[AAVSO-HEN] GRB 090807: Enhanced Swift-XRT position

[grb at aavso.org]

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TITLE:   GCN CIRCULAR
NUMBER:  9748
SUBJECT: GRB 090807: Enhanced Swift-XRT position
DATE:    09/08/07 19:10:10 GMT
FROM:    Phil Evans at U of Leicester  <pae9 at star.le.ac.uk>

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

Using 1531 s of XRT Photon Counting mode data and 2 UVOT
images for GRB 090807, 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 = 273.74377, +10.26583 which is equivalent
to:

RA (J2000): 18h 14m 58.50s
Dec (J2000): +10d 15' 57.0"

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) and Evans
et al. (2009, arXiv:0812.3662).

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