GCN Circular 3977

D. Grupe (PSU), A. Beardmore (U. Leicester), D. Burrows (PSU),
J. Cummings (GSFC/NRC), K. Page (U. Leicester), D. Palmer (LANL),
P. Roming (PSU), E. Rol (U. Leicester) N. Gehrels (GSFC)
on behalf of the Swift Team


At 11:22:42 UT, Swift-BAT triggered and located GRB050915
(trigger=155242).  The BAT on-board calculated location is
RA,Dec 81.714d, -28.030d {05h 26m 51s, -28d 01' 48"} (J2000),
with an uncertainty of 3 arcmin (radius, 90% containment, stat+sys).
The BAT light curve showed a multi-peak structure with at least
4 well-separated peaks and a total duration of 25 sec.  The peak
count rate was ~1500 counts/sec (15-350 keV), at ~14 seconds after
the trigger.

The spacecraft slewed immediately and the XRT began
observing the BAT position at 11:24:09 UT (T+87 s).  The
count rate was too low for an on-board centroid, but the
spectrum and lightcurve strongly suggest that XRT observed a
rapidly-fading X-ray source in the field.  The XRT position
will be available following the next ground station data
dump.

UVOT finds no obvious new sources in the BAT error circle in
a 100 sec image starting at T+85 s.  Further analysis will
follow.