Commission 4: Ephemerides

The terms of reference of Commission 4 is reproduced here. More information is available by visiting the Commission 4 website directly.

  1. Maintain cooperation and collaboration between the national offices providing ephemerides, prediction of phenomena, astronomical reference data, and navigational almanacs.
  2. Encourage agreement on the bases (reference systems, time scales, models, and constants) of astronomical ephemerides and reference data in the various countries. Promote improvements to the usability and accuracy of astronomical ephemerides, and provide information comparing computational methods, models, and results to ensure the accuracy of data provided.
  3. Maintain databases, available on the Internet to the national ephemeris offices and qualified researchers, containing observations of all types on which the ephemerides are based. Promote the continued importance of observations needed to improve the ephemerides, and encourage prompt availibility of these observations, especially those from space missions, to the science community.
  4. Encourage the development of software and web sites that provide astronomical ephemerides, prediction of phenomena, and astronomical reference data to the scientific community and public.
  5. Promote the development of explanatory material that fosters better understanding of the use and bases of ephemerides and related data.
Commission 7: Celestial Mechanics and Dynamical Astronomy

Commission 7 is responsible ''for promoting the scientific progress and major achievements in the broad field of Celestial Mechanics and its applications, as well as in the peripheral fields.'' Specific applications and fields are mentioned on their website.

In addition, Commission 7 is responsible for sponsoring and/or co-sponsoring the organization of IAU symposia on its own field and related fields. A reproduction of the Commission's terms of reference is available for download.

Commission 8: Astrometry

As stated on their website, Commission 8 ''coordinates all aspects of positional astronomy which involve positions, proper motions, and parallaxes of celestial objects.'' These include establishing celestial reference frames and systems; their maintenance, densification and further improvement using the existing ground-based and space instrumentation and theoretical advancements.

More information, including the organization's structure and terms of reference, is available from Commission 8's website.

Commission 19: Rotation of the Earth

Commission 19 supports and coordinates scientific investigations on the Earth rotation and related reference frames. Its mission objectives are reproduced here.

  1. Encourage and develop cooperation and collaboration in observation and theoretical studies of Earth orientation (the motions of the pole in the terrestrial and celestial reference systems and the rotation about the pole).
  2. Serve the astronomical community by linking it to the official organizations providing the International Terrestrial and Celestial Reference Systems/Frames (ITRS/ITRF and ICRS/ICRF) and Earth orientation parameters (EOP): International Association of Geodesy (IAG), International Earth Rotation and Reference Systems Service (IERS), International VLBI Service for Geodesy and Astrometry (IVS), International GNSS Service (IGS), International Laser Ranging Service (ILRS), International DORIS Service (IDS).
  3. Develop methods for improving the accuracy and understanding of Earth orientation and related reference systems/frames.
  4. Ensure agreement and continuity of the reference frames used for Earth orientation with other astronomical reference frames and their densification.
  5. Provide means for comparing observational and analysis methods and results to ensure accuracy of data and models.

The complete terms of reference is available for download.

Commission 31: Time

Commission 31's terms of reference are reproduced here. More information is available at their website.

  1. Maintain cooperation with national and international institutions providing atomic timekeeping information.
  2. Develop cooperation between observatories and other institutions providing and archiving astronomical data relevant to atomic timekeeping, such as pulsar data.
  3. Develop methods of analyzing and evaluating astronomical data relevant to fundamental concepts of time.
  4. Develop methods of publicizing astronomical data and results relevant to time.
Commission 52: Relativity in Fundamental Astronomy

The scientific objectives of Commission 52 are reproduced here. Their website provides additional information.

  1. Clarify geometric and dynamical concepts of Fundamental Astronomy within relativistic framework.
  2. Provide adequate mathematical and physical formulations to be used in Fundamental Astronomy.
  3. Deepen understandings of the above results among astronomers and students in astronomy.
  4. Promote research needed to accomplish these tasks.

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