GCN Circular 3849

A. Blustin (UCL-MSSL), S. Barthelmy (GSFC), D. Burrows (PSU), M. Chester (PSU),
J. Cummings (GSFC/NRC), N. Gehrels (GSFC), J. Kennea (PSU), F. Marshall (GSFC),
D. Palmer (LANL), T. Sakamoto (GSFC)
on behalf of the Swift team:

At 03:49:29 UT, Swift-BAT triggered and located GRB050822 (trigger=151486).
The BAT on-board calculated location is RA,Dec 51.080d,-46.023d
{03h 24m 19s,-46d 01' 22"} (J2000), with an uncertainty of 2 arcmin
(radius, 90% containment, stat+sys).  The BAT light curve shows two peaks
(at T+5 sec and T+50 sec) with a total duration of 70 sec.  The peak count rate
was ~1500 counts/sec (15-350 keV), at ~5 sec after the trigger.

The spacecraft slewed promptly and the XRT began observing the GRB
at 03:51:05 UT (96 sec after the BAT trigger).  A bright source was found
by the on-board centroiding algorithm at RA=03h 24m 26.7s, Dec=-46d 01' 58"
(J2000), with an estimated uncertainty of 8 arcsec (90% containment radius).
This is 86 arcsec from the BAT position.  The count rate decreases during
the first 100 sec, although the fact that Swift was exiting from the SAA
could contribute to this.

The UVOT began observing the field of GRB050822 at 03:51:47, 138 sec 
after the BAT trigger.  No new source with respect to the DSS image is 
detected at the XRT position in a 100 s V-band exposure down to a 3-sigma 
upper limit of 18.4 mag.