In the future the analysis will be extended to a large number of arcs covering

many years.

The GEOSAT software will be used in all analyses. All major components of GEOSAT have

been successfully validated with a combination of data from VLBI, GPS and SLR. Consistent

models for all techniques have been verified at the sub-ppb level. The processing at the arc or

session level is completely automated using C-shell scripts.

The CSRIFS program for combining arcs has been successfully applied in the generation of

a VLBI-only solution covering 623 sessions during the last 10 years. A paper containing the

mathematics of CSRIFS and the results of the VLBI analysis has recently been submitted for

publication in Journal of Geodesy [1]. Results from a combined analysis of 12 days of VLBI,

GPS, and SLR observations in the period Jan 12 - 23, 1994 (CONT94), were presented at the

IERS Symposium at GFZ in 1998. Both the VLBI-only solution and the combined solution were

submitted to the IERS at the end of March 1999. More complete analyses will be presented at

international meetings later in 1999.

198 1999 IVS Annual Report
Forsvarets forskningsinstitutt (FFI) (Norwegian Defence Research Establishment) FFI Analysis Center

We plan, as part of the IVS analysis, to test different analysis strategies related to especially the

weighting of the a priori information (observations and a priori parameter estimates), the selection

of dynamical parameters to be estimated for the GPS satellites, data editing, the estimation of

eccentricity vectors, the use of multi-arc orbital elements for the GPS and the LAGEOS satellites,

and the estimation of geophysical parameters.

3. Technical Staff

Table 1 lists the FFI staff involved in IVS activities. The development and validation of

GEOSAT have resulted in a substantial theoretical understanding and practical experience with

all available types of high-precision space geodetic data (VLBI, GPS, SLR, PRARE, DORIS and

radar altimetry).

Table 1. Staff working at the FFI AC and TDC

I Name I Background I Dedication t Agency I

l Per Helge Andersen I geodesy I 40% I FFI I

4. Outlook

The computation time for the processing of 24 hours of VLBI, GPS, and SLR data is presently

approximately 14 hours using a HP C180 (one CPU) computer. We plan to buy a new computer

within the end of this year or early next year, probably a HP J5000 (with two CPU's) or a HP

J7000 (with four CPU's) including 1 Gb RAM. This should give an increase of a factor 5 or 10

in processing capacity. The disk storage capacity will be extended from 65 Cb to 100 Gb with

additional 30 Gb each year. With such a computation power it should be possible to generate

global combined multi-technique solutions based on a large number of arcs.

References

[1] Andersen, P. H. (1999) Multi-level arc combination with stochastic parameters. Paper submitted for

publication in Journal of Geodesy.

[2] Andersen, P. H. (1995) High-precision station positioning and satellite orbit determination. PhD Thesis,

NDRE/Publication 95/01094.

1999 IVS Annual Report 199
GIUB/BKG Analysis Center Geod_tisches Institut der Universit_t Bonn

The GIUB/BKG VLBI Analysis Center

Axe1 Nothnagel, Volkmar Thorandt, Leonid Petrow

1. Overview

The GIUB/BKG VLBI Analysis Center has been estabished jointly by the Bundesamt fiir

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 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. The new software, which is

called f-SOLVE, accelerates processing by additional automation procedures.

Both groups use HP9000 Series 700 computers with sufficient hard disk space and Internet

connection for their analyses.

1 Data Analysis

The following sessions have been analysed at GIUB and BKG during the last year:

• Measurement of Vertical Crustal Motion in Europe by VLBI (EURO)

(EU Project FMRX-CT960071)

Six sessions per year with the stations Ny_.lesund, Onsala, Wettzell, Simeiz, Madrid (DSS65),

Yebes, Medicina, Matera and Noto. Effelsberg and TIGO-WTZL participated occasionally.

• Polarization tests

In order to investigate polarization impurities two regular EURO 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.

• Wettzell local ties (WTIES)

Two sessions between Wettzell 20-m telescope and TIGO-WTZL which are about 59 m apart.

• International Radio Interferometric Surveying - South (IRIS-S):

Twelve sessions per year with the stations Wettzell, HartRAO, Fortaleza, Fairbanks and

Westford.

• Continuous Observations of the Rotation of the Earth - O'Higgins (COREOHIG)

with stations HartRAO, O'Higgins, Fortaleza, Hobart, Kokee and DSS45.

• Annual Solution for Submission to IERS

In addition to the session by session analysis one combined solution is computed cooperatively

every year which comprises most of the dual frequency fixed station Mark III data available

1999 IVS Annual RepoL t

200
Geod_tisches Institut der Universit_it Bonn GIUB/BKG Analysis Center

worldwide. This solution is the basis for the annual submission to the IERS. Station coordinates and velocities, radio source positions and Earth orientation parameters are estimated

in one global solution. Station coordinates, velocities and their covariances are converted into

SINEX format which is the input format for contributions to the International Terrestrial

Reference Frame maintained by the IERS.

3. Development of Technology of VLBI Data Analysis

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 of the 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 may, thus, 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.

Algorithm GAMB for automatic group delay ambiguity resolution was developed and implemented in SOLVE. It serves four purposes: a) resolving group delay ambiguities at both

bands; b) estimation of quadratic clock function; c) detection and removing of outliers; d)

computation of ionosphere path delay.

Algorithm ELIM has been developed and implemented in SOLVE for automatic outlier elimination and/or restoration of observations which may have been eliminated in earlier analysis

steps. The automatic procedure finds the best candidate for elimination/restoration by least

squares residual snooping and repeats the process until the predefined criteria are met. ELIM

allows one to carry out the data editing process in an automatic and objective way providing

fast and better results than manual editing.

Algorithm PAMB for phase delay ambiguity resolution. Phase delays are roughly 40-fold

more precise than group delays but are lacking the integer number of phase cycles. Algorithm PAMB allows one to resolve these phase delay ambiguities in semi-automatic mode for

observing sessions which have to meet certain quality criteria.

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 starting in 1998.

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.

4. Research topics

• Thermal expansion of radio telescopes

(in cooperation with Onsala Space Observatory)

1999 IVS Annual Report 201
GIUB/BKG Analysis Center Geod_tische8 Institut der Universit_it Bonn

In situ measurements of thermal expansion of the Wettzell and Onsala radio telescopes by invat wire are compared with model parameters. The most critical aspects are the temperature

transfer into concrete and representative temperature measurements in a radome.

Geocentric relativistic VLBI formulation

Although solar system barycentric and geocentric relativistic formulations of VLBI observations are equivalent, the development of a geocentric model bears some benefits. It includes a

separate stellar model and it may be adapted and applied to other space geodetic techniques.

Determination of telescope displacements by local engineering work at Medicina

and Effelsberg

Both the Effelsberg and Medicina telescopes have been displaced slightly due to track repairs.

Local surveys before and after the displacements are being analysed.

Joint least squares adjustment of GPS and VLBI observations

(in cooperation with DGFI)

A combination of space geodetic measurements at the level of observables is being carried out

at DGFI. 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.

Investigation of the influence of errors in phase calibration of group delay

Initial steps of studying phase calibration errors have been carried out. In many cases phase

calibration is corrupted by phase variations appearing as additive signals. A prototype of a

procedure has been developed restoring the phase calibration signal by subtracting spurious

signals.

202 1999 IVS Annual Report
NASA Goddard Space Flight Center GSFC VLBI Analysis Center

GSFC VLBI Analysis Center Annual Report

David Gordon, Chopo Ma, Dan MacMillan

1. Introduction

The GSFC VLBI group, located at NASA's Goddard Space Flight Center in Greenbelt, MD, is

a part of the NASA Space Geodesy Program. Since its inception in the mid 1970's, this group has

been involved with and been a leader in most aspects of geodetic and astrometric VLBI. Current

major activities include coordination of the international geodetic observing program; coordination

and analysis of the CORE program; VLBI technique development; and all types of data processing,

analysis, and research activities.

2. Analysis Activities

The GSFC VLBI group has been at the forefront of geodetic research since its beginning,

reporting some of the first direct measurements of regional and global tectonic motions in the

mid 1980's. Currently, the main research and analysis activities of the group involve improving

the measurement and understanding of Earth rotation, improving VLBI analysis techniques, and

refining and maintaining the celestial and terrestrial reference frames.

The GSFC VLBI group coordinates the CORE program, which concentrates on making high

precision measurements of EOP and other geophysical parameters. We currently conduct about

50 CORE experiments yearly. The long term goal of CORE, along with NEOS, is to provide continuous VLBI monitoring of EOP. It will take several years and full Mark IV correlator capabilities

to reach this goal however. The GSFC VLBI group coordinates all aspects of the CORE program,

including initial data base processing, analysis and distribution to the VLBI community.

The VLBI group also coordinates and performs the initial processing, analysis, and distribution

of several miscellaneous types of experiments, such as the Source Survey experiments. We also

obtain and independently re-analyze all available geodetic/astrometric VLBI experiments from

other analysis centers, such as the NEOS, CRF, EUROPE, IRIS-S, and others. The group now

has a data set approaching 6000 Mark III/IV experiments, spanning some 21 years. We regularly

perform large global analysis solutions of this data set, using the SOLVE package, for EOP, TRF,

and CRF solutions, and make regular contributions for the maintenance of the ITRF and the

ICRF.

A joint activity between the GSFC VLBI group, the USNO VLBI group, and several NRAO

personnel has been the RDV program, which uses the VLBA and several Mark IV stations, and

concentrates on both high precision geodesy and astrometry. The RDVs are correlated at the

VLBA correlator in Socorro and released as FITS-format, station-based visibility data. We use

NRAO's AIPS software package for further processing into the regular geodetic observables -

delays, rates, and phases. The GSFC VLBI group has taken the lead in developing the processing

steps and additional software required for this, but there is still much to be done in this area.

AIPS processing currently takes about two weeks per experiment, and the results may suffer from

some unknown error sources. The same type of VLBA-style output will also be used by the JIVE

1999 IVS Annual Report 203
GSFC VLBI Analysis Center NASA Goddard Space Flight Center

correlator and by a new Chinese correlator and will require the same type of AIPS processing for

any geodetic/astrometric experiments.

The GSFC VLBI group cooperates with colleagues at the Bordeaux, La Plata, Paris and US

Naval Observatories and JPL in the maintenance and extension of the ICRF. This activity, done

under the aegis of the IAU and IERS, updates the ICRF for new sources and improved positions

using VLBI data that become available.

The GSFC VLBI group maintains and develops the Calc/SOLVE analysis software system.

A major accomplishment during the past year was the completion and release of Calc version

9.0, which provides compliance with the latest IERS Conventions. Calc 9.0, with its much more

accurate nutation model, is now in use at the VLBA Correlator and will be installed on the Mark

IV and most other correlators. Our group has also been the primary developer of the SOLVE

analysis package and the Mark III catalog/archiving system.

An important research area in our group is troposphere modeling. Recent work has shown that

atmospheric gradient modeling is improved if reasonable a priori mean site gradients are applied.

This technique improves baseline repeatability and reduces the length scale error by 0.1 ppb. It

also systematically reduces source declinations by an amount that peaks at around 0.1 mas near

the equator, and decreases towards the poles.

During the previous year, our group started a VLBI web site which allows access to all the

VLBI experiments in our data set, as well as our latest TRF, CRF, and EOP results and velocity

plots from SOLVE analysis. In May 1999, we also began submitting data base files and ancillary

files to the CDDIS data center for those experiments we are primarily responsible for.

A recent joint activity of our group, the USNO VLBI group, and Haystack Observatory has

been VLBI observations of the Mars Global Surveyor (MGS) spacecraft. Two MGS experiments

have been correlated so far, and initial analysis has been made to compute the MGS orbit using

a priori VLBI delays and delay partials derived from range and range rate observations. Further

work is planned to improve the orbit determination precision.

3. Staff

The GSFC VLBI group consists of approximately 20 civil servant and contractor personnel, led

by Dr. Thomas A. Clark. Although many members of the group have some involvement in analysis

activities, five members in particular are involved full time or nearly so in analysis activities, and

their activities are described below.

Dr. Chopo Ma leads the analysis group. He has been with the VLBI group since the 1970s. He

also currently serves as one member of the acting IVS Analysis Coordinator team. His interests

and activities include astrometry, the celestial and terrestrial reference systems, Earth orientation,

and technique development. He regularly generates the large global EOP, TRF, and CRF solutions submitted annually to the IERS and used in numerous research activities. He heads the

T1 subgroup for the maintenance and extension of the ICRS under the IAU Working Group on

Reference Systems.

Dr. David Gordon, a member of the VLBI group since 1983, manages all routine data processing

and analysis activities for the VLBI group. He also performs the AIPS geodetic processing of

VLBA experiments and maintains the initial data processing software at GSFC. He is the primary

developer of Calc, Pwxcb, several AIPS programs, and numerous minor programs. His interests

include global and regional tectonic motions, improving the VLBI modeling, correlator support,

204 1999 IVS Annual Report
NASA Goddard Space Flight Center GSFC VLBI Analysis Center

and phase delay development and analysis.

Dr. Dan MacMillan, a member of the VLBI group since 1990, is involved primarily in troposphere modeling and other methods of VLBI technique improvement. His interests and activities

include study and characterization of atmospheric gradients and mapping functions; use of meteorological assimilation data to improve atmospheric delay modeling; EOP, TRF, and CRF studies;

and analysis system software development (SOLVE). He recently wrote a paper (GRL, Vol. 26, p.

919) on interpretation of VLBI measurements of motions in the Caribbean and South America. He

is also studying the problem of why different VLBI networks produce systematically different EOP

results. An understanding of this problem will be critical to the success of the CORE program.

Karen Bayer is a programmer and analyst who has been with the VLBI Group since 1986. She

has responsibility for a wide range of software packages including the SOLVE package; the Mark III

data base and solution archive catalog systems; the analysis graphics programs; and the reporting

software packages. Karen also supports our web page activities; assists Dr. Ma in generating all

types of TRF, CRF, and EOP reports; generates site and velocity plots; and provides assistance

to new and current users of the Mark III/IV analysis package.

Cindy Lonigro is a data processing and analysis technician, with the VLBI Group since 1990.

She works on initial experiment preparation, data archiving, VLBI web page support, and correlator experiment setup.

Dr. John Gipson retired from the VLBI group in January 1999. John's work and interests

included tidal modeling, Earth orientation research, E1 Nino/La Nina effects, SOLVE development,

and numerous aspects of technique improvement.

4. Current Status

The VLBI group moved into new quarters in a new Earth Sciences building at GSFC last

February. This presented an opportunity for house cleaning and getting rid of obsolete equipment.

The analysis group currently uses one HP C160, and five HP 735 and 745 machines. Unfortunately

these are all slow and outdated by today's standards. SOLVE global solutions and AIPS processing

place a large strain on these resources. The current manpower situation also sets some limitations

on software development and additional research activities.

5. Outlook

During the coming year, the GSFC VLBI analysis center will convert to using Calc 9.0 theoreticals, and will reprocess all earlier data bases through Calc 9.0. We will also install and convert

to using the new Fast version of program SOLVE (currently called F-SOLVE). All of our HP

computers will be upgraded to the HPUX 10.20 operating system for Y2K compliance. We are

hopeful of obtaining more modern and faster computer systems as well. Also, we anticipate that

Dr. Leonid Petrov, currently with the Bonn VLBI group, will join our group.

Also during the coming year, the GSFC VLBI analysis center will begin making formal submissions to the IVS of data and analysis products and contributions. These submissions will

include:

• NASA experiments in both Mark III data base and NGS card forms.

• Single experiment SINEX format files for NASA experiments.

1999 IVS Annual Report 205
GSFC VLBI Analysis Center NASA Goddard Space Flight Center

• A UT1 IRIS-Intensive series, updated weekly.

• A session EOP series, and a Kalman-filtered 1-day EOP series, updated weekly.

• Hourly EOP series for all sessions.

• TRF solutions, updated every three months.

• CRF solutions, updated every six months.

206 1999 IVS Annual Repo_ t
MIT Haystack Observatory Haystack Observatory Analysis Center

Analysis and Research at the Haystack Observatory

Arthur Niell, Brian Corey

Abstract

Analysis efforts at the Haystack Observatory have been concentrated on improving the accuracy of

geodetic VLBI measurements. The primary result has been the development of better models for the

variation with elevation of the delay through the atmosphere.

1. Geodetic Research at the Haystack Observatory

Although Haystack Observatory is best known for the design and production of VLBI systems

for data acquisition and correlation, considerable effort has been invested in improving the accuracy

of geodetic VLBI measurements. This has included the planning and scheduling of special Research

and Development projects such as the ATD, ERDE, and the early CONT experiments. All were

designed primarily to provide data to investigate how to better measure the vertical component of

station position. These and the later CONT series provide an excellent data set for testing model

changes intended to improve accuracy.

Analysis

Our analysis of geodetic VLBI data uses the solvk package [1] with data bases obtained from

Goddard Space Flight Center. The solvk set of programs was developed with modeling of the

atmosphere a primary concern. One goal of our research is to compare the available geodetic

VLBI analysis packages on a set of high quality data in order to evaluate the effect of different

models. Of particular interest is any difference in results that may depend on how the atmosphere

is parameterized. For example solvk models the atmosphere zenith delay and the gradient of the

delay as stochastic processes while solve allows only a piecewise continuous variation in time but

with constraints on the amount of change after fixed time intervals.

Atmosphere Research

The NMF mapping functions [2] that were developed at Haystack for the hydrostatic and

wet components of the atmosphere are in wide use for both VLBI and GPS. These were based

on a seasonal model and do not accurately reflect daily to weekly variation. A new model is

being developed that will make use of daily measurements of the atmosphere to be obtained from

assimilated weather data sets or, on shorter time scales, from the output of numerical weather

predictions from one of the major forecast services [3].

Instrumentation

Instrumental polarization may be a significant error source as higher accuracy is sought through

the use of phase delays. Experiments to determine the polarization characteristics of most antennas

in the geodetic network have been carried out and correlated and need only be analyzed.

Terrestrial Reference Frame

The accuracy of the terrestrial reference frame depends on the quality of the ties among the

various techniques at common sites. At Westford the GPS and VLBI antennas are only 60 m apart,

1999 IVS Annual Report 207
Haystack Observatory Analysis Center MIT Haystack Observatory

and the conventionally measured vector has a nominal accuracy of a few millimeters. However, the

apparent difference in vertical position between the GPS and VLBI determinations for the ITRF

at the common mark is a few centimeters. Leveling has been repeated, and GPS measurements

have been made to confirm the accuracy of the local ties. The leveling repeats within a millimeter

for the position of the GPS antenna, but differs from earlier measurements for the VLBI antenna

by a centimeter. More seriously, the GPS height has a serious systematic uncertainty of several

centimeters that depends on the analysis. This problem, due to multipath and near-field scattering

in the vicinity of the GPS antenna [4], is known to affect all GPS sites at some level. Methods to

reduce or calibrate the effect are being tested.

2. Outlook

During the first year of IVS we hope to complete the new mapping functions and evaluate the

accuracy and feasibility on a large set of VLBI data using solvk. These data will provide the basis

for comparison with other analysis packages (e.g. solve, OCCAM, GLORIA, MODEST) using

either the new mapping function or reverting to one currently in use.

Analysis of the polarization data should help us to understand why we are not achieving the

accuracy expected for the parameters of the individual VLBI systems. Increasing the number

of baselines and stations for which phase delays can be utilized should also provide additional

accuracy and better data for studying the atmosphere effects on VLBI.

As errors in the vertical are reduced for all techniques the determination of the Terrestrial

Reference Frame can be improved.

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.: Can geodetic errors caused by the atmosphere be significantly reduced?, AGU Fall Meeting,

San Francisco, CA, Dec 6, 1998.

[4] Elbsegui, P., Davis, J.L., Jaldehag, R.T.K., Johansson, J.M., Niell, A.E., Shapiro, I.I.: Geodesy Using

the Global Positioning System: The Effects of Signal Scattering on Estimates of Site Position, J.

Geophys. Res., Vol. 100, No. BT, 9921-9934, June 10, 1995.

208 1999 IVS Annual Report
Institute of Applied Astronomy of Russian Academy of Sciences IAA Analysis Center

IAA VLBI Analysis Center Report for 1998-1999

Zinovy Malkin, Elena Skurikhina, George Krasinsky, Vadim Gubanov, Igor Surkis,

Alexander Stotskii

Abstract

The report contains a brief overview of IAA activity as IVS Analysis Center in 1998-1999 and our

plans for near future in the following fields: EOP service, investigation of short-time irregularities in

Earth rotation, atmosphere investigations, combination of VLBI data with ones obtained with other

space geodesy techniques, comparison of EOP series and software. Results of investigations obtained

during period March 1998 - March 1999 are presented.

1. Introduction

Four groups of four labs of the Institute of Applied Astronomy of the Russian Academy of

Sciences (IAA) have been involved in processing of the VLBI observations:

1. Lab of Space Geodesy and Earth Rotation: Dr. Zinovy Malkin (head), Elena Skurikhina,

Dr. Alexander Voinov, Dr. Mariya Sokolskaya. The main tasks of this group related to IVS

activity are: management of the IAA EOP Service, determination of EOP and station coordinates

using OCCAM package, combination of VLBI data with other ones, comparison of EOP series

and software. Recently ERA package is under installation in the lab, too. See section 2 for more

details.

2. Lab of Ephemeris Astronomy: Dr. George Krasinsky (head). The main tasks of this group

related to IVS activity are: determination of EOP, station and source coordinates using ERA

package [1], combination of VLBI data with SLR and LLR. See sections 2 and 3 for more details.

3. Lab of New Methods in Astrometry and Geodynamics: Prof. Vadim Gubanov (head), Igor

Surkis, Sergei Petrov. The main tasks of this group related to IVS activity are: determination of

EOP, station and source coordinates using new package QUASAR with emphasis on investigation

of stochastic parameters (EOP, troposphere). See section 4 for more details.

4. Laboratory of Radio Physics: Prof. Alexander Stotskii. The main task of this group related

to IVS activity is investigation of the Earth atmosphere path delay fluctuations. See section 5 for

more details.

2. EOP Service

EOP Service of the IAA based on regular processing of VLBI observations collected f_om

NEOS-A program is being worked beginning from 1997. Package OCCAM is used for routine

processing. Both operative and yearly final EOP series have been regularly contributed to IERS.

Last final solution EOP(IAA)99R01 is based on NEOS-A VLBI observations from 05-May-1993

till 16-Mar-1999 (306 sessions with 7 days interval). The solution was obtained using OCCAM

package v. 3.5 developed during last year. Model of reduction follows IERS Conventions (1996)

except relativistic correction which was computed according to IERS Standards (1992). Celestial reference frame was fixed to RSC(IAA)99R02 (see section 3). Wet tropospheric delays and

clock offsets were modeled as random walk stochastic process and estimated using Kalman filter

1999 IVS Annual Report 209
IAA Analysis Center Institute of Applied Astronomy of Russian Academy of Sciences

technique. Wettzell was used as reference station for most sessions. Pole coordinates, UT1-UTC

and nutation angles have been estimated. Terrestrial reference frame ITRF97 with the associated

velocity field was used for station coordinates.

Random and especially systematic accuracy of this series have been significantly improved as

compared with previous solution obtained with OCCAM v. 3.4.

In 1999 the first global solution with package ERA was obtained. Solution includes two series

EOP(IAA)99R02 and RSC(IAA)99R02 and based on processing VLBI observations, made in the

frame of NEOS-A program (251 sessions observed in 1994-1998). The following data are presented:

EOP (X, Y, UT1, dPsi, dEps), a catalog of 301 sources, and estimated corrections to the sine and

cosine coefficients of eight short-periodic terms in UT1 as given by Ray theory (see section 3).

