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Karine Le Bail
Type of contribution: poster

Observing Gaia transfer sources in R&D and RDV sessions

Karine LeBail, NVI, Inc. at GSFC/NASA David Gordon, NVI, Inc. at GSFC/NASA John M. Gipson, NVI, Inc. at GSFC/NASA

The ESA mission Gaia was successfully launched on December 19, 2013. For five years, it is expected to observe and map billion of objects, including 500 000 quasars. The team of the Observatory of Bordeaux identified 195 sources to link the Gaia-optical frame and the VLBI-radio frame. They submitted a proposal that was approved in 2012 to include these sources in the IVS monitoring program and observe them regularly. Over the 195 sources, sixty six were not sufficiently observed and forty were not part of the IVS monitoring program. We included the sources in the IVS monitoring program in two steps. First, we modified the observation target of all the sources to twelve successful sessions per year. Second, as the forty sources not initially in the IVS monitoring program were mostly weak, we specifically scheduled them in R&D and RDV sessions. Since the beginning of this effort in 2013, we are now able to see significant improvements in position uncertainties and we know better the flux values of the 195 transfer sources. We were also able to identify a set of sources too weak to be observed regularly in regular IVS sessions. This paper explains the strategy developed, shows the significant improvements, and discusses the next step, taking into account the updates on the mission.