Observations of QSOs and Reference Frame with GAIA

OCA/CERGA, avenue Copernic, 06130 Grasse, France

Abstract

The astrometric mission GAIA will provide a flux limited census of quasi stellar objects to V=20 mag. This paper addresses the main physical and observational properties of the quasars, the existing surveys and the relevant statistical distributions of the compilation catalogue of Véron-Cetty & Véron. Then I consider the detection and recognition with GAIA which should be based on the multicolour photometry complemented by hints on the parallaxes and proper motions. In the last section I discuss the possibility to materialize directly in the optical the quasi-inertial frame to the sub-μas accuracy. It is shown that that with a clean sample of less than 10 000 quasars the residual spin of the GAIA reference frame can be determined to 0.5 μas yr^-1.