Involve all the IVSAssociate Membersmore actively in the

"IVS life".

Dear IVS Associate Membersand Friends,

It's with pleasure that Iwelcome you to the firstissue of the IVS Newslet-ter. The suggestion forthe Newsletter camefrom our Technology Co-

ordinator Alan Whitney, stimulatedby Arthur Niell from Haystack Ob-servatory who sent an e-mail to the Direct-ing Board with the request to involve all theIVS Associate Members more actively in the"IVS life". The Directing Board discussed thisitem at its board meeting and decided topublish a newsletter three times a year. Theintention is to improve the flow of informa-tion among IVS members and to keep ev-eryone aware of major events. The news-letter will give IVS higher visibility not onlywithin the IVS member organizations and af-filiated organizations, but also to scientists

IVS NewsletterINAUGURAL ISSUEIssue 1, December 2001

Wolfgang Schlüter,

Dec. 2001Page 1

Second IVS General Meetingto be Held in Japanese EarlySpring−Fujinobu Takahashi, CRLLOC Chairman

VLBI technological development in Japan has a historyof more than 25 years. Japan has always developed VLBIsystems with the latest technologies. On this basis, CRL,GSI, NAO and other Japanese institutes actively continuelarge-scale and advanced VLBI observation networks

in related areas such as astronomy, geo-physics, and geodynamics. At least thenewsletter will help to make us as members

feel more a part of IVS.Everybody is encouraged and

invited to support the Newsletterby providing contributions. TheNewsletter will cover topics suchas new members, programs, re-sults, technology, network, boardmeetings summaries, meetings of

IVS and other services and more. If you haveany topic you feel is important for the com-munity send your contribution to the IVS Co-ordinating Center.

With my best wishes

throughout the Japanese islands. Moreover, JapaneseVLBIers support VLBI research and development in theAsia-Pacific region.

It is meaningful that the second General Meeting ofIVS will be held in Japan based on these activities.Participants will be able to observe the newest informationtechnologies as well as the newest VLBI systems.

February 4 when the General Meeting will start is aday called the first day of spring or “Risshun” in theJapanese calendar. It is said on the eastern Asian calendarthat spring starts from this day. Since the Japanese islandshave a long north-south extent, they will have many areaswhere still cold winter continues. Please come in earlyspring to Japan and feel the breath of “Risshun”.

Please visit the meeting web page athttp://ivscc.gsfc.nasa.gov/meetings/gm2002.

Wolfgang Schluter

IVS Chair

..

security, lighting, and housing should be finished by the end of2001.

A Scientific Board of TIGO for the supervision of thescientific exploitation of TIGO was selected from among themembers of the Chilean consortium and BKG.

During October 2001 the TIGO containers were loaded fortransport, with a planned departure from Hamburg onNovember 30. After a five-week sea voyage TIGO will arrive inPuerto Lirquen near Concepcion and be moved to its permanenthome the following week. Installation and check-out will occupythe first few months. The TIGO crew anticipates beginningoperations in the second quarter of 2002.

TIGO prepares for departure from Germany toChile.−Hayo Hase, BKG

With the sign-ature of an“A r r a n g e m e n t ”between BKG andthe Chilean con-sort ium (three

Universities in Concepcion and the mappingauthority IGM in Santiago) on June 21, 2000, theTIGO project became a joint project.

The realization of a new IVS network stationby the TIGO VLBI module in Concepcion, Chile,is progressing at various levels: policy, staffrecruitments, and platform construction.

Based on a bilateral note between Germany andChi le BKG wil l be able to relocate thefundamental station TIGO and three BKGexperts. The approval by the Chilean governmenthas just been received. The Chilean consortium willparticipate with 11 staff in total who will join thethree BKG experts.

