GCN Circular 12774

A. Y. Lien (NASA/GSFC/ORAU), S. D. Barthelmy (GSFC),
A. P. Beardmore (U Leicester), D. N. Burrows (PSU),
S. Campana (INAF-OAB), P. D'Avanzo (INAF-OAB), N. Gehrels (NASA/GSFC),
S. T. Holland (CRESST/USRA/GSFC), E. A. Hoversten (PSU),
H. A. Krimm (CRESST/GSFC/USRA), V. Mangano (INAF-IASFPA),
A. Melandri (INAF-OAB), J. L. Racusin (NASA/GSFC),
P. Romano (INAF-IASFPA), E. Troja (NASA/GSFC/ORAU) and
B.-B. Zhang (PSU) report on behalf of the Swift Team:

At 22:37:52 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 111229A (trigger=510736).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 76.282, -84.723, which is 
   RA(J2000)  =  05h 05m 08s
   Dec(J2000) = -84d 43' 20"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve shows two or three peaks
with a total duration of about 25 sec.  The peak count rate
was ~1300 counts/sec (15-350 keV), at ~1 sec after the trigger. 

The XRT began observing the field at 22:39:15.5 UT, 83.3 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source with an enhanced position: RA, Dec 76.2885, -84.7108 which
is equivalent to:
   RA(J2000)  = 05h 05m 09.25s
   Dec(J2000) = -84d 42' 38.8"
with an uncertainty of 2.5 arcseconds (radius, 90% containment). This
location is 43 arcseconds from the BAT onboard position, within the BAT
error circle. This position may be improved as more data are received;
the latest position is available at http://www.swift.ac.uk/sper.  We
cannot determine whether the source is fading at the present time. 

A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density in excess of the Galactic value (1.04 x
10^21 cm^-2, Kalberla et al. 2005), with an excess column of 9.2
(+7.65/-5.74) x 10^21 cm^-2 (90% confidence). 

UVOT took a finding chart exposure of 150 seconds with the White
filter  starting 87 seconds after the BAT trigger. No credible
afterglow candidate has  been found in the initial data products. The
2.7'x2.7' sub-image processing  failed because of no aspect solution. 
Results from the list of sources  generated on-board are not available
at this time. A full analysis will not be possible until the full data
set is downlinked. 

Burst Advocate for this burst is A. Y. Lien (yarleen 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/too.html.)