GRB 060202: Swift detection of a burst

TITLE: GCN GRB OBSERVATION REPORT
NUMBER: 4629
SUBJECT: GRB 060202: Swift detection of a burst
DATE: 06/02/02 09:33:04 GMT
FROM: Scott Barthelmy at NASA/GSFC Scott@lheamail.gsfc.nasa.gov

D. Fox (PSU), S. Barthelmy (GSFC), D. Burrows (PSU), J. Cummings (GSFC/NRC), N. Gehrels (GSFC), S.T. Holland (GSFC/USRA), S. Hunsberger (PSU), H. Krimm (GSFC/USRA), D. Morris (PSU), D. Palmer (LANL) on behalf of the Swift team:

At 08:40:55 UT, Swift-BAT triggered and located GRB 060202 (trigger=179968). The spacecraft slewed immediately. The BAT on-board calculated location is RA,Dec 35.843d,+38.362d {02h 23m 22s,+38d 21′ 43″} (J2000), with an uncertainty of 3 arcmin (radius, 90% containment, stat+sys). This was a 64-sec image trigger. The BAT light curve shows a broad and weak peak with a total duration of >20 sec. The peak count rate was ~500 counts/sec (15-350 keV), at ~5 seconds after the trigger.

XRT began observing the GRB at 08:43:18 UT, 143.3s after the BAT trigger. A bright, uncatalogued, fading source, was found by the on-board centroiding algorithm at

RA(J2000)=02h 23m 23.1s

DEC(J2000)=+38d 23′ 09.2″

with an uncertainty of 6 arcseconds radius (90% containment). This position lies 87 arcseconds from the center of the BAT error circle. The XRT count rate clearly decreases as a power law in the first 100s. The initial XRT flux was ~2.5E-8 ergs/cm2/s.

UVOT took a finding chart exposure of 200 seconds with the V filter starting 148 seconds after the BAT trigger. No afterglow candidate has been found in the initial data products. The 2.7’x2.7′ sub-image covers 100% of the XRT 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 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 0.2 magnitudes.