Residual HCRF rotation relative to the inertial coordinate system

Abstract

VLBI measurements of the absolute proper motions of 23 radio stars have been collected from published data. These are stars with maser emission, or very young stars, or asymptotic-giant-branch stars. By comparing these measurements with the stellar proper motions from the optical catalogs of the Hipparcos Celestial Reference Frame (HCRF), we have found the components of the residual rotation vector of this frame relative to the inertial coordinate system: (\omega_x,\omega_y,\omega_z) = (-0.39,-0.51,-1.25)+/-(0.58,0.57,0.56) mas/yr. Based on all the available data, we have determined new values of the components of the residual rotation vector for the optical realization of the HCRF relative to the inertial coordinate system: (\omega_x,\omega_y,\omega_z) = (-0.15,+0.24,-0.53)+/-(0.11,0.10,0.13) mas/yr.