MERLIN ASTROMETRY OF 11 RADIO STARS

We report accurate positions in the International Celestial Reference Frame (ICRF) for 11 radio stars. Observations were made using the Multi-Element Radio Linked Interferometer Network at a radio frequency of 5 GHz. The positions are estimated to be accurate at the 5 mas level. Positions were obtained directly in the ICRF by phase referencing the radio stars to ICRF quasars whose positions are estimated to be accurate at the 0.25 mas level. We use our results together with results of previous observations to obtain proper-motion estimates for these stars. The average proper-motion uncertainties are 1.1 mas yr^-1 in (mu)(alpha) cos(delta) and 1.2 mas yr^-1 in (mu)(delta), comparable to the Hipparcos values.