VLBI Data Structure, Analysis Strategies and Software Optical Characteristics of Astrometric Radio Sources

Abstract. A new list of physical characteristics of 3914 astrometric radio sources, including all the 717 ICRF-Ext.2 sources, observed during IVS and NRAO VCS sessions have been compiled. The source list was taken from the Goddard VLBI astrometric catalog astro 2007c with addition of two ICRF-Ext.2 sources. At this stage the source characteristics were mainly taken from the NASA/IPAC Extragalactic Database (NED). Our list includes source type, redshift and visual magnitude (if available). In case of doubt detailed comment is provided. 667 sources from our list are included into the IERS list. Compar-ison of two lists has shown a significant difference in characteristics for about half of common sources. A list of frequently observed sources without known physical characteristics for urgent observations with large optical telescopes has been compiled. 1