[vsnet-grb-info 20122] GRB 171209A: Enhanced Swift-XRT position

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  22218
SUBJECT: GRB 171209A: Enhanced Swift-XRT position
DATE:    17/12/09 19:57:15 GMT
FROM:    Paolo D'Avanzo at INAF-OAB  <paolo.davanzo at brera.inaf.it>

P. D’Avanzo, A. Melandri (INAF-OAB), J. A. Kennea (PSU), P.A. Evans 
and M.R. Goad (U. Leicester) report on behalf of the Swift-XRT team:

Using 2454 s of XRT Photon Counting mode data and 6 UVOT 
images, 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 = 139.40280, -30.52016 which is equivalent to:

RA (J2000):  09 17 36.67
Dec (J2000): -30 31 12.6

with an uncertainty of 1.7 arcsec (radius, 90% confidence).

This position is consistent with the one reported for the Swift/UVOT 
candidate (LaPorte et al., GCN 22213). 

This position may be improved as more data are received.  The latest
position can be viewed at http://www.swift.ac.uk/xrt_positions <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.