TITLE: GCN CIRCULAR NUMBER: 13032 SUBJECT: GRB 120311A: Swift detection of a burst DATE: 12/03/11 05:42:58 GMT FROM: Scott Barthelmy at NASA/GSFC C. B. Markwardt (NASA/GSFC), S. D. Barthelmy (GSFC), M. M. Chester (PSU), J. R. Cummings (NASA/UMBC), P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), A. Melandri (INAF-OAB), D. M. Palmer (LANL), M. H. Siegel (PSU) and M. Stamatikos (OSU/NASA/GSFC) report on behalf of the Swift Team: At 05:33:38 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 120311A (trigger=517469). Swift did not slew because of the Earth limb observing constraint. The BAT on-board calculated location is RA, Dec 273.087, +14.275, which is RA(J2000) = 18h 12m 21s Dec(J2000) = +14d 16' 32" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows a single peak structure with a duration of about 6 sec. The peak count rate was ~5100 counts/sec (15-350 keV), at ~0 sec after the trigger. Due to an observing constraint, Swift will not slew until T0+50.1 minutes. There will be no XRT or UVOT data until this time. Burst Advocate for this burst is C. B. Markwardt (Craig.Markwardt AT 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.)