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David Mayer
Type of contribution: oral

Earth Orientation Parameters for VLBA Calibrator Survey Sessions

D. Mayer, Technische Universit{"a}t Wien H. Krasna, Technische Universit{"a}t Wien J. B{"o}hm, Technische Universit{"a}t Wien

About two thirds of the sources in the ICRF-2 catalogue are estimated from VLBA Calibrator Survey (VCS) sessions. These sessions were carried out from 1994 to 2007 by a network of ten radio telescopes in North America with the densification of the celestial reference frame as the primary goal. A total of twenty-four VCS sessions, each with duration of 24 h, were observed in six campaigns. Coordinates estimated from these sessions have up to five times worse precision when compared to non-VCS sources from the ICRF catalogue, which is to a great extent due to the limited number of observations. In the analysis of VCS sessions Earth Orientation Parameters (EOP) were estimated alongside source coordinates and other parameters. This, however, is not ideal, since the network is regional (only North American telescopes) and, therefore, not suitable for EOP estimation. We examine the effect of EOP estimation on source coordinates from VCS sessions. This is done by comparing solutions with EOP estimated in the analysis with solutions where EOP are fixed to IERS C0408 combined series. Furthermore, we recommend strategies on how to reduce the effect of EOP uncertainties on the source estimates.