After determining the EOP, time scale and atmospheric extra-path delay parameters from diurnal

sessions, the observations for each of the five years were processed simultaneously and as a result

the improved coordinates of the sources and participated stations were obtained. Coordinates of

the station NRAO20 as well as the longitude and latitude of the station Wettzell were fixed. The

process was iterated until convergence was reached. Then the resulting catalog of 301 quasars was

obtained by averaging the coordinates from the five annual catalogs.

Estimations of accuracy of both EOP series are given in Table 1.

Table 1. Estimated accuracy of the IAA EOP series

Series Xp, mas Yp UT1, 0.1 ms A¢, mas A_, mas

EOP(IAA)99R01 0.22 0.19 0.11 0.35 0.16

EOP(IAA)99R02 0.30 0.29 0.11 0.57 0.22

In the near future we are going to focus our researches on development software, improvement

of our analysis products, combination of VLBI EOP (and later SSC) series with ones obtained

with satellite techniques, comparison of OCCAM, ERA (and later QUASAR) packages. It is

planned also to provide daily coordinate solutions in parallel to operative EOP series. In addition

to NEOS-A, observations of other programs will be included in processing, too.

3. Ocean Tidal Effects in Universal Time

Geodetic VLBI observations of 1984-1998 have been processed to estimate eight diurnal and

semi-diurnal terms in UT induced by oceanic tides. The estimates were obtained independently

for each of the 13 annual time intervals and then their time behavior was studied. We have used

VLBI observations of 1984-1998 carried out in the frame of IRIS, CDP and NEOS-A programs

(about 530,000 observations excluding for some technical reasons the years 1987 and 1992).

All stages of processing were carried out with the help of the universal program package ERA

designed for solving ephemeris and dynamic problem of various types (see [1]). First the observations of each diurnal session were processed separately considering coordinates of stations and

quasars as known parameters. In this step we estimated coefficients of a polynomial approximation of the atmospheric delays and the clock behavior, as well as five EOP parameters with their

diurnal trends. In the second step the observations of every year were treated simultaneously to

estimate corrections to the coordinates of stars and quasars, and corrections to eight ocean tidal

terms in UT (sine and cosine components). The theory of the ocean tides, recommended by IERS

210 1999 IVS Annual Report
Institute of Applied Astronomy of Russian Academy of Sciences IAA Analysis Center

standards, was used as a nominal model.

The station NRAO20 was chosen as a reference after the year 1994; for the earlier dates

Westford was used as reference station. As constraints we fixed the longitude and latitude of the

station Wettzell. The two steps were repeated until convergence was reached. RMS of residuals of

the annual series change from 35 ps to 50 ps (for the old observations).

The corrections obtained after averaging the annual estimates of the tidal terms are given in

Table 2.

Table 2. Corrections

Tide l I'

to diurnal and semi-diurnal terms in UT (in/_s).

F D _ 0 sin a cos cr

Q1 -1 0 -2 0 -2 1 -0.2 0.2 0.3 0.1

01 0 0 -2 0 -2 1 -0.4 0.1 0.0 0.2

0 0 -2 2 -2 1 0.3 0.3 0.1 0.3

K1 0 0 0 0 0 1 0.1 0.4 -0.9 0.7

-1 0 -2 0 -2 2 -0.4 0.2 0.0 0.2

M2 0 0 -2 0 -2 2 0.2 0.2 0.6 0.3

0 0 -2 2 -2 2 0.1 0.3 0.3 0.1

K2 0 0 0 0 0 2 0.9 0.3 -0.1 0.3

The corrections are small affirming the high accuracy of the nominal model. However, some

of them are statistically significant. It is interesting to study repeatability of the corrections for

every year. For that the phases of the largest corrections (KlandK2 tides) are presented in Fig. 1.

300 ...........................................................

I

200. _

I00 : ,I': [

0 _, t' "_' ': !

-100 ..............

84 86 88 90 92 94 96 98

300 ..................

2OO

i

100 _ i'

0

-100

84 86

J

'3

m

_ f ̧ ̧

F

88 90 92 94 96 98

Figure 1. Tides K1 (left) and K2 (right): time dependence of ph:,ses of corrections.

One can see that the corrections are strongly correlated. Moreover, for K1 the phase slowly changes

with time.

4. Package QUASAR for Processing VLBI Observations

New program package QUASAR designed for scientific studies based upon VLBI observations

on global networks is being developed during last year. Calculation of (O-C) values are made in

line with the IERS Conventions (1996), they are referred to the ICRF celestial reference frame and

the ITRF96 terrestrial reference frame. Parameters are evaluated by means of the least squares

colocation technique. Stochastic parameters are as follows:

a) sub-diurnal fluctuations of the wet tropospheric delay in zenith for all the stations;

1999 IVS Annual Report 211
IAA Analysis Center Institute of Applied Astronomy of Russian Academy of Sciences

b) sub-diurnal variations of hydrogen masers phase for all the stations with respect to a reference

station;

c) nearly-diurnal variation of polar motion and Universal time due to geophysical effects.

Main part of the package is already completed and applied for analysis of the CONT'94 campaign. Among the achieved results, the most interesting are the estimates of regular and stochastic

components of the wet tropospheric delay for station ONSALA in good agreement with independent WVR-measurements. Important is the fact that taking into account the stochastic parameters

decreases by several times the RMS of the residual deviations of the data model and makes them

closer to the formal errors given in the Mark III files.

5. Modeling of the Earth Atmosphere Path Delay Fluctuations

In the previous years the model of spatial/temporal structure function of the electrical thickness

of the Earth neutral atmosphere was developed [2]. Last solution is presented in Fig. 2.

Path separation p (kin)

10 -_ 10 -_ I 10 I{) 2 10 z

The model consists of three domains:

(I) - power-law of 5/3 described three-dimen10

sional small scale turbulence; _,

(II) - power-low of 2/3 for two-dimensional

large scale turbulence; c.

(III) saturation of random fluctuations and _"

regular variations.

The model parameters - structure coefficients,

domain boundaries, and the relationship be- 1o

tween spatial and temporal structure functions

was defined from radioastronomical and ra-

¢- diosonde measurements. Next year plan is to ¢

N i0_ 2

use the results of VLBI experiments for refine

rr

the model parameters and for further improvement of the model especially in the large scale

region of the spatial structure function.

10 "_ t0 -_ 10 -_ 10 -= 10" 1

Time interval T (days)

10'

I I II ''*'I i 1,11,1,1 i l,,.,,l i iHull i Cji,,_i , Lll,,.l

L_ = 2.2 km L_ = 24.00 km

10 10' 10 J

Figure 2. The model of the Earth atmosphere

electrical thickness fluctuations.

References

[1] Krasinsky G. A., Vasilyev M.V.: ERA: Knowledge base for ephemeris and dynamical astronomy.

In: Proc. IAA Coll. 165, Poznan, Poland, Kluwer Acad. Publ., 239-244, 1997.

[2] Stotskii A. A.: Propagation delay fluctuations in the Earth troposphere: random and regular components. In: Proc. llth Working Meeting on European VLBI for Geodesy and Astrometry, Onsala, 1996,

83-88, 1996

212 1999 IVS Annual Report
Istituto di Radioastronomia-Bologna Italy CNR Data Center

Italy CNR Analysis Center Report

P. Tomasi, M. Rioja, E. Gueguen

Abstract

This report summarizes 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 Institute of Radio Astronomy (IRA) located in Bologna, where the main research activity

is carried out, both in radioastronomy and geodesy;

b) the 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 axe located.

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 have been

installed on an HP360 workstation and later on on a HP715/50 workstation. From that time the

software have been regularly updated following the indications of the VLBI group working at the

Goddard Flight Space Center at Washington. We have analyzed here mostly database with some

European baselines, generally at least three. The originals databases have been imported from the

Geodetic Institute of the Bonn University or from GSFC - Washington, generally via ftp, and in

one case via tapes. Most of the database have been reprocessed here in Bologna (using CALC and

then SOLVE). During 1998 the European experiments have been released by the Bonn group at

the final stage of processing. In these case the database have been used without any more editing.

From 1997 also ITIS have installed the CALC/SOLVE software and after some tests we have

specialized the Bologna section to analyze single database, in order to produce the final database.

The global solutions have been computed in Matera at the ITIS.

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.

During 1998 we have also started 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 that data into the database using the water vapor radiometer route. The tropospheric

data have been collected to the Berna site of the IGS. However the IGS data, with an hour

interval, are the total tropospheric delay. For that we have subtracted the dry delay, from the

VLBI data, in order to produce the "wet" zenith delay. These data have been inserted into the

1999 IVS Annual Report 213
Italy CNR Data Center Istituto di Radioastronomia-Boiogna

VLBI database using an update version of DBCAL. In this new version the Niell mapping function

was implemented and also some others errors present in the program have been corrected.

We have installed f-solve (L. Petrov) on boira6 (the center name in this case is IRACNR) and

we are using this software on a regular basis.

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 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 the 1998, the use of the new way of analysing VLBI data, seems to produce

a better repeatability on the European baseline length (Rioja and Tomasi, 1999).

3. References

M. Rioja and P. Tomasi Integrating GPS zenith path-delay measurements into the analysis of

geodetic VLBI observations from European Network. - Proceedings of the 13th Working Meeting

on European VLBI for Geodesy and Astrometry. W. Schluter and Hase editors, BKG 1999.

214 1999 IVS Annual Report
Jet Propulsion Laboratory JPL Analysis Center

JPL VLBI Group Report for 1998-1999

Chris Jacobs, Ojars Sovers

Abstract

This report describes the transitional activities of the JPL Analysis Center.

1. Introduction

For JPL the year from March 1998 to March 1999 has been one of many transitions. We are

currently making changes in just about every aspect of our VLBI program.

2. Field Operations

In the field, the transition from Mark III to Mark IV has stabilized and we are striving to

improve the operability of the Deep Space Network (DSN) antennas for VLBI. We continue to use

both 34m and 70m antennas in Goldstone California, Tidbinbilla, Australia, and Madrid, Spain.

These sites are transitioning to the new triple-cap heads thus allowing recording of either the

old-style thick tapes or the newer, higher capacity thin tapes.

We also began to collect K-band (19 to 26 GHz) VLBI data on a semi-regular basis. We hope

to eventually observe at even higher frequencies. The DSN wants to raise its deep space telemetry

carriers from X-band (8.4 Ghz) to Ka-band (32 GHz) in order to support higher telemetry rates.

Thus we may have an opportunity in the coming years to extend our celestial reference frame work

to a new region of the spectrum.

In an effort to tame that long time nemesis of VLBI, water vapor fluctuations, we have been

developing an advanced Water Vapor Radiometer (WVR). This instrument measures the brightness

temperature of the 22 GHz rotational line and supplements that data with measurements of the

temperature vs. altitude. By improving gain stability and narrowing the instrument beam to allow

co-pointing at low elevations, we hope to achieve mm level calibrations of water vapor induced

path delay variations.

3. Data Processing

Turning to data processing, the JPL Block II Correlator is now reliably correlating Mark IV

data recorded at 135 ips. Our next generation correlator, the Block III, is under development

and will support a wide range of Mark IV modes while greatly reducing maintenance costs. This

upgrade is inheriting technology developed for arraying Deep Space Network antennas for reception

of Galileo spacecraft transmissions. This should reduce development time and maintenance costs.

Over the last year we began a fruitful collaboration with a new industry partner, Remote

Sensing and Analysis (RSA) of Altadena, California. Many of you have had the good fortune of

working with Ojars Sovers and Jack Fanselow-both of whom are now with RSA.

Our MODEST VLBI modelling and parameter estimation software saw two major milestones

over the last year. First, the MODEST software was ported from Compaq/DEC VMS to Compaq/DEC Unix as well as HP-UX, Sun Solaris and Linux. The other milestone was the publication

1999 IVS Annual Report 215
JPL Analysis Center Jet Propulsion Laboratory

of a comprehensive review article in Reviews of Modern Physics (Sovers, Fanselow, and Jacobs,

vol 70, no. 4, Oct 98) covering our modelling efforts over the last two decades and reviewing the

scientific results produced by the larger VLBI community over a similar period.

4. Publications

Several reports relevant to VLBI analysis were published in JPL's online technical journal, the

TMO Progress Reports, which is available at http://tmo, jpl .nasa. gov/tmo/progress_report

1. Jacobs et al., The JPL Extragalactic Radio Reference Frame

http ://tmo.jpl.nasa. gov/tmo/progress_eport/42-133/133E, pdf

describes in detail our celestial frame work including a lengthy discussion of the current VLBI

error budget.

2. Gorham, Designing Optimal Bandwidth Synthesis Arrays for VLBI

http ://tmo.jpl. nasa. gov/tmo/progress_report/42-133/133D, pdf

discusses the design of the frequency sequences we use in astrometric/geodetic S/X observing.

3. Jacobs, Phase Calibration Tone Processing with the BlockII VLBI Correlator

http: Iltmo. jpl .nasa. gov/tmo/progress_report/42-134/134A .pdf

describes in detail the phase calibration tone processing done by the JPL BlockII Correlator.

4. Lanyi, Determination of the Tropospheric Fluctuation Coefficients in VLBI Parameter Estimates

http ://tmo. jpl. nasa. gov/tmo/progre s s_report/42-133/133I, pdf

discusses our use of a combined temporal-spatial observation covariance in the analysis of

VLBI data. This is an alternative approach to the more common technique of stochastic

estimation of temporal variations.

Finally, our multi-year collaboration with colleagues from several institutes has been documented in Ma et al., The International Celestial Reference Frame based on VLBI Observations of

Extragalactic Radio Sources

http ://_. journals, uchicago, edu/AJ/j ournal/issues/v116ni/970504/970504, him1

This paper describes the new IAU celestial reference frame which since 1 Jan 1998 has been the

official definition of coordinates on the sky.

5. Outlook

So considering all the above developments, one can see that it has been a fruitful year for our

group. The many ongoing transitions will be taking us into a number of new areas in the coming

years. We look forward to these opportunities and to continued collaboration with our colleagues

in the IVS.

1999 IVS Annual Report

216
Main Astronomical Observatory, Ukrainian National Academy of Sciences MAO Analysis Center

IVS Analysis Center at MAO UNAS

Sergei Bolotin

Abstract

The report briefly describes current and planning MAO activity in the field of the VLBI data

processing.

1. MAO UNAS Analysis Center

The MAO VLBI Analysis Center was established by Main Astronomical Observatory of the

Ukrainian National Academy of Sciences in 1994. It is located in MAO Primary building (see

Fig. 1).

The main goal of the Center is developing software for VLBI data processing. It is also to

prepare global solutions of EOP, CRS and TRS to make a submission to IERS on an annual basis.

Figure 1. Main Astronomical Observatory, Ukrainian National Academy of Scienses, Kiev. General view.

2. Technical Parameters

The VLBI data processing software SteelBreeze developed by the Analysis Center is able to

make a global solution of a set of the Earth Orientation Parameters, Celestial and Terrestrial

Reference Systems. It is also able to produce the estimation of the parameters with high time

resolution (e.g., [1] and [2]).

1999 IVS Annual Report 217
MAO Analysis Center Main Astronomical Observatory, Ukrainian National Academy of Sciences

The software is running on the dedicated Pentium-II computer with 192 Mb RAM and 19 Gb

total space of SCSI hard disks. It is possible to expand both RAM and HDD set if necessary.

3. Technical Staff of the Center

We have a small and dynamic group of persons who are contributing to IVS:

• Yaroslav Yatskiv, professor, Space Geodynamics Dept., MAO: general coordination;

• Sergei Bolotin, astronomer, Space Geodynamics Dept., MAO: data processing, development

of the software;

• Olexander Molotaj, astronomer, Kiev University Observatory: analysing and combining of

catalogues of radio sources (CRS).

4. Current status

The development of version 1.2 of the SteelBreeze software has been finished. It has been used

in the VLBI data processing of the annual IERS submission from 1995 until 1998. An example of

the sofware's screen shot is shown on the Fig. 2.

Figure 2. A screen shot of the SteelBreeze-l.2 software.

5. Future Plans

During these past years we have discovered weaknesses in the software design and now we

are planning to produce a new version of the SteelBreeze. This new version will be essentially

218

1999 IVS Annual Repot
Main Astronomical Observatory, Ukrainian National Academy of Sciences MAO Analysis Center

improved and will be run on the most of popular hardware platforms. We are also going to make

a submission of our results of global solutions of the EOP/TRS/CRS to IVS annually.

References

[1]

[2]

Bolotin, S.: High frequency variations of EOP from extensive VLBI operations in January, 1994. Proc.

of the 2nd JIVE/EVN Symposium.

Bolotin, S., Bizouard, C., Loyer, S. and Capitaine, N.: High frequency variations of the Earth's instantaneous angular velocity vector, Astron. Astrophys., 317, 601-609, 1997.

1999 IVS Annual Report 219
Paris Observatory Analysis Center (OPAR) Observatoire de Paris, DANOF/UMR 8630

Paris Observatory Analysis Center OPAR: Report on Activities

January 1998 - March 1999

A.-M. Gontier, M. Feissel, N. Essai'fi, D. Jean-Alexis

Abstract

The OPAR Analysis Center, its organisation and technical means are briefly presented. The general

scientific and operational alms of the Analysis Center are summarized. The current state of two projects

that were developed during 1998 and up to 1999 March is described: the operational determination of

UT1-UTC from the intensive sessions, and the studies of the stability of the celestial reference frame.

1. The OPAR Analysis Center

The team

The analysis center is run by the following team: A.-M. Gontier is the head of the group, N.

Essaifi is in charge of all the technical and database aspects, M. Feissel is participating in the

scientific developments, D. Jean-Alexis is in charge of the operational analysis. There are two

associated members, M. Bougeard and D. Gambis.

Characteristics o] the analyses

Analyses are performed using the software GLORIA (GLObal Radio Interferometry Analysis)

developed at Paris Observatory. The software package has available a number of models, including

those recommended in the IERS Conventions (1996) [9]. The GLORIA modelling was compared

in detail with that of MODEST [4]. The two models agree within 1 ps on delays and 1 fs/s on

delay rates.

The solve segment of the software uses the SRIFT algorithm. The input data are extracted

from the Calc VLBI database files (delay, delay rate), collected automatically from an IVS Data

Center, preferably the Paris Observatory one. The complete observation/results database is managed with Oracle system. The computer used to perform analyses is an HP735 under Unix that

will be replaced, in the middle of 1999, by an HPC200.

Main objectives of the Analysis Center

Already operational:

• Operational calculations for the Earth's orientation (intensive sessions).

• Studies of the celestial reference frame.

• Software development and documentation.

Under development:

• Operational calculations for the Earth's orientation (24h sessions).

• Multi-week operational calculations for the terrestrial frame.

Further plans:

220 1999 IVS Annual Report
Obsexvatoire de Paris, DANOF/UMR 8630 Paris Observatory Analysis Center (OPAR)

• Provide feedback about station performance.

• Perform global, multi-year analyses.

• Participate in multi-technique combination projects.

2. Analysis of the Intensive Sessions

Results for 1998-1999

The IRIS Intensive VLBI observations obtained over 1998-1999 on a single baseline have been

analysed. The program consists of 20 daily observations of about 16 sources observed on a single

baseline. The following stations are used:

40441S007 Greenbank Jan-Dec

14201S004 Wettzell Jan-Fev, May-Jun

12734S005 Matera Mar-Apr

40408S002 Gilcreek Jun, Oct, Nov

4443 observations kept

3947 observations kept

563 observations kept

137 observations kept

Every two months the list of observed sources is changed except for five of them. This schedule

results in two month batches with nearly constant geometry and sidereal time of observation; every

Saturday, the schedule for the next bi-month is observed in addition to the current one. The observation scheme is optimised for the determination of universal time (UT1-UTC). With the available

observations the four other parameters which can be estimated together with UT1-UTC from one

session are the clock offset and the clock rate between the two stations, and a tropospheric zenith

delay for each station.

The first date of analysis is 1998 JAN 03 (MJD: 50816.8). The data analysis uses as adopted

references the ITRF97 and its velocity field for the terrestrial frame, the ICRF for the celestial

frame, the EOP(IERS) C 04 series for the pole coordinates (Xpm, Ypm) and the IERS(1996) Theory

of Precession/Nutation [9] referred to the ICRF [2] for the celestial pole offsets (de, de). The UT1

results have no diurnal/semi diurnal variations (taken off using the Ray 1995 model [9]). The other

modelisations are: the IERS TN 13 model [10] for the solid Earth tides, the Scherneck model [9]

for ocean loading and the Niell model [11] for the troposphere mapping function.

Statistical editing of observations results in the deweighting of 15% of the observations in the

average. The estimation of UT1-UTC obtained from this analysis is shown in figure 1. The global

rms postfit residuals is 45 ps. The mean difference of the series with EOP(IERS) C 04 is equivalent

to 0.1 mas.

Sensitivity to the adopted references

Because of the minimal geometry of a one-hour observing session, the UT1 results axe expected

to be sensitive to the a priori references that axe adopted in the analysis as well as to the particular

set of sources observed [4, 5]. Our approach is to adopt entirely the IERS references. In practice

this can be done in several ways. A series of tests was conducted during 1998 to evaluate the influence of the choice of references. The successive experiments (Table 1) concerned the terrestrial

frame (including the site velocity field) and the celestial pole offsets.

1999 IVS Annual Report 221
Paris Observatory Analysis Center (OPAR) Observatoire de Paris, DANOF/UMR 8630

GLORIA ERSCC4 UTI-gTC [,3 O001s]

r r I T _-

l

,_ I J _ J I

1998 1998 2 19984 19986 19988 1999 1999.2 1999 4

Figure 1. Estimated UT1-UTC with respect to EOP(IERS) C 04 for 1998-1999.

Table 1. Sets of a priori fixed references: terrestrial reference frame and celestial pole offsets. The

celestial reference frame and the coordinates of the pole were held respectively to the ICRF and

EOP(IERS) C 04. The combination corresponding to figure 1 is set #5.

terrestrial frame celestial pole offset

1

2

3

4

5

ITRF94 (epoch 1993.0)

ITRF96 (epoch 1997.0)

ITRF96 (epoch 1997.0)

ITRF97 (epoch 1997.0)

ITRF97 (epoch 1997.0)

NNR_NuvellA

NNR_NuvellA

NNR_NuvellA

NNR_NuvellA

velocity field

EOP(IERS) C 04

EOP(IERS) C 04

IERS (1996) model

IERS (1996) model

IERS (1996) model

The effects of the changes are summarized in Figure 2 where the discrepancy of the estimated

UT1-UTC with EOP(IERS) C 04 are plotted under the form of weighted means for the six schedules

implemented in 1998. The error bars are the standard errors of the means. Each point results

from all observations of the same schedule, be it during the main time frame, or on the Saturdays

in the previous schedule time frame.

The change from the sets of a prioris #1 to #2 (change of ITRF and of reference epoch for the

velocities) is particularly large (30 microseconds) for the second bi-month, the only one in which

Matera is used-its predicted coordinates change by about 2 cm, both in X and in Z. The rms postfit residuals decrease by 5-10% in experiment #2. These effects suggest that the NNR_NuvellA

velocities axe not optimal to model the observations. The next change (#2, #3) consists in replacing an operational series of the celestial pole offsets by the recommended model. The differences of

the estimated UT1-UTC with IERS become more consistent (decrease of the error bars by 25-30%).

The results of experiments #3 and #4 suggest the presence of a seasonal difference. However, the

222

1999 IVS Annual Report
Observatoire de Paris, DANOF/UMR 8630 Paris Observatory Analysis Center (OPAR)

B;as relative _o <OF'(ERS) C ©4 {Unit: mcra se::snd}

r T

C, L

od

l

ck

L __

1998

1999

Figure 2. Weighted means of the discrepancy between estimated UT1-UTC and EOP(IERS) C 04

for the five experiments.

last change (#4, #5), that consists in the replacement of the NNR_NuvellA velocity field by the

one determined with the ITRF, shows a different structure: the adoption of observed velocities

changes by 8 microseconds the level of results involving Matera, and the possibility of systematic

differences per bi-month becomes more probable. In the investigation described in the next paragraph, we found that several sources in each bi-month schedule have positions discrepancies in

1998 in the range 0.3-0.8 mas. This changes may explain part of the biases in UT1.

