Astronomical and Astrophysical Objectives of Sub-Milliarcsecond Optical Astrometry: Proceedings of the 166th Symposium of the International Astronomical Union, Held in the Hague, The Netherlands, August 15-19, 1994

Astrometry is on the threshold of great changes due to the fact that this decade, alone, is witnessing an improvement of stellar positions equivalent to the total improvement of the previous two centuries. The Hipparcos Satellite has concluded its observations, and the catalog is in preparation. Preliminary results assure that the Hipparcos catalog will provide positions, parallaxes and annual proper motions for over 100,000 stars with accuracies of 1.5 milliarcseconds. In addition, the Tyc...