Kinematic Control of the Inertiality of ICRS Catalogs

Abstract

We perform a kinematic analysis of the Hipparcos and TRC proper motions of stars by using a linear Ogorodnikov-Milne model. All of the distant (r more than 0.2 kpc) stars of the Hipparcos catalog have been found to rotate around the Galactic y axis with an angular velocity of -0.36 +/- 0.09 mas/year. One of the causes of this rotation may be an uncertainty in the lunisolar precession constant adopted when constructing the ICRS. In this case? the correction to the IAU (1976) lunisolar precession constant in longitude is shown to be -3.26 +/- 0.10 mas/yr. Based on the TRC catalog, we have determined the main Oort constants: A = 14.9 +/- 1.0 and B = -10.8 +/- 0.3 km/s/kpc. The component of the model that describes the rotation of all TRC stars around the Galactic y axis is nonzero for all magnitudes, My= -0.86 +/- 0.11 mas/yr.