3. Stability of Radio Source Positions

After the adoption of ICRS by the IAU [2], studies are necessary to assess the stability of the

ICRF and to prepare its future revision. This study is based on a series of source positions per

session computed by M. Eubanks (ftp: casa.nsno.navy.mil/navnet/frame20.arcs.iers). A total of

75000 individual positions are available for 610 sources from August 1979 through March 1999.

The positions per session are expressed in a unique reference frame that is close to the ICRF. A

number of sources have an observational history dense enough to build continuous time series of

coordinates at a constant time-interval (e.g. 0.5 year, 1.0 year).

Figure 3 show examples of the time evolution of coordinates for three of the defining sources of

ICRF, 1308+326, 1606+106, and 2145+067, under the form of weighted yearly averages referred

to their respective means over 1983-1999. The error bars shown are the standard errors of the

averages. The numbers of observations available each year are also shown in the plot. Those three

sources were chosen because they were mentioned as having potential stability problems in the

discussions for preparing a new analysis of the celestial reference frame (study group chaired by

C. Ma).

A distinct feature of these time series, that is also true for the other sources, is the continuous

1999 IVS Annual Report 223
Paris Observatory Analysis Center (OPAR) Observatoire de Paris, DANOF/UMR 8630

improvement in quality with time, as can be seen from the error bars of the yearly averages. Results

after the start of 1990 are quite better than those in the earlier period. However, instabilities with

sizes several times the error bars are also present. This calls for a systematic study of the time

series of coordinates in order to derive a statistical qualification of their time-stability.

It is reminded that the sources published with the ICRF [5] were categorized as defining for

those with the most precise and accurate coordinates, candidates for those that were assumed suitable for precise astrometric purposes but need additional observations, and other for those judged

not suitable for precise astrometric reference due to large variability in the emission structure or

other observational problems, even if they had a rich observational history. This original classification is based on a number of quality criteria, such as quality of data and observational history,

consistency of coordinates derived from subsets of data, and repercussions of source structure.

Due to the data available, in particular source structure mapping at a single epoch, these criteria

involved little consideration of time evolution.

The following is an illustration of a complementary approach, based on the Allan variance

analysis [1]. In a few words, this technique allows to distinguish characteristic time variability

spectra, such as white noise, flicker noise and random walk. It is applied to 65 sources for which a

continons series of coordinates at 0.5 year interval could be built over 1990-1999. The results are

shown in Table 2. Considering the time span of available good quality data, this qualification of

stability is valid up to about five years. For comparison with the existing categories, the results

are shown separately for the Defining, Candidate, and Other sources, roughly in decreasing order

of stability. Most of the sources show a white noise spectrum over the time span studied. In such a

situation, acumulating data should help improving progressively the coordinates. For the minority

of sources that are found to have a flicker noise spectrum, extending the time span of observations

are not expected to result in the stabilization of the estimated coordinates.

References

[1] D.W. Allan: Proceeding IEEE, 54, 2, 221,1996.

[2] C. Bizouard: private communication, 1998.

[3] M. Feissel, F. Mignard: The adoption of ICRS on 1 January 1998: meaning and consequences, Astron.

Astrophys., 331, L33-L36, 1998.

[4] A.-M. Gontier, E. Eisop, M. Feisseh Analysis of the IRIS VLBI intensive sessions, IERS Technical Note

14, Observatoire de Paris, France, R77-R80, 1993.

[5] J. Hefty, A.-M. Gontier: Sensitivity of UT1 determined by single-baseline VLBI to atmospheric delay

model, terrestrial and celestial reference frame, Journal of Geodesy, 71,253-261, 1997.

[6] C.J. Jacobs, O.J. Sovers, D. Gordon, C. Ma, A.-M. Gontier: The accuracy of the ICRF: an intercomparison of VLBI analysis software, IAU Highligth of Astronomy, Vol. llA, 1998.

[7] C. Ma, E.F. Arias, T.M. Eubanks, A.L. Fey, A.M. Gontier, C.S. Jacobs, O.J. Sovers, B.A. Archinal, P.

Charlot: The International Celestial Reference Frame realized by Very Long Baseline Interferometry,

Astron. Jour., 116,516-546, 1998.

[8] C. Ma, M. Feissel (eds.): Definition and Realization of the International Celestial Reference System by

VLBI astrometry of extragalactic objects, IERS Technical Note 23, Observatoire de Paris, France, 1997.

[9] D.D. McCarthy (ed.): IERS Conventions (1996), IERS Technical Note 21, Observatoire de Paris, France,

1996.

1999 IVS Annual Repmt

224
Observatoire de Paris, DANOF/UMR 8630 Paris Observatory Analysis Center (OPAR)

[10] D.D. McCarthy (ed.): IERS Standards (1992), IERS Technical Note 13, Observatoire de Paris, France,

1992.

[11] A.E. Niell: Global mapping functions for the atmospheric delay of radio wavelengths, J. Geophys. Res.,

101, 3227-3246, 1996.

1999 IVS Annual Report 225
Paris Observatory Analysis Center (OPAR) Observatoire de Paris, DANOF/UMR 8630

R _ :I_SI_[ ) i.), L)ec (::l I : _flrl r,q _:_u'ce " 308+:_26 119"l_ " I:_ :1

- - --_ _ _- • _ -'T _ T..... _------ T ̧- "

/r'

i

!

i

i T 63 I

i

I

_9 1034 737 748 6118 12393 8956 3592

) ÷ i , °

f

1559 8_8 1163 11435 9787 4191

I

m L

(.} b_ (,) b_q_j ::,J,:e IF,::64"06 {,,_l r'ss::

= - r • T • -, _ 7 - _ r • T- -

i

[

15 23 3708 6567 4881 3807

L

/ ,

j j

4 ̧

458 5848 5203 4017

1 )_i4 19_ 6 _9_8 - ff_)71 19i_ 2 19,94 ! 99 _I _I_ 9_

I

I

....i 600 11oo

i

i'

1

T

[

460 770 4275 9340

i

I .¢

628 292 4 4531 7772 6267

I :),_,4 ' :_h6 ' _? "9:),::, 199?

i

5348 2677 i

2798 I

I

Figure 3. Yearly average coordinates for three defining sources, 1984-1999. The numbers of

observations are given alternatively up and down for each year

1999 IVS Annual Report

226
Observatoire de Paris, DANOF/UMR 8630 Paris Observatory Analysis Center (OPAR)

Table 2. Stability for a one-year sampling time (unit: #as) and spectral type of radio source

instabilities (1990-1999) in Right Ascension *cos(declination) and in declination.

Source stability stability

#as spectrum

am a_ White Flicker

Source stability stability

#as spectrum

am a_ White Flicker

1128+385 43 38 (i

0014+813 49 46 5

1637+574 53 59 a

0642+449 53 62 a,

1606+106 69 61 a, 5

0133+476 90 61 a,

1308+326 92 97

1357+769 16 34 a

0552+398 31 25

1803+784 45 54

0851+202 73 66 a, 5

1611+343 32 103 a, 5

1739+522 84 100 a,

1156+295 56 199 a,

0528+134 117 87 a, 5

0202+149 86 147 a,

0657+172 72 230

1044+719 108 114

0814+425 132 203 a,

0923+392 90 30 a

1638+398 91 88

0300+470 94 123 a, 5

0735+178 84 128 a,

2200+420 85 172 _,

2007+777 190 53 a

1741-038 69 351

2243-123 51 558 a,

1334-127 141 169 a

0212+735 163 164 5

0727-115 147 164 a,

1610-771 133 202 a, 6

1901+319 134 227 a,

0953+254 182 201 a, 5

Defining

a 2145+067

a 1057-797

0954+658

0235+164

0637-752

1038+528

a, _ 0457+024

Candidates

1749+096

a, 6 2234+282

a, 5 1614+051

0229+131

0119+041

0458-020

0823+033

0201+113

2355-106

a, 5 0336-019

a 1244-255

1519-273

Other

1354+195

a 1921-293

2255-282

1633+382

0537-441

0420-014

a 1815-553

1622-253

0208-512

a 0048-097

1034-293

1958-179

2128-123

94 112 5 a

157 95 a,

143 121 a, 5

116 252 a,

252 154 a,

48 361 a, 5

649 592 a

143 209 a

162 165 a,

151 229 a, 5

148 256 5

153 287 a,

101 393 a,

122 392 a,

129 334

261 936 a,

354 579 a,

315 933

588 1831 a,

374 259 a, 5

190 517 a,

347 288 a,

466 323 a

389 583 a, 6

202 750 a

616 468 a,

563 761 a, 6

649 860 5

492 1031 a,

718 1179 a,

248 1153 a,

384 2166

1999 IVS Annual Report

227

c_
Onsala Space Observatory (OSO) Analysis Center Onsala Space Observatory (OSO)

The IVS Special Analysis Center at the Onsala Space

Observatory

Rfidiger Haas, Hans-Georg Scherneck, Gunnar Elgered, Jan M. Johansson

Abstract

We give a short overview about the Onsala Space Observatory (OSO) in its function as an IVS Special

Analysis Center. We present topics currently worked on at Onsala and describe future plans.

1. Introduction

The Onsala Space Observatory (OSO) is active as an IVS Special Analysis Center. OSO focuses

on a number of special problems which can be investigated using and developing VLBI databases

and analysis programs, and providing ancillary parameters. There is no intention and no capability

at Onsala to do global VLBI analysis on a routine basis.

2. Staff at Onsala associated to the IVS Special Analysis Center

The staff at Onsala associated to the IVS Special Analysis center is: Hans-Georg Scherneck

(scientist), Gunnar Elgered (scientist), Jan M. Johansson (scientist) and Riidiger Haas (scientist).

Corresponding e-mail addresses and telephone numbers can be found on the Onsala web page.

3. Special Analysis at Onsala

Solid Earth tides:

Space geodetic observations are affected by site deformations caused by solid Earth tides. Geodetic

VLBI data are used to determine frequency dependent complex Love and Shida numbers and the

complex eigenfrequency of the Free Core Nutation resonance [1].

Ocean tide loading:

Ocean tide loading is the second largest Earth deformation effect after the solid Earth tides.

Geodetic VLBI observations are sensitive to this effect and it has to be accounted for in the analysis of geodetic VLBI data. Several different theoretical ocean tide loading models exist which

are based on different ocean tide models [2], [3]. Ocean tide loading parameters are provided

from OSO for all VLBI stations world wide. Estimates of ocean tide loading effects from geodetic

VLBI observations can be used to verify and/or refine the theoretical ocean tide loading models [4].

Ocean tide loading and Earth orientation:

Ocean tide loading influences the determination of Earth orientation parameters with space geodetic techniques. Particularly mismodelling of horizontal ocean tide loading possesses a common

rotation mode for a network of space geodetic stations. Neglect or mismodelling will therefore

contaminate the derived Earth orientation parameters by so-called "virtual polar motion and UT1

variations". In a recent paper [5] we presented predictions for this effect for different currently used

geodetic VLBI networks used for Earth rotation studies. The predictions are proved by analysis

of the CONT94 VLBI data.

1999 IVS Annual Repo_

228
Onsala Space Observatory (OSO) Onsala Space Observatory (OSO) Analysis Cente,

Atmospheric loading: Redistribution of atmospheric masses loads the Earth's surface and leads

to large-scale deformations. Corrections for this effect based on different theoretical approaches

are introduced in the analysis of VLBI data [6]. Empirical estimates for the effect are compared to

theoretical predictions. A data base with atmospheric loading predictions based on global pressure

fields has been generated for 1989-1997.

European geodetic VLBI network:

Concerning the European geodetic VLBI network the analysis at Onsala concentrates on the development of alternative analysis strategies. In collaboration with the Geodetic Institute of the

University of Bonn (GIUB) we developed a two-step analysis strategy to derive realistic station

displacements [7]. Based on a session by session analysis of the data in a second step station displacements are derived. This approach allows, as compared to usual vector solutions, an improved

quality check of the derived displacements since obvious deviations are detected and cross-talk of

station deficiencies can thus be reduced.

Integrating VLBI and GPS:

The different space geodetic methods have their advantages and disadvantages. Especially for the

determination of absolute sea level changes it is useful to integrate several space geodetic techniques. For this purpose we work on the combination of GPS data from the BIFROST project

with European VLBI data [8].

Thermal deformation of VLBI radio telescopes:

VLBI radio telescopes deform due to thermal influences, an effect that is continuously monitored

at Onsala [9]. The thermal deformation effects show seasonal and short term behaviour. A simple

model for the effect based on the telescope dimensions and ambient temperature has been described in [10]. In collaboration with the Geodetic Institute at the University of Bonn (GIUB) we

started the collection of telescope dimensions to model the thermal deformation effect routinely in

the VLBI analysis using SOLVE (see http://giub.geod.uni-bonn.de/vlbi/thermal-ex/index.html).

Water vapor in the atmosphere:

Water vapor in the atmosphere influences radio wave propagation and so affects the colocated

techniques VLBI and GPS at Onsala. The colocated water vapor radiometer (WVR) is sensitive

to emission close to the water vapor emission line. Good agreement is found for the atmospheric

zenith parameters derived from simultaneous observations using the three techniques [11] [12].

4. Outlook

Special emphasis of our analysis in the near future will be on Earth tides and ocean tide loading.

We will work on new formulations of loading models and the implementation into VLBI analysis

software. Of importance will be parameter estimation and covariances with other parameters like

terms of polar motion and UT1.

We will work on a strategy for a combined determination of parameters of the Free Core

Nutation resonance from solid Earth tide deformations and nutation.

Work with global atmospheric pressure fields will be continued and used for studying atmospheric loading effects and the corresponding parameter estimation. Of special concern are dynamic

1999 IVS Annual Report 229
Onsala Space Observatory (OSO) Analysis Center Onsala Space Observatory (OSO)

response effects in near-by oceanic basins.

We will continue to study analysis strategies for the European geodetic VLBI network in order

to derive the most reliable station displacements. These results will be interpreted with respect to

geophysical models.

We will continue to investigate thermal deformation of VLBI telescopes and other local effects.

The actually monitored vertical deformations due to thermal expansion will be used to calibrate

simple models for this effect.

We will use simultaneous observations with the colocated techniques of VLBI, GPS and WVR

to study atmospheric properties. We will study the effect of incorporating atmospheric propagation

delay corrections derived from the other techniques in the analysis geodetic VLBI and its impact

on parameter estimation.

References

[1] Schuh, H., and R. Haas, Earth tides in VLBI observations, In: Proceedings of the 13th International

Symposium on Earth Tides, Brussels, July 22-25, 1997, S6rie G_ophysique, Observatoire Royal de

Belgique, edited by B. Ducarme and P. P£quet, 101-110, Bruxelles, 1998

[2] Scherneck, H.-G., A parameterized solid earth tide model and ocean tide loading effects for global

geodetic baseline measurements, Geophys. J. Int., 106, pp. 677-694, 1991

[3] Scherneck, H.-G., A comprehensive and tentatively complete summary of oceanic effects in space

geodetic baseline measurements, In: Proceedings of the llth Working Meeting on European VLBI

for Geodesy and Astrometry, held at Onsala, Sweden, August 23-24, 1996, edited by G. Elgered,

Research report No 177, Onsala Space Observatory, Chalmers University of Technology, pp. 121-133,

1996

[4] Haas, R., and H. Schuh, Ocean loading observed by VLBI, In: Proceedings of the 13th International

Symposium on Earth Tides, Brussels, July 22-25, 1997, S6rie G_ophysique, Observatoire Royal de

Belgique, edited by B. Ducarme and P. P_quet, 111-120, Bruxelles, 1998

[5] Scherneck, H.-G., and R. Haas, Effect of horizontal displacements due to ocean tide loading on the

determination of polar motion and UT1, Geophys. Res. Left., 26, pp. 501-504, 1999

[6] Haas, R., H.-G. Scherneck, and H. Schuh, Atmospheric loading corrections in geodetic VLBI and

determination of atmospheric loading coefficients, In: Proceedings of the 12th Working Meeting on

European VLBI for Geodesy and Astrometry, held at Hcnefoss, Norway, September 12-13, 1997, edited

by B. R. Pettersen, Statens Kartverk, pp. 111-121, 1997

[7] Haas, R., and A. Nothnagel, A two-step approach to analyze European geodetic Very Long Baseline

Interferometry (VLBI) data, In: Proceedings of the 13th Working Meeting on European VLBI for

Geodesy and Astrometry, held at Viechtach, February 12-13, 1999, edited by W. Schl/iter and H.

Hase, Bundesamt fiir Kartographie und Geod_ie, Wettzell, pp. 108-114, 1999

[8] 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: Proceedings of the International

Symposium of IAG Section II Towards an Integrated Global Geodetic Observing System (IGGOS),

October 5-9, 1998 Miinchen (Germany), in press, 1998

[9] Haas, R., G. Elgered, G. and H.-G. Scherneck, Onsala Space Observatory - IVS network station, (this

volume)

[10] Haas, R., A. Nothnagel, H. Schuh, and O. Titov, Explanatory supplement to the section "Antenna

Deformation" of the IERS Conventions (1996), DGFI Report 71, edited by H. Schuh, Deutsches

Geod_tisches Forschungsinstitut (DGFI), pp. 26-29, 1999

1999 IVS Annual Repro L

230
Onsala Space Observatory (OSO) Onsala Space Observatory (OSO) Ana_lysis Cents,

[11] Gradinarsky, L. P., R. Haas, J. M. Johansson, and G. Elgered, Comparison of atmospheric parameters

estimated from VLBI, GPS and microwave radiometer data, In: Proceedings of the 13th Working

Meeting on European VLBI for Geodesy and Astrometry, held at Viechtach, February 12-13, 1999,

edited by W. Schliiter and H. Hase, Bundesamt fiir Kartographie und Geod_ie, Wettzell, pp. 161-165, 1999

[12] Haas R., L. P. Gradinarsky, J. M. Johansson, and G. Elgered, The atmospheric propagation delay: A

common error source for colocated space techniques of VLBI and GPS, Proceedings of International

workshop on GEodetic Measurements by the colocation of Space Techniques ON Earth (GEMSTONE),

25-28 January, 1999 Koganei, Japan, pp. 230-234, 1999

1999 IVS Annual Report

231
Shanghai Astronomical Observatory Analysis Center SHAO, Chinese Academy of Sciences

VLBI Research Activities for Astrometry and Geodesy at

Shanghai Astronomical Observatory

Jinling Li, Guangli Wang, Zhihan Qian

Abstract

This report summarizes the current status, research activitiesand plans of the astrometric and

geodetic VLBI group of Shanghai Astronomical Observatory for VLBI and IVS.

1. Introduction

Under the umbrella of Chinese national reforming and opening policy, the Creative Project

of Chinese Academy of Sciences, which will be carried over to the next century, was started last

year. Personnel and research activities of the astrometric and geodetic VLBI group of Shanghai

Astronomical Observatory (SHAO), also as one of the 27 research groups of the National Astronomical Observatory, were reorganized to fit with this project. In this report we will address to

colleagues our current status, research activities and plans for future work in order to promote

basic understandings and cooperations.

2. Current Status and Research Activities

2.1. The Astrometric and Geodetic VLBI Group, SHAO

The Astrometric and Geodetic VLBI Group at SHAO was established in the middle of the

1980s. At that time, the VLBI group belonged to the Radio Astronomy Division, SHAO. The

research divisions were reformed and the Center for Astro-geodynamics Research was established

at SHAO in 1995. Since then, the Astrometric and Geodetic VLBI Group belongs to this center.

Recently, the VLBI Group and the fundamental astrometry group were combined as one group,

and is one of the research groups of the National Astronomical Observatory.

The members of the VLBI Group are as follows:

Li, Jinling

Qian, Zhihan

Jin, Wenjing

Yan, Haojian

Wang, Guangli

Wang, Shuhe

Zhou, Ruixian

Research Professor, head of the VLBI Group

Research Professor

Research Professor

Research Professor

Research Assistant

Associate Research

Senior Engineer

Tang, Zhenghong Research Assistant

The NASA/GSFC's Geodetic VLBI software, CALCS.2/SOLVE/GLOBL which has been installed on a HP C-180 workstation is used for VLBI data analysis.

1999 IVS Annual Report

232
SHAO, Chinese Academy of Sciences Shanghai Astronomical Observatory Analysis Center

2.2. Global Solution for Astrometric and Geodetic VLBI Experiments

Shanghai Astronomical Observatory is one of the VLBI data analysis centers of the International Earth Rotation Service (IERS) and the International VLBI Service (IVS). We have submitted our analysis results to IERS annually. This year, our analysis covers the celestial and terrestrial

reference frames (CRF and TRF) and Earth Orientation Parameters (EOP), and is based on all

the historical astrometric and geodetic VLBI observations available to us up to January of 1999.

It is the first time for us to perform a global solution with the data spanning more than 20 years.

Comparisons of our solutions with ITRF (96), ICRF (RSC (WGRF) 95 R01) and EOP (IERS)

C04 are performed. For CRF, the three orientation angles are not significant at the level of precision

of O.02mas. However, though no significant values are found for the three deformation parameters,

local deformations up to 0.5mas are still identifiable. Details are still under investigation. For TRF,

the orientation angles and their rates of change are not significant respectively at the precision level

of 0. lmas and O.05mas/yr. Detailed comparisons with ITRF96 show that our solution gives higher

motions for the eastern part of the Eurasian plate in the southeast direction and for Australian

plate in the south direction by several millimeters per year. About EOP series, the systematic

differences and the relative drifts are also not significant respectively at the precision level of

0.1mas and O.05mas/yr. These show that our solutions this year are pretty good.

2.3. Asia-Pacific Space Geodynamics Project

The Asian-Pacific Space Geodynamics (APSG) project was sponsored and organized by Prof.

Shuhua Ye, Academician of the Chinese Academy of Sciences (CAS) in 1996, and is an international

cooperation program being carried over to the next century. The primary objectives for the APSG

project are to measure and monitor the current crustal movement and deformation in the AsianPacific region using high precision space geodetic techniques such as VLBI, GPS and SLR, and

so to investigate various crustal motion rooted natural hazards, such as earthquakes, volcanic

eruptions, etc. The project is expected to contribute to the means for mitigating and preventing

natural disasters as well.

In October of 1997, the astrometric and geodetic VLBI group of SHAO, cooperating with

GSFC VLBI group, NASA, USA, organized the VLBI experiments of the first APSG campaign.

The second APSG VLBI campaign was carried out in November of 1998. We presently intend to

organize one campaign per year in the following years. Each campaign consists of two 24-hour

sessions.

From data analysis of the 1997 and 1998 APSG VLBI compaigns, the followings are illustrated:

• The mean accuracy of the baseline length measurements for the VLBI stations in the AsianPacific region is about 1.3 × 10 -9, which is consistent with the repeatability of baseline length

measurement for other VLBI stations in the world.

• Regarding the VLBI measurements of the station velocities, they are in good consistence

with the predictions of NUVEL1A-NNR for stations such as Gilcreek, Alaska (USA) and

Hobart, Tasmania (Australia). However, they are not well consistent for stations such as

Sheshan and Urumqi (China), Kashima (Japan) and Kokee, Hawaii (USA). Therefore, the

plate motion model well describes the large-scale behaviors of global tectonic plates, rather

than contemporary deformations taking place within plates or along boundary region.

• The detected eastward motion of Sheshan station and the north by northeast motion of

1999 IVS Annual Report 233
Shanghai Astronomical Observatory Analysis Center SHAO, Chinese Academy of Sciences

Urumqi station are of important significance to the study of the modern crustal movement

of China, which directly indicates the effect of the northward movement of the Indo plate

on the rising Tibetan Plateau and on the motion of the Tian Shan mountain area in the

northwest part of China as well as on that of the eastern part of China.

