Authors / CoAuthors
Titov, O.
Abstract
Analysis of very long baseline interferometry (VLBI) records of distant radio source signals allows one to determine the proper motions of extragalactic objects with an accuracy of a few tens of microseconds of arc per year. Such an accuracy is sufficient to investigate the aberration in proper motions of distant bodies due to the rotation of the Solar system barycenter around the Galactic center, as well as higher degree systematics of the velocity field. We analyzed geodetic and astrometric VLBI data of 1979--2010 to produce radio source coordinate time series. The velocity field made up of the proper motions of 497 sources of good observational history is investigated by fitting the vector spherical harmonic components of degree 1 and 2. Within error bars, the magnitude and the direction of the dipole component agree with predictions made by using the most recent estimates of the Galactic parameters. The acceleration vector, estimated together with a non significant global rotation, has an amplitude of 5.8+/-1.4 microseconds of arc per year and is directed towards equatorial coordinates alpha = 266+/-8 deg and delta = -18+/- 18 deg. Degree 2 harmonics of the velocity fields appear to be less significant. It yields that the primordial gravitational wave density integrated over a range of frequencies less than 10^{-9} Hz is lower than 0.0031+/- 0.0002h^{-2}.
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nonGeographicDataset
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71006
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- External Publication
- ( Theme )
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- geodesy
- Australian and New Zealand Standard Research Classification (ANZSRC)
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- Earth Sciences
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- Published_Internal
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2010-01-01T00:00:00
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