[vsnet-grb-info 1904] GRB050803: Swift-BAT detection of a very long burst

[GCN Circulars]

TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  3748
SUBJECT: GRB050803: Swift-BAT detection of a very long burst
DATE:    05/08/03 20:10:23 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <Scott at lheamail.gsfc.nasa.gov>

D.L. Band (GSFC-UMBC), S. Barthelmy (GSFC), P. Boyd (GSFC-UMBC), P. Brown (PSU),
D. Burrows (PSU), M. Chester (PSU), J. Cummings (GSFC/NRC), N. Gehrels (GSFC),
C. Markwardt (GSFC), J. Nousek (PSU), K. Page (U. Leicester), C. Pagani (PSU),
D. Palmer (LANL), T. Sakamoto (GSFC), J. Racusin (PSU)
on behalf of the Swift team:

At 19:14:00 UT, Swift-BAT triggered and located GRB050803 (trigger=148833).
The spacecraft slewed immediately.  The BAT on-board calculated location
is RA,Dec 350.650d,+5.800d {23h 22m 36s,+05d 48' 00"} (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 at least 150 sec.
There is a fairly strong short peak at T+145 sec.  The peak count rate was
~1000 counts/sec (15-350 keV), at ~80 seconds after the trigger.

The XRT began observing at 19:16:31.6 UT, 151.6 seconds after the BAT trigger.
An uncatalogued, rapidly fading X-ray source was detected at an RA and Dec of
23h 22m 37.7s, 05d 47m 7.4s (J2000; 90% containment uncertainty of 6 arcsec),
which is 58.4" from the BAT position.

The UVOT began settled exposures about 3 minutes after the burst.  Using a
preliminary ground-processed 100-sec image, the upper limit is 18.5 (3 sigma)
in the V band.

We are currently in the portion of the orbits where the spacecraft does not 
pass over the Malindi downlink station.  Therefore, it will be ~4 hours
before we have access to the full data set for the refined analyses.