GCN Circular 4096

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.