TITLE:   GCN CIRCULAR
NUMBER:  29106
SUBJECT: Swift Trigger 1014012: possible GRB 201221C
DATE:    20/12/21 19:07:16 GMT
FROM:    Kim Page at U.of Leicester  <klp5@leicester.ac.uk>

K. L. Page (U Leicester), J.D. Gropp (PSU), J. A. Kennea (PSU),
N. J. Klingler (PSU), F. E. Marshall (NASA/GSFC), M. J. Moss (GWU) and
A. Tohuvavohu (U Toronto) report on behalf of the Neil Gehrels Swift
Observatory Team:

At 18:41:33 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 201221C (trigger=1014012).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 278.205, +34.411 which is 
   RA(J2000) = 18h 32m 49s
   Dec(J2000) = +34d 24' 39"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty). As is typical for image triggers, there is 
nothing significant in the real-time light curves. 

The XRT began observing the field at 18:43:46.4 UT, 132.7 seconds after
the BAT trigger. No source was detected in 215 s of promptly downlinked
data. 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 136 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
0.07. 

Burst Advocate for this burst is K. L. Page (klp5 AT leicester.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/)