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GCN Circular 9891

Subject
GRB 090904A: Enhanced Swift XRT position
Date
2009-09-04T14:28:45Z (15 years ago)
From
Phil Evans at U of Leicester <pae9@star.le.ac.uk>
P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team.

With 6 ks of XRT data, and 5 UVOT images from recent data downlinks we 
have generated an enhanced XRT position for GRB 090904A, which does not
include the problematic first image and is thus reliable.

The enhanced position is RA, Dec = 100.88480, +50.20300 which is
equivalent to:

RA (J2000): 06h 43m 32.35s
Dec (J2000): +50d 12' 10.8"

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, MNRAS, 397, 1177).

This circular is an official product of the Swift-XRT team.

[GCN OPS NOTE(04sep09):  Per operator's desire, the Subject-line
was changed from "090404A" to "090904A". F.Marshall noticed this.]
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