[AAVSO-HEN] Enhanced Swift-XRT position of SGR 0501+4516

[grb at aavso.org]

The following is a GCN Circular circulated via the AAVSO network.
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TITLE:   GCN CIRCULAR
NUMBER:  8148
SUBJECT: Enhanced Swift-XRT position of SGR 0501+4516 
DATE:    08/08/27 19:10:32 GMT
FROM:    Phil Evans at U of Leicester  <pae9 at star.le.ac.uk>

P.A. Evans and J.P. Osborne (U. Leicester) report on behalf of the
Swift-XRT team:

Using 9.1 ks of XRT Photon Counting mode data and 35 UVOT images, we find 
an astrometrically corrected X-ray position for SGR 0501+4516 (using the 
XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 
catalogue): RA, Dec = 75.27834, +45.27649 which is equivalent to:

RA (J2000):   05h 01m 6.80s
Dec (J2000):  +45d 16' 35.4"

with an uncertainty of 1.4 arcsec (radius, 90% confidence). This 
position is consistent with the possible infra-red counterpart (Tanvir &
Varricatt, GCN Circ. 8126).

The position enhancement process 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 is an official product of the Swift-XRT team.