The necessary infrastructure for TIGO has beenunder construction since January 2001 . A 2.5 km

access road in the forest of Concepcion was prepared for heavytrucks. Electricity was brought to the TIGO platform. InAugust and September the concrete foundation was poured forthe geodetic monuments for the radio telescope, SLR telescope,GPS, gravity meter, seismometer, and cable ducts.Communications access, water supply and sewage, fencing and

Mark 5 VLBI Data System to deployin 2002−Alan Whitney, MIT Haystack Observatory

The first prototype deployment of the Mark 5 disc-basedVLBI data system is expected in Spring 2002. This system,called Mark 5A, is the first stage of Mark 5 developmentand will directly replace an existing Mark 4 or VLBA tape drive.The Mark 5A builds on the success of the Mark 5demonstration system shown at the IVS TOW meeting atHaystack Observatory in March 2001. Approximately10 Mark 5A prototype systems will be delivered to sponsors ofthe Mark 5 development effort, including BKG, EVN/JIVE,KVN, MPI, NASA, NRAO and USNO. These systems will beused to validate proper operation with existing stations andcorrelators and to evaluate the Mark 5A system for effectivenessand robustness.

NEWS

Dec. 2001Page 2 Continued on next page

Mark 5 demonstration model.

"Lift-the-TIGOcontainers" trainingduring the visit of ourfuture TIGO colleaguesfrom Concepcion atWettzell, December2000.Left to right:Raul Escobar(UCSC),Eduardo Carvacho(UdeC),Oscar Cifuentes (IGM),Carlos Bustamante(UBioBio)

Future TIGO platform prepared for pouring the concrete.

The Mark 5 system is based almost entirely on commercialoff-the-shelf (COTS) components to provide a low-cost dataplatform capable of sustained operation at data rates up to1024 Mbps. The data is collected on an array of up to 16 discswhich are mounted in removable carriers (see photo) for ease ofuse. Current disc prices, based on $/GB are comparable to theprice of Mark4/VLBA tapes but continue to fall rapidly. By2004-5 , it is expected that disc prices will fall well below1 $US/GB. In addition, storage capacity of discs is rapidlyincreasing, with 100 Gb discs now readily available andexpected to increase to 1000 GB within the next 3 years.Loaded with sixteen 100 GB discs a Mark 5 system supportsabout 2.5 times the capacity of a single Mark4/VLBA tape.Loaded with sixteen 1000 GB discs, a Mark 5 system willsupport continuous recording at 1 Gbps for about 34 hours.

Other features of the Mark 5 system include the ability tosupport e-VLBI either by direct real-time data transmission overa network or buffered through the Mark 5 discs. In worksupported by DARPA, this capability will be tested over thenext year with an e-VLBI demonstration at near-Gbps speedsusing antennas at Haystack Observatory and NASA/GSFC,with correlation at Haystack.

The second stage of the Mark 5 effort is the development ofthe Mark 5B system, which will be fully VSI compliant and isexpected to be ready in late 2003. Considerable effort is beingmade to support interoperability between Mark 5A and Mark 5Bsystems for maximum flexibility and usefulness.

For more information on the Mark 5 system, please visithttp://fourier.haystack.mit.edu/haystack/vlbi.html where thereare also links to more detailed information, including the Mark 5memo series for detailed technical information.

Mark 5 Deploy cont.

Dec. 2001Page 3

NEWS

IAU Resolutions B1.1 Maintenance and Establish-ment of Reference Frames and Systems

The International Astronomical UnionNoting1. that Resolution B2 of the XXIIIrd General Assembly

(1997) specifies that "the fundamental reference frameshall be the International Celestial Reference Frame(ICRF) constructed by the IAU Working Group onReference Frames",

2. that Resolution B2 of the XXIIIrd General Assembly(1997) specifies "That the Hipparcos Catalogue shallbe the primary realisation of the International CelestialReference System (ICRS) at optical wavelengths", and

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

Recognising1. the importance of continuing operational observations

made with Very Long Baseline Interferometry (VLBI)to maintain the ICRF,

2. the importance of VLBI observations to the operationaldetermination of the parameters needed to specify thetime-variable transformation between the InternationalCelestial and Terrestrial Reference Frames,

