Working Group on Natural Satellites

For data on natural satellites, refer to the Natural Satellites Data Center.

Members:

R. Vieira-Martins

Draft charter, to be proposed and possibly adopted during GA 24 in August, 2000:

The WG was created in 1973 and dedicated to the motions of the natural planetary satellites. A considerable work was made in order to build theories and ephemerides. In 1991, a resolution was taken by Commission 20 to create a Data Center gathering all the astrometric data on Natural Satellites.

At the present time, accurate ephemerides are available only for a part of the natural satellites. The data base NSDC provides a large amount of data for the ephemerides builders and for the analysis of data. A work is still engaged to make available the data from the countries of the former soviet union (thanks to N. Emelianov who replaced V. Shor as member of the working group).

The present purposes of the working group are:
- to continue to feed and maintain the data base and to promote the observations of the natural planetary satellites (these objects are fast moving and observations are necessary to maintain the accuracy of the ephemerides)
- to promote the building of theories of motions (most of the newly discovered satellites have their motion modelized only as an ellipse with some precession added, that is not sufficient for accurate ephemerides).

The natural planetary satellites are the goal of space missions. They are also references for the observations of the planets. The purpose of the working group is to coordinate and encourage studies in that branch and to make available the data necessary for theoretical works and the making of ephemerides.