TITLE:   GCN CIRCULAR
NUMBER:  13038
SUBJECT: GRB 120311B: Swift detection of a burst
DATE:    12/03/11 15:17:28 GMT
FROM:    David Palmer at LANL  <palmer@lanl.gov>

F. E. Marshall (NASA/GSFC), S. D. Barthelmy (GSFC),
M. M. Chester (PSU), J. R. Cummings (NASA/UMBC),
P. D'Avanzo (INAF-OAB), C. Guidorzi (U Ferrara),
A. Maselli (INAF-IASFPA), A. Melandri (INAF-OAB), D. M. Palmer (LANL),
B. Sbarufatti (INAF-OAB/PSU), E. Sonbas (NASA/GSFC/Adiyaman Univ.) and
B.-B. Zhang (PSU) report on behalf of the Swift Team:

At 15:08:10 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 120311B (trigger=517489).  Swift did not slew immediately
because of the Earth limb observing constraint. 
The BAT on-board calculated location is 
RA, Dec 258.501, -13.060 which is 
   RA(J2000)  =  17h 14m 00s
   Dec(J2000) = -13d 03' 34"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve shows two peaks
structure with a duration of about 20 sec.  The peak count rate
was ~1000 counts/sec (15-350 keV), at ~10 sec after the trigger. 

Due to an observing constraint, Swift will not slew until T0+49.0
minutes. There will be no XRT or UVOT data until this time. 

Burst Advocate for this burst is F. E. Marshall (marshall 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.)