GCN Circular 15468
Subject
GRB 131108A: Swift detection of a possible X-ray afterglow
Event
Date
2013-11-09T03:31:55Z (12 years ago)
From
Michael Stroh at PSU/Swift <stroh@astroh.org>
M. C. Stroh and J. A. Kennea (PSU) report on behalf of the Swift/XRT team:
Swift-XRT has observed the error circle of the Fermi/LAT GRB 131108A (Racusin et al., GCN #15464, Evans, GCN #15465) in a series of observations tiled on the sky. In 621 s of data, beginning 3.9 ks after the Fermi/LAT trigger, we detect a bright, fading, uncatalogued X-ray source at RA, Dec = 156.50066, 9.66232 which is equivalent to:
RA (J2000.0) = 10h 26m 0.16s
Dec (J2000.0) = +09d 39' 44.4"
with an uncertainty of 3.6 arcsec (radius, 90% confidence). We note that this position lies 14.4' from the center of the Fermi/LAT
error circle (GCN #15464), consistant with that position, and inside the IPN error box (GCN #15466).
This previously uncatalogued source is significantly brighter than the RASS limit and fading, and we thus consider it the likely GRB afterglow.
The source was detected in 2 overlapping fields, with target IDs:
00020321, 00020322.
The results of the automated XRT processing of the source in these fields are available at:
http://www.swift.ac.uk/xrt_products/TILED_GRB00021/00020321
http://www.swift.ac.uk/xrt_products/TILED_GRB00021/00020322
This circular is an official product of the Swift-XRT team.