TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4885 SUBJECT: GRB 060319: Swift detection of a burst DATE: 06/03/19 01:25:58 GMT FROM: Jamie A. Kennea at PSU/Swift-XRT H. Z. Ziaeepour (UCL-MSSL), S. D. Barthelmy (GSFC), A. P. Beardmore (U Leicester), A. J. Blustin (UCL-MSSL), D. N. Burrows (PSU), J. R. Cummings (NASA/ORAU), N. Gehrels (NASA/GSFC), J. A. Kennea (PSU), F. E. Marshall (NASA/GSFC), D. M. Palmer (LANL), E. Rol (U Leicester) and T. Sakamoto (NASA/ORAU) report on behalf of the Swift Team: At 00:55:42 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 060319 (trigger=202035). Swift slewed immediately to the burst. The BAT on-board calculated location is RA,Dec 176.370, +59.990 {11h 45m 29s, +59d 59' 25"} (J2000) with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a single-peaked structure with a duration of about 15 sec. The peak count rate was ~2000 counts/sec (15-350 keV), at ~4 sec after the trigger. The XRT began taking data at 00:57:56 UT, 134 seconds after the BAT trigger. The XRT on-board centroid algorithm did not find a source in the image and no prompt position is available. We are waiting for down-linked data to detect and determine a position for the source. UVOT took a finding chart exposure of 100 seconds with the WHITE filter starting 140 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 18th 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 extinction.