The Problem of the HIPPARCOS Reference Frame

Abstract

The basic principles of the realization of a fundamental optical reference frame by using space platforms are outlined in the light of the first of such astrometry projects, i.e., the HIPPARCOS mission of the European Space Agency. The available adaptations of these principles, expected to lead to a HIPPARCOS catalog of more than 100,000 star positions, annual proper motions, and parallaxes having internal precision close to 2 mas (depending upon star magnitudes and mission duration), are revisited through a new theoretical framework. This framework is used to highlight the shortcomings inherent to the current data reduction methods and to develop an approach for investigating systematic errors in the HIPPARCOS reference frame. It is shown, by means of simulations, that a distortion of order 2 mas might result. Such a distortion would not be recovered by linking the HIPPARCOS catalog to a quasi-inertial reference frame. Ways to avoid this occurrence are recalled, and additional new suggestions are made.