TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4682 SUBJECT: GRB060206: Swift-BAT detection of a burst DATE: 06/02/06 05:36:23 GMT FROM: David Palmer at LANL D. Morris (PSU), L. Barbier (GSFC), S. Barthelmy (GSFC), J. Cummings (GSFC/ORAU), N. Gehrels (GSFC), S. Hunsberger (PSU), C. Markwardt (GSFC/UMd), D. Palmer (LANL), and E. Rol (U. Leicester) on behalf of the Swift team: At 04:46:53 UT, Swift-BAT triggered and located GRB060206 (trigger=180455). The spacecraft slewed immediately. The BAT on-board location is RA,Dec 202.946d,+35.075d {13h 31m 47s,+35d 04' 29"} (J2000), with an uncertainty of 3 arcmin (radius, 90% containment, stat+sys). The BAT light curve showed a single bright gaussian-peak structure from T-1 to T+10 sec. The peak count rate was ~6000 counts/sec (15-350 keV), at ~2 seconds after the trigger. The XRT began taking data at 04:47:52, 58 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. The burst occurred shortly before entry into the SAA, and therefore the count-rate lightcurve may be insensitive to a fading source. We are waiting for down-linked data to determine a position. UVOT took a finding chart exposure of 72 seconds with the V filter starting 58 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 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 0.04 magnitudes.