GRB 051109B: Swift detection of a burst
TITLE: GCN GRB OBSERVATION REPORT
NUMBER: 4222
SUBJECT: GRB 051109B: Swift detection of a burst
DATE: 05/11/09 09:35:58 GMT
FROM: Scott Barthelmy at NASA/GSFC Scott@lheamail.gsfc.nasa.gov
G. Tagliaferri (INAF-OAB), S. Barthelmy (GSFC), D. Burrows (PSU), S. Campana (INAF-OAB), M. Chester (PSU), N. Gehrels (GSFC), T. Mineo (INAF-IASF PA), K. Page (U Leicester), D. Palmer (LANL), T. Sakamoto (GSFC) on behalf of the Swift team:
At 08:39:39 UT, Swift-BAT triggered and located GRB 051109B (trigger=163170). The BAT on-board calculated location is RA,Dec 345.440d,+38.672d {23h 01m 46s,+38d 40′ 20″} (J2000), with an uncertainty of 3 arcmin (radius, 90% containment, stat+sys). The BAT light curve shows a multi-peak structure with a total duration of ~20 sec. The peak count rate was ~2000 counts/sec (15-350 keV), at ~1 sec after the trigger.
The S/C slewed immediately and the XRT began observations at 08:41:06 UT (86 seconds after the BAT trigger) in auto state. The on-board detection algorithm failed to find a centroid, although the lightcurve suggests a faint source. More information will be available after the next Malindi pass.
UVOT began observing at 08:41:03 UT, 84 sec after the BAT trigger. The on-board source detection algorithm reports an uncataloged source at RA=345.46 {23h 01m 50.40s}, DEC=+38.66 {38d 39′ 36.0″}, 76 arcsec from the BAT position, with V magnitude 18.4 +/-0.1, in a 200 sec observation covering the BAT error circle. V-band extinction in the direction of the BAT position is A_V = 0.55.
