Nomenclature for Fundamental Astronomy (NFA)


This web page provides documents that have been prepared by the IAU Division I Working Group "Nomenclature for Fundamental Astronomy" during the period 2003-2006. The purpose of the NFA WG was to facilitate the understanding of the IAU 2000 resolutions and their implementation and to provide a well defined terminology, which was endorsed by the IAU 2006 Resolutions.

The intention of this website is to give users access to all the various documents and thus provide a useful educational pool of material, at various levels of complexity.


Summary of the NFA Working Group activities  ( PDF file )

Final NFA Recommendations (August 2006)  ( PDF file )

Explanation behind the terms  ( PDF file )

NFA IAU 2006 Glossary  ( PDF file )
This glossary provides a set of detailed definitions that best explain all the terms required for implementing the IAU 2000/2006 resolutions. It includes terms that have some impact on the definitions as well as some more general definitions. (9 pages)

Complementary and supporting material

The following material is provided to help users understand the IAU 2000/2006 resolutions as well as illustrating the NFA Glossary.

List of terms by category  ( PDF file )
A list of terms (excluding those on time) that are used in the process of implementing the Resolutions; they have been grouped by categories in order to help users see where the CIO based method fits into the long established equinox based approach. (3 pages)

List of acronyms & symbols  ( PDF file )
Two lists, one containing an alphabetic list of abbreviations and acronyms, the other a list of symbols. (3 pages)

Chart of transformation process  ( PDF file )
An illustration showing the BCRS → GCRS → ITRS transformations in the framework of General Relativity (Resolution B.3), including and the parallel CIO and equinox based processes (Resolution B1.8). The Chart is schematic and is supplied as an aid to understanding, and not as WG recommendations. (3 pages)

Related educational documents

Report of NFA WG to IAU 2006, IAU Transactions XXVIB

Archive of NFA WG documents

References  ( PDF file )

Links (latest revision: 29 August 2008)

IAU 2000 Resolutions

IAU 2006 Resolutions

IUGG Resolutions

IAU Division 1

SOFA: The IAU approved software that implements the IAU 2000 and 2006 models. The library incorporating the IAU 2006 resolutions may be downloaded from the SOFA Libraries Issue 2008-03-01. A cookbook explaining 'SOFA Tools for Earth Attitude' may be downloaded from here.

IERS Conventions 2003: The set of files and associated software which define the standard reference systems realized by the International Earth Rotation and Reference Systems Service (IERS) and the models and procedures used for this purpose. The IERS Conventions update provides a working version that contains all corrections to the IERS Conventions (2003) that have been identified.