• The westward motion of the Kashima station of Japan is closely related with the westward

motion of the Pacific plate.

2.4. Chinese National Research Projects

Our activities are also involved in several Chinese national research projects, such as:

• Contemporary Crustal Motion and Geodynamics;

• Crustal Movement Observation Network of China;

• Mechanism and Prediction of Chinese Continental Intensive Earthquakes.

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 these projects. We mainly undertake the

coordination of VLBI experiments, data processing, archive and reduction. Also, we provide the

data analysis results of the change rates of baseline components and current motions of VLBI sites

in China for further investigations.

2.5. Application Studies and Modeling of Data of VLBI

We are also devoted to application studies of VLBI to the establishment and maintenance

of celestial and terrestrial reference frames (CRF and TRF), and the determination of Earth

orientation parameters (EOP) and their interpretation.

On the CRF, we are interested in factors related to maintenance and stability, such as the

method for the selection of defining sources, improvement of position precision of other sources,

identification of local deformations, source structure and its variation, the rotational Galaxy and

so on. We are also devoted to the improvement of the proper motion precision of Hipparcos

stars using historical plates archived in Sheshan Section of Shanghai Astronomical Observatory,

to precise position determination of optical counterparts of radio sources with CCD, and so to the

tie between the optical and radio frames.

On the TRF, we are interested in the determination of local motion of stations relative to

the prediction of plate models. Then, regional local motion can be statistically identified. These

are important inputs for geodynamic studies of current crustal movement. Because of the high

repeatability for the measurement of long baseline length, VLBI station is qualified as high precision

reference point for regional geodesy.

On modeling the data, we are devoted to the improvements for corrections of the atmosphere

effect.

3. Plans for VLBI and IVS

VLBI will continue to plan an important role in the establishment and maintenance of celestial

reference frame, the determination of Earth orientation parameter and in global and regional

234 1999 IVS Annual Report
SHAO, Chinese Academy of Sciences Shanghai Astronomical Observatory Analysis Center

studies of crustal motions. We will be devoted much to global and regional VLBI data reduction,

applications and modeling data.

4. Recent publications

• Jinling Li, Wenjing Jin. A new approach to the compilation of combined extragalactic radio

source catalogues. Astronomical and Astrophysical Transactions, 1998,Vo1.16, 31-35.

• Jinling Li, Guangli Wang. Corrections to the IAU 1976 precession constant and the coefficients of the IAU 1980 nutaiton series from VLBI observations. Chinese Science Bulletin,

1998, Vol.43 No.12, 1019-1023

• Jinling Li, Dawei Zheng, Guangli Wang. An analysis of the pole offset series in EOP (GSFC)

96 R 01.Publications of Yunnan Observatory, 1998(2), 33-44

• Jinling Li. An introduction of the SVD algorithm and its test of artificial data. Annals of

Shanghai Astronomical Observatory, 1998 (19), 16-21

• Jinling Li, Dawei Zheng The temporal variations of the free core nutation, Acta Astronomical

Sinica, 1998, Vol.39, No.3,308-312

• Jinling Li, Dawei Zheng. Possible temporal variations of the free core nutation and forced

nutations. In: Geodesy on the Move, Gravity, Geoid, Geodynamics and antarctica. IAG

Symp.119 , 1998. IAG Scientific Assembly, Rio de Janeiro, September 3-9, 1997,pp326-331

• Jinling Li, Zhihan Qian, Guangli Wang. The motion of the Shanghai colocation site relative

to the Eurasia plate. In: Proceedings of the international workshop on geodetic measurements by the colocation of space techniques on earth. January 25-28, 1999, at the Communications Research Laboratory, Koganei, Tokyo, Japan. pp184-188

1999 IVS Annual Report 235
U.S. Naval Observatory Analysis Center U.S. Naval Observatory

Earth Orientation Analyis from the U.S. Naval Observatory

VLBI Program

T.M. Eubanks, B.A. Archinal, F.J. Josties, J.R. Ray

Abstract

As part of its participation in the National Earth Orientation Service (NEOS) the U.S. Naval

Observatory (USNO) operates a program in Very Long Baseline Interferometry (VLBI) data acquisition

and analysis to monitor changes in the orientation of the Earth on a regular basis. This report describes

the VLBI observations conducted by the USNO, the methods of data reduction and analysis, and the

Navy 1999-3 reference frame created for use in operational VLBI data reduction for Earth orientation.

The major differences between Navy 1999-3 and the previously used 1998-10 system consist of changes

in the atmospheric parameterization, and a change in the a priori Terrestrial Reference Frame (TRF)

used from ITRF-96 to ITRF-97. This reports provides details both of recent NEOS VLBI operations,

and of the Navy 1999-3 system.

1. VLBI Operations

Current NEOS operations consist 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 NEOS VLBI data are correlated at the Washington Correlator, which is located at the U.S. Naval Observatory and run by the NEOS. After correlation,

fringe fitting, and the removal of any remaining bandwidth synthesis delay ambiguities, data from

all available multiple baseline VLBI sessions are used in a series of weighted least-squares solutions to define a USNO VLBI reference frame and to estimate the Earth orientation within that

reference frame. This report provides details on the procedures and models used at the USNO in

the reduction of these data.

2. The Navy 1999-3 Reference System

The current USNO VLBI practice is to define a reference system and to realize the frame anew

from each (weekly) global solution. For some purposes, however, such as the reduction of the

UT1 Intensive data, it is desirable to use a fixed reference frame based on a particular solution in

the Navy 1999-3 system; this will be called the "reference" solution. The results from both the

reference solution and the "current" (i.e., most up-to-date) solution are available on the WorldWide-Web [2], and the technical description for this system is described in [3]. All of the VLBI

results described in this report are based on the reference solution, which is also the solution

submitted to the IERS for the 1998 IERS Annual Report. The reference 1999-3 solution used

2,295,502 delay and rate observation pairs from 2695 observing sessions, with useful data on 652

sources from 1119 baselines and a total of 115 observing stations. The reference Navy 1999-3

solution has a Weighted Root Sum Square (wrms) delay residual scatter of 29.97 picoseconds, and

a wrms phase delay rate scatter of 89.67 femtoseconds / second. The reference time adopted was

January 1, 1997.

236 1999 IVS Annual Report
U.S. Naval Observatory U.S. Naval Observatory Analysis Center

2.1. Differences Between the 1998-10 and 1999-3 Systems

The Navy 1999-3 reference system is intended for operational use by the U.S. Naval Observatory

(USNO) VLBI program in the reduction of VLBI data for the determination of Earth orientation.

It is in general very similar to the Navy 1998-6 system in its 1998-10 realization, which is described

in the IERS Annual Report for 1997 [1]. The differences between the 1999-3 and the earlier 1998-10

system axe:

• The ITRF-97 is used instead of the ITRF-96 to define the origin of the system. The system

is tied to the a priori TRF by minimal constraints, such that there is no-net rotation, translation, rotation rate and translation rate between the a priori TRF and its VLBI realization.

Further details on these constraints axe provided below.

• The Niell Mapping Function (NMF) is used instead of the MTT mapping function.

• The constraints on the piecewise linear tropospheric gradient model were changed from 25

mm and 25 mm day -1 to 1.25 mm and 15.0 mm day -1.

Note that the Celestial Reference Frame tie has not changed: both systems are tied to the International Celestial Reference Frame (ICRF) [5] through a no-net rotation constraint.

In a detailed analysis of the differences between the 1998-10 and 1999-3 systems [4], the parameterization changes are found to cause about 60-80 micro arc second (#as) scatter in the Earth

Orientation Parameters (EOP), while the TRF change causes a rotation of order 200 pas and a

rotation rate of as much as 40 ttas yr -1.

2.2. Models Used in the VLBI Reduction

The data used in the report are processed with models consistent with the IERS Conventions[6]

to the maximum extent possible, with the CALC 8.2 software being used throughout in the data

reduction process. The NMF dry tropospheric mapping function is used to relate line of sight

tropospheric propagation delays to the tropospheric zenith delay, the NMF wet mapping function

is used for the tropospheric zenith parameter partial, and an elevation angle lower limit of 7 degrees

is used in all solutions. The IERS standard model for both horizontal and vertical deformations

due to ocean tidal loading is applied, although neither atmospheric loading deformations of the

ground nor thermally induced antenna deformations are modeled at present.

Unmodeled variations in the tropospheric propagation delays and the relative time offset between the station clocks are a significant source of error in geodetic VLBI. The surface pressure,

temperature and relative humidity are recorded at each station and the pressure is used to estimate

the variations in the hydrostatic zenith tropospheric propagation delay. Further variations in this

quantity are treated by the estimation of piecewise continuous linear models directly in the least

squares solutions. A new piecewise continuous linear function is introduced every 60 minutes for

the zenith tropospheric propagation and every 90 minutes for the relative station clocks. In order

to account for variations of atmospheric properties near each observing station, parameters of a

linear gradient model for the tropospheric propagation delay axe now estimated, with an East-West

and North-South piecewise continuous linear gradient function being estimated for each station

every 3 hours.

1999 IVS Annual Report 237
U.S. Naval Observatory Analysis Center U.S. Naval Observatory

2.3. The Terrestrial Frame Tie

The USNO Navy 1999-3 Earth orientation reference frame is obtained directly in a solution for

all terrestrial and celestial reference frame parameters, subject to minimal ties to a priori reference

frames. This makes it possible to estimate the TRF, CRF and the Earth orientation parameters for

all observing sessions simultaneously in one solution. The TRF tie is to the ITRF-97, and consists

of no-net translation and rotation, together with translation rate and rotation rate constraints,

to the positions and velocities of the 27 stations given in the technical description [3]. Only the

horizontal components of position and velocity are used in these constraints, and the sum over each

component is weighted by the corresponding diagonal element of the inverse covariance matrix.

There is no constraint of any sort on the frame scale or scale rate. In general, collocated VLBI

stations are used to derive independent velocity estimates. There axe six collocated pairs of stations

where this could not be usefully done for one of the two stations, or, in the case of Fort Ord, it was

judged better to have one rate estimate. These close station pairs, also described in the technical

description [3], were constrained to have the same velocities in the solution. For 26 stations, there

was insufficient data to estimate a meaningful velocity, and so the data from these stations were

only used to estimate the station positions, with their velocities being those given in ITRF-97. In

addition, 14 stations suffered from discontinuous position shifts, either due to earthquakes or due

to repair or other changes at the station, and for these stations a step-function in position was

estimated together with one station velocity for the entire period of data. Further details on all of

these special cases is given in [3].

2.4. The Celestial Frame Tie

The Celestial Reference Frame (CRF) is tied in rotation to the positions of 198 of the 212

defining sources of the IAU International Celestial Reference Frame (ICRF). Fourteen defining

sources, as described in [3], were dropped from this constraint as they have not provided good data

in recent observations. Again, the sum over each component used is weighted by the corresponding

diagonal element of the inverse covariance matrix.

2.5. Details on the Changes in Atmospheric Parameterization

The Niell Mapping Function (NMF) was adopted for the first time in the Navy 1999-3 system.

(The "dry" mapping function is used with the surface pressure and the Saastamoinen hydrostatic

model [6] to calculate the a priori tropospheric delay, while the "wet" mapping function is used

for the zenith delay partial.) Although this was done primarily because this mapping function is

thought to produce a more reliable absolute VLBI frame scale, there is also internal evidence that

the NMF is better than the MTT mapping function used previously [4].

In the Solve software used for VLBI data reduction at the USNO, the tropospheric gradients

are estimated as piece-wise continuous linear functions, and both the 1998-10 and 1999-3 systems

introduce a new gradient rate pair (North-South and East-West gradients) every 3 hours at each

station, in order to capture the observed diurnal gradient variations. There is one constraint on

the bias of each component of each station, averaged over the entire session, plus a constraint on

each piece-wise linear rate parameter. The a priori values for these parameters are currently zero,

so using any constraint will statistically bias the results towards zero. In the 1998-10 system the

constraints were set to be "loose," at 25 mm and 25 mm day -1. This was found to cause problems

238 1999 IVS Annual Report
U.S. Naval Observatory U.S. Naval Observatory Analysis Center

with the VLBI data from before --4986, which have very poor gradient determinations, and it

seemed desirable to tighten these constraints. Adopting too strong a gradient constraint, however,

also causes problems as most stations have a persistent bias of ,,-1/2 mm in the North-South

gradients, due to the equatorial bulge of the troposphere, and there are also observed variations at

seasonal, diurnal, and maybe other periods. The 1999-3 constraints were determined by adopting

a criteria that neither the observed annual nor diurnal gradient oscillations should be attenuated

by more than ,-_10% in the recent data, which yielded a gradient offset constraint of 1.25 mm, and

a rate constraint of 15 mm day -1.

2.6. EOP Parameterization

The USNO Earth orientation results are obtained from the long duration experiments in a

multi-parameter least squares adjustment for UT1, polar motion and both components of nutation, together with the minimally constrained CRF and TRF, in addition to piecewise linear clock

and troposphere models. Additional baseline-dependent clock offsets are added whenever the nonclosure of the clock estimates around station triangles is judged to be significant. The operational

USNO solutions also estimate the rate of change of the UT1 and polar motion for each observing

session. These rate estimates, converted to the more geophysically useful "X" excitation parameters, are provided routinely. The TRF and CRF are now updated in the course of each solution,

and the updated reference frames are now routinely provided in addition to the Earth orientation

parameters.

3. UT1 Intensive Data Reduction

The UT1 Intensive Series is derived from short-duration (,,-1 hour) single-baseline observations

conducted solely to monitor daily changes in the UT1. One difference between the intensive

solutions and the regular NEOS solutions lies in the treatment of nutation and polar motion,

which axe not estimated in the intensive solutions, but are instead held fixed to the values given in

the IERS Bulletin A, linearly interpolated to the epoch of the data. The station coordinates and

velocities, axis offsets, and the source positions are fixed at the a priori values given by the Navy

1999-3 reference frame, with the reporting epoch for each observing session being the mid-point

of the session. The NEOS/IRIS UT1 Intensive files produced by the USNO now extend back to

1984 in one homogeneous solution.

3.1. High-Frequency EOP Variations and the Intensive Results

The current accuracy of VLBI Earth orientation results is sufficient to clearly detect tidally

coherent diurnal and semi-diurnal variations in UT1 and polar motion, mostly due to the non-linear

response of the oceans to the luni-solar gravitational tides. These variations can be a significant

source of systematic error, and so have been removed from the 1999-3 solutions using the empirical

hf966b model prepared by John Gipson and his colleagues in the Goddard Space Flight Center

VLBI group. The model values are not added back into the UT1 and polar motion estimates, so

that the orientation results provided in the operational Earth orientation solutions are close to the

24-hour average values for the Earth orientation centered on the epoch of observation. The same

model is used in the reduction of the IRIS/NEOS Intensives. Again, the model values are not

added back into the Intensive results; these short duration estimates thus do not reflect the true

1999 IVS Annual Report 239
U.S. Naval Observatory Analysis Center U.S. Naval Observatory

orientation at the reporting epoch, but are instead closer to the 24-hour average for the reporting

epoch.

References

[1] The USNO Annual Report for 1997 is obtainable from

ftp : l/casa.usno, navy. mil/navnet/ier s_report •97.

[2] The availability of the Navy 1999-3 system is described in

ftp :llcasa, usno .navy.mi llnavnet/README, n9903.

[3] The USNO Technical Descriptions for the full Navy 1999-3 solution, and the Intensive solutions, are

obtainable from

ftp ://casa. usno. navy .mil/navnet/n9903 •descript and

ftp ://casa. usno .navy .mil/navnet/n9903. int.descr ipt.

[4] A memo giving further details of the Navy 1999-3 system is currently available in draft form from

ftp ://cas a.usno. navy. mi 1/navnet/po st scr ipt/iv s_memo _i.ps.

[5] Ma, C., et ai., 1998, AJ 116 516-546.

[6] McCarthy, D.D., (edt.), IERS Conventions 1996, IERS Technical Note 21, Observatoire de Paris, Paris,

1996.

1999 IVS Annual Repo_

240
TECHNOLOGY

[ EVELOPMENT

CENTERS

From the Terms of Reference:

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.

CRESTech Space Geodynamics Laboratory Canadian VLBI Technology Development Cente,

Canadian VLBI Technology Development Center

Wayne Cannon, Calvin Klatt

Abstract

The $2 VLBI data record and playback systems, developed at CRESTech's Space Geodynamics

Laboratory on the campus of York Universit); are now in use around the world for a variety of radio

astronomy, VLBI, and space VLBI applications in over a dozen countries.

The $2 VLBI correlator, developed jointly by the the Canadian Space Agency, the Geodetic Survey

Division of NRCan, the Herzberg Institute for Astrophysics, and the Space Geodynamics Laboratory

has been operational in a six station configuration for more than two years at the Dominion Radio

Astrophysical Observatory (DRAO) in Penticton BC, Canada mainly in support of space VLBI observations. The "end-to-end" completion of the $2 VLBI system will be achieved with the final deployment

of the frequency switched, $2 VLBI data acquisition system. The frequency switched $2 VLBI data

acquisition system is intended to enable geodetic VLBI measurements with sensitivities comparable to

the Mark IIIA using only two base band converters. The Canadian geodetic VLBI program using the

$2 system also involves the development of the Canadian Transportable VLBI Antenna (CTVA) to be

used to establish quasar referenced geodetic control points over the Canadian landmass.

The next-generation, $3, VLBI system capable of 1 Gbit/sec recording with unattended record

times as long as 60 hours using robotic tape changers, is also under active development at the Space

Geodynamics Laboratory.

1. Introduction

The Canadian VLBI Technical 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

2.1. Introduction

The Canadian $2 geodetic VLBI program involves development of 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 correlator capabilities to process frequency switched VLBI observations, utilization of a

transportable antenna and the expansion of analytical capabilities for scheduling and analysis.

2.2. $2 VLBI Data Acquisition System (S2-DAS)

The $2 VLBI data acquistion system is being jointly developed by SGL and the GSD. The S2-

DAS is designed to accept up to four IF inputs between 100 MHz and 1000 MHz and to accomodate

up to four VLBA/Mark IV-type single sideband baseband converters (BBCs). Each BBC in the

S2-DAS is provided with a local oscillator (LO) that is independently frequency switchable under

computer control over the entire 900 MHz IF range. LO frequency switching in the S2-DAS is

1999 IVS Annual Report 243
Canadian VLBI Technology Development Center CRESTech Space Geodynamics Laboratory

phase coherent and requires less than 1 ms to settle to within 1 degree of its final phase. Resolution

of the LO is 1 Hz, limited only by software. The objective of the development of the S2-DAS is to

enable high sensitivity, bandwidth synthesis, group delay measurements for geodetic VLBI without

appealing to a more costly parallel IF/baseband sub-system.

The "end-to-end" $2 geodetic VLBI system including the transportable antenna, the frequency

switched S2-DAS, and the "frequency switched" $2 correlator are currently undergoing a program

of shakedown field testing. This field testing program is designed to progressively test and debug

all aspects of the system, culminating in the demonstration of a high precision geodetic capability.

2.3. $2 VLBI Correlator

The Canadian $2 VLBI Correlator development has been supported by the Canadian Space

Agency (CSA) as a contribution to the international space VLBI missions (RadioAstron, VSOP)

and has been in a "production" operational mode for space VLBI for more than two years.

The Canadian $2 Correlator 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 development of post processing software to reduce the UVFITS standard output of the

correlator to a format usable in the CALC/SOLVE analysis software package.

2.4. Canadian Transportable VLBI Antenna (CTVA)

The CTVA is a 3.6-m radio telescope acquired to facilitate densification of the terrestrial reference frame 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.

In 1997 the antenna was moved from the Ottawa area to a site at the Dominion Radio Astrophysical Observatory (DRAO) near Penticton, B.C. In the past year several site-related tasks have

been completed. Recent work focusses on antenna sensitivity and system stability and reliability.

2.5. CTVA Specifications

• Reflector : 3.6 m diameter

• Receiver : S and X (uncooled)

• Azimuth speed : 150 degrees per minute

• Elevation speed : 60 degrees per minute

• PCFS version : 9.3.17

• VLBI equipment : $2 VLBI data acquisition system and $2 VLBI data record system

• Time standard : CH-75 Transportable Hydrogen Maser

2.6. $2 Geodetic Experiment Scheduling, Operations and Analysis

The Canadian Geodetic VLBI program involves all aspects of Geodetic VLBI operations, from

experiment design through analysis. Considerable effort in the past year has been made to establish

experiment design, optimal scheduling and analysis capabilities. Scheduling is currently performed

1999 IVS Annual Report

244
CRESTech Space Geodynamics Laboratory Canadian VLBI Technology Development Centel

Figure 1. Canadian Transportable VLBI Antenna (CTVA)

using SKED, SCHED and DRUDG. The current version of SKED is not S2-tape friendly, requiring

the use of SCHED for final schedule production.

The simulation capabilities of SKED have been used for optimization of geodetic $2 schedules.

These simulations require the SOLVE software, which was installed at GSD in 1997-1998. The GSD

installation of CALC/SOLVE and associated software approximately matches that at the USNO.

Local changes to the software in the past year have been made to account for the anticipated

differences between $2 and Mark III/Mark IV databases.

The GSD has successfully proposed to support the IVS by providing a VLBI Analysis web site

which is expected to be available in "Beta" form in the coining year.

2.7. Interferometric Experiments in 1998

The developmental experiments listed in 1 have been performed using the $2 VLBI system and

the CTVA. Fringes have been obtained in each $2 interferometric experiment.

1999 IVS Annual Report 245
Canadian VLBI Technology Development Center CRESTech Space Geodynamics Laboratory

Table 1. Canadian $2 Development Experiments: 1998

Experiment Date Stations Principal Objective

CG002 July 10, 1998 CTVA-ARO Interferometer Sensitivity

CG003 July 30, 1998 CTVA-ARO Frequency-Switching Functionality

CG004 August 20, 1998 CTVA-ARO Automatic Gain Control

CG005 October 19, 1998 CTVA-ARO Overall System Performance

2.8. Staff Responsibilities

Table 2 lists staff responsibilities for the $2 development.

Table 2. $2 Geodetic VLBI System Development Team Members

Team Member Principal Interest/Activity

Mario B_rub@ CTVA, Operations

Marc Bujold $2 DAS Software

Georg Feil $2 DAS Software

Calvin Klatt Scheduling, Analysis

Alexander Novikov $2 DAS Hardware

Bill Petrachenko Overall Project Leadership, Correlator, CTVA, DAS

Josef Popelar Scientific Leadership

3. The $3 and S3-E VLBI Data Record and Playback Systems

3.1. Introduction

The Space Geodynamics Laboratory has begun work on the development of the $3 VLBI data

record and playback system, which will resemble the $2 in that it will consist of an array of eight

digital videotape transports. A brief description of the $3 and progress to date on its development

is presented below.

The $3 is designed as a VLBI data record/playback system based on an array of eight digital video tape transports with a modular architecture similar to the $2 consisting of two rack

mountable or "desk top" $3 Tape Transport Array Modules (S3-TAMs) and one rack mountable

or "desk top" $3 Data, Signal, and Control Module (S3-DSCM). Each tape transport in the $3

array will record/playback VLBI data at a rate of 128 Mbit/sec for an overall data rate of 1024

Mbit/sec. The unattended data record/playback time at a data rate of 1024 Mbit/sec for the $3

will be 2.5 hours with longer unattended record/playback times available in the $3 when used at

lower bandwidths using a subset of tape transports. For example:

DATA RATE

1024 Mbit/sec

512 Mbit/sec

256 Mbit/sec

128 Mbit/sec

UNATTENDED OPERATION TIME

2.5 hours

5 hours

10 hours

20 hours

1999 IVS Annual Report

246
CRESTech Space Geodynamics Laboratory Canadian VLBI Technology Development Cente,

The S3-Extended (S3-E) VLBI data record and playback system would be a dual, 16 tape

transport, version of the $3 which could record/playback VLBI data at a rate of 2048 Mbit/sec

with an unattended record/playback time of 2.5 hours.