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

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

Recommends1. that IAU Division I maintain the Working Group on

Celestial Reference Systems formed from Division Imembers to consult with the International Earth RotationService (IERS) regarding the maintenance of the ICRS,

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

3. that an official representative of the IVS be invited toparticipate in the IAU Working Group on CelestialReference Systems,

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

5. that the astrometric and geodetic VLBI observingprograms consider the requirements for maintenanceof the ICRF and linking to the Hipparcos optical frame inthe selection of sources to be observed (with emphasison the Southern Hemisphere), design of observingnetworks, and the distribution of data, and

6. that the scientific community continue with high priorityground- and space-based observations (a) for themaintenance of the optical Hipparcos frames andframes at other wavelengths and (b) for links of theframes to the ICRF.

"Teach me howto design VLBIcorrelators. Idon't care if ittakes all day."

IVS is a service of the IAU

IVS has been recognized as a Service of the International Associa-tion of Geodesy (IAG) since July 1999 when the General Assem-bly was held in Birmingham/England. Since the XXIVth GeneralAssembly of the International Astronomical Union (IAU) held inManchester/England, August 2000 the IVS is also recognized as aService of the IAU. Below is a reprint of the IAU resolution B1.1.

"Alan, Ineed a

career thathas job

security."

State of the Service:IVS After 2.5 Years−Wolfgang Schlüter, BKGIVS Chair

With only 2.5 years of existence, IVS is internationallyrecognized as a vital community. Evidence of our spirit can beseen by the support for our publications and by participationin IVS meetings. Nearly all the IVS components publishedcontributions in the 1999 and 2000 Annual Reports. Manycomponents provided important inputs to the Proceedings ofthe IVS 2000 General Meeting. Participation was much morethan expected in the 2000 IVS General Meeting, in two AnalysisWorkshops and in the Technical and Operations Workshop(TOW). On one side it is an indication of interest and willingnessto support IVS by the collaborating agencies. On the other sideit has to be recognized that the expectations of the agencies, theIAG and the IAU are high for generation of reliable, high quality,

timely products.Very impressive responses were

given to the Pilot Projects in dataanalysis organized by the AnalysisCoordinator, Axel Nothnagel. Mostof the IVS Analysis Centerscontributed solutions and thecomparisons were very encouraging.We anticipate that more AnalysisCenters will become involved inregular data analysis which willsignificantly improve the level ofconfidence in IVS products. So farthe Earth Orientation Parameterstime series are derived by solutionsof five IVS Analysis Centers,combined by the AnalysisCoordinator. The combined resultsare accepted as the official IVSproducts by the IERS. The stabilityof the combined time series isimproved by roughly 20% and theresults are much more robust withrespect to outliers.

The Mark 4 correlators becameoperational and the processingbacklog is nearly gone. From nowon we can pursue more andimproved observing programs for

better high quality products. The specification for the VLBIStandard Interface (VSI) was released, and it is hoped that itwill lead to more involvement of the various VLBI technologies(Mark 4, K4, S2) in the observing programs. The global VSIWorking Group, chaired by the IVS Technology Coordinator,Alan Whitney, and strongly supported by some IVS Associate

Members, was extremely successful (see the article on page 6about the award from the Japanese Ministry). Standard softwareinterface specifications are currently under development. Thedevelopment of Mark 5 and of e-VLBI will allow us to makedata transfer more efficient and will open new applications.

Two working groups set up by the IVS Directing Board haveperformed their obligations successfully. The working group(WG1) for mapping the GPS antenna phase center, chaired byBrian Corey, evaluated an error budget for possible VLBIcontributions in order to map the phase center of thetransmitting antennas of GPS satellites with respect to quasars.The WG1 reports indicated the limits of current VLBIpossibilities. One result has been not to propose an observingcampaign as no gain can be expected. The working group(WG2) on the IVS product definitions and related observingprograms, chaired by Harald Schuh, has written a report thatwill be important for evolving the IVS service functions over thenext few years. Clear specifications for the products are definedand related observing programs are proposed to generate thebest time series for the products with respect to the availableresources.

