TITLE:   GCN CIRCULAR
NUMBER:  8241
SUBJECT: GRB 080916A: Enhanced Swift-XRT position
DATE:    08/09/16 15:21:27 GMT
FROM:    Phil Evans at U of Leicester  <pae9@star.le.ac.uk>

P.A. Evans, M.R. Goad, J.P. Osborne and A.P. Beardmore (U. Leicester) 
report on behalf of the Swift-XRT team.

Using 2559 s of XRT Photon Counting mode data and 3 UVOT
images for GRB 080916A, 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 = 336.27682, -57.02271 which is equivalent
to:

RA (J2000): 22h 25m 6.44s
Dec (J2000): -57d 01' 21.7"

with an uncertainty of 1.8 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
http://www.swift.ac.uk/xrt_positions/Goad.pdf), the current algorithm is an
extension of this method.

This circular was automatically generated, and is an official product of the
Swift-XRT team.