Optical Characteristics of the Astrometric Radio Sources

TL;DR

This paper compiles a comprehensive list of physical and positional characteristics of 3914 astrometric radio sources, aiding optical identification, kinematic studies, and improving the ICRF-2 reference frame.

Contribution

It provides the first extensive compilation of physical characteristics for a large set of radio sources, including new data and comparison with existing catalogs.

Findings

Significant differences found in characteristics for about half of the common sources.

List of sources without known physical characteristics compiled for targeted optical observations.

The dataset can supplement ICRF-2 and support kinematic and scheduling studies.

Abstract

A new list of physical characteristics of 3914 astrometric radio sources, including all 717 ICRF-Ext.2 sources, observed during IVS and NRAO VCS sessions have been compiled. The list includes source type, redshift and visual magnitude (if available). In case of doubt detailed comment is provided. The list of sources with their positions was taken from the Goddard VLBI astrometric catalog with addition of two ICRF-Ext.2 sources. At this stage the source characteristics were mainly taken from the NASA/IPAC Extragalactic Database (NED). 667 sources from our list are included into the IERS list. Comparison has shown a significant difference in characteristics for about half of these 667 common sources. We compiled a list of frequently observed sources without known physical characteristics for urgent optical identification and spectrophotometric observations with large optical telescopes. This presented list of physical characteristics can be used as a supplement material for the ICRF-2, as well as a database for kinematic studies of the Universe and other related works, including scheduling of dedicated IVS programs.