The $3 and S3-E would both be available with an optional robotic tape changer. The $3

robotic tape changer would permit operation of the $3 at data rates of 1024 Mbit/sec for as long

as 60 hours without operator intervention. The cost of recording media for the $3 is expected to

be $140 (US) per hour at a data rate of 1024 Mbit/sec and for the S3-E $280 (US) per hour at a

data rate of 2048 Mbit/sec.

3.2. Staff Responsibilities

Table 3 lists staff responsibilities for $3 development.

Table 3. $3 VLBI Data Record and playback System Development Team Members

Team Member Principal Interest/Activity

Wayne Cannon Project Management, Scientific Objectives

Georg Feil $3 Software, Software Management

Bryan Feir $3 Software, Transport Control

Paul Newby Signal Channel Electronics, Engineering Management

Alexander Novikov $3 Software and Hardware

1999 IVS Annual Report 247
Technology Development Center at CRL Communications Research Laboratory

Technology Development Center at CRL

Tetsuro Kondo

Abstract

Communications Research Laboratory (CRL) has led the development of 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. TDC at CRL

Communications Research Laboratory (CRL) has been leading the development of the VLBI

system in Japan. CRL started the development of the K3 VLBI system in 1979 which is compatible

with the Mark III VLBI system developed by the US group and successfully carried out a USJapan VLBI in 1983. 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. In accordance with the establishment of the International

VLBI Service (IVS) for Geodesy and Astrometry on March 1, 1999, the function of the IERS VLBI

Technical Development Center was taken over by that of the IVS Technology Development Center.

CRL participates in IVS as one of the Technology Development Centers.

VLBI Technology Development Center (TDC) at the Communications Research Laboratory

(CRL) is supposed

1) to develop new observation techniques and new systems for advanced Earth's rotation observations by VLBI and other space techniques,

2) to promote research in Earth rotation using VLBI,

3) to distribute new VLBI technology,

4) to contribute the standardization of VLBI interface, and

5) to deploy the real-time VLBI technique.

The CRL TDC meeting, attended by the ordinary members from inside the CRL and special

members from the outside, is held twice a year. The special members advise the committee concerning the plan of technical developments. The TDC newsletter is published biannually by CRL to

inform the VLBI community about its current activities. The newsletter is also available through

the Internet at following URL http://www.crl.go.jp/ka/radioastro/tdc/index'html"

2. Staff Members of CRL TDC

Table 1 lists the staff members at CRL who are members of IVS and are involved in the VLBI

technology development center at CRL.

248

1999 IVS Annual Repo, L
Communications Research Laboratory Technology Development Center at CRL

Table 1. Staff Members of CRL TDC (alphabetical).

Name Works

Amagai, Jun

Ichikawa, Ryuichi

Kaneko, Akihiro

Kawai, Eiji

Kiuchi, Hitoshi

Kondo, Tetsuro

Koyama, Yasuhiro

Kurihara, Noriyuki

Nakajima, Junichi

Sebata, Kouichi

Sekido, Mamoru

Takahashi, Yukio

Yoshino, Taizoh

Optical-linked RF Interferometer

Analysis software

Operation software

Antenna system

K4 (KSP) VLBI system, real-time VLBI, and high-speed

recorders

Leader of the CRL TDC

Operation, monitoring, and analysis softwares

Antenna System

Giga-bit VLBI system

Observation support system

Correlation processing software

Analysis software

Leader of the Key Stone Project team in CRL

3. Recent Activities

3.1. Real-Time VLBI

CRL has developed a compact VLBI network named KSP which consists of four stations

around the Tokyo metropolitan area and is dedicated to monitoring the crustal deformation (Figure 1)[1][2]. In 1995, the KSP started regular observations. Observations and analyses are fully

automated in the KSP. Real-time VLBI technique using a 2.488 Gbps ATM communications network (STM-16) was also developed on the KSP network in cooperation with the Nippon Telephone

and Telegraph Corporation (NTT)[3]. Now routine observations spanning 24 hours are carrying

out every other day using the real-time VLBI technique. Measurement accuracy in terms of the

repeatability of baseline length measurements reaches about a 2-mm level in our VLBI network

[4].

This real-time VLBI technique is now used to realize a large virtual radio telescope by connecting a 64-m antenna at USUDA and a 34-m antenna at Kashima besides KSP stations to increase

sensitivity to detect very weak radio sources. Test observation was successfully carried out in

December 1998 [5].

3.2. Giga-bit VLBI System

In parallel with the KSP operation, the Giga-bit VLBI system consisting of a high speed

sampler (1Gsps/4ch/2bit) and a high speed digital data recorder (1024 Mbps) has been developed

to increase the sensitivity of observations (Figure 2). Test observations using this system were

carried out on the Kashima-Koganei baseline of KSP VLBI network on July 10, 1998, and the

first fringes were successfully detected [6]. Data were processed by GICO (Giga-bit COrrelator)

which consists of UWBC (Ultra Wide Band Correlator) originally developed for the Nobeyama

Millimeter array of the National Astronomical Observatory. The processor is an XF type correlator

1999 IVS Annual Report 249
Technology Development Center at CRL Communications Research Laboratory

KSP

VLBI

Network

/ Around Tokyo

Tateyama

Japan ,

Figure 1. Location of the Keystone Project VLBI network (left) and the real-time correlation processing

system (right).

with 256 lags of cross-correlation function capable to process at 2048 Mbps.

3.3. Optical-linked RF Interferometer

In addition to these technology developments, a different approach to increase the accuracy of

measurements has been investigated. It is an optical-linked RF interferometer aiming to measure

phase delay precisely [7]. The concept of optical-linked RF interferometer is a connected-element

interferometer. RF signals received by antenna are directly converted into optical signals and

then transmitted through a fiber optic link instead of use of metal lines like a coaxial cable. In

a connected-element interferometer, common local oscillator signals are used for the frequency

conversion of RF signals from each antenna. Thus no clock parameter estimation is necessary

in a baseline analysis unlike in general VLBI analysis for geodetic purpose. Even though higher

stability against the temperature change is expected for optical fiber link than metal lines, delay

change occurred in the transmission line should be compensated for the application of precise

geodetic observation. Maximum fiber length capable to use in this system was estimated from

signal-to-noise ratio analysis at fiber optic links. It was estimated to be about 40 km when the

combination of Ortel 3541A laser diode and Ortel 4515A photo detector is used.

3.4. VLBI Standard Interface

Besides these technology developments, CRL TDC is contributing to establish the VLBI standard interface (VSI) which is first proposed by Dr. Alan R. Whitney, Technology Coordinator of

IVS. We have had meeting several times to discuss VSI in Japan.

1999 IVS Annual Report

25O
Communications Research Laboratory Technology Development Center at CRL

Figure 2. Completed Giga-bit recorder (left) and UWBC-GICO experimental correlator (right)

4. Future Perspectives

CRL TDC will continue to make efforts to develop new technologies introduced in this report

and to apply them to actual observations. We also have a plan to develop "Internet VLBI" system

in cooperation with the NTT 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).

Acknowledgements. The real-time VLBI technique for the KSP has been developed in cooperation with the Telecommunication Network Laboratory Group of Nippon Telegraph and Telephone

Corporation (NTT). We thank all staff members of NTT involved in the real-time VLBI Project

for their efforts to maintain the high speed network of the KSP. The large virtual radio telescope

project has been promoted in collaboration with the Institute of Space and Astronautical Science

(ISAS), National Astronomical Observatory (NAO), and NTT. The Giga-bit VLBI system has

been developed under a cooperative effort by Communications Research Laboratory, NAO, and

Tokyo University. We would like to express deep appreciations to colleagues in these organizations.

References

[1] Koyama, Y., N. Kurihara, T. Kondo, M. Sekido, Y. Takahashi, H. Kiuchi, and K. Heki, Automated

geodetic very long baseline interferometry observation and data analysis system, Earth Planets Space,

50, 709-722, 1998.

[2] Key Stone Project - Crustal deformation monitoring system around the Tokyo metropolitan area -,

Special Issue of J. Commun. Res. Lab., Vo1.46, No.l, 1999.

[3] Kiuchi, H., T. Kondo, M. Sekido, Y. Koyama, M. Imae, Hoshino, Uose, Real-Time VLBI Data Transfer

and Correlation System, J. Commun. Res. Lab., Vol.46, No.l, 83-90,1999.

[4] Kondo, T., N. Kurihara, Y. Koyama, M. Sekido, R. Ichikawa, T. Yoshino, J. Amagai, K. Sebata, M.

1999 IVS Annual Report 251
Technology Development Center at CRL Communications Research Laboratory

Furuya, Y. Takahashi, H. Kiuchi, and A. Kaneko, Evaluation of repeatability of baseline lengths in the

VLBI network around the Tokyo metropolitan area, Geophys. Res. Lett., 25, 1047-1050, 1998.

[5] 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.

[6] Koyama, Y., J. Nakajima, M. Sekido, and M. Kimura, The first fringes from the Giga-bit VLBI system,

Technical Development Center News CRL, No.13, 14-16, 1998.

[7] Amagai, J., H. Kunimori, and H. Kiuchi, Preliminary experiments of improved optical-linked RF

interferometer, Technical Development Center News CRL, No.12, 20-23, 1998.

252 1999 IVS Annual Report
Forsvarets forskningsinstitutt (FFI) (Norwegian Defence Research Establishment) FFI Tech. Dev. Center

Combination of Results at FFI - Software Development

Per Helge Andersen

Abstract

FFI's contribution to the IVS as a Technology Development Center will focus on the development

of software (GEOSAT) for a combined analysis at the observation level of data from VLBI, GPS and

SLR. This report shortly summarises the current status of the GEOSAT software development and

validation including some future plans.

1. Introduction

FFI is centrally located in the Kjeller area, 30 minutes east of Oslo (near LillestrOm). Here

approximatelu 2400 people are engaged in several research establishments, technical institutions,

university branches and Air Force Material Command. FFI is a state operated, civilian research

establishment reporting directly to the Ministry of Defence. The number of employees is approximately 550.

For many years FFI has performed research in space science and remote sensing using satellites.

As a part of this research FFI has developed a highly sophisticated software (GEOSAT, [2]) for

satellite orbit determination and space geodesy. With this software all types of high precision

space geodetic observations can be combined and analyzed at the observation level.

2. Goals for FFI's Contribution to the IVS

Based on contributions from a number of analysis centers the International Earth Rotation

Service (IERS) calculates on a regular basis realizations of a terrestrial and a celestial reference

frame including their interconnections given by the Earth Orientation Parameters (EOP). It is a

serious problem that the individual solutions submitted to the IERS are calculated using different

software with partly inconsistent models and strategies. This can lead to inconsistencies within

one technique of several mm in station coordinates. The between-technique inconsistencies can be

as high as 1 cm in the combined IERS solution for the terrestrial reference frame. The GEOSAT

software will for the first time make it possible to perform analyses of VLBI and satellite tracking

data with one consistent model and strategy.

Analysis of data from any of the IERS techniques requires the calculation of a large number of

parameters. Some of these parameters are highly correlated leading to a reduction in accuracy. The

strength of VLBI is in the determination of distances and directions while the satellite techniques

are especially important for the determination of the Earth's center of mass. In order to obtain

high-precision results with VLBI and GPS the water vapor content of the troposphere or the

zenith wet delay must be precisely estimated. The introduction of SLR data, independent of the

water vapor, will contribute to the decorrelation of the zenith wet delay parameter from all the

other estimated parameters especially the height component of the station coordinates. In general,

the combination of independent and complementary information from different types of data will

reduce the parameter correlations and lead to more accurate results.

There are several additional advantages with the combination of VLBI and satellite tracking

1999 IVS Annual Report 253
FFI Tech. Dev. Center Forsvarets forskningsinstitutt (FFI) (Norwegian Defence Research Establishment)

data: the estimated satellite orbital elements, radio source coordinates, and EOPs will be realized

in a long-term stable celestial reference frame realized primarily by the radio sources. This means

that the GPS and SLR observations for the first time can be used in the determination of UT1

itself and not only the length of day (LOD). Another advantage is that all estimates of geodetic

and geodynamic parameters axe given in the same realization of a terrestrial reference frame.

Finally, the combined analysis of VLBI, GPS, and SLR can be used to estimate the eccentricity

vectors between the different antenna phase centers within each colocated station. It is a fact that

much eccentricity information is missing and some of the existing information is quite unreliable

or inaccurate.

FFI will, as a Technology Development Center for IVS, develop the GEOSAT software to

demonstrate the feasibility and potential of a combination of VLBI, GPS and SLR data at the

observation level. We will especially focus on the establishment of consistent observation models

for all three techniques. The a posteriori residuals will be investigated in order to detect systematic

technique-dependent errors. Solutions for the individual techniques will be compared with a combined solution to evaluate the contribution fxom each technique to the determination of important

geodetic and geodynamical parameters.

The different data types axe combined for each arc at the observation level using a UD-factorized

filter. The arc length is defined by the length of the VLBI session. The arc-by-arc state vectors and

complete covaxiance matrices are combined into a multi-year solution using a highly sophisticated

and flexible Square-Root-Information-Filter-and-Smoother (CSRIFS, [1]). Four parameter levels

are available in the CSRIFS program and any parameter can, at each level, either be represented

as a constant or a stochastic parameter. The batch length can be made time- and parameterdependent. The state vectors will include station coordinates and velocities for some selected multitechnique stations in addition to Earth orientation parameters (EOP), radio source coordinates,

and other geophysical and geodynamical parameters.

3. Status

All planed components of GEOSAT have been successfully validated with a combination of

data from VLBI, GPS and SLR. Consistent models for all techniques have been verified at the

sub-ppb level. The processing at the arc and session levels axe completely automated using C-shell

scripts. In some cases the processing crashes and additional work must be done in order to make

the processing scheme more robust against errors in the input data.

The CSRIFS program for combining arcs has been successfully applied in the generation of

a VLBI-only solution covering 623 sessions during the last 10 years. A paper containing the

mathematics of CSRIFS and the results of the VLBI analysis has recently been submitted for

publication in Journal of Geodesy.

4. Technical Staff

Table 1 lists the FFI staff involved in IVS activities. The development and validation of

GEOSAT have resulted in a substantial theoretical understanding and practical experience with

all available types of high-precision space geodetic data (VLBI, GPS, SLR, PRARE, DORIS and

radar altimetry).

254 1999 IVS Annual Report
Forsvarets forskningsinstitutt (FFI) (Norwegian Defence Research Establishment) FFI Tech. Dev. Center

Table 1. Staff working at the FFI AC and TDC

I Name I Background [Dedication I Agency [

[Per Helge Andersen I geodesy [ 40% [ FFI I

5. Outlook

The computation time for the processing of 24 hours of VLBI, GPS, and SLR data is presently

approximately 14 hours using a HP C180 (one CPU) computer. We plan to buy a new computer

within the end of this year or early next year, probably a HP J5000 (with two CPUs) or a HP

J7000 (with four CPUs) including 1 Gb RAM. This should give an increase of a factor 5 or l0

in processing capacity. The disk storage capacity will be extended from 65 Gb to 100 Gb with

additional 30 Gb each year. With such computation power it should be possible to generate global

combined multi-technique solutions based on a large number of arcs.

References

[1] Andersen, P. H. (1999) Multi-level arc combination with stochastic parameters. Paper submitted for

publication in Journal of Geodesy.

[2] Andersen, P. H. (1995) High-precision station positioning and satellite orbit determination. PhD Thesis,

NDRE/Publieation 95/01094.

1999 IVS Annual Report 255
GSFC Technology Development Center NASA Goddard Space Flight Center

Goddard Space Flight Center IVS Technology Development

Center

Ed Himwich, Nancy Vandenberg, Tom Clark

Abstract

The GSFC IVS Technology Deveiopemt Center (TDC) develops station software including the Field

System (FS), scheduling software (SKED), hardware including tools for station timing and meteorlogy,

scheduling algoritnhms, operational procedures, and provides a pool of individuals to assist with station

implementation, check-out, upgrades, and traning.

1. Introduction

The GSFC IVS Technology Developemt 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 Willam Wildes.

The remainder of this report covers the status of the main areas of development that are

currently being pursued.

2. Field System

Several major ehancements for the Field System (FS) are planned for this year. These will

include: mode independent parity checks, Y2K compliance, sequential dual recorder support,

automated Tsys, an SEFD analysis tool for antenna calibration, and user interface enhancements.

The most significant of these changes is the Y2K upgrade. In addition to making the FS operate

in year 2000 and beyond several other small improvements were undertaken at the same time. The

resulting changes are fairly substantial. These changes include: 4-digit year and punctuation in

log file time tags, correct operation across year boundaries, use of punctuation in timed wait

commands, and upgrades to all post processing software ("logex", "logpl", "xtrac", "pdlpt") to

support new and old log formats.

Mode independent parity checks will remove the need to change parity procedures depending

on the mode and recording speed.

Sequential dual recorder support is intended to allow longer periods of unattended operation

at stations with two recorders. In this approach one recorder would have its tape filled, then the

operation would switch over to the other tape drive. The tape can then be changed on the first

drive whenever is convenient, perhaps just before the second tape is filled.

Automated Tsys is similar to mode indepedent parity checks in that it will free the operator

from having to adjust the Tsys measurement procedures depending on the recording mode. In this

case DRUDG will emit mode specific procedures for "preob" and "midob".

A new analysis tool will be developed for examining SEFD data from ONOFF to estimate gain

curves and other performance information.

1999 IVS Annual Report

256
NASA Goddard Space Flight Center GSFC Technology Development Center

The user interface will be improved. This will include an improved log display window with

better scrolling capability. A more sophisticated window manager may be used as well.

3. Hardware

The development of Totally Accurate Clock (TAC) systems continues. The new 8-channel

units show RMS precision compared to USNO at the 30 nanosecond level or better. TACs are now

readily available commercially. The new control software is Windows 95/98/NT based and very

robust.

To replace the antique FTS8400 GPS timing receivers, NASA has adopted the TAC plus an

HP53131A counter plus Windows-based software to control the TAC and make routine data logs

of timing data. These are being implemented now at several VLBI and SLR stations.

A new meterological sensor package is being developed. The pressure, temperature, and humidity sensor is the same as used in many GPS installations and for SLR2000. The new wind-speed

sensor has no moving parts.

4. Site Visits

GSFC will provide personnel for several site visits this year. The visits will include some

combination of upgrades, training, and troubleshooting. The exact mix will be depend on the

station's needs. Station that will probably be visited this year include: Fairbanks, Goldstone,

Kashima34, Kokee Park, Noto, Shanghai, Tsukuba, and Urumqi.

5. 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. The normal flow is that first SKED is run at Operation Centers to make the .skd file

that contains the full network observing schedule. Then the stations use the .skd file as input to

DRUDG for making the control files and procedures for their station.

A major upgrade to SKED in 1997 was the ability to schedule continuous tape motion. This

feature is used only for RDV sessions; it is not generally available because it still has some quirks.

We will add the ability to write a VEX output file to SKED just in time for use by the Mark IV

correlator. We also plan to add the ability to schedule K4 and $2 experiments using their native

tape characteristics instead of faking the footages assuming Mark III/IV tapes.

DRUDG is distributed with Field System updates. SKED is distributed via anonymous ftp to

the Goddard server. A new release of the SKED software is planned for fall 1999. The release will

also include updated documentation.

6. VEX

GSFC works in collaboration with Haystack and JIVE to develop the VEX scheduling language.

This year a new release, 1.6, is planned. This will add some significant new features, but which

ones have not be finalized at this point. In addition to added new features, some of the changes

1999 IVS Annual Report 257
GSFC Technology Development Center NASA Goddard Space Flight Center

will be oriented toward helping smooth operation of the system when VEX schedules are used. We

also hope to begin implementing VEX observation logs and tables of ancillary data, such as cable

and sysystem temperature, this year.

A library of VEX writing utilities will be developed this year. This will complement the existing

VEX reading utilities.

1999 IVS Annual Repol

258
MIT Haystack Observatory Haystack Technology Development Center

IVS Technology Development Center at Haystack Observatory

Alan Whitney

Abstract

Recent and planned activities of the IVS Technology Development Center at Haystack Observatory

are reviewed, with an emphasis on tile Mark IV correlator, Mark IV decoder, and thin-film head array

projects.

1. Mark IV Correlator

Introduction

The Mark IV correlator development at Haystack Observatory is nearing completion. Copies

of this correlator will soon be in place at USNO in Washington, D.C., MPI/Bonn in Germany, and

MIT Haystack Observatory in Westford, Massachusetts. A nearly identical copy is in operation

at JIVE in Dwingeloo, The Netherlands. Development of the Mark IV VLBI correlator system is

a joint U.S.-European effort, with sponsorship by NASA, USNO, and the Smithsonian Institution

in the U.S., and BKG, JIVE, and NFRA in Europe. Two large correlators for connected-element

interferometers, in Westerbork, The Netherlands and on Mauna Kea, Hawaii, are also based on

the same correlation engine as the Mark IV correlators.

In the intial implementation the USNO, MPI, and Haystack correlators will all support _8

stations, though the architecture allows easy future expansion to many more stations.

Features of the Mark IV Correlator

The Mark IV correlator system is designed as a major upgrade of the venerable Mark IIIA correlator, which has been in use since 1985 at Haystack, USNO, and MPI/Bonn. The characteristics

of the Mark IV correlator can be summarized as follows:

• 1 Gbit/sec/station playback rate, expandable to 2 Gbits/sec/station

• Scalable architecture allowing up to 32 stations with 16 channels/station, all baselines correlated simultaneously

• Compatibility with Mark IIIA, Mark IV and VLBA format tapes

• Station-based XF architecture utilizing full-custom VLSI correlator chips

• 4× playback speedup compared to Mark IIIA correlator

• Extensive use of VEX files for correlator operation/configuration

• Updated HOPS post-correlation package

Architectural Overview

Figure 1 shows a simplified block diagram of a 16-station, 1 Gbit/sec/station Mark IV correlator. Each Playback Unit (PBU) is attached to a Station Crate which reconstructs the data from

the tape into channels and then applies the proper computer model to the delay and delay rate of

the data. The delay, delay rate, and phase models for each channel of each station are periodically

1999 IVS Annual Report 259
Haystack Technology Development Center MIT Haystack Observatory

inserted into the data streams transmitted to the Correlator Crate. In order to minimize cabling

complexity between the Station Crates and the Correlator Crate, the transmission between them

takes place over high-speed serial links on coax cable.

Figure 1. Block diagram of Mark IV correlator.

At the Correlator Crate the data are resychronized and passed to the Correlator Board where

the station parameters are captured and are used to compute the baseline processing parameters

supplied to the correlator chips. The lag-correlation results are periodically read from the correlator

chips and passed to the Correlator Control Computer (CCC) for further processing.

Correlator Chip and Board

Haystack Observatory was responsible for the development of the correlation engine, which

includes a full-custom VLSI correlator chip and the correlator board which hosts the correlator

chips. Approximately 10,000 chips were fabricated by Hewlett-Packard. The characteristics of the

correlator chip are as follows:

• Full-custom CMOS with _1,000,000 transistors

• 1 or 2 bits/sample

• 64 MHz clock rate

1999 IVS Annual Repro L

260
MIT Haystack Observatory Haystack Technology Development Center

• 512 lags which can be re-arranged internally into several independent correlator sections,

each having from 16 to 512 lags

• 8 internal 32-bit phase generators and rotators for rotation rates to full channel bandwidth

• internal bit-shift/phase-shift algorithm

• internal vernier-delay management

• 24-bit latchable ripple counter on each lag

• Power dissipation: _3W at 64 MHz

• 208-pin PGA package, _2 inches square

Figure 2 shows a single correlator board. Each correlator board, which is approximately 40 cm

by 50 cm in size, hosts 32 correlator chips, two high-speed DSP chips, and 10 64x64 custom ASIC

crossbar switches. The characteristics of a correlator board are as follows:

• 32 VLSI correlator chips

• access to 64 2-bit data streams configurable through 10 64x64 custom ASIC cross-bar switches

• 64 MHz maximum clock rate (tested to 70 MHz)

• 16,384 real lags per board, flexibly configurable

• support of 128 baselines of 32 complex lags per baseline for a single channel

• auto-correlation modes

...... :,

Figure 2. Mark IV correlator board.

