[vsnet-grb-info 7462] GRB 090323: Possible XRT Counterpart
GCN Circulars
gcncirc at capella.gsfc.nasa.gov
Tue Mar 24 12:31:49 JST 2009
TITLE: GCN CIRCULAR
NUMBER: 9024
SUBJECT: GRB 090323: Possible XRT Counterpart
DATE: 09/03/24 03:31:40 GMT
FROM: Jamie A. Kennea at PSU/Swift-XRT <kennea at astro.psu.edu>
J. Kennea (PSU), P. Evans and M. Goad (U Leicester) report on behalf of
the Swift/XRT Team:
At 19:27UT on March 23rd, 2009, Swift began a TOO observation of the
Fermi/LAT error circle of GRB 090323 (GCN #9021). Ground analysis of the
initial data finds an uncatalogued point source inside the LAT error
circle. Currently only one orbit of data has been downlinked so it is not
possible to determine if the source is fading.
Using 1137 s of XRT Photon Counting mode data and 2 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 =
190.70940, 17.05390 which is equivalent to:
RA (J2000): 12 42 50.26
Dec (J2000): +17 03 14.2
with an uncertainty of 2.7 arcsec (radius, 90% confidence). This position
is 1.9 arcminutes from the LAT on-ground localization given in GCN #9021.
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.
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