An analysis of source motions derived from position time series
  In this paper an attempt is made to extract a systematic part from the source motions obtained from the position time series provided by several IVS Analysis Centers in the framework of the ICRF-2 project. Our preliminary results show that the radio source velocities and the parameters of the systematic part of the velocity field differ substantially between the source position time series, which does not allow us to get a reliable solution for the coefficients of spherical harmonics. 
Z. Malkin, E. Popova
astro-ph.IM astro-ph.CO