[vsnet-grb-info 2222] GRB051006: Swift detection of a burst

[GCN Circulars]

TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  4061
SUBJECT: GRB051006: Swift detection of a burst
DATE:    05/10/06 21:32:24 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <Scott at lheamail.gsfc.nasa.gov>

J. Norris (GSFC), S. Barthelmy (GSFC), D. Burrows (PSU), M. Capalbi (ASDC),
N. Gehrels (GSFC), S.T. Holland (GSFC), J. Kennea (PSU),
C. Markwardt (GSFC/UMD), F. Marshall (GSFC), D. Morris (PSU),
J. Nousek (PSU), C. Pagani (PSU), D. Palmer (LANL), P. Roming (PSU)
on behalf of the Swift team:

At 20:30:33 UT, Swift-BAT triggered and located GRB051006 (trigger=158593).
The spacecraft slewed immediately.  The BAT on-board calculated location
is RA,Dec 110.830d,+9.531d {07h 23m 19s,+09d 31' 50"} (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 ~1500 counts/sec (15-350 keV),
at ~3 seconds after the trigger.

XRT began observing the field at 20:32:21.46, 108 seconds after the  
BAT trigger.  No prompt X-ray position is available.  The XRT lightcurve
suggests a fading source is present in the field of view.  The TDRSS  
downlinked spectrum is inconclusive.  Further analysis of the XRT data
will be reported when the full data set becomes available.

The UVOT began observing the position of trigger #158593 at 20:32:20.4 UT, 
107 s after the BAT trigger.  In the 200 s V-band image, no new source is 
detected with respect to the DSS down to a 3-sigma limiting mag of 18.8.
The estimated extinction in this direction is A_V ~ 0.2 magnitudes.
The UVOT image gives 25% coverage of the BAT error circle.  The BAT source
is located in a crowded star field.