News from IAU Division I "Fundamental Astronomy"



General Information n°5 (4 October 2002, IAU IB n 92)

General Information n°4 (20 June 2002, IAU IB n° 91)

General Information n°3 (17 April 2001)

General Information n°2 (12 April 2001, IAU IB89)

General Information n°1 (4 November 2000, IAU IB88)



General information n°5 (4 October 2002, IAU IB n 92)


Information on the next IAU GA :

The one-day Joint Discussion on "The International Celestial Reference System (ICRS): Maintenance and Future Realization" (chairs of the SOC: F. Mignard and D.D McCarthy), which was proposed by Commission 19 and Division I for the next IAU GA, has been selected as JD16 by the IAU Executive Committee and this JD has received the support of Division V (Stars) and Division X (Radio Astronomy) as well as of the International Association of Geodesy. This JD will include invited, contributed and poster presentations of the most recent scientific developments on the ICRS as well as revised concepts and models to access the system. It will also consider the plans for future maintenance and improvements of the ICRS, extension to other wavelengths, impact of space-based astrometry and relation to the dynamical reference system.

A one-day scientific meeting of Division will be held during the next GA, possibly on Monday, July 21. Scientific matters of Division I Working Groups and Commissions will be discussed during this meeting, as well as the future organization of these WG and Commissions and future scientific meetings in the scope of the Division. Among possible topics of discussions are issues relative to the implementation of IAU Resolutions 2000 and corresponding terminologies and future practices. The participation of all people belonging to Division I, or interested in the work of this Division, is welcome. Additionally, meetings of commissions 4, 7, 8 , 19 and 31 are planned as usual with possible scientific sessions to be advertized in advance. All the members of the commissions are invited to participate in these meetings.

The Joint Discussion on ICRS will be on Tuesday 22 July (2003) and the scientific meeting of Division I, possibly on Monday 21 July. Among the other selected meetings, the following ones are of interest for Division I: JD02 on "Mercury" (proposed by Division III : comm 16, 49 and WG ESP,), a "special session" on Recent Progress in planetary exploration" (proposed by Division III : comm 16) and a special session on "New classification schemes for multiple objects" (proposed by Division IV ). Is is hoped that the largest number of members of Division I participate in the GA in order that the discussions during the meetings above can be efficient for the progress in the scientific topics of the Division.



General information n°4 (20 June 2002, IAU IB n° 91)


Since the beginning of this year, there have been two scientific meetings organized by International Services which are Services of the IAU.

- The 3rd IVS (International Service for Geodesy & Astrometry) General Meeting was held, from 4 to 6 February 2002, in Tsukuba (Japan) and was followed by a one-day Workshop. The IVS holds such a meeting every two years. The purpose is to assemble representatives from all IVS components (Network Stations, Operation Centers, Correlators, Data Centers, Analysis Centers, Technology Development Centers and Coordinating Center) to share information, hear reports, and plan future activities. The meeting also provides a forum for interaction with other members of the VLBI and Earth science communities.

- A special IERS (International Earth Rotation Service) Workshop, devoted to the "Implementation of the new IAU Resolutions", was organized at Paris Observatory on 18 & 19 April 2002. The purpose of this Workshop was to prepare the scientific community to the implementation of the IAU 2000 (GA XXIV) Resolutions which should become effective on January 1, 2003 (see: These Resolutions define a new IAU framework concerning relativity for present and future applications in astrometry, celestial mechanics, time, and geodesy. A new precession-nutation model was adopted, and the new Celestial Intermediate Pole, Celestial and Terrestrial Ephemeris Origins were defined. During this Workshop, there have been fruitful discussions on the reasons for the adoption of the Resolutions, on their consequences as well as on the details concerning their implementation in astronomy, Earth rotation, ephemerides, etc. Some actions were required from the IERS in order to facilitate the practical use of the Conventions and to provide explanations and routines for the conversion between the old and new systems. Some actions were also required in education of the astronomical community. The details of the scientific input should be reflected in the Proceedings of this Workshop which will be published electronically before the end of June 2002 (see


General information n°3 (17 April 2001)


The IAU's SOFA (Standards Of Fundamental Astronomy) initiative seeks to promulgate an authoritative set of fundamental-astronomy constants and algorithms. The work is carried out by a panel called the SOFA Review Board, the membership of which was agreed just prior to the 1997 General Assembly.

