IAU Division I Working Group
``Nomenclature for Fundamental Astronomy'' (NFA)
Newsletter 7
Nicole Capitaine, 26 December 2005
All the NFA Working Group documents have been posted on the NFA web site, which includes
links to other sites relevant to the WG activities. A special page of the web site
provides links to educational documents that explain the NFA issue.
The WG has worked on selecting a consistent and well defined terminology for all the
quantities based on the IAU 2000 Resolutions in order that it will be recognized and adopted
by the astronomical community for various astronomical applications.
There has been detailed WG e-mail discussion on the terminology choices. The agreements
reached by the WG on these choices have been reflected in the
Draft NFA Recommendations which are supported by the NFA
explanatory documents.
The NFA issues and documents have been discussed during international meetings
in 2004 (see NFA WG report at the
Journées 2004 and NFA Discussion
at the Journées 2004 ) and in 2005 (see Latest Proposals
of the IAU NFA WG presented at the Journées 2005).
The NFA explanatory documents have been recently re-organized into two parts,
Part A which reports on the basis for the IAU Resolutions
and their implementation and Part B which provides
a more detailed description of the proposed terminology.
The latest revised version of the NFA WG Explanatory
Document B), entitled "Explanation of the proposed terminology",
is the nearly final revision of the B document. It has resulted from the WG
comments on previous versions of the documents, the very active WG e-mail
exchanges during the period March 2005-October 2005 and
discussion at the Journées 2005 (19-22 September) in Warsaw.
It contains the "NFA IAU 2000 Glossary"
that provides a set of detailed definitions that best explain all the terms
required for implementing the IAU 2000 resolutions.
Complementary and supporting material (e.g.a chart of the transformation process
from ICRS to observed places of stars) are included
in order to facilitate the understanding and implementation of the IAU 2000 resolutions,
as well as illustrating the Glossary.
Recent progress have been made in astronomical nomenclature in the relativistic
framework (Klioner and Soffel 2005). It should also be noted that the
Almanac Offices have begun to implement the WG recommendations beginning
with their 2006 editions (Hohenkerk 2005).
For more details on these issues, see the Proceedings of the Journées 2004
(N. Capitaine, ed.) and the Educational documents.
The NFA WG report to the IAU, 2003-2005, which will be
be published in the IAU Transactions A (Reports in Astronomy 2003-2006), contains an
updated version of the WG recommendations.
The Draft NFA WG IAU Resolution proposal
is intended to be submitted to the IAU by the NFA WG as an
IAU 2006 Resolution entitled "Supplement to the IAU 2000 Resolutions on reference frames"
containing two Recommendations of the NFA WG.
Recommendation 1 is on "Harmonizing the name of the pole and origin
to intermediate" and Recommendation 2 reports on the BCRS
and GCRS orientation that has been added to the IAU 2000 definition of BCRS and GCRS during
the WG discussion. It is also supported by the IAU Division 1 Working Group "Relativity
in Celestial mechanics, Astrometry and metrology" (RCMAM).
The next step of the NFA WG work will be the preparation of Part A of the explanatory document,
which is intended to explain the basis for the IAU Resolutions and their implementation
using the terminology proposed by the WG.
Proceedings of
the Journées 2004 "Systèmes de Référence
Spatio-Temporels", N. Capitaine (ed.), Observatoire de Paris
Hohenkerk, C., 2005, in Proceedings of the "Journées
2004 "Systèmes de Référence
Spatio-Temporels", N. Capitaine (ed.), Observatoire de Paris,
p 168.