High-precision VLBI astrometry of the radio-emitting star sigma rho a step in linking the HIPPARCOS and extragalactic reference frames.
Preston, Robert A.; Lestrade, Jean-Francois; Phillips, Robert B.; Gabuzda, Denise C.
France, United States, Canada
Abstract
VLBI observations of the optically bright radio-emitting star Sigma Coronae Borealis (Sigma CrB) have yielded its position relative to an angularly nearby quasar, its annual proper motion and its trigonometric parallax with formal uncertainties slightly better than 0.2 milliarcsec. This is the first result of the VLBI astrometric program we are conducting on 11 radio stars similar to Sigma CrB. We plan to obtain comparable results for all stars when enough epochs of observations are acquired. These stars will be used to astrometrically link the Hipparcos and VLBI extragalactic reference frames.