TITLE:   GCN CIRCULAR
NUMBER:  32955
SUBJECT: GRB 221120A: Swift detection of a likely short burst
DATE:    22/11/20 21:57:40 GMT
FROM:    David Palmer at LANL  <palmer@lanl.gov>

R. A. J. Eyles-Ferris (U Leicester), J.D. Gropp (PSU),
J. A. Kennea (PSU), K. L. Page (U Leicester), D. M. Palmer (LANL),
M. H. Siegel (PSU) and A. Tohuvavohu (U Toronto) report on behalf of
the Neil Gehrels Swift Observatory Team:

At 21:29:28 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 221120A (trigger=1141030). Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 41.3225  43.1970 which is 
   RA(J2000) = 02h 45m 17s
   Dec(J2000) = 43d 11' 49"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT trigger duration was 0.256 s, suggesting
a possible short burst.  Due to a telemetry gap, no further BAT information
will be available until ground contact. 

Using promptly downlinked data we find an uncatalogued X-ray source
with an enhanced position: RA, Dec 41.33852, 43.24280 which is
equivalent to:
   RA(J2000)  = 02h 45m 21.24s
   Dec(J2000) = +43d 14' 34.1"
with an uncertainty of 1.9 arcseconds (radius, 90% containment). This
position may be improved as more data are received; the latest position
is available at https://www.swift.ac.uk/sper. 

A power-law fit to a spectrum formed from promptly downlinked event
data does not constrain the column density. 

UVOT took a finding chart exposure of 150 seconds with the White
filter. No credible afterglow candidate has been found in the initial
data products. The 2.7'x2.7' sub-image covers 0% of  the XRT error
circle. The 8'x8' region for the list of sources generated on-board
covers 100% of the  XRT error circle. The list of sources is typically
complete to about 18 mag. 

Burst Advocate for this burst is R. A. J. Eyles-Ferris (raje1 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/)