Comparison and Combination of CRF Catalogues

TL;DR

This paper explores improving the International Celestial Reference Frame (ICRF) by combining multiple radio source catalogues to enhance accuracy and account for systematic errors, proposing a new combined catalogue version.

Contribution

It introduces a new combined ICRF catalogue using a novel method, demonstrating improvements over single-centre catalogues in accuracy and systematic error correction.

Findings

Two combined catalogues improve stochastic accuracy of ICRF.

Two combined catalogues account for systematic errors in ICRF.

New catalogue version enhances celestial reference frame precision.

Abstract

In 2007, a joint IERS/IVS Working Group has been established to consider practical issues of creating the next ICRF generation, ICRF-2. The goal of the WG is to seek after ways to improve the existing ICRF. In this study we investigate a possibility of ICRF improvement by means of using combined ICRF catalogue instead of a catalogue computed in a single analysis centre, even though using most advanced models and software. In this work, we present a new version of Pulkovo combined catalogue of radio source positions computed using the method proposed in \cite{SokMal07}. Radio source catalogues that were submitted in 2007 in the framework of the WG activity were used as input for mutual comparison and combination. Four combined catalogues have been calculated: Two first of them provide a stochastic improvement of the ICRF, and last two of them allow us to account also for systematic errors in the current ICRF version.