Each correlator crate houses eight correlator boards. Two such crates are necessary for a full

16-station, 1-Gbit/sec/station correlator.

1999 IVS Annual Report 261
Haystack Technology Development Center MIT Haystack Observatory

Status and Plans

All Mark IV correlator hardware has been constructed, and software development is in the final

stages, with deliveries of operational correlators to USNO and MPI/Bonn expected in late summer

or early fall of 1999. Figure 3 shows a diagram of the final configuration with 8 playback units.

The correlator rack is in the center, and each Station Crate is surrounded by the four playback

units it serves. The Mark IV correlators will replace the Mark IIIA correlators now currently in

use at these locations.

[] V- E

i i t .

N¢J

J _ LI l J

(

u

,I

Figure 3. Mark IV correlator configuration with eight playback units.

2. Mark IV Decoder

The Mark IV decoder module is designed as a plug-in upgrade/replacement for the Mark III

decoder. As a direct replacement, it acts as a two-channel data-quality analyzer operating the

same way as the Mark III decoder, that is, it accepts two tape-tracks of data from either the

formatter or from the playback-monitor tracks on the recorder. However, it can operate at up to

the full 18 Mbps rate of the Mark IV formatter.

In addition, the Mark IV decoder accepts four selectable channels of 2 bits/sample data from

the Mark IV formatter via a separate connector on the rear panel. These data can be analyzed

by an internal Mark IV correlator chip to simultaneously extract up to four arbitrarily placed

phase_cal tones from any of the four selected channels, or the correlator chip may act as a state

counter for a single selected channel. Future plans include the ability of the correlator chip to also

extract high-resolution bandpass information from any or all of the selected Mark IV formatter

channels.

The Mark IV decoder utilizes a Motorola 68340 processor with 64 MB of internal RAM, of

which about 60 MB is available for data capture, either from one playback track or from one

Mark IV formatter channel. The data may then be read out from the decoder either through the

standard MAT bus or via a separate high-speed SCSI connection.

Production of a number of Mark IV decoders is now proceeding at Haystack Observatory. The

design will soon be transferred to industry and made available to interested parties.

1999 IVS Annual Report

262
MIT Haystack Observatory Haystack Technology Development Center

3. Thin-Film Head Array Project

Haystack Observatory is working with industry, with support from NASA, NRAO and JIVE,

to develop thin-film (TF) head array technology suitable for use with VLBI. In particular, the goal

of the project is to develop a thin-film array replacement for the current headstacks used in the

Mark IV/VLBA recording systems.

Thin-film head technology utilizes semi-conductor fabrication techniques to construct read/write

heads. Write heads are created by constructing thin-film coils which drive a magnetic gap in the

conventional manner. Read heads utilize magneto-resistive technology (MR) which is increasingly

prevalent in the hard disc industry. These read/write head pairs are deposited in arrays along a

1-inch substrate bar; standard wire-bonding techniques axe used to attached flexible printed-circuit

assemblies to the bar for access by the external world.

Haystack has received and tested several prototype TF/MR headarrays and has found excellent

performance under a wide variety of tape speeds and tensions using an innovative "flat-lap" contour

invented at Haystack. This "flat-lap" contour has been extensively analyzed, both theoretically

and experimentally, and is now understood to actually create a suction of the tape to the head in

such a way as to always maintain excellent head-to-tape contact.

In addition to excellent performance, the TF/MR headarrays show practically no wear after

thousands of hours of operation; this is due to the extremely hard substrate material used in their

manufacture.

Haystack Observatory is now exploring with industry ways in which these TF/MR headarrays

can be replicated in a cost effective way. Our goal is to be able to manufacture a complete headarray

assembly for a price substantially less than a conventional headstack. Negotiations with industry

in this regard are now underway. A new design for the read/write electronics will be required to

support the TF/MR headarrays. Work on these components will accelerate once the availability

of the headarrays is assured.

4. Mark IV Acquisition Systems

To help stations that currently have either Mark IIIA or VLBA data acquisition systems convert

to Mark IV, we are providing assistance through acquisition of hardware, installation of the new

hardware at the stations, and training the local staff in its use. In the past year we helped upgrade

the systems at Hartebeesthoek and Wettzell, and in the coming year we will upgrade Matera and

O'Higgins.

5. Personnel

The Haystack Observatory scientists, engineers, and technicians who have contributed to the

work described in this report are Will Aldrich, John Ball, Ed Beauchemin, Tom Buretta, Peter

Bolis, Roger Cappallo, Kevin Dudevoir, David Fields, Roger Genereux, Joel Goodman, Hans

Hinteregger, Colin Lonsdale, Sinan Miiftfi, Ed Nesman, Arthur Niell, Alan Rogers, Stu Sherman,

Dan Smythe, Alan Whitney, and Ken Wilson.

1999 IVS Annum Report 263
IAA Technology Development Center Institute of Applied Astronomy of Russian Academy of Sciences

Institute of Applied Astronomy Technology Development Center

Alexander Ipatov

Abstract

Our Institute was organized as a main research institute in the geodetic VLBI field of Russian

Academy of Science, especially for scientific development and constructing Russian technical facilities

for Quasar project. This report describes the IAA activities in this direction.

1. General

Technology Development Center is responsible for all parts of the Russian VLBI network and

consists of separate laboratories, which develop hardware and software for this project. Now the

32 m radio telescope in Svetloe is under preparing to take part in international VLBI network observations, radio telescope in Zelenchukskaya is under testing and in Bodary - under construction.

2. Technical/Scientific

Dish metal constructions. This group is responsible for dish, electrical drive, main reflector

and subreflector quality, and geodesy adjustment.

Antenna tracking control system. The IAA developed software allows control the antenna

TNA-400-1 by the computer Field System on the base of own exchange protocol.

Table 1.

Cha.ra_teristic

speed in the

"low speed" mode

speed in the

"high speed" mode

Tracking error

Technical characteristics of antenna tracking control system radio telescope TNA-400-1.

Azimuth

not more than 3'/sec.

Elevation

not more than 50"/sec.

not more than 1°lOtsee. not more than 55'/sec.

not more than 10"/see. not more than 10"/sec.

Receivers. Receivers on the 32 m telescope are installed in the secondary focus and can be

interchanged as required. Changing a receiver from standby to operation requires only changing

position of subreflector. At the present there are five receiver systems (10 channels) providing

observation R and L circular polarisations simultaneously.

1999 IVS Annual Report

264
Institute of Applied Astronomy of Russian Academy of Sciences IAA Technology Development Cente,

Table 2. Receivers Parameters.

Band, cm Input Noise temperature, K

18/21 10

13

6

3,5

1.35

10

10

17

60

Our hardware staff is continuing investigations of new dish in Svetloe station. It has performed:

adjustment and main parameters measurement of radio telescope in Svetloe Network Station, the

quality Investigations of cryogenically cooled receivers installed on antenna in Svetloe, determine

calibration noise signals for the receivers of all bands. Observation of the references sources,

maintenance receivers and cryogenic equipment in Svetloe Network Station, assist and training

station staff for routine operations on service receivers and refrigerators equipment.

The new radiometric registration device was designed. This design was implemented for providing of single dish observations in four wide band channels simultaneously, antenna performance

and pointing measurements. It is connected to IF outputs of cryoelectronic receivers and controlled

by Mark IV Field System program.

Table 3. Data of the module.

Frequency band, MHz 100 +1000

Channels Number 4

Radiometer type switching or compensation

Quantizer capacity 13

Cumulation time, s 0.1 or more

It was elaborated the software integrated into the Field System environment for control of this

device. The software permits radiometer data recording into the special file during VLBI observations in coordination with the experiment schedule or the using of Field System for single dish

observations scheduling. The software makes the standard Field System programs "fivpt" and

"onoff" workable with radiometric registration. This was implemented using new Field System

feature: station specific detectors support. The software for the control of antenna and radiometric registration was complemented with operator interface programs. The programs work in the

XWindow environment on the FS computer and provide the possibility of visual graphical monitoring of antenna position and radiometer data in real time. The operator programs also permit

control of antenna and other equipment with graphical interface.

DAT. Four-channel data acquisition rack with Canadian recording terminal $2 was worked

out and installed at the Svetloe observatory and is using for VLBI experiments (on baselines

Svetloe-Bears Lake-Pushino, Svetloe-Evpatoria-Bears Lake).

Frequency and Timing System. The active hydrogen masers CH1-80 are used at the

network station Svetloe. Frequency stability of this maser is presented in Table 5.

IAA found in 1998-1999 years the local Frequency and Time Standard at Technology Development Center for metrology supporting of the VLBI observations. This Frequency and Time

1999 IVS Annual Report 265
IAA Technology Development Center Institute of Applied Astronomy of Russian Academy of Sciences

Table 4. Data of the system.

Frequency band, MHz 100 - 600

Frequency tuning step, kHz 10

Number of down converters 4

Bandpasses, MHz 0.25, 2, 8 and 16

Using of clipping levels 2, 3 or 4

Recording terminal S2-RT

Format of output data $2 or MarkIII

Table 5. Frequency stability of maser.

Sample time interval (AllanVariance) 1/z

1 sec 3.10 -13

10 sec 3.10 -14

100 sec 1 • 10 -14

1000 sec 5.10 -15

Standard includes active hydrogen maser CH1-70, passive hydrogen masers CH1-76, cesium and

rubidium quantum clocks. Passive hydrogen maser CH1-76 may be used as mobile clock.

Time and frequency calibrations are provided by mobile clock, TV calibration facility, GPS

receiver 4000 SST Trimble Navigation and GLONASS receiver A-724M.

Microwave holography equipments. In the years of 1997-98 the original microwave holography measuring system was created in the Institute of Applied Astronomy. The accuracy of

holography measurements in one scan is of 0.12 ram. In February of 1999, after preliminary

geodetic adjustment, the first session of the microwave holography measurements was carried out.

Seven scans with resolution of 0.75 m were used for measure the phase errors and amplitude

distribution on the aperture. The holography adjustment of the dish at Svetloe station will be

made during this summer.

Communication and Calculation Systems. The project VLBI network Quasar foresees

creation of system remote control and data real-time processing of spectral and VLBI-observations.

To the moment, the hardware and software system has been designed and checked in IAA ,

which allows to do spectral and correlate processing limited samples of videosignals (at 20 MHz)

from VLBI station Svetloe with the special processor TISS1-M (placed in S.Petersburg).

The Automatic meteorological station. The parameters are presented in Table 6.

3. Technical Staff

For all persons the IAA address (Zhdanovskaya st., 8, St. Petersburg, 197110, Institute of

Applied Astronomy (IAA) RAS, Russia, Director Andrey Finkelstein, FAX: +7-812-230-74-13) is

common.

1999 IVS Annual Repmt

266
Institute of Applied Astronomy of Russian Academy of Sciences IAA Technology Development Center

Table 6. The parameters of the automatic meteorological station.

Measured parameter Range Accuracy

Temperature (C) -50 - +50 0.25

Pressure (mba) 600 - 1090 0.5

Humidity (Mean wind velocity (v) for 10 1.5 - 40 0.5+0.05v

min (m/s) 8 - 55 0.5+0.05v

Max. wind velocity (v) for 10 0 + 360 10

min (m/s) Yes/No

Wind direction (degree) 0 - 150 0.2+0.05P

Rain Yes/No

Sample rate: 1 min (except wind velocity),

10 rain, 1 hour.

Prof.Alexander

Stotsky

Prof.Nikolal

Koltsov

Dr.Sergey

Smolentsev

Dr.Alexandre

Salnikov

Table 7. Technical Staff.

Main Scientific Radio Physics +7-812-235-32-16 stotskii_ipa.rssi.ru

Researcher Radio holography

Chef the Laboratory VLBI and radiometric +7-812-235-33-16 nec_ipa.rssi.ru

Signals Conversion registration system

and Registration

Vice Director Time keeping +7-812-230-74-16 smolen@ipa.rssi.ru

frequency standard

Chef the Laboratory

Communication and

Calculation Systems

Network

Communication

Computers

+7-812-230-83-51 ais@isida.ipa.rssi.ru

Dr.Edward Chef the Laboratory Dish metal +7-812-230-74-15 amf@ipa.rssi.ru

Korkin of Radio Antennae constructions

Dr.Irina Senior Scientific Receivers +7-812-230-64-96 ipatov@ipa.rssi.ru

Ipatova Researcher Antenna

performance

Dr.Vyaeheslav Senior Scientific +7-812-230-64-96 vvm_ipa.rssi.ru

Mardyshkin Researcher,

Scientific

Researcher

Scientific

Researcher

Joiner Scientific

Researcher

Mr.Andrey

Michailov

Receivers

Re_igerators

Antenna performance

FS software

Radio telescope

control system

Receivers

Re_igerators

Antenna performance

Stations software

Radio telescope

control system

Mr.Dmitriy

Ivanov

+7-812-230-64-96

+7-812-230-64-96

Mr.Sergey +7-812-230-64-96

Syrovoy

agm@ipa.rssi.ru

ipatov_ipa.rssi.ru

ipatov@ipa.rssi.ru

J Outlook

At the new IVS year we axe planning:

• To include the VLBI site Svetloe into routine CORE-A observations.

1999 IVS Annual Report 267
IAA Technology Development Center Institute of Applied Astronomy of Russian Academy of Sciences

• Holography adjustment in Svetloe.

• Receivers and cryogenic equipment installation at new dish in Zelenchuckskay.

• Adjustment of reflector and feed system in new dish, including holography adjustment.

• Parameters measurement at new dish and testing VLBI observations.

268 1999 IVS Annual Report
Institut d'Estudis Espacials de Catalunya IEEC Analysis Center

Institut d'Estudis Espacials de Catalunya (IEEC)

Dirk Behrend, Antonio Rius

Abstract

We summarize the tasks and work carried out at the Institut d'Estudis Espa_ials de Catalunya (IEEC)

regarding geodetic VLBI within the frame of the IVS. Main activities are, firstly, geodetic surveillance

of the DSS65 VLBI antenna at the Robledo (Madrid) site; and, secondly, investigations pertaining to

improvements of the tropospheric correction using GPS, WVR, and local meteorological data as well

as meteorological models.

1. General Information

The Institut d'Estudis Espacials de Catalunya (IEEC) is located in Barcelona in the north-east

of Spain. It occupies quarters in the Nexus building (Figure 1) of the Universitat Polit_cnica de

Catalunya (UPC) North Campus in the west-end of town (see also Table 1).

Figure 1. Home of the IEEC: the Nexus building of the UPC North Campus.

IEEC is a research unit of the Consejo Superior de Investigaciones Cientfficas (CSIC), the

Spanish research council. In the IVS it fulfills the task of a technology development center. The

main study areas lie in the determination of the stability of VLBI sites, i.e. the surveillance of the

horizontal and vertical stability of the antenna reference point, and in improving the modelling of

atmospheric parameters.

1999 IVS Annual Report 269
IEEC Analysis Center Institut d'Estudis Espacials de Catalunya

Table 1. Addressing the IEEC using different means.

Address Type Current Address

geographical address longitude A = 2.11°E

latitude _o = 41.39°N

postal address Institut d'Estudis Espacials de Catalunya

Edif. Nexus-204, Gran Capitk 2-4

E-08034 Barcelona, Spain

WEB address http://_r_ru, ieec. fcr. es

2. Technological Developments in Progress

For the DSS65 VLBI antenna at the NASA Madrid Deep Space Communications Complex

(MDSCC), Spain, the stability of the antenna site was controlled using geodetic measurements

taken at different epochs and covering the time span from 1988 to 1998. A least squares evaluation

procedure yielded 3D-coordinates of the antenna reference point with an accuracy of a few mm.

Thus, the antenna can be considered stable in position (showing no significant change) over the

past decade. This excludes a significant 7 mm change in the north component in March 97. The

height, on the other hand, has undergone two significant height changes: an uplift of 17 mm from

December 88 to March 97 and an uplift of 6 mm from March 97 to June 97. For more information

the reader is referred to the following references: [1], [2], and [3].

In addition to VLBI, the DSN station at Robledo (Madrid) also runs collocated microwave

techniques. These comprise a GPS receiver and a water vapour radiometer (WVR). Data from

these techniques as well as local meteorological data and, eventually, meteorological models are

utilized to improve the modelling of atmospheric parameters. Corresponding investigations are

currently underway.

3. Staff Members Working in the VLBI Field

The IEEC staff members who are involved in VLBI work and are contributing to the IVS

consists of two people (cf. Table 2).

Table 2. Staff members in IVS related work.

Name Background Dedication Agency

Dirk Behrend geodesy 100% IEEC

Antonio Rius astronomy 50% IEEC

Antonio Rius had been a member of the technical staff of the MDSCC from 1975 to 1985 being

responsible for the radioastronomical activities, before he became head of the Earth Sciences

Department of the IEEC. Dirk Behrend is financed by the European Community in the TMR

network grant FMRX-CT960071 "Measurement of Vertical Crustal Motion in Europe by VLBI".

270

1999 IVS Annual Report
Institut d'Estudis Espacials de Catalunya IEEC Analysis CenteL

4. Current Status of IVS Related Activities

The evaluation of the already performed geodetic observation campaigns is accomplished and

the results have been published. It is planned that future campaigns, which should be performed

on a yearly basis, be evaluated using the same software and the results be published as soon as

possible.

The application of GPS technology to studying the water vapour distribution and evolution

in the study area of the MDSCC is underway. Comparisons with results from independent techniques (e.g. WVR) as well as with values retrieved from meteorological models will further the

understanding of this crucial variable and are currently in progress. Eventually, the understanding

of the water vapour distribution will help to improve the modelling of the atmospheric parameters

in the analysis of VLBI data.

5. Future Plans and Outlook

For this spring/summer, it is scheduled the next geodetic observation campaign of the DSS65

antenna. Furthermore, it is planned to investigate additional possibilities of controlling the DSS65

site stability. This stems primarily from the fact that there exists a large time gap of about nine

years between the first and the second geodetic control measurements.

Another critical point associated with the geodetic surveillance concerns the stability of the

local geodetic network. So far, it was assumed that there was no significant change in the stations

of this network. As this might not be completely true, it is vital to also control the coordinates of

the local net. Thus, a control survey of this net is planned for later this year.

As the water vapour distribution at the VLBI site is a crucial variable, additional information

sources should be exploited to improve the modelling of the atmospheric parameters. This summer

a new water vapour radiometer will be installed at the MDSCC: a D2 radiometer from JPL. It is

envisaged that data from this WVR be evaluated at the IEEC. The software package to be used

shall be an in-house product which is largely based on the "hotrid" package running at Onsala

Space Observatory (OSO), Sweden.

References

[1] 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.

[2] Behrend, D. and A. Rius: Geodetic Control of the Madrid DSS65 VLBI Antenna. In: W. Schlfiter

and H. Hase (Ed.): Proceedings of the 13th Working Meeting on European VLBI for Geodesy and

Astrometry. Viechtach, February 12-13, 1999, Bundesa_nt ffir Kartographie und Geod/isie, Wettzell, 1999.

[3] Rius, A., A. Alberdi, D. Behrend, C. Garc/a-Mir6, J.A. Perea: Radioastronomy at the NASA Madrid

Deep Space Communications Complex (MDSCC) - Status Report. In: W. Schlfiter and H. Hase (Ed.):

Proceedings of the 13th Working Meeting on European VLBI for Geodesy and Astrometry. Viechtach,

February 12-13, 1999, Bundesamt ffir Kartographie und Geod_ie, Wettzell, 1999.

1999 IVS Annual Report 271
Onsala Space Observatory (OSO) Technology Development Center Onsala Space Observatory (OSO)

The IVS Technical Development Center at the Onsala Space

Observatory

Gunnar Elgered, Rfidiger Haas, Lars Pettersson

Abstract

We give a short overview of the activities at the Onsala Space Observatory related to the function as an

IVS Technology Development Center. We concentrate on the ongoing work with the development of a

new S/X-band feed system for the 20-m telescope and the design and construction of a new microwave

radiometer.

1. Staff at Onsala Associated with the IVS Technology Development Center

The staff at Onsala associated with the IVS Technology Development Center is: Rune BystrSm

(engineer), Gunnar Elgered (scientist), Lubomir Gradinarsky (Ph.D. student), Riidiger Haas (scientist), Jan M. Johansson (scientist), Karl-Ake Johansson (engineer), Lars Pettersson (engineer),

Hans-Georg Scherneck (scientist) and Borys Stoew (Ph.D. student).

2. Technical development at Onsala

2.1. New S/X feed system

The development of a new S- and X-band feed is ongoing. It consists of two feed reflectors used

for both S- and the X-band. A more detailed description of the feed has been reported earlier [1],

[2]. Two dual-band corrugated horns have been manufactured. The first version turned out to have

a frequency band which was not centered correctly. A second, rescaled version was measured and

showed a good antenna diagram for both bands. The coaxial waveguide transformer (COWAT) is

the component which makes it possible to have access to the X-band ports (Right Hand Circular

Polarization and Left Hand Circular Polarization) that are inside the coaxial S-band waveguide,

before transforming the S-band coaxial waveguide into the S-band septum polarizer in circular

waveguide (see Figure 2). Also the prototype COWAT was found to have the center frequency

slightly off the desired value and it is now being redesigned. Simulations show that a reduction

in length of some parts of the COWAT will lower the center frequency. The amount of reduction

has not yet been decided. An X-band polarizer of septum type has been built (see Figure 4) and

measurements show that it works though more measurements are needed before it can be decided

if it fully meets the specifications. The S-band polarizer will be a scaled version of the X-band

polarizer and has not yet been manufactured.

1999 IVS Annual Report

272
Onsala Space Observatory (OSO) Onsala Space Observatory (OSO) Technology Development Center

Figure 1: The dual-frequency corrugated horn. Figure 2: The coaxial waveguide transformer

(COWAT). Note the X-band waveguide with output ports for both right and left circular polarizations.

Figure 4: View into the COWAT showing the Xband septum polarizer sitting inside. The polarizer uses a stepped metal septum to separate the

two modes into two rectangular waveguides for

right hand and left hand circular polarization.

Figure 3: The feed

mounted together.

horn and the COWAT

2.2. A Micro Rain Radar

In the fall of 1997 a small radar was obtained for characterization of rain events at the Onsala Space Observatory. It is a Frequency Modulated-Continuous Wave (FM-CW) radar and is

1999 IVS Annual Report 273
Onsala Space Observatory (OSO) Technology Development Center Onsala Space Observatory (OSO)

always measuring in the zenith direction. A picture of the radar is shown together with a block

diagram in Figures 5 and 6. The radar measures the velocity spectra of the falling drops. From

these data the rain rate and the liquid water density can be inferred. During the first year the

radar was operating to a height of 1200 m with a range resolution of 200 m. The data so far

used is the rain rate at the height of 200 m. This information is used to develop an independent

method to firstly have an archive of rain events at the Onsala site, and secondly to assess the

quality of microwave radiometer data used for propagation delay studies. A preliminary investigation concerning the use of rain radar data for automatic editing of microwave radiometer data

was recently presented. It was found that the earlier used threshold value of 0.7 mm liquid water

content is reasonable when trying to eliminate microwave radiometer data acquired during rain [3].

Figure 5: The zenith looking Micro Rain Radar

(MRR) at the Onsala site.

e

_7 Cl_k_g_uency Deviat"

l t

Figure 6: Block diagram of the Micro Rain Radar

(MRR) at the Onsala site.

