The apparent motions of extragalactic sources and their angular spectrums

The apparent motions of extragalactic ICRF sources are considered. Computer simulation of apparent motions is carried out assuming that they are stochastic and uncorrelated, while the position angle of the velocity for each source has a uniform distribution. We calculate the vector amplitudes of spherical harmonics and show that the corresponding spectrum has the form of “white noise.” In addition, we discuss observational data and calculate their angular spectra. Preliminary conclusions on the origin of the observed multipolar harmonics in the velocity angular spectrum are given.