TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4345 SUBJECT: GRB 051213: Swift-BAT detection of a burst DATE: 05/12/13 08:09:13 GMT FROM: Scott Barthelmy at NASA/GSFC T. Mineo (IASF-Pa INAF), S. Barthelmy (GSFC), G. Cusumano (IASF-Pa INAF), N. Gehrels (GSFC), S. Hunsberger (PSU), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), K. Page (U Leicester), D. Palmer (LANL) on behalf of the Swift team: At 07:13:04 UT, Swift-BAT triggered and located GRB 051213 (trigger=172516). The BAT on-board calculated location is RA,Dec 252.123d,-59.207d {16h 48m 29s,-59d 12' 25"} (J2000), with an uncertainty of 3 arcmin (radius, 90% containment, stat+sys). The spacecraft did not slew because of the Sun observing constraint. The location is 36 deg from the Sun, and it will not be observable by Swift NFIs for at least three weeks. This was a 64-sec image trigger with a 9-sigma significance in the image domain. The BAT lightcurve shows hints of emission, but it is not possible to separate source variations from background variations in the rate domain. The full data set from the next Malindi downlinks in a few hours will allow the separation of source from background.