TITLE: GCN CIRCULAR NUMBER: 5675 SUBJECT: GRB 061002: Swift detection of a burst DATE: 06/10/02 01:34:04 GMT FROM: Scott Barthelmy at NASA/GSFC J, K. C. Cannizzo (NASA/UMBC), S. D. Barthelmy (GSFC), A. P. Beardmore (U Leicester), J. R. Cummings (NASA/UMBC), S. D. Hunsberger (PSU), F. E. Marshall (NASA/GSFC), K. M. McLean (LANL/UTD), K. L. Page (U Leicester), D. M. Palmer (LANL) and M. Stamatikos (NASA/ORAU) report on behalf of the Swift Team: At 01:03:29 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 061002 (trigger=231974). Swift slewed immediately to the burst. The BAT on-board calculated location is RA,Dec 220.346, +48.736 {14h 41m 23s, +48d 44' 11"} (J2000) with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows a weak peak with a duration of about 20 sec. The peak count rate was ~500 counts/sec (15-350 keV), at ~5 sec after the trigger. The XRT began taking data at 01:05:41 UT, 132 seconds after the BAT trigger. The XRT on-board centroid algorithm did not find a source in the image, but ground analysis reveals a faint, probably fading source at RA, Dec = 14h 41m 23.62s, +48d 44' 23.4" (J2000) with an estimated uncertainty of 15 arcsec radius (90% containment). This is 14.9 arcsec from the BAT position. UVOT took a finding chart exposure of 400 seconds with the V filter starting 128 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 and 100% of the XRT error circle. The 3-sigma upper limit is about 19.0 mag. The 8'x8'region for the list of sources generated on-board covers 100% of the BAT error circle. No correction has been made for the expected extinction of about 0.1 magnitudes. ---APPENDED NEW UVOT PARAGRAPH--- UVOT took a finding chart exposure of 400 seconds with the V filter starting 128 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 XRT 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 0.1 magnitudes.