338f753e-80df-4d7b-ba5f-2dd32aa6d56e urn:uuid eng UTF-8 nonGeographicDataset nonGeographicDataset 2025-10-17T04:40:39 creation ISO 19115 2016 VLBI2020: from Reality to Vision 338f753e-80df-4d7b-ba5f-2dd32aa6d56e The individual apparent motions of distant radio sources are believed to be caused by the effect of intrinsic structure variations of the active galactic nuclei (AGN). However, some cosmological models of the expanded Universe predict that systematic astrometric proper motions of distant quasars do not vanish as the radial distance from the observer to the quasar grows. These systematic effects can even increase with the distance, making it possible to measure them with high-precision astrometric techniques like VLBI. The Galactocentric acceleration of the Solar System barycenter may cause a secular aberration drift with a magnitude of 4 µas/yr. The Solar System motion relative to the cosmic microwave background produces an additional dipole effect, proportional to red shift. We analyzed geodetic VLBI data spanning from 1979 until 2009 to estimate the vector spherical harmonics in the expansion of the vector field of the proper motion of 687 radio sources. The dipole and quadrupole vector spherical harmonics were estimated with an accuracy of 1-5 µas/yr. We have shown that over the next decade the geodetic VLBI may approach the level of accuracy on which the cosmological models of the Universe could be tested. Hence, it is important to organize a dedicated observational program to increase the number of measured proper motions to 3000. Paper presented at the IVS 2010 General Meeting December 2010, Hobart, Tasmania. {"type": "Polygon", "coordinates": [[[112.0, -44.0], [154.0, -44.0], [154.0, -9.0], [112.0, -9.0], [112.0, -44.0]]]} 112.0 154.0 -44.0 -9.0 Earth Sciences External Publication Published_External geodesy Link to conference paper documentDigital Link to conference paper PDF Link to conference proceedings documentDigital Link to conference proceedings PDF Unnamed resource documentDigital HTML