Since its beginning IVS has been a service of IAG(International Association of Geodesy). Due to the uniqueimportance of VLBI for the realization of the CRF, IVS is alsorecognized as a service of IAU (International AstronomicalUnion). IVS is also a service of FAGS (Federation of Astronomicaland Geophysical Data Analysis Services).

A change in the IVS Terms of Reference (ToR) was made toimprove the information flow with related groups by adding amembership category for Affiliated Organizations. Anotherchange in the ToR allows a better balance within the DirectingBoard in the representation of IVS components. The latter changeresulted in increasing the number of At Large positions fromtwo to three, so that a total of 15 members now serve on theboard.

A Taste of History....

30 Years Ago....

The first hardware VLBI correlator was put intooperation in 1971. This unit, designed at MITHaystack Observatory, was attached to a CDC3300general-purpose computer to correlate data takenwith the Mark I system, which recorded data ontostandard 1/2" open-reel computer tapes at 720 kbps.The Mark I correlator served faithfully until the late1970s when it was replaced by the Mark IIIcorrelator. How things have changed!

Dec. 2001Page 4

NEWS

The IVS Newsletter is publishedthree times annually, in April,August, and December.Contributed articles, pictures,cartoons, and feedback arewelcome at any time.

Please send contributions toivs-news@ivscc.gsfc.nasa.gov.The editors reserve the right toedit contributions. The deadlinefor contributions is one monthbefore the publication date.

Editors:Nancy Vandenberg, General Editor nrv@gemini.gsfc.nasa.govHayo Hase, Feature Editor hase@wettzell.ifag.deHeidi Johnson, Layout Editor hnj@haystack.mit.edu

The newsletter is published incolor with live links on the IVSweb site athttp://ivscc.gsfc.nasa.gov/.

NEWS

Dec. 2001Page 5

Dates to remember..

Annual Report deadlineJanuary 15, 2002

Registration deadline forGeneral Meeting 2January 10, 2002

Upcoming Meetings..

Fall AGUDec. 10-14, 2001San Francisco, CA

Second IVS General Mtg.Feb. 4-7, 2002Tsukuba, Japan

Mini-TOWFeb. 6, 2002Tsukuba, Japan

Third Analysis Mtg.Feb. 8, 2002Tsukuba, Japan

European GeophysicalSocietyApr. 21-26, 2001Nice, France

Spring AGUMay 28 - June 1, 2002Washington, D.C.

VLBI HOW TO...NEWSNews from the IVS AnalysisCoordinator−Axel Nothnagel and Christoph Steinforth,Geodetic Institute of the University of Bonn

The IVS combined solution for 24-hour NEOS-A derivedEOPs is generated using the following regular file submissionsfrom IVS Analysis Centers:

• bkg00001.eops (BKG)• gsf2001c.eops (GSF)• iaao0106.eops (IAA)• spu00001.eops (SPU)

In order to maintain consistency with the IERS C04 series,the biases as listed in table 1 are subtracted prior to thecombination process. These biases were determined from dataup to September 30, 2000. The weight factors for eachAnalysis Center are listed in the last column.

Table 1. Biases of each series relative to IERS C04 and weight factors.

Table 2 lists the current post fit biases and WRMS relative to theIVS combined series for polar motion and UT1-UTC. Thesmall residual biases which should ideally be zero are aconsequence of the fact that the initial bias determination aslisted in table 1 does not include data between the start of thecombination on October 1, 2000 and today. The WRMS valuesare computed after the biases have been removed.

Table 2. Biases and WRMS of EOP of each series relative to IVS combinedseries.

More details can be found on the IVS Analysis Coordinator’shome page http://giub.geod.uni-bonn.de/vlbi/IVS-AC.

