Early radio positions of stars

Early radio positions for a sample of 100 Hipparcos stars, three Tycho-only stars, and nine radio stars with optical positions referred to the Hipparc os/ICRS frame are analyzed. The optical proper motions are used to compare the optical and radio positions. From an original sample of 247 radio posit ions for the above 112 stars, a set of 220 shows coincidence between the op tical and radio centers of emission closer than 500 mas. This set is analyz ed for systematic departures between the optical and radio positions. A sma ller subset of 136 early radio positions for 72 stars show radio-minus-opti cal offsets smaller than 100 mas and are useful for monitoring of the spin of the Hipparcos frame.