Prospective Views in Space Astrometry

Abstract

The Hipparcos project of Space Astrometry was adopted by the European Space Agency (E.S.A.) in March 1980. The corresponding satellite will be launched in 1986 and, after 2.5 years of observation and about 2 years of reductions we will be able to obtain the coordinates, the proper motions and the parallaxes of 100.000 stars with uncertainty very much smaller than now. The mean values will be:

These stars will determine a very consistent sphere without systematic local errors. However, the absolute rotation by reference to the faint distant objects will be determined with other instruments.

In this way we obtain on the one hand a reference system much better than the one now available and very easy to use, and on the other hand parallaxes more numerous and more accurate which will be very useful in Astrophysics.

Hipparcos is evidently a completely new type of instrument. Our purpose is to study the foreseeable improvements and to discern the technical part of this instrumental type in the future of Astrometry.