The K-Band (24 GHz) Celestial Reference Frame Determined from Very Long Baseline Interferometry Sessions Conducted Over the Past 20 Years

Abstract The third realization of the International Celestial Reference Frame (ICRF3) was adopted in August 2018 and includes positions extragalactic objects at three frequencies: 8.4 GHz, 24 32 GHz. In this paper, we present celestial reference frames estimated from Very Long Baseline Interferometry measurements K-band (24 GHz) including data until June 2022. set starts May 2002 currently consists more than 120 24h observing sessions performed over past 20 years. Since publication ICRF3, additional observations sources during last four years allow maintenance frame 200 radio ensure an expansion frame. A study presented solutions is carried out helping us to understand systematic differences between astrometric catalogs moving towards a better next ICRF solution. We compare (VIE-K-2022b USNO-K-2022July05) computed by two analysts with independent software packages (VieVS Calc/Solve) describe solution strategy. assess using vector spherical harmonics reasons for most prominent ones.