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Minghui XU
Type of contribution: oral

Estimating the velocity of the Solar barycenter from VLBI observations

Minghui Xu, Shanghai Astronomical Observatory and GeoForschungsZentrum GFZ; James M. Anderson, GeoForschungsZentrum GFZ; Robert Heinkelmann, GeoForschungsZentrum GFZ; Harald Schuh, GeoForschungsZentrum GFZ; Guangli Wang, Shanghai Astronomical Observator.

The property of time independence of the International Celestial Reference Frame (ICRF) requires a careful contemplation especially for the aim of establishing and using the ICRF at the microarcseconds level. The proper motion of radio source, which has been ignored in geodetic VLBI, is actually caused by the relative motion of the observed object and the observer. The motion field of radio sources with respect to the Cosmic Microwave Background (CMB) may be regarded as random over the sky, but the motion of the barycenter with respect to the CMB is identical for all the observed objects. Therefore, proper motions caused by the motion of barycenter should be systematic variations. Based on the current value of this motion from astrophysical research, around 400 km/s, the magnitude of this systematical variation would be 1 microarcsecond per year for a radio source with redshift of 0.02. We investigate the possibility to estimate the velocity of the Solar barycenter by simulation using the ICRF2 catalog with redshifts, a priori values for the velocity and the acceleration of the Solar barycenter, and a random motion field of radio sources. We present the result of the estimation of the Solar velocity from VLBI data, and investigate the determination of the velocity from the Gaia data.