GCN Circular 31160
Subject
GRB 211203A: Swift detection of a burst
Date
2021-12-03T09:33:20Z (3 years ago)
From
Phil Evans at U of Leicester <pae9@star.le.ac.uk>
P. A. Evans (U Leicester), S. Dichiara (PSU), J.D. Gropp (PSU) and
K. L. Page (U Leicester) report on behalf of the Neil Gehrels Swift
Observatory Team:
At 09:02:38 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 211203A (trigger=1086826). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 170.174, +16.256 which is
RA(J2000) = 11h 20m 42s
Dec(J2000) = +16d 15' 21"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve showed a complex
structure with a duration of about 25 sec. The peak count rate
was ~3000 counts/sec (15-350 keV), at ~7 sec after the trigger.
The XRT began observing the field at 09:03:56.8 UT, 78.5 seconds after
the BAT trigger. No source was detected in 2 s of promptly downlinked
data, which covered 93% of the BAT error circle. We are waiting for the
full dataset to detect and localise the XRT counterpart.
UVOT took a finding chart exposure of 150 seconds with the White filter
starting 81 seconds after the BAT trigger. No credible afterglow candidate has
been found in the initial data products. The 2.7'x2.7' sub-image covers 25% of
the BAT error circle. The typical 3-sigma upper limit has been about 19.6 mag.
The 8'x8' region for the list of sources generated on-board covers 100% of the
BAT error circle. The list of sources is typically complete to about 18 mag. No
correction has been made for the expected extinction corresponding to E(B-V) of
0.023.
Burst Advocate for this burst is P. A. Evans (pae9 AT star.le.ac.uk).
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/)