TITLE: GCN CIRCULAR NUMBER: 19837 SUBJECT: GRB 160821B: Enhanced Swift-XRT position DATE: 16/08/22 07:39:48 GMT FROM: Phil Evans at U of Leicester P.A. Evans, M.R. Goad, J.P. Osborne and A.P. Beardmore (U. Leicester) report on behalf of the Swift-XRT team. Using 1754 s of XRT Photon Counting mode data and 2 UVOT images for GRB 160821B, we find an astrometrically corrected X-ray position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 279.97653, +62.39129 which is equivalent to: RA (J2000): 18h 39m 54.37s Dec (J2000): +62d 23' 28.6" with an uncertainty of 2.5 arcsec (radius, 90% confidence). This position may be improved as more data are received. The latest position can be viewed at http://www.swift.ac.uk/xrt_positions. Position enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans et al. (2009, MNRAS, 397, 1177). This circular was automatically generated, and is an official product of the Swift-XRT team.