GRB051016: Swift detection of a burst

TITLE: GCN GRB OBSERVATION REPORT
NUMBER: 4096
SUBJECT: GRB051016: Swift detection of a burst
DATE: 05/10/16 06:07:36 GMT
FROM: Scott Barthelmy at NASA/GSFC Scott@lheamail.gsfc.nasa.gov

P. Boyd (GSFC/UMBC), S. Barthelmy (GSFC), A. Beardmore (U. Leicester), D. Burrows (PSU), N. Gehrels (GSFC), C. Gronwall (PSU), S.T. Holland (GSFC), J. Kennea (PSU), C. Markwardt (GSFC/UMD), D. Palmer (LANL), T. Sakamoto (GSFC) on behalf of the Swift team:

At 05:23:31 UT, Swift-BAT triggered and located GRB051016 (trigger=159913). The BAT on-board calculated location is RA,Dec 122.811,-18.311d {08h 11m 15s,-18d 18′ 39″} (J2000), with an uncertainty of 3 arcmin (radius, 90% containment, stat+sys). The BAT light curve shows a single peak with a total duration of ~15 sec. The peak count rate was ~1200 counts/sec (15-350 keV), at ~2 seconds after the trigger.

The spacecraft slewed promptly and the XRT began observing the GRB at 05:25:23 UT, 112 sec after the BAT trigger. An uncatalogued source was found by the on-board centroiding algorithm at

RA(J2000)= 08h 11m 16.3s
DEC(J2000)=-18d 17′ 49.2″

with an uncertainty of 8 arcseconds radius (90% containment). This position lies 56 arcseconds from the centre of the BAT error circle. The initial flux is approximately 3.8E-10 ergs/cm2/s (0.3-10 keV). The count rate decreases during the first 100 seconds.

UVOT began observing the field at 05:25:26 UT. The small image includes the BAT and the XRT error circles. This image contains no new sources down to a V limiting magnitude of 19.1 (3-sigma). No new source was seen in the list of sources from the entire UVOT field of view. E(B-V) in this direction is 0.088.