[vsnet-grb-info 12760] Swift Trigger 544381 is unlikely to be a GRB

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  14119
SUBJECT: Swift Trigger 544381 is unlikely to be a GRB
DATE:    12/12/29 13:26:04 GMT
FROM:    Mike Siegel at PSU/Swift MOC  <siegel at swift.psu.edu>

J. K. Cannizzo (NASA/UMBC), W. H. Baumgartner (GSFC/UMBC),
V. D'Elia (ASDC), H. A. Krimm (CRESST/GSFC/USRA),
F. E. Marshall (NASA/GSFC), T. Sakamoto (AGU), M. H. Siegel (PSU) and
E. Sonbas (NASA/GSFC/Adiyaman Univ.) report on behalf of the Swift
Team:

At 12:51:51 UT, the Swift Burst Alert Telescope (BAT) triggered and
located trigger=544381, which is possibly, but unlikely to be, a GRB.  
Swift slewed immediately to the trigger location. The BAT on-board 
calculated location is 
RA, Dec 185.493, -47.928 which is 
   RA(J2000) = 12h 21m 58s
   Dec(J2000) = -47d 55' 39"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed weak
structure superimposed on a rising count rate due to entry into the South 
Atlantic Anomaly.  This, combined with the low image significance 
(6.8-sigma) makes this trigger unlikely to be a burst.  However,
further analysis of the full BAT data is required to make a final 
determination. 

The XRT began observing the field at 12:52:41.4 UT, 49.8 seconds after
the BAT trigger. No source was detected in the 2.5-s promptly available
image. We are waiting for the full dataset to detect and localise the possible
XRT counterpart. 

Full XRT and UVOT products are not available at this time because
Swift entered the South Atlantic Anomaly shortly after the BAT
trigger. 

Burst Advocate for this burst is J. K. Cannizzo (cannizzo AT milkyway.gsfc.nasa.gov). 
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/too.html.)