X/Ka Network Enhanced by Misasa, Japan's 54-meter antenna

The Japan Aerospace Exploration Agency (JAXA) is finishing a new 54-meter antenna at Misasa, Japan for tracking spacecraft which will replace the Usuda 64-m. It will operate at X-band (8.4 GHz) and Ka- band (32 GHz). As part of ongoing joint support of deep space missions amongst JAXA, ESA, and NASA, we are developing a united multi-agency effort to improve the X/Ka celestial reference frame as well as a unified X/Ka terrestrial frame to be shared by the three agencies. The Misasa 54-m antenna enhances X/Ka sensitivity by virtue of having an aperture area 2.5 times larger than the NASA and ESA antennas in the network. Misasa improves the network geometry by providing four new baselines including the first direct north-south baseline (Japan-Australia) in the X/Ka VLBI network which will provide optimal geometry for improving declinations. The X/Ka component of the ICRF-3 has almost a factor of two lower precision in declination than in RA. Also, the X/Ka frame has systematic distortions vs. declination which may be partially modeled as Z-dipole and quadrupole 2,0 spherical harmonics. VLBI measurements with the Misasa 54-m are expected to reduce both the random error limiting precision and the systematic distortions vs. declination limiting accuracy. This paper will describe the new 54-m antenna and present the first Ka-band VLBI results on baselines to the Misasa 54-m.