Position and Proper Motion of Sagittarius A* in the ICRF3 Frame from VLBI Absolute Astrometry

Abstract Sagittarius A* (Sgr A*) is a strong, compact radio source believed to be powered by supermassive black hole at the galactic center. Extinction dust and gas in plane prevents observing it optically, but its position proper motion have previously been estimated using interferometry. We present new VLBI absolute astrometry measurements of precise frame third realization International Celestial Reference Frame (ICRF3). The observations used were made 52 epochs on VLBA K band (24 GHz) between 2006 June 2022 August. find Sgr −3.128 ± 0.042 mas yr −1 R.A. −5.584 0.075 decl., or 6.400 0.073 angle 209.°26 0.°51. also J2000 ICRF3 coordinates 2015.0 epoch 17 h 45 m 40.ˢ034047 0.ˢ000018, −29°00′28.″21601 0.″00044. In coordinates, shows −6.396 0.071 longitude −0.239 0.045 latitude, indicating solar 248.0 2.8 km s 9.3 1.9 toward north pole.