TITLE:   GCN CIRCULAR
NUMBER:  31305
SUBJECT: GRB 211225B: Swift detection of a burst
DATE:    21/12/25 13:27:21 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott@milkyway.gsfc.nasa.gov>

K. L. Page (U Leicester), S. D. Barthelmy (GSFC),
N. P. M. Kuin (UCL-MSSL), A. Y. Lien (U Tampa),
F. E. Marshall (NASA/GSFC), T. M. Parsotan (GSFC/UMBC/CRESSTII) and
A. Tohuvavohu (U Toronto) report on behalf of the Neil Gehrels Swift
Observatory Team:

At 13:12:19 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 211225B (trigger=1090853).  Swift did not slew because
of Sun constraint.  The BAT on-board calculated location is 
RA, Dec 258.568, +17.262 which is 
   RA(J2000)  =  17h 14m 16s
   Dec(J2000) = +17d 15' 45"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve is missing data from T+8 to T+108
sec, but there is an increase of 1400 event/sec at ~T+5 sec. 

Due to a Sun observing constraint, Swift cannot slew to the BAT
position until 23:13 UT on 2022 January 02. There will thus be no XRT
or UVOT data for this trigger before this time. 

Burst Advocate for this burst is K. L. Page (kimlpage1978 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/)