TITLE:   GCN CIRCULAR
NUMBER:  26595
SUBJECT: GRB 191227A: Swift detection of a burst
DATE:    19/12/27 01:52:07 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

A. Melandri (INAF-OAB), S. D. Barthelmy (GSFC),
M. G. Bernardini (INAF-OAB), N. J. Klingler (PSU),
S Laha (GSFC/UMBC/CRESST), A. Y. Lien (GSFC/UMBC) and M. J. Moss (GWU)
report on behalf of the Neil Gehrels Swift Observatory Team:

At 01:39:37 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 191227A (trigger=946344).  Swift did not slew immediately
due to an observing constraint. 
The BAT on-board calculated location is 
RA, Dec 319.170, -16.704 which is 
   RA(J2000) = 21h 16m 41s
   Dec(J2000) = -16d 42' 15"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a multi-peaked
structure with a duration of about 30 sec.  The peak count rate
was ~12000 counts/sec (15-350 keV), at ~3 sec after the trigger. 

Due to a Sun observing constraint, Swift cannot slew to the BAT
position until 15:10 UT on 2020 March 23. There will thus be no XRT or
UVOT data for this trigger before this time. 

Burst Advocate for this burst is A. Melandri (andrea.melandri AT brera.inaf.it). 
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/)