GCN Circular 3942

M. Goad (U. Leicester), H. Krimm (GSFC/USRA), D. Burrows (PSU),
M. Chester (PSU), N. Gehrels (GSFC), C. Markwardt (GSFC/UMD),
J. Osborne (U. Leicester), C. Pagani (PSU), K. Page (U. Leicester),
D. Palmer (LANL), A. Parsons (GSFC) on behalf of the Swift team:

At 05:42:31 UT, Swift-BAT triggered and located GRB050908
(trigger=154112). The BAT on-board calculated location is RA,Dec 20.464,
-12.971 {01h 21m 51s, -12d 58' 16"} (J2000), with an uncertainty of
3 arcmin (radius, 90% containment, stat+sys).  The BAT light curve shows
a roughly triangular shape with a possible two peaks and total duration
of ~25 seconds.  The peak count rate is ~1000 cts/sec.

The S/C slewed immediately and the XRT began observations at
05:44:18 UT, T+106.2 seconds. The instrument was not able to calculate
an on-board centroid. No bright source was initially apparent, but the initial
lightcurve suggests that a source in the field of view may have brightened
and then decayed in the first few minutes of the observation.  Further
analysis will require processing of the full telemetry data following the
next ground station contact.

The UVOT began observations at 05:44:15.6.  Further analysis will require
processing of the full telemetry data following the next ground 
station contact.