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Arnaud Collioud
Type of contribution: oral

Imaging the IYA09 VLBI super-session

Arnaud Collioud, Laboratoire d'Astrophysique de Bordeaux Patrick Charlot, Laboratoire d'Astrophysique de Bordeaux

In the framework of the International Year of Astronomy (IYA2009), the IVS organized a dedicated 24-hour astrometric VLBI session with a large network of radiotelescopes in order to observe as many of the 295 ICRF2 defining sources as possible. This "super-session" took place on the 18th of November 2009. In all, 35 radiotelescopes observed 243 sources, which made the IYA09 session the largest VLBI session ever conducted. Although the session was primary targeted to astrometry, the observations are also useful to produce VLBI images of the sources due to the large network of telescopes that participated. In this paper, we present results of such imaging, including details about the data path and procedures. Overall, 228 sources were successfully imaged at X-band and 230 at S-band, corresponding to more than 90% of the scheduled sources. Taking an additional step, we derived structure indices from the resulting IYA09 images in order to assess the astrometric suitability of the sources. By studying the distribution of the structure indices, we discuss the relevance of the “ICRF2-defining” status for these sources.