Effect of asymmetry of the radio source distribution on the apparent proper motion kinematic analysis

TL;DR

This paper compiles a comprehensive list of radio source characteristics, highlights discrepancies with existing data, and discusses how source distribution asymmetry affects proper motion analysis, recommending targeted observations for improvement.

Contribution

It provides a new, detailed catalog of radio source characteristics and analyzes the impact of distribution asymmetry on kinematic analysis, offering recommendations for future observations.

Findings

Significant discrepancies found between optical and official radio source data.

Asymmetry in source distribution causes correlation in spherical harmonic analysis.

Identification of sources lacking redshift data for targeted observation.

Abstract

A new list of physical characteristics of 4261 astrometric radio sources, including all 717 ICRF-Ext.2 sources has been compiled. Comparison of our data of optical characteristics with the official International Earth Rotation and Reference Systems Service (IERS) list showed significant discrepancies for about half of 667 common sources. We also found that asymmetry in the radio sources distribution between hemispheres could cause significant correlation between the vector spherical harmonics, especially if the case of sparse distribution of the sources with high redshift. We identified radio sources having many-year observation history and lack redshift. This sources should be urgently observed at large optical telescopes. The list of optical characteristics created in this paper is recommended for use as a supplement material for the next International Celestial Reference Frame (ICRF) realization. It can be also effectively used for cosmological studies and planning of observing programs both in radio and optics.