On the Selection of Core Sources
IVS 2014 General Meeting Proceedings "VGOS: The New VLBI Network", Dirk Behrend, Karen D. Baver, and Kyla L. Armstrong (Eds), 399–401 (2014)
Keywords: VLBI, CRF, ICRF, core, defining sourcesAbout the paper Full text
In earlier work [3, 4], we had suggested a method of ranking source sets in order to select the list of sources that better define the orientation parameters of rigid rotation transformation from one system to another. The transformation parameters’ formal errors were selected as a characteristic of the source set. For all catalogs, IVS WG2 selected a special order for the source lists and obtained an accuracy for the transformation parameters as a function of the number of sources. For all catalogs with a minimum between 300 and 400 sources, adding sources after the minimum leads to increasing formal errors of the orientation parameters. After that, we selected the common sources which were selected before the minimum, and we obtained the “optimal set”. Source position time series were obtained and analyzed for the optimal set of sources. It was shown that some of the core sources have unstable positions and need to be excluded from the optimal set. Nevertheless, the time series show that the stable sources compose a mainly optimal source set.