Search Publications

Astrometric Star Catalogues as Combination of Hipparcos/Tycho Catalogues with Ground-Based Observations

Vondrak, J.

The successful ESA mission Hipparcos provided very precise parallaxes, positions and proper motions of many stars in optical wavelength. Therefore, it is a primary representation of International Celestial Reference System in this wavelength. However, the shortness of the mission (less than four years) causes some problems with proper motions of t…