2.3. A New Microwave Radiometer

A second microwave radiometer for observations of the atmospheric emission around the 22 GHz

water vapor emission line is being developed [4]. The main application will be comparison measurements at the Onsala site. Temporary measurement campaigns at other sites, e.g. in the Swedish

GPS network, are also planned. A major difference compared to the existing Onsala radiometer is

that the half power antenna beam widths are approximately 2° instead of 6°. Figure 7 shows the

design of the instrument and Figure 8 shows the microwave part.

1999 IVS Annual Repol t

274
Onsala Space Observatory (OSO) Onsala Space Observatory (OSO) Technology Development Center

Figure 7: The design of the new microwave radiometer. Using two synchronized flat mirrors

the antenna beams will be sensing the sky in the

same direction.

Figure 8: The microwave part of the new radiometer. The horn antennas are equipped with

lenses and are looking in opposite directions.

References

[1] Elgered, G., and R. Haas, Geodetic Very-Long-Baseline Interferometry at the Onsala Space Observatory 1996-1997, In: Proceedings of the 12th Working Meeting on European VLBI for Geodesy and

Astrometry, held at H¢nefoss, September 12-13, 1997, edited by B. R. Pettersen, Statens Kartverk,

H0nefoss, Norway, pp. 49-53, 1997

[2] Elgered, G, P.-S. Kildal, J. Flodin, B. Hansson, L. Pettersson, S. Raffaelli, J._. 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, 27-29 maj, 1997, pp. 279-287,

1997.

[3] Gradinarsky, L. P., G. Elgered, and Y. Xue, Combining data from a ground-based radiometer and a

micro-rain radar for estimation of atmospheric water vapour and cloud liquid, 6th Specialist Meeting

on Microwave Radiometry and Remote sensing of the Environment, 16-18 March 1999, Firenze, Italy

[4] Stoew, B., and C. Pdeck, Dual channel water vapour radiometer development, In: Proceedings of the

13th Working Meeting on European VLBI for Geodesy and Astrometry, held at Viechtach, February

12-13, 1999, edited by W. Schlfiter and H. Hase, Bundesamt fiir Kartographie und Geod_sie, Wettzell,

pp. 261-264, 1999

1999 IVS Annual Report 275

IVS

INFORMATION

Terms of Reference

IVS Terms of Reference

1. Summary

1.1. Objectives

The International VLBI Service for Geodesy and Astrometry (IVS) is an international collaboration of organizations which operate or support Very Long Baseline Interferometry (VLBI)

components. The primary objective of IVS is to foster VLBI programs as a joint service to support geodetic, geophysical, astrometric, and other research and operational activities. This is

accomplished 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 further education and training of VLBI participants is supported

through workshops, reports, electronic network connections, 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 frames 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 delivery methods to ensure suitable product quality

and timeliness. IVS closely coordinates its activities with the astronomical community because of

the dual use of many VLBI facilities and technologies for both astronomy and astrometry/geodesy.

IVS accepts observing proposals for research and operational programs that conform to the

IVS objectives.

1.2. 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 many scientific and practical applications requiring the use

of an accurate inertial reference frame, such as high-precision navigation and positioning.

IVS 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

1999 IVS Annual Report 279
Terms of Reference

• 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 axe publicly available.

1.3. Research

The VLBI data products axe 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

1.4. 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 component described in the next section. IVS will accept proposals at any time for any of its

components. Such proposals will be reviewed by the Directing Board. The IVS components are

the following:

• Network Stations

• Operation Centers

• Correlators

• Analysis Centers

• Data Centers

1999 IVS Annual Repo_ L

280
TermsofReference

• TechnologyDevelopmentCenters

• CoordinatingCenter

• DirectingBoard

• AssociateMembers

• Corresponding Members

1.5. Coordination

Specific activities for technology, network data quality, and data products are accomplished

through the functions performed by three coordinators:

• Technology Coordinator

• Network Coordinator

• Analysis Coordinator

2. Components

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

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 multiple uses (including astronomical observations or satellite tracking applications).

• Stations comply 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. Operation Center activities include:

• planning 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,

1999 IVS Annual Report 281
Terms of Reference

• 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.

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 coordinates VLBI data analysis to produce high-quality results for its users. These

activities are performed by Analysis Centers, which contribute to the IVS core products, and by

Associate Analysis Centers, which contribute other specialized products. Two types of Associate

Analysis Centers are recognized: Global and Special.

The Analysis Centers receive and process VLBI data from one or more IVS Data Centers and

are committed to produce the core products, without interruption, and at a specified time lag

to meet IVS requirements. The IVS core products, at a minimum, consist of Earth orientation

parameters, station coordinates, and source coordinates. 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 from IVS recommendations are properly

documented. Analysis Centers provide timely feedback about station performance.

The Global Associate Analysis Centers process all the observed VLBI data. Some process data

directly from Correlators and then make available as products the final VLBI database files and

SINEX files. Others start with these database to perform their analyses, but will process all the

databases.

The Special Associate Analysis Centers analyze selected databases for one (or more) specific

interests, such as regional data processing, terrestrial reference frame maintenance, or Earth orientation results.

In addition, all types of IVS analysis centers satisfy the following standards:

282 1999 IVS Annual Report
Terms of Reference

• Analysis is performed using VLBI software packages that adhere to IVS recommendations.

• Centers perform software development and produce documentation. They periodically compare their products.

• Centers adhere to IERS Conventions. Any exceptions axe 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 closely with the Coordinating Center and with the Analysis Centers to

ensure that all the information and data required by IVS components are quickly and reliably

available.

Data Centers provide the following functions:

• receive and archive schedule files from Operation Centers,

• receive and archive log files and ancillary data files from the Network Stations,

• receive and archive data products from the Analysis Centers,

• 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

1999 IVS Annual Report 283
TermsofReference

of the NetworkStations,OperationCenters,Correlators,Data Centers,AnalysisCenters,and

TechnologyDevelopmentCenters.The CoordinatingCenterworkscloselywith the Technology

Coordinator,theNetworkCoordinator,andthe AnalysisCoordinatorto coordinateall IVS activities.

The primary functionsof the CoordinatingCenterareto:

• coordinateobservingprogramsapprovedby the DirectingBoard,

• maintainthe masterscheduleof observingsessions,coordinatingthe schedulewith astronomicalobservingprogramsandwith IVSnetworks,

• fostercommunicationsamongall componentsof the IVS,

• definethebestuseof communityresources,

• developstandardsforIVS components,

• providetrainingin VLBI techniques,

• organizeworkshopsandmeetings,includinganannualIVS technicalmeeting,

• produceandpublishreportsof activitiesof IVS components,

• maintainthe IVS informationsystemandarchiveall documents,standards,specifications,

manuals,reports,andpublications,

• provideliaisonwith the IERS,IAG, IAU, andotherorganizations,

• providetheSecretariatof the DirectingBoard.

Througha reciprocityagreementbetweenIVS and IERSthe CoordinatingCenterservesas

theVLBI CoordinatingCenterforIERS,andassuchits designatedrepresentative,subjectto the

DirectingBoard approval,is a memberof the IERS DirectingBoard. Sucha representativeis a

non-votingmemberof the IVS DirectingBoard. In turn, the IERSDirectingBoarddesignatesa

representativeto theIVSDirectingBoard.Thisarrangementisto assurefull cooperationbetween

the twoservices.

2.8. Technology Coordinator

The IVS TechnologyCoordinatoris selectedby the Directing Board from responsesto an

opensolicitationto the IVS TechnologyDevelopmentCenters.The TechnologyCoordinatoris

responsiblefor coordinatingthenewtechnologyactivitiesofIVS andfor stimulatingadvancement

of theVLBI technique.TheTechnologyCoordinatorperformsthe followingfunctions:

• maintainscognizanceof all currentVLBI technologiesandongoingdevelopment

• coordinatesdevelopmentof newtechnologyamongvariousIVS components

• helpspromulgatenewtechnologiesto thegeodetic/astrometricommunity

• strivesto ensurethehighestdegreeof globalcompatibilityofVLBI dataacquisitionsystems

The TechnologyCoordinatorworkscloselywith the astronomicalcommunitybecauseof the

manyparallelsbetweenthe technologydevelopmentrequiredfor both groups.

284 1999IVSAnnualReport
Terms of Reference

2.9. 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

performance,

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.

2.10. 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 from 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

combination of the analysis results submitted by the Analysis Centers.

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 the IVS Coordinating

Center and with the IERS.

2.11. Directing Board

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

1999 IVS Annual Report 285
Terms of Reference

including modifications to the organization that are deemed appropriate and necessary to maintain

efficiency and reliability.

A specific function of the Board is to set scientific goals for the IVS observing program. The

Board will establish procedures for external research programs and will review any proposals thus

received.

The Board may determine appropriate actions to ensure the quality of the IVS products and

that the IVS components maintain the adopted standards.

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:

Appointed members ex officio:

• IAG representative

• IAU representative

• IERS representative

• Coordinating Center Director

Selected by Directing Board upon review of proposals from the relevant IVS component (see

below):

• Technology, Network, and Analysis Coordinators (3 total)

Elected by Directing Board upon recommendation from the Coordinating Center (see below):

• Members 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 other 10 persons must be members of different IVS components. 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 four-year terms once renewable.

Election of Board members 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 nominations for each representative from the relevant IVS components.

Networks representatives can be nominated by well-defined, operating networks accepted as such

by the Directing Board. For each position, the candidate who receives the largest number of votes

from the Associate Members will be elected. In case of a tie the Directing Board will make the

decision.

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.

1999 IVS Annual RepoLt

286
TermsofReference

Mostdecisionsby theBoardaremadebyconsensusor bysimplemajority voteof themembers

present.In caseof a tie, thechairshallvotebut otherwisedoesnot vote.If a two-thirdsquormnis

not present,thevoteshallbeheldlaterbyelectronicmail. A two-thirdsvoteof all Boardmembers

isrequiredto modifytheTermsof Reference,to changethechair,or to changeanyof themembers

electedby the DirectingBoardbeforethe normalterm expires.

The Boardmeetsat leastannually,or morefrequentlyif meetingsarecalledby the chairor at

the requestof at leastthreeBoardmembers.The Boardwill conductperiodicreviewsof theIVS

organizationandits mandate,functions,andcomponents.Thereviewsshouldbedoneeveryfour

years.

TheSecretariatof the DirectingBoardisprovidedby the CoordinatingCenter.

2.12. IVS Associate Members

Individuals affiliated with organizations that participate in any of the IVS components 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.

2.13. IVS Correspondents

IVS Correspondents 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 correspondents 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

• 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

Version date: 20 October, 1998

1999 IVS Annual Report 287
IVS Components

IVS Components

(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 P_dio Astronomia e Aplica_Ses Brazil

Nordes (ROEN) Espaciais

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

Key Stone Project Koganei 11m antenna Communications Research Laboratory Japan

Key Stone Project Kashima 11m antenna Communications Research Laboratory Japan

Key Stone Project Miura 11m antenna Communications Research Laboratory Japan

Key Stone Project Tateyama 11m 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 Alesund 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 l lm antenna National Institute of Polar Research Japan

288 1999 IVS Annual Report
IVS Components

Transportable Integrated Geodetic Bundesamt ffir Kartographie und Geod/isie Germany

Observatory (TIGO)

Tsukuba VLBI Station Geographical Survey Institute Japan

Nanshan VLBI Station of Urumqi Shanghai Observatory, Chinese Academy China

Astronomical Observatory (UAO) of Sciences

Westford Antenna, Haystack Observatory NASA Goddard Space Flight Center USA

Fundamentalstation Wettzell Bundesamt ffir Kartographie und Germany

Geod_isie and Forschungseinrichtung

Satellitengeod_ie de Technischen

Universit_t Mfinchen

Observatorio Astrondmico Nacional - Instituto Geografico Nacional Spain

Yebes

Yellowknife Geophysical Observatory Geodetic Survey Division, Natural Canada

Resources Canada

Operation Centers

Component Name Sponsoring Organization Country

Geodetic Institute Bonn Geod_itisches Institut der Universit_it Bonn Germany

CORE Operation Center NASA Goddard Space Flight Center USA

NEOS Operation Center National Earth Orientation Service USA

Correlators

Component Name Sponsoring Organization Country

Bonn Astro/Geo Correlator at the Bundesamt ffir Kartographie und Germany

Max-Planck-Institute for Radio Astronomy Geod_ie and Geod_tisches Institut der

Universit_t Bonn

EVN Data Processor at JIVE Joint Institute for VLBI in Eur_])e Netherlands

Key Stone Project Communications Research Labcratory Japan

MIT Haystack Observatory Correlator NASA Goddard Space Flight ,(;enter USA

Institute of Applied Astronomy Correlator Institute of Applied Astrono_:y Russia

Tsukuba VLBI Center Geographical Survey Institute Japan

Washington Correlator National Earth Orientation Service USA

1999 IVS Annual Report 289
IVSCo_lponents

Data Centers

Component Name Sponsoring Organization Country

BKG, Leipzig Bundesamt fiir Kartographie und Geod_ie 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_tisches Forschungsinstitut Germany

Forsvarets forskningsinstitutt (FFI) Norwegian Defence Research Norway

Establishment

GIUB-BKG Analysis Center Geod_tisches Institut der Universitiit Germany

Bonn and Bundesamt ffir Kartographie

und Geod_ie

Goddard Space Flight Flight Center NASA Goddard Space Center USA

Haystack Observatory NASA Goddard Space Flight Center USA

Institute of Applied Astronomy Institute of Applied Astronomy Russia

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

Shanghai Observatory Shanghai Observatory, Chinese Academy China

of Sciences

U. S. Naval Observatory U.S. Naval Observatory USA

290 1999 IVS Annual Repro t
IVS Components

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

Institut d'Estudis Espacials de Catalunya Institut d'Estudis Espacials de Catalunya Spain

Joint Institute for VLBI in Europe (JIVE) Joint Institute for VLBI in Europe Netherlands

Onsala Space Observatory Chalmers University of Technology Sweden

1999 IVS Annual Report 291
ContributingInstitutions

Addresses of Institutions Contributing to this Report

(listed alphabetically by country)

Centro de R_dio-Astronomia e Aplica_Ses Espaciais (CRAAE)

Instituto Presbiteriano Mackenzie

Rua da Consola_fio 896

01302-907 S_o Paulo

SP

Brazil

http://craae.mackenzie-br

R_dio-Observatdrio Espacial do Nordeste, ROEN

Rua Josd Hipolito S/N

Bairro Tupuid

61760-000 Eusdbio

CE

Brazil

Geodetic Survey Division, Natural Resources Canada

615 Booth Street

Ottawa

Canada KIA 0E9

http://www.geod.nrcan.gc-ca

CRESTech Space Geodynaznics Laboratory

4850 Keele St.

Floor 1 North York

Ontario

Canada M3J 3K1

http://www.sgl.crestech.ca

National Astronomical Observatory, Chinese Academy of Sciences

80 Nandan Rd.

Shanghai 200030

P.R. China

National Astronomical Observatory, Chinese Academy of Sciences

South Beijing Road 40

sub-5

Urumqi

Xinjiang 830011

P.R. China

1999 IVS Annual Report

292
ContributingInstitution_

ObservatoiredeParis,DANOF/UMR8630

61avenuedel'Observatoire

75014Paris

France

http://www.obspm.fr

ObservatoiredeBordeaux

2ruedel'Observatoire

BP89

33270Floirac

France

http://www.observ.u-bordeaux.fr

Bundesamt ffir KartographieundGeod_ie,Leipzig

Karl-Rothe-Strai3e10-14

D-04105Leipzig

Germany

http://www.leipzig.ifag.de

Bundesamt ffir Kartographie und Geod_sie

Sackenrieder Strat3e 25

D-93444 KStzting

Germany

http://www.wettzell.ifag.de

Geod_itisches Institut der Universit_t Bonn

Nussallee 17

D-53115 Bonn

Germany

http://giub.geod.uni-bonn.de/vlbi

Deutsches Geod_itisches Forschungsinstitut (DGFI)

Marstallplatz 8

80539 Miinchen

Germany

http://www.dgfi.badw-muenchen.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 Gobetti 101

40129 Bologna

Italy

http://www.ira.cnr.it

1999 IVS Annum Report 293
ContributingInstitutions

IstitutodiRadioastronomiadelCNR,StazioneVLBIdi Noto

C.P.141

1-96017NotoSR

Italy

http://www.ira-noto-cnr.it

KashimaSpaceResearchCenter,CommunicationsResearchLaboratory

893-1Hirai

Kashima

Ibaraki314-0012

Japan

http://www.crl.go.jp/ka/index.html

NationalinstituteofPolarResearch

1-9-10Kaga

Itabashi-ku

Tokyo173-8515

Japan

http://www.nipr.ac.jp/welcome.html

Geographical Surveyinstitute,JAPAN

Kitasato1Tsukuba

Ibaraki

Japan

http://vldb.gsi-mc.go.jp/sokuchi/vlbi/

Geodeticinstitute,NorwegianMappingAuthority

Kartverksveien

Hcnefoss

Norway

http://www.statkart.no

Forsvaretsforskningsinstitutt (FFI) (NorwegianDefenceResearchEstablishment)

FFI/E

Box25

2007Kjeller

Norway

Astronomical InstituteofSaint-PetersburgUniversity

Bibliotechnayasq.

Petrodvorets

St. Petersburg

Russia198904

http://www.astro.spb.ru

InstituteofAppliedAstronomyofRussianAcademyofSciences

Zhdanovskayastreet8

St. Petersburg

Russia197110

http://www.ipa.rssi-ru

1999IVSAnnualRepoiL

294
ContributingInstitution_

InstituteofAppliedAstronomyof RussianAcademyofSciences

nab.Kutuzova10

St. Petersburg

Russia191187

http://www.ipa.nw.ru

HartebeesthoekRadioAstronomyObservatory

POBox443

Krugersdorp1740

SouthAfrica

http://www.hartrao.ac.za

ObservatorioAstronSmicoNacional

Apartado1143

E-28800Alcal_deHenares

Spain

http://www.oan.es/

Institutd'EstudisEspacialsdeCatalunya

Edif.Nexus-204

GranCapitan2-4

08034Barcelona

Espafia

http:/ /www.ieec.fcr.es /

Onsala Space Observatory

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

Main Astronomical Observatory, Ukrainian National Academy of Sciences

Main Astronomical Observatory

Golosiiv

252650 Kiev-022

Ukraine

http://www.mao.kiev.ua

Jet Propulsion Laboratory

4800 Oak Grove Drive

Pasadena, CA 91109

USA

http://www.jpl.nasa.gov

1999 IVS Annual Report 295
ContributingInstitutions

MIT Haystack Observatory

Off Route 40

Westford, MA 01886-1299

USA

http: //www.haystack.mit.edu

Gilmore Creek Geophysical Observatory

NOAA/NESDIS CDA Station

GCGO/VLBI

1300 Eisele Rd

Fairbanks, Alaska 99712

USA

http://www.fcdas.noaa.gov

Kokee Park Geophysical Observatory

Kokee State Park

P.O. Box 538

Waimea, Hawaii 96798

USA

NASA Goddard Space Flight Center

Code 926 and 920.1

Greenbelt, MD 20771

USA

http://lupus.gsfc.nasa-gov

National Radio Astronomy Observatory (NRAO)

PO Box 2

Green Bank, WV 24944

USA

http://www.gb.nrao.edu

U.S. Naval Observatory

Code EO

3450 Massachusetts Avenue NW

Washington, D.C. 20392

USA

ftp://casa.usno.navy.mil/navnet/README.n9903

1999 IVS Annual Report

296
AssociateMembers,

IVS Associate Members

Name Institution ]Country

Amagai, Jun Communications Research Japan

Laboratory

Andersen, Per Norwegian Defence Research Norway

Helge Establishment

Aoki, Kazuo

Archinal, Brent

Arias, Felicitas

Bauernfeind,

Erhard

Bayer, Karen

Geographical Survey Institute

U. S. Naval Observatory

Facultad de Ciencias

Astronomicas y Geofisicas, Univ.

Nac. De La Plata

Forschungseinrichtung

SatellitengeodKsie de

Technischen Universit/it

Miinchen

Raytheon/Goddard Space Flight

Center

Beck, Norman Geodetic Survey Division,

Natural Resources Canada

Behrend, Dirk

Bergman, Per

B_rub@, Mario

Bianco,

Giuseppe

Institut d'Estudis Espacials de

Catalunya

Onsala Space Observatory

Geodetic Survey Division,

Natural Resources Canada

Agenzia Spaziale Italiana

Boerger, Klaus Geod_tisches Institut der

Universit_tt Bonn

Bolotin, Sergei

Booth, Roy

Bosworth, John

Bougeard,

Mireille

Brazeau,

Sylvain

Buretta, Tom

Buttaccio, Salvo

Campbell,

James

National Academy of Sciences,

Kiev

Onsala Space Observatory

NASA Goddard Space Flight

Center

Observatoire de Paris

Geodetic Survey Division,

Natural Resources Canada

MIT Haystack Observatory

Istituto di Radioastronomia

CNR

Geod_itisches Institut der

Universit_t Bonn

E-mail

amagai@crl.go.jp

per-helge.andersen@ffi.no

Japan vlbi@gaos.gsi-mc.go.jp

USA baa@casa.usno.navy.mil

Argentina felicita@fcaglp.fcaglp.unlp.edu.ar

Germany bauernfeind@wettzell.ifag.de

USA

Canada

kdb@leo.gsfc.nasa.gov

norman.beck@geocan.nrcan.

gc.ca

Spain behrend @ieec.fcr.es

Sweden bergman@oso.chalmers.se

Canada mario@gdim.geod.nrcan.gc.ca

Italy

Germany

Ukraine

Sweden

USA

bianco@asi.it

boerger@uni-bonn.de

bolotin@mao.kiev.ua

roy@oso.chalmers.se

jmb@ltpmail.gsfc.nasa.gov

France bougeard@hpvlbi.obspm.fr

Canada brazeau@geod.nrcan.gc.ca

USA

Italy

Germany

tburetta@haystack.mit.edu

buttaccio@ira.noto.cnr.it

campbell@sn_geod_l .geod.unibonn.de

1999 IVS Annual Report 297
AssociateMembers

Name Institution Country E-mail

Cannon, Wayne SpaceGeodynamicsLaboratory Canada wayne@sgl.crestech.ca

H.

Cappallo, Roger

Carlson, Brent

Carter, Merri

Sue

Caskey, Steve

Chao, Benjamin

Chestnut, Pete

Clark, Thomas

A.

MIT Haystack Observatory

Dominion Radio Astrophysical

Observatory

U. S. Naval Observatory

Lockheed Martin

NASA Goddard Space Flight

Center

National Radio Astronomy

Observatory, Green Bank

NASA Goddard Space Flight

Center

Observatorio Astron6mico

National

USA

Canada

USA

USA

USA

USA

USA

Spain Colomer,

Francisco

Colucci, Telespazio SpA Italy

Giuseppe

Combrinck, Hartebeesthoek Radio South

Ludwig Astronomy Observatory Africa

Corey, Brian MIT Haystack Observatory USA

Onsala Space Observatory

AlliedSignal Technical Services

Corp

AlliedSignal Technical Services

Corp.

