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IERS Message No. 28                                           June 12, 2002
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IERS Workshop on the Implementation of the IAU 2000 Resolutions, 
held in Paris Observatory, 18-19 April 2002

The Workshop was organized after the initiative of the President of IAU
Division I, Nicole Capitaine, in order to widely discuss and explain all
possible aspects of the implementation of the new resolutions adopted by
the IAU at its General Assembly in August 2000. Having in mind that
these resolutions are to become effective since January 1, 2003, it was
decided by the IERS Directing Board to organize the Workshop in Paris in
April 2002, just before the General Assembly of EGS at Nice. The
composition of the SOC was approved, under the chair of Nicole
Capitaine. Other members of the SOC were D. Gambis, D.D. McCarthy, G.
Petit, J. Ray, B. Richter, M. Rothacher, M. Standish, and J. Vondrak. It
was decided that there will be only invited position papers presented
orally (provided in written form and displayed on the website before the
Workshop). A questionnaire was sent to the participants in advance to
identify key problems and questions to be taken into account in the
presentations. The responses (18 received before the Workshop) were
summarized by Bernd Richter in a document that was distributed to the
SOC members and invited speakers.

The program was divided into two parts. The first part included detailed
presentations and explanations of the contents of the Resolutions, the
background reasons for their adoption, associated concepts and
implementations as well as answers to specific questions, followed by a
summary of the responses to the questionnaire. This part included a
concrete proposal for the future IERS products that would be in
agreement with the Resolutions, and a poster session. The second part
was devoted to an extended discussion based on the responses to the
questionnaire and other questions asked by the audience.

About 80 participants from 20 countries took part in the meeting. The
program, as well as drafts of the position papers and other information
may be found at

   http://www.iers.org/workshop_2002/

During the discussions it was noted that the IUGG/IAG had not been
officially informed on the adoption of the resolutions, whereas these
concern reference systems and Earth's rotation, and therefore also
geodesy and geophysics. This point of view was not supported by the
IAG/IUGG Representative in the IERS Directing Board and it was pointed
out by several speakers that the IAU Resolutions resulted from the
discussions within the scientific community during more than ten years
and relied on the conclusions of several scientific meetings involving
scientists of broad astronomy/geodesy interests. It has however been
required that IUGG and IAG be officially consulted. Therefore Nicole
Capitaine was asked by the IERS Directing Board to initiate an official
letter to be sent by the IAU to the IUGG and IAG so that this can be
considered by the IUGG, before its next GA in 2003; the letter, signed
by the IAU General Secretary, was sent in May 2002.

The Workshop provided a good base for fruitful exchange of ideas between
the participants and presenters concerning the reasons for the adoption
of the Resolutions, their consequences and the details of their
implementation not only in Earth rotation studies, but also in
astrometry, ephemerides, astronomical almanacs etc. It allowed the
scientific community to have a better understanding of the Resolutions
and of their implementation and answered a large part of the questions
and criticisms which appeared in the responses to the Workshop
questionnaire. It also provided clear requirements from the users to the
IERS and to the scientists which are involved in the theoretical part of
the implementation of the Resolutions or in education of the
astronomical community. One of the most important results of the
Workshop is the decision of the IERS Directing Board to publish the
products both in the new and old system in parallel, beginning January
2003.

It followed from the discussions that certain actions are required from
the IERS and/or some of the presenters in order to improve the
consistency in the explanations for the implementation of the
Resolutions, to facilitate the practical use of the Conventions and to
provide explanations and routines for the conversion between the old and
new systems. All this shall be reflected in the final version of the
position papers to appear in the Proceedings of the Workshop that will
be published as a special issue of the IERS Technical Notes.

Jan Vondrak (IERS Directing Board, Chairman),
Nicole Capitaine (SOC, Chair)


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