OPTICAL ASTROMETRY OF BENCHMARK RADIO-SOURCES .2. POSITIONS OF 29 COMPACT EXTRAGALACTIC RADIO-SOURCES WITH RESPECT TO THE INTERNATIONAL REFERENCE STARS CATALOG

Optical positions, relative to the newly available International Refer ence Stars catalogue (IRS) have been obtained for the optical counterp arts of 29 compact extragalactic radio sources south of delta approxim ately +12-degrees; Most of these sources have been selected by IAU Com mission 24 to be used as Benchmark objects for the establishment of a high-precision radio/optical reference frame. Precision levels better than 0.2'' in both coordinates were achieved. Comparisons with indepen dent optical surveys and with VLBI radio positions available for these sources are presented. The use of the IRS catalogue is strongly suppo rted.