How to Synchronize FormatterTime to GPS Time−Ed Himwich, NVI Inc./GSFC−Hayo Hase, BKG

Why measure offsets? The clock offsets betweenthe VLBI formatter and the global GPS timemust be known on the sub-microsecond level.The offset is used not only to align the data atthe correlators, but it will also be used toimprove the final values of the UT1 and UT1rate observables derived from quasarobservations. The IVS is pushing to achievehigher accuracies in its products, in particularthe UT1 goal is 2–3 µsec and the UT1 rategoal is 0.3–0.5 µsec/day. More care in handlingclock offsets at the stations and during dataanalysis will be required to achieve this goal.

Measuring the offsets. Every station needs touse the gps-fmout command to measure thesub-second portion of the clock offset andsy=run setcl & to check for clock jumps ofmore than one second. With these twocommands logged, the correlator can recoverthe data even if the formatter jumps during anexperiment. The value of gps-fmout willalso be used to calibrate the time of theobservations to better than a microsecond.

Two important points need to be emphasized about the offsetmeasurement. (1) The command form must agree with thewiring. Use gps-fmout if the GPS 1 PPS starts the time intervalcounter; use fmout-gps if the formatter 1 PPS starts thecounter. (2) We really want to use the formatter and not themaser which may have some unknown offset relative to theformatter.

Clock jumps. If the clock jumps during asession, we don’t normally reset the clock becausethis means you have just introduced anotherjump. The first jump degrades the geodeticsolution and the second one would degrade itfurther. There are only two conditions underwhich a station clock should be reset, whichdepend on the size of the jump as well as thecorrelator. Read the full memo (see referencebelow) for the details.

For more information on setting up the gps-fmoutmeasurement at your station, please read the full clock offsetmemo on the Network Coordinator’s page athttp://ivscc.gsfc.nasa.gov/nc.

� �

The units in the tables were incorrect in the printed version.The editors regret the errror.

IVS Coordinating CenterNASA GSFCCode 920.1

Greenbelt, MD 20771

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

phone: 301-614-5939fax: 301-614-5970

Dec. 2001 page 6

Meeting CRL PresidentTakashi Iida.(left to right:

Nancy Vandenberg,TetsuroKondo,

Wolfgang Schlüter,Takashi Iida)

Wolfgang Schlüter receiving the award fromMinister Toranosuke Katayama

IVS Receives Award fromJapanese Ministry on "RadioDay"−Nancy Vandenberg, NVI Inc./GSFC

The IVS Directing Board received an award from theJapanese Ministry of Public Management, Home Affairs,Posts, and Telecommunications on June 1, 2001.

Within the ministry, the month of June celebrates eventsrelated to radio waves and June 1 is known as Radio Day.Awards are presented on this day to begin the month-long celebration.

In February, Dr. Tetsuro Kondo of CommunicationsResearch Laboratory (CRL) submitted the nominationof IVS for consideration for these annual awards. CRL

strongly supported thenomination, and it was announcedin late April that we won! It is agreat honour for IVS, and we haveto thank Tetsuro Kondo for theinitiative and his activity. Theinternational and interdisciplinarycooperation of the group aroundAlan Whitney and the strongcontribution of CRL and

personally from Kondo-san resulting in the releasing ofthe VSI-H specifications has been regarded as animportant step in VLBI and worthy for an award. IVSexpresses its appreciation and gratitude to the VSI workinggroup, in which IVS and related groups are involved,and explicitly to Alan Whitney and to Kondo-san for thesuccess.

CRL invited Wolfgang Schlüter, IVS Chair, and NancyVandenberg, IVS Coordinating Center Director, to Japanto participate in the ceremony and receive the award onJune 1, 2001. The ceremony and other events of the daywere held in the Imperial Hotel in Tokyo. The full storyis available at http://ivscc.gsfc.nasa.gov/radio/.