TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4188 SUBJECT: GRB 051105: Swift detection of a short burst DATE: 05/11/05 07:17:42 GMT FROM: Scott Barthelmy at NASA/GSFC T. Mineo (IASF-Pa/INAF), L. Barbier (GSFC), S. Barthelmy (GSFC), D. Burrows (PSU), M. Chester (PSU), N. Gehrels (GSFC), J. Kennea (PSU), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), D. Palmer (LANL), G. Tagliaferri (OAB/INAF) on behalf of the Swift team: At 06:26:41 UT, Swift-BAT triggered and located GRB 051105 (trigger=162580). The spacecraft slewed immediately. The BAT on-board calculated location is RA,Dec 265.289d,+34.921d {17h 41m 09s,+34d 55' 15"} (J2000), with an uncertainty of 3 arcmin (radius, 90% containment, stat+sys). The BAT light curve shows a single spike with a total duration of less than 128 msec. The peak count rate was ~3000 counts/sec (15-350 keV), at 0.0 seconds after the trigger. XRT began observing at 06:27:49.09 UT, 67.6 sec after BAT Trigger time. The on-board detection algorithm failed to find a centroid due to low source counts. The XRT light curve shows no X-ray emission in the field. Further analysis will require processing of the XRT full telemetry data following the next ground station contact. The UVOT began observing at 06:27:48 UT, 66.5 sec after the BAT trigger. Due to a delay in receipt of the initial data files, no results are currently available. The V-band extinction in the direction of the BAT GRB position is A_V = 0.11.