GCN Circular 4006
Subject
GRB050918: Possible Swift/XRT detected afterglow
Date
2005-09-21T12:55:35Z (19 years ago)
From
Jamie A. Kennea at PSU/Swift-XRT <kennea@astro.psu.edu>
J. A. Kennea, D. N. Burrows, D. Grupe, P. Roming (PSU), J. Osborne (U.
Leicester), S. T. Holland (GSFC/USRA) and N. Gehrels (GSFC) report on
behalf of the Swift team:
At September 20th 22:08 UT, Swift began a 10ks TOO observation of the
Integral discovered burst GRB050918 (GCN 4002). Analysis of ground
processed data from Swift/XRT reveals a previously uncatalogued faint
X-ray point source inside the 2.8 arcminute Integral error circle, at the
following coordinates:
RA(J2000): 17:50:28.7,
Dec(J2000): -25:24:41.2.
The uncertainty on this position is estimated to be 7 arcseconds radius
(90% containment). This position is 34 arcseconds from the center of the
Integral error circle given in GCN 4002.
There is no evidence of fading in this source, however as this observation
occured more than 2 days after the burst this result is expected. Further
observations will be required to determine if this source is the afterglow
of GRB050918.
A UVOT V-band image shows no new source, with respect to the DSS, inside
the INTEGRAL 2.8 arcminute radius error circle. The 5-sigma limiting
magnitude in a circular aperture with a radius of six arcseconds is
V_lim=19.3.