[AAVSO-HEN] GRB 090518: Enhanced Swift-XRT position

[grb at aavso.org]

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TITLE:   GCN CIRCULAR
NUMBER:  9387
SUBJECT: GRB 090518: Enhanced Swift-XRT position
DATE:    09/05/18 08:33:11 GMT
FROM:    Phil Evans at U of Leicester  <pae9 at 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 3965 s of XRT Photon Counting mode data and 8 UVOT
images for GRB 090518, 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 = 119.95404, +0.75921 which is equivalent
to:

RA (J2000): 07h 59m 48.97s
Dec (J2000): +00d 45' 33.2"

with an uncertainty of 1.6 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.