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IAU C.A3 facilitates advances in astronomy, and other fields in science and engineering, by developing, implementing, and communicating fundamental IAU-endorsed standards for astronomy. Such standards include, but are not limited to:

  • celestial & terrestrial reference systems/frames and the transformations among them;
  • time scales;
  • precession-nutation models;
  • Earth rotation and polar motion, including physical models (e.g., Earth's gravity field, lunar gravity field, Earth interior model, solid Earth-tide modelling);
  • star catalogues;
  • ephemerides of Solar System bodies;
  • coordinate systems of Solar System bodies;
  • special and general relativistic models for time and space.
The lists of Current Best Estimates and Constants Fixed by Convention are on the Nominal Standards for Fundamental Astronomy WG page hosted by C.A3.

News ...

2022 June: Commission A3 Website Updates
  • Added emerging issues for masses of Mercury and Mars and Cislunar standards
2022 March: Commission A3 Website Updates
  • Organizing Committee for next triennium updated
  • New reports available for CA3 available below
  • Final report for the NSFA available (link to the NSFA WG site hosted by CA3 in menu)
2020 April: Commission A3 Website Updates
  • A3 webages transferred to gitlab hosting; content updated
  • NSFA WG website and lists of standards websites now being hosted by Commission A3
  • Masses of Ceres & Vesta added as Developing Standards for discussion
  • NSFA Best Estimates updated for new potential of geoid value

Commission A3 Meetings and Reports

Send comments, questions, suggestions, corrections to us at: @ iauca3standards@gmail.com and follow us on Twitter at @IAU_CA3

Last modified: 2022 Feb