Geodetic Survey Division,

Natural Resources Canada

AlliedSignal Technical Services

Corp

Corneliusson,

Fredrik

Covey, Rawland

Cox, Clyde

Sweden

Daniels, Mike

de-Vicente, Observatorio Astron6mico Spain

Pablo Nacional

Deigel, Irv USA

del Rosso,

Domenico

Dewdney, Peter

Digre, Helge

Doi, Koichiro

Telespazio SpA

Dominion Radio Astrophysical

Observatory

Norwegian Mapping Authority

National Institute of Polar

Research

Chinese Academy of Sciences

Joint Laboratory for Radio

Astronomy

rcappallo@haystack.mit.edu

bcarlson@drao.nrc.ca

msc@usno01.usno.navy.mil

steese@icefog.gcgo.nasa.gov

chao@denali.gsfc.nasa.gov

Dong, Yousuo

Drewes,

Hermann

pchestnu@nrao.edu

clark@tomcat.gsfc.nasa.gov

colomer@oan.es

colucci@asi.it

ludwig@bootes.hartrao.ac.za

bcorey@haystack.mit.edu

fredrikc@oso.chalmers.se

USA mv3@cddis.gsfc.nasa.gov

USA kokee@pele.kpgo.hawaii.edu

Canada mike.daniels@gdim.geod.nrcan.

gc.ca

Italy

vicente@cay.oan.es

diegeli@clmmp003.atsc.

allied.corn

domenico_delrosso@telespazio.it

Canada ped@drao.nrc.ca

Norway helge@gdiv.statkaxt.no

Japan doi@nipr.ac.jp

China

Deutsches Geodotisches Germany

Forschungsinstitut

uaoQpublic.wl.xj.cn

drewes@dgfi.badw-muenchen.de

298 1999 IVS Annual Report
AssociateMembers

Name Institution Country E-mail

Dube, Maurice USA dube@cddis.gsfc.nasa.gov

Elgered, Gunnar

Engen, Bjorn

Essa'ifi, Najat

Eubanks, T.

Marshall

Farley, Stephen

Feil, Georg

Raytheon/Goddard Space Flight

Center

Onsala Space Observatory

Norwegian Mapping Authority

Observatoire de Paris

U. S. Naval Observatory

Geodetic Survey Division,

Natural Resources Canada

Space Geodynamics Laboratory

Sweden

Norway

Ft'a.nce

USA

Canada

Canada

Feissel, Martine Observatoire de Paris France

Fey, Alan U.S. Naval Observatory USA

Frolov, Vladimir Institute of Applied Astronomy Russia

Fujita,

Masaharu

Communications Research

Laboratory

Fukuzaki,

Yoshihiro

Furuya, Masato

Geographical Survey Institute

Communications Research

Laboratory

Observatoire de Paris

National Radio Astronomy

Observatory, Green Bank

Raytheon/Goddard Space Flight

Center

Observatorio Astrondmico

Nacional

Observatoire de Paris

Raytheon/Goddard Space Flight

Center

Gambis, Daniel

Ghigo, Frank

Gomez, Frank

G6mezGonz£1ez,

Jesfis

Gontier,

Anne-Marie

Gordon, David

Japan

kge@oso.chalmers.se

bjorne@gdiv.statkart.no

essaifi@hpvlbi.obspm.fr

tme@cygx3.usno.navy.mil

farley@geod.nrcan.gc.ca

georg@sgl.erestech.ca

feissel@obspm.fr

alf@alf.usno.navy.mil

fvn@isida.ipa.rssi.ru

Gubanov,

Vadim

mfujita@crl.go.jp

Japan vlbi@gaos.gsi-mc.go.jp

Japan mf@crl.go.jp

France

USA

USA

Spain

France

USA

Grachev, Valery Institute of Applied Astronomy Russia

Gradinarsky, Onsala Space Observatory Sweden

Lubomir

Institute of Applied Astronomy Russia

Gueguen,

Erwan

Haas, Rfidiger

Hammargren,

Roger

Hanssen, Rune

I.

Istituto di Radioastronomia

CNR

Onsala Space Observatory

Onsala Space Observatory

Norwegian Mapping Authority

AlliedSignal Technical Services

Corp.

Harms, Matt

gambis@obspm.fr

fghigo@nrao.edu

fgg@gemini.gsfc.nasa.gov

gomez@oan.es

gontier@obspm.fr

dgg@leo.gsfc.nasa.gov

gratch@isida.ipa.rssi.ru

lbg@oso.chalmers.se

gubanov@isida.ipa.rssi.ru

Italy gueguen@hp-j.itis.mt.cnr.it

Sweden

Sweden

Norway

USA

hmas@oso.chalmers.se

roger@oso.chalmers.se

rune.hanssen@gdiv.statkart.no

kokee@pele.kpgo.hawaii.edu

1999 IVS Annual Report 299
AssociateMembers

[Name

Hase, Hayo

Himwich, Ed

Hinteregger,

Hans

Holland, David

Huang, Xinyong

Ichikawa,

Ryuichi

Ipatov,

Alexander

Ipatova, Irina

Ishihara, Misao

Iwata, Masao

Jacobs, Chris

Jenson, George

Johansson,

Karl-]_ke

Johansson, Jan

M.

Johansson, Lars

E.B.

Johnston,

Kenneth

Josties, Jerry

Kaneko, Akihiro

Kaufmann,

Pierre

Kawai, Eiji

Kaydanovsky,

Michael

Kennard, Ruth

Kilger, Richard

Kim, Kelly

Kinzham, Kerry

Institution

Bundesamt fiir Kartographie

und Geod_ie

NVI, Inc./Goddard Space Flight

Center

MIT Haystack Observatory

Country

Germany

USA

USA

Norwegian Mapping Authority Norway

China Shanghai Observatory, Chinese

Academy of Sciences

Communications Research

Laboratory

Institute of Applied Astronomy

Institute of Applied Astronomy

Geographical Survey Institute Japan

Geographical Survey Institute Japan

Jet Propulsion Laboratory

Geodetic Survey Division,

Natural Resources Canada

Onsala Space Observatory

Onsala Space Observatory

E-mail

hase@wettzell.ifag.de

weh@vega.gsfc.nasa.gov

hhinteregger @haystack.mit .edu

david@gdiv.statkart.no

xhuang_shao.ac.cn

Japan richi@crl.go.jp

Russia lpatov@ipa.rssi.ru

Russia lpatova@isida.ipa.rssi.ru

USA

vlbiQgaos.gsi-mc.go.jp

vlbi@gaos.gsi-mc.go.jp

chris.j acobs@jpl.nasa.gov

Canada xgeop@ssimicro.com

Sweden kaj@oso.chalmers.se

Sweden jmj@oso.chalmers.se

Onsala Space Observatory Sweden

U. S. Naval Observatory USA

USA

Japan

U. S. Naval Observatory

Communications Research

Laboratory

Centro de Radio Astronomia e

Aplicacoes Espaciais

Brazil

Communications Research Japan

Laboratory

Institute of Applied Astronomy Russia

Raytheon/Goddard Space Flight

Center

Forschungseinrichtung

Satellitengeodiisie de

Technischen Universit_it

Miinchen

AlliedSignal Technical Services

Corp.

U. S. Naval Observatory

USA

Germany

USA

USA

leb@oso.chalmers.se

kjj @astro.usno.navy.mil

jos@casa.usno.navy.mil

kaneko@crl.go.jp

kaufmann@usp.br

kawa@crl.go.jp

kmn@isida.ipa.rssi.ru

kennard@cddis.gsfc.nasa.gov

kilger@wettzell.ifag.de

kokee@pele.kpgo.hawaii.edu

kak@cygx3.usno.navy.mil

1999 IVS Annual P_po, L

300
AssociateMembem

Name

Kiuchi,Hitoshi

Klatt, Calvin

Kodak,Charles

A.

Koltsov,Nikolay

Kondo,Tetsuro

Korkin,Edward

Koyama,

Yasuhiro

Kronschnabl,

Gerhard

Kurihara,

Noriyuki

LaFrance,

Jacques

Lanotte,

Roberto

Li, Suqin

Li, Jinling

Liang,Shiguang

Liu,Xiang

Lizin,Igor

Lonsdale,Colin

Lucena,Antonio

Macilio

Ma,Chopo

Maccaferri,

Giuseppe

MacMillan,Dan

Malkin,Zinovy

Mamat,Rizwan

Institution

CommunicationsResearch

Laboratory

GeodeticSurveyDivision,

NaturalResourcesCanada

AlliedSignal Technical Services

Corp

InstituteofAppliedAstronomy

CommunicationsResearch

Laboratory

InstituteofAppliedAstronomy

Communications Research

Laboratory

Bundesamt fiir Kartographie

undGeod_ie

CommunicationsResearch

Laboratory

Geodetic Survey Division,

Natural Resources Canada

Telespazio SpA

Chinese Academy of Sciences

Joint Laboratory for Radio

Astronomy

Shanghai Observatory, Chinese

Academy of Sciences

Shanghai Observatory, Chinese

Academy of Sciences

Chinese Academy of Sciences

Joint Laboratory for Radio

Astronomy

Institute of Applied Astronomy

MIT Haystack Observatory

Centro de Radio Astronomia e

Aplicacoes Espaciais

NASA Goddard Space Flight

Center

Istituto di Radioastronomia

CNR

NVI, Inc./Goddard Space Flight

Center

Institute of Applied Astronomy

Chinese Academy of Sciences

Joint Laboratory for Radio

Astronomy

[Country

Japan

Canada

USA

Russia

Japan

Russia

Japan

Germany

Japan

Canada

Italy

China

China

China

China

Russia

USA

Brazil

USA

E-mail

kiuchi@crl.go.jp

klatt@geod.emr.ca

kodakc@thorin.atsc.allied.com

nec@isida.ipa.rssi.ru

kondo@crl.go.jp

korkin@isida.ipa.rssi.ru

koyama@crl.go.jp

kron@wettzell.ifag.de

kurihara@crl.go.jp

lafrance@geod.emr.ca

lanotte@hp835.mt.asi.it

uao@public.wl.xj.cn

jll@shao.ac.cn

sgliang@shao.ac.cn

uao@public.wl.xj.cn

lizin@isida.ipa.rssi.ru

clonsdale@haystack.mit.edu

macilio@roen.inpe.br

cma@virgo.gsfc.nasa.gov

Italy beppe@ira.bo.cnr.it

USA dsm@leo.gsfc.nasa.gov

Russia

China

malkin@isida.ipa.rssi.ru

uao@public.wl.xj.cn

1999 IVS Annual Report 301
AssociateMembers

Namc

Manabe,Seiji

Mantovani,

Franco

Mardyshkin,

Vyacheslav

Martin,Jim

Matsuzaka,

Shigeru

McCarthy,

Dennis

Michailov,

Andrey

Mitchell,

Donald

Molotaj,

Olexander

MortenTangen,

Leif

Miiskens,Arno

Nakajima,

Junichi

Nanni,Mauro

Negusini,Monia

Nemoto,Keizo

Nesterov,

Nikolay

]Institution

NationalAstronomical

ObservatoryofJapan

IstitutodiRadioastronomia

CNR

InstituteofAppliedAstronomy

U.S.NavalObservatory

Geographical SurveyInstitute

U.S.NavalObservatory

InstituteofAppliedAstronomy

AlliedSignal TechnicalServices

Corp.

NationalAcademyofSciences,

Kiev

NorwegianMappingAuthority

Geod_tischesInstitutder

Universit_tBonn

CommunicationsResearch

Laboratory

IstitutodiRadioastronomia

CNR

Istitutodi Radioastronomia

CNR

Geographical SurveyInstitute

LaboratoryofRadioastronomy

of CrimeanAstrophysical

Observatory

Newby,Paul SpaceGeodynamicsLaboratory

Nicolson,

George

Niell,Arthur

Nikitin,Pavel

Nilsson,Bi5rn

Noll,Carey

Nothnagel,Axel

Novikov,

Alexander

Hartebeesthoek Radio

Astronomy Observatory

MIT Haystack Observatory

Laboratory of Radioastronomy

of Crimean Astrophysical

Observatory

Onsala Space Observatory

NASA Goddard Space Flight

Center

Country E-mail

Japan manabe@gprx.miz.nao.ac.jp

Italy

Russia

USA

Japan

USA

Russia

USA

Ukraine

Norway

Germany

Japan

Italy

Italy

fmantovani@astbol.bo.cnr.it

vvm@isida.ipa.rssi.ru

]om@cygx3.usno.navy.mil

vlbi@gaos.gsi-mc.go.jp

dmc@maia.usno.navy.mil

agm@isida.ipa.rssi.ru

kokee@pele.kpgo.hawaii.edu

mol@aoku.freenet.kiev.ua

leifm@gdiv.statkart.no

mueskens@mpifr-bonn.mpg.de

nakajiQcrl.go.jp

nanni@ira.bo.cnr.it

negusini@astbol.bo.cnr.it

Japan vlbi@gaos.gsi-mc.go.jp

Ukraine nesterov@crao.crimea.ua

Canada paul@sgl.crestech.ca

South

Africa

USA

Ukraine

Sweden

USA

Geod_tisches Institut der Germany

Universit_t Bonn

Space Geodynamics Laboratory Canada

george@bootes.hartrao.ac.za

aniellQhaystack.mit.edu

nikitin@crao.crimea.ua

bin@oso.chalmers.se

noll@cddis.gsfc.nasa.gov

nothnagel@uni-bonn.de

sasha@sgl.crestech.ca

1999 IVS Annual Repo, t

302
AssociateMembers

Name Institution Country E-mail

Ogi,Shoichi Geographical SurveyInstitute Japan vlbi@gaos.gsi-mc.go.jp

Okamoto, CommunicationsResearch Japan okamoto@crl.go.jp

Ken'ichi Laboratory

Orfei,Sandro Istitutodi Radioastronomia Italy orfei@astbol.bo.cnr.it

CNR

Outhwaite,Bill GeodeticSurveyDivision, Canada xgeop@ssimicro.com

NaturalResourcesCanada

Parsley,Stephen JointInstituteforVLBIin Netherlandsparsley@jive.nfra.nl

Europe

Petrachenko, GeodeticSurveyDivision, Canada billp@cass.drao.nrc.ca

William NaturalResourcesCanada

Petrov,Leonid Geod_itisches Institutder Germany petrov@picasso.geod.uni-bonn.de

Universit_tBonn

Pettersson, Lars OnsalaSpaceObservatory Sweden larsp@oso.chalmers.se

Plag, NorwegianMappingAuthority Norway plag@gdiv.statkart.no

Hans-Peter

Poirier,Michael MIT HaystackObservatory USA mpoirier@haystack.mit.edu

Popelar,Josef Canada popelar@geod.emr.ca

Qian,Zhihan

Quick,Jonathan

Rahimov,Ismail

Ray,Jim

Reinhold,

Andreas

Rekkedai,Svein

Rioja,Maria

Rius,Antonio

Salnikov,

Alexander

GeodeticSurveyDivision,

NaturalResourcesCanada

Schatz,

Raimund

ShanghaiObservatory, Chinese

AcademyofSciences

HartebeesthoekRadio

AstronomyObservatory

China

South

Africa

qzh@shao.ac.cn

jonQbootes.hartrao.ac.za

InstituteofAppliedAstronomy Russia iar@ipa.rssi.ru

U.S.NavalObservatory USA jimr@maia.usno.navy.mil

Bundesamt fiir Kartographie Germany ar@leipzig.ifag.de

undGeod_ie

NorwegianMappingAuthority Norway sveinr@gdiv.statkaxt.no

Istitutodi Radioastronomia Italy rioja@ira.bo.cnr.it

CNR

Spain

Russia

Institutd'EstudisEspacialsde

Catalunya

InstituteofAppliedAstronomy

rius@ieec.fcr.es

salnikov@isida.ipa.rssi.ru

Sarti,Pierguido Istitutodi Radioastronomia Italy psarti@astbol.bo.cnr.it

CNR

Forschungseinrichtung Germany schatz@wettzell.ifag.de

Satellitengeod_ie de

Technischen Universit_it

Miinchen

Sweden

Germany

Scherneck, Onsala Space Observatory

Hans-Georg

Schliiter,

Wolf gang

Bundesamt fiir Kartographie

und Geodfisie

hgs@oso.chalmers.se

Schlueter@wettzell.ifag.de

1999 IVS Annual Report 303
Associate Members

Name

Wojdziak,

Reiner

Xue, Zhouhe

Yang, Zhigen

Yatskiv,

Yaroslav

Ye, Shuhua

Yoshino, Taizoh

Yusup, Aili

Zeitlhoefler,

Reinhard

Zen, Yong

Zernecke,

Rudolf

Zhang, All

Zhang, Hongbo

Institution

Bundesamt fiir Kartographie

und Geod_ie

Shanghai Observatory, Chinese

Academy of Sciences

Shanghai Observatory, Chinese

Academy of Sciences

National Academy of Sciences,

Kiev

Shanghai Observatory, Chinese

Academy of Sciences

Communications Research

Laboratory

Chinese Academy of Sciences

Joint Laboratory for Radio

Astronomy

Forschungseinrichtung

Satellitengeodiisie de

Technischen Universit_t

Miinchen

Chinese Academy of Sciences

Joint Laboratory for Radio

Astronomy

Forschungseinrichtung

Satellitengeodiisie de

Technischen Universit_t

Mfinchen

Chinese Academy of Sciences

Joint Laboratory for Radio

Astronomy

Chinese Academy of Sciences

Joint Laboratory for Radio

Astronomy

Country

Germany

China

China

Ukraine

China

Japan

China

Germany

China

Germany

China

China

E-mail

rw@leipzig.ifag.de

zhxue@shao.ac.cn

yangz@shat).ac.cn

yatskiv@mao.kiev.ua

ysh@shao.ac.cn

yosh@crl.go.jp

uao@public.wl.xj.cn

zeitlhoefler @wettzell.ifag.de

uao@public.wl.xj.cn

zernecke@wettzell.ifag.de

uao@public.wl.xj.cn

uao@public.wl.xj.cn

Zhang, Jin Chinese Academy of Sciences China uao@public.wl.xj.cn

Joint Laboratory for Radio

Astronomy

Zhou, Ruixian Shanghai Observatory, Chinese China zrxQshao.ac.cn

Academy of Sciences

306 1999 IVS Annual Report
List of Acronyms

List of Acronyms

APSG

APT

ARO

ASI

ATSC

BKG

CAS

CDDIS

CDP

CGS

CNR

CORE

CRAAE

CRF

CRL

CSTG

CTVA

DGFI

DORIS

DSN

EOP

EVN

FESG

FFI

GARS

GCGO

GGAO

GIUB

GLORIA

GPS

GSFC

GSI

GeoDAF

HartRAO

IAA

IAG

IAU

ICRF

IEEC

Asia Pacific Space Geodetic Program

Asia Pacific Telescope

Algonquin Radio Observatory (Canada)

Agenzia Spaziale Italiana (Italian Space Agency)

AlliedSignal Technical Services Corporation

Bundesamt fiir Kartographie und Geod£sie (Germany)

Chinese Academy of Sciences (China)

Crustal Dynamics Data Information System (USA)

Crustal Dynamics Project

Centro di Geodesia Spaziale (Italy)

Consiglio Nazionale delle Ricerche (Italy)

Continuous Observations of the Rotation of the Earth

Center for Radio Astronomy and Space Applications (Brazil)

Celestial Reference Frame

Communications Research Laboratory (Japan)

Commission on International Coordination of Space Techniques for Geodesy and

Geodynamics

Canadian Transportable VLBI Antenna

Deutsches Geod£tisches Forschungsinstitut (Germany)

Doppler Orbitography by Radiopositioning Integrated on Satellite

Deep Space Network

Earth Orientation Parameters

European VLBI Network

Forschungseinrichtung Satellitengeod/isie (Germany)

Forsvarets forskningsinstitutt (Norwegian Defence Research Establishment)

German Antarctic Receiving Station (Antarctica)

Gilmore Creek Geophysical Observatory (USA)

Goddard Geophysical and Astronomical Observatory (USA)

Geodetic Institute of the University of Bonn (Germany)

GLObal Radio Interferometry Analysis

Global Positioning System

Goddard Space Flight Center (USA)

Geographical Survey Institute (Japan)

Geodetical Data Archive Facility (Italy)

Hartebeesthoek Radio Astronomy Observatory (South Africa)

Institute of Applied Astronomy (Russia)

International Association of Geodesy

International Astronomical Union

International Celestial Reference Frame

Institut d'Estudis Espacials de Catalunya (Spain)

1999 IVS Annual Report 307
ListofAcronyms

IERS

IRIS-S

ITRF

IUGG

IVS

JARE

JIVE

JPL

KPGO

KSP

LNA

MAO

NAO

NASA

NEOS

NGS

NIPR

NOAA

NRAO

NRCan

OAN

OPAR

OSO

PRARE

ROEN

SEFD

SGP

SHAO

SINEX

SLR

TAC

TIGO

TRF

UAO

USNO

UT1

UTC

VLBA

VLBI

VSOP

WACO

WVR

International Earth Rotation Service

International Radio Interferometric Surveying-South

International Terrestrial Reference Frame

International Union of Geodesy and Geophysics

International VLBI Service for Geodesy and Astrometry

Japanese Antarctic Research Expedition (Japan)

Joint Institute for VLBI in Europe

Jet Propulsion Laboratory (USA)

Kokee Park Geophysical Observatory (USA)

Keystone Project (Japan)

Low noise amplifier

Main Astronomical Observatory (Ukraine)

National Astronomical Observatory (Japan)

National Aeronautics and Space Administration (USA)

National Earth Orientation Service (USA)

National Geodetic Survey (USA)

National Institute of Polar Research (Japan)

National Oceanic and Atmospheric Administration (USA)

National Radio Astronomy Observatory (USA)

Natural Resources Canada

Observatorio Astrondmico National (Spain)

Paris Observatory (France)

Onsala Space Observatory (Sweden)

Precision RAnge and Range-rate Experiment

ttAdio-Observatdrio Espacial do Nordeste (Brazil)

System Equivalent Flux Density

Space Geodesy Program (USA)

Shanghai Astronomical Observatory (China)

Solution INdependent EXchange format

Satellite Laser Ranging

Totally Accurate Clock

Transportable Integrated Geodetic Observatory (Germany)

Terrestrial Reference Frame

Urumqi Astronomical Observatory (China)

U. S. Naval Observatory (USA)

Universal Time

Coordinated Universal Time

Very Long Baseline Array (USA)

Very Long Baseline Interferometry

VLBI Space Observatory Program

Washington Correlator (USA)

Water Vapor Radiometer

308

1999 IVS Annual Report
REPORT DOCUMENTATION PAGE Form Approved

OMB No. 0704-0188

Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources,

gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this

collection of information, including suggestions for reducing this burden, to Washington Headquarters 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 Project (0704-0188), Washington, DC 20503.

1. AGENCY USE ONLY (Leave blank) 2. REPORT DATE 3. REPORT TYPE AND DATES COVERED

August 1999 Technical Paper

4. TITLE AND SUBTITLE 5. FUNDING NUMBERS

International VLBI Service for Geodesy and Astrometry--1999 Annual

Report

6. AUTHOR(S)

N.R. Vandenberg, Editor

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

11. SUPPLEMENTARY NOTES

920.3

8. PEFORMING ORGANIZATION

REPORT NUMBER

99B00075

10. SPONSORING / MONITORING

AGENCY REPORT NUMBER

TP--1999-209243

12a. DISTRIBUTION /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 1999 Annual Report of the International VLBI Service for Geodesy and

Astrometry -- IVS. The individual reports were contributed by VLBI groups in the international

geodetic community who constitute the components of IVS. The 1999 Annual Report documents

thework of the IVS components for the year ending March 1, 1999, the official inauguration date of

IVS. As the newest of the space technique services, IVS decided to publish this Annual Report as a

reference to our organization and its components. The entire contents of this Annual Report also

appear on the IVS website at: http://ivscc.gsfc.nasa.gov/pub/ar1999. The IVS 1999 Annual Report will

be a valuable reference for information about IVS and its components. This Annual Report will serve

as a baseline from which we can measure the anticipated progress of IVS in coming years.

14. SUBJECT TERMS

Geodesy, astrometry, VLBI, geophysics, Earth orientation, very long baseline

interferometry, interferometry, radio astronomy, geodynamics, reference frames, terrestrial

reference frame r celestial reference frame r lenigth of da_,rEarth s_'stem sciencer 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

3O8

16. PRICE CODE

20. LIMITATION OF ABSTRACT

UL

Standard Form 298 (Rev. 2-89)

Prescribed by ANSI Std Z39.18

298-102