[AAVSO-HEN] GRB 091020: Enhanced Swift-XRT position

[grb at aavso.org]

The following is a GCN Circular circulated via the AAVSO network.
For an archive and more information on circulars visit:
http://lheawww.gsfc.nasa.gov/docs/gamcosray/legr/bacodine/gcn3_archive.html

TITLE:   GCN CIRCULAR
NUMBER:  10050
SUBJECT: GRB 091020: Enhanced Swift-XRT position
DATE:    09/10/21 00:30:43 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 1088 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 091020, 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 = 175.73005, +50.97839 which is equivalent
to:

RA (J2000): 11h 42m 55.21s
Dec (J2000): +50d 58' 42.2"

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, MNRAS, 397, 1177).

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