GCN Circular 6151
J. Racusin (PSU), M. Goad (U. Leicester), D.N. Burrows (PSU), O. Godet (U. Leicester), R. Starling (U. Leicester) report on behalf of the Swift XRT team: Based on an accurate mapping between the XRT and UVOT detector coordinate systems, we have used the simultaneous UVOT V-band images to astrometrically correct (relative to stellar catalogues, e.g. USNO-B1) the XRT world coordinate system, and thereby refine the XRT position. We obtain a new XRT position at RA,Dec=179.02792,-13.3304 which is: RA(J2000): 11h 56m 06.7s Dec(J2000): -13d 19' 49.6" with an uncertainty of 2.6 arcseconds (90% containment). This is 3.8 arcseconds from the refined XRT position (Racusin et al., GCN 6143), and 2.0 arcseconds from the optical candidate first identified by Thoene et al. (GCN 6142). This circular is an official product of the Swift-XRT team.