TITLE: GCN CIRCULAR NUMBER: 7416 SUBJECT: GRB 080315: Swift detection of a possible burst DATE: 08/03/15 02:46:19 GMT FROM: David Palmer at LANL K. L. Page (U Leicester), W. H. Baumgartner (GSFC/UMBC), A. P. Beardmore (U Leicester), D. N. Burrows (PSU), M. M. Chester (PSU), N. Gehrels (NASA/GSFC), S. T. Holland (CRESST/USRA/GSFC), J. A. Kennea (PSU), H. A. Krimm (GSFC/USRA), C. B. Markwardt (CRESST/GSFC/UMD), F. E. Marshall (NASA/GSFC), D. M. Palmer (LANL), M. Stamatikos (NASA/ORAU), E. Troja (U Leicester/INAF-IASFPA) and T. N. Ukwatta (GSFC/GWU) report on behalf of the Swift Team: At 02:25:01 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 080315 (trigger=306323). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 155.182, +41.729 which is RA(J2000) = 10h 20m 44s Dec(J2000) = +41d 43' 44" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). As is usual for a 64-second image trigger, the TDRSS light curve shows no obvious variation. Further BAT analysis will rely on the Malindi-downlinked data. The XRT began observing the field at 02:27:07.3 UT, 125.9 seconds after the BAT trigger. No source was detected in the promptly available XRT data. We are waiting for the full dataset to detect and localise the XRT counterpart. UVOT took a finding chart exposure of 400 seconds with the V filter starting 125 seconds after the BAT trigger. No afterglow candidate has been found in the initial data products. The 2.7'x2.7' sub-image covers 25% of the BAT error circle. The typical 3-sigma upper limit has been about 18.5 mag. The 8'x8' region for the list of sources generated on-board covers 100% of the BAT error circle. The list of sources is typically complete to about 18.0 mag. No correction has been made for the expected extinction of about 0.04 magnitudes. Burst Advocate for this burst is K. L. Page (kpa AT star.le.ac.uk). 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.)