[AAVSO-HEN] GRB 090309: Enhanced Swift-XRT position

[grb at aavso.org]

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TITLE:   GCN CIRCULAR
NUMBER:  8969
SUBJECT: GRB 090309: Enhanced Swift-XRT position
DATE:    09/03/10 15:00:31 GMT
FROM:    Phil Evans at U of Leicester  <pae9 at star.le.ac.uk>

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

Using 1230 s of XRT Photon Counting mode data and 3 UVOT
images for GRB 090309, 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 = 284.97425, -25.26099 which is equivalent
to:

RA (J2000): 18h 59m 53.82s
Dec (J2000): -25d 15' 39.6"

with an uncertainty of 2.0 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.