TITLE: GCN CIRCULAR NUMBER: 12439 SUBJECT: GRB 111016A: Swift detection of a burst DATE: 11/10/16 19:13:07 GMT FROM: Scott Barthelmy at NASA/GSFC V. Mangano (INAF-IASFPA), S. D. Barthelmy (GSFC), D. N. Burrows (PSU), N. Gehrels (NASA/GSFC), C. Guidorzi (U Ferrara), J. A. Kennea (PSU), D. M. Palmer (LANL), P. Romano (INAF-IASFPA), C. J. Saxton (UCL-MSSL), M. H. Siegel (PSU), M. Stamatikos (OSU/NASA/GSFC) and G. Tagliaferri (INAF-OAB) report on behalf of the Swift Team: At 18:37:04 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 111016A (trigger=505646). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 153.806, +27.476 which is RA(J2000) = 10h 15m 13s Dec(J2000) = +27d 28' 32" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows at least 7 well separated peaks with a total duration of at least 230 sec. The peak count rate was ~1600 counts/sec (15-350 keV), at ~0 sec after the trigger, and another equally bright peak at T+160 sec. And there is a possible peak at T+600 sec. The XRT began observing the field at 18:40:03.2 UT, 180 seconds after the BAT trigger. A bright source was present in the field, at the following location RA,Dec(J2000) = 153.8334, 27.4634, which is equivalent to: RA(J2000) = 10h 15m 20.0s Dec(J2000) = +27d 27' 48.3" with an estimated error of 5 arc-seconds radius (90% confidence). UVOT took a finding chart exposure of 150 seconds with the White filter starting 187 seconds after the BAT trigger. No credible afterglow candidate has been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of the XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag. The 8'x8' region for the list of sources generated on-board covers 100% of the XRT error circle. The list of sources is typically complete to about 18 mag. No correction has been made for the expected extinction corresponding to E(B-V) of 0.04. Burst Advocate for this burst is V. Mangano (vanessa AT ifc.inaf.it). 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.)