The Board is pleased to announce that a first release of software is now available. The SOFA software libraries are a collection of subprograms, in source-code form, that implement official IAU algorithms for fundamental-astronomy computations. The subprograms at present comprise 27 "astronomy" routines supported by 52 "vector/matrix" routines, all written in Fortran. In future releases, the astronomy library will expand, and implementations in other languages will be introduced.

For further details please see the SOFA Center's website at


General Information n°2 (12 April 2001, IAU IB89)

The IAU Division I Working Groups for the triennium 2000-2003 have now been officially approved by the IAU Executive Committee. Some of these WG are the reappointment or the extension of previous ones and new WG have been formed on the "Redefinition of Universal Time Coordinated (UTC)" (chair: D.D.McCarthy, USA) and on "Future developments in ground based Astrometry" (chair: M. Stavinschi, Romania; co-chair: J. Kovalevsky, France). More information on these WG can been found here.

The International Earth Rotation Service (IERS), which was created in 1988 by the IAU and the IUGG, has got a new structure since January 1, 2001, corresponding to new Terms of Reference. IERS is now composed of a Central Bureau, six Product Centres, ten Combination Research Centres and the Analysis Coordinator. External services like IGS, ILRS and IVS serve as Technique Centres for the IERS. A new Directing Board has been formed (Chair: Jan Vondrak) and the new web site of the IERS, , provides key information on the IERS and its components as well as links to the IERS components

The International VLBI Service for Geodesy and Astrometry (IVS), which was created on 1 March 1999 as a Service of IAG and has been recognised as an IAU Service Organisation at the last General assembly in Manchester (Resolution B1.1), has now become, in 2001, a new member of the Federation of Astronomical and Geophysical Data Analysis Services (FAGS).

Very relevant to the activities of the Division I is the selection on 13 October 2000 of the GAIA mission as cornerstone 6 of the ESA science program. GAIA will analyze the composition, formation and evolution of our Galaxy by mapping with unprecedented precision one billion stars, and is due for launch no later than 2012. GAIA will reach an astrometric accuracy of 10 microarcseconds for star brighter than 15th magnitude, together with photometric measurements in the millimagnitude range and a survey of radial velocity down to magnitude 17. Virtually every branch of the astronomical research will be affected by the GAIA results when they are made available around 2017.



General Information n°1 (4 November 2000, IAU IB88)

New resolutions have been adopted during the General Assembly in Manchester among which resolutions B1 and B2 are of special interest to Division I; they have been prepared and discussed at IAU Colloquium 180 in Washington (March 2000) and then discussed again at Joint Discussion 2 "Models and Constants for Sub-microarsecond Astrometry" during the GA. Resolution B1 provides definitions, standard algorithms and parameters for modern realisations and transformations of space and time reference systems within the framework of General Relativity; this resolution, which is based on the adoption of the International Celestial Reference System (ICRS) as the IAU celestial reference system, from 1 January 1998, results from the proposals of Working Groups of the Division. Resolution B2 recommends to investigate possible changes in the current definition of UTC, which concerns especially time and Earth rotation studies. Working Groups of Division I have been organized to implement these resolutions. In order to follow the evolution of astrometry, Commissions 8 "Positional Astronomy" and 24 "Photographic Astrometry" have merged at the GA into one new Commission 8 "Astrometry". The new Organizing Committee of Division I consists of Presidents of commissions 4, 7, 8, 19 and 31 and of the past-President of the Division.

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