The X/Ka 2023b Celestial Frame
Christopher Jacobs  1@  , Shinji Horiuchi  2  , Daniel Firre  3  , Yasuhiro Murata  4  , Hiroshi Takeuchi  4  , Takahashi Uchimura  4  
1 : Jet Propulsion Laboratory - California Institute of Technology  (JPL)
Jet Propulsion Laboratory 4800 Oak Grove Drive Pasadena, California 91109 -  United States
2 : CSIRO Astronomy and Space Science, Canberra Deep Space Communication Complex
3 : European Space Agency
4 : JAXA

The X/Ka-band (8.4/32 GHz) Celestial Reference Frame became one component of the ICRF-3 in 2018. In the five years since, the X/Ka data set has increased by about a factor of two as well as adding the much needed north-south geometry from Japan to Australia. The latest solutions have median formal precisions of ~40 μas in α cosδ and ~65 μas in δ. The large spherical harmonics distortions seen in the ICRF3-XKa are greatly reduced with the Z-dipole term reduced from 314 μas to statistical insignificance and with the quadrupole 2,0 magnetic term reduced to ∼100 μas. Noting that the X/Ka frame is derived from a limited geometry of only five observing sites, we discuss the susceptibility of this frame to geometric distortion. Finally, we discuss the prospects for future improvements.

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