GCN Circular 29323

M. J. Moss (GWU), S. D. Barthelmy (GSFC), H. A. Krimm (NSF),
A. Y. Lien (GSFC/UMBC), K. L. Page (U Leicester) and
D. M. Palmer (LANL) report on behalf of the Neil Gehrels Swift
Observatory Team:

At 02:54:09 UT, the Swift Burst Alert Telescope (BAT) triggered and
located a short burst which would be either an unknown Soft Gamma 
Repeater or GRB 210119A (trigger=1017711). 
The BAT on-board calculated location is 
RA, Dec 282.804, -61.801 which is 
   RA(J2000) = 18h 51m 13s
   Dec(J2000) = -61d 48' 02"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a single peak
structure with a duration of 0.128 sec or less.  The peak count rate
was ~8000 counts/sec (15-350 keV), at ~0 sec after the trigger. 

Due to a Sun observing constraint, Swift cannot slew to the BAT
position until 12:54 UT on 2021 January 26. There will thus be no XRT
or UVOT data for this trigger before this time. 

Due to the short timescale of the peak and the location of the source
in the Galactic bulge (lat, lon = 333.99, -23.67) this event may be
from a previously unknown Soft Gamma Repeater, which we would name
SGR Swift J1851.2-6148 . 

Burst Advocate for this burst is M. J. Moss (mikejmoss3 AT gmail.com). 
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/)