A New Way of Tying Together the Hipparcos Frame to the VLBI Extragalactic Frame: Astrometric Observations of Stellar Maser Sources

Abstract

The Hipparcos (H) reference system will contain 100 000 stars whose positions and proper motions will be known with an accuracy of 0″.002 and 0″.002/yr respectively. Because a residual rotation of the H system may exist and because a VLBI extragalactic frame is being constructed one must (i) determine an eventual rotation of the H rigid frame, (ii) link the H system to the VLBI extragalactic frame. VLBI observations at JPL (Fanselow et al., 1981) have provided a catalogue of about 100 quasars with internal accuracy of' ~ 0″.001.