Results of the HIPPARCOS in-orbit payload calibration.

Abstract

The HIPPARCOS satellite is the European Space Agency's first mission dedicated to global astrometry. The spacecraft is in a geostationary transfer-type orbit with perigee at about 500 km instead of the planned geostationary orbit. From this orbit, the satellite will systematically scan the entire sky using a predefined attitude law. The output of the revised main mission will be a catalogue of the positions, proper motions and parallaxes for up to 120,000 pre-selected sources brighter than a B magnitude of about 13. Also, the Tycho project which uses the HIPPARCOS star mappers will provide less precise astrometry and photometry for up to 400,000 sources. This paper presents the results of the preliminary in-orbit calibration of the payload. In particular, results are presented that have an impact on the direct operation of the spacecraft.