[vsnet-grb-info 1886] GRB050801: Swift-BAT detection of a burst

[GCN Circulars]

TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  3725
SUBJECT: GRB050801: Swift-BAT detection of a burst
DATE:    05/08/01 19:25:50 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <Scott at lheamail.gsfc.nasa.gov>

D.L. Band (GSFC), S. Barthelmy (GSFC), J. Cummings (GSFC/NRC),
N. Gehrels (GSFC), C. Gronwall (PSU) S. Hunsberger (PSU),
J. Kennea (PSU), D. Palmer (LANL), M. Perri (ASDC)
on behalf of the Swift team:

At 18:28:02.07 UT, Swift-BAT triggered and located GRB050801 (trigger=148522).
The spacecraft slewed immediately.  The BAT on-board calculated location
is RA,Dec 204.139d,-21.950d {+13h 36m 33s,-21d 57' 00"} (J2000), with an
uncertainty of 3 arcmin (radius, 90% containment, stat+sys).  The BAT
light curve shows a single FRED structure with a total duration of 3 sec.
The peak count rate was ~900 counts/sec (15-350 keV), which peaks
at ~T+0.5 seconds.

The XRT began observing at 18:29:03 UT, 61 seconds after the BAT trigger.
XRT did centroid on a position, but on-ground examination of the image
revealed that the object found by the centroiding algorithm is a CCD
artifact (Kennea, GCN 3724).

Swift-UVOT began observations of GRB 050801 after the slew, however,
the UVOT dark burst image did not come down via TDRSS so no information
is available at this time.  Detailed analysis will be performed
when data is available after the next Malindi pass.

Because of orbit trajectory with respect to the Malindi ground station,
we will not have access to the full data sets to produce the refined analyses
for several hours.