10 Distribution of astronomical data

10.1 Observations

Observations should be recorded with information such that all reductions could be redone with improved constants and methods in the future. The observations should be in the form for combination with other similar observations from other sources. Observational star catalogs should be for the mean epoch of the observations as barycentric mean positions on ICRS and TCB. Compiled catalogs as reference star catalogs should be on the ICRS in TCB for the epoch J2000.0.

10.2 Almanacs

Almanacs should provide star catalog data in geocentric apparent positions for an epoch in the applicable year in TT or TCG. Solar system data should be provided as geocentric apparent positions for individual dates on GCRS and TT or TCG. For the transition, an ephemeris of the difference between the equinox and the CEO should be given. Thus, it would be possible to convert the Stellar Angle into GAST and CEO right ascensions into equinox right ascensions of both apparent and true positions.

10.3 Ephemerides

Ephemerides for solar system bodies should be calculated on the ICRS fixed reference frame and the TCB time scale. Satellite ephemerides should be done on planet-centered ICRF in TCB. These ephemerides can be transformed into true or apparent positions dependent on the observation type for determination of ephemerides corrections.

10.4 Artificial satellites

The most useful reference system and time system for calculating the motions of the artificial satellites and providing a catalog of the elements of their orbits would be a geocentric dynamically fixed reference frame on TT. This would provide the reference frame for computation of the ephemerides of the satellities. Thus, they should be reduced as indicated above (item 7 of Sect. 9.2). Artificial satellite catalogs should be given on the GCRF and TT or TCG (Seago & Vallado 2000).