[vsnet-grb-info 2045] GRB050826: Swift-BAT detection of a long burst

[GCN Circulars]

TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  3884
SUBJECT: GRB050826: Swift-BAT detection of a long burst
DATE:    05/08/26 07:02:02 GMT
FROM:    Craig Markwardt at NASA/GSFC/UMD  <craigm at milkyway.gsfc.nasa.gov>

V. Mangano (INAF-IASF), L. Barbier (GSFC), A. Blustin (UCL-MSSL),
D. Burrows (PSU), J. Cummings (GSFC), S. Hunsberger (PSU),
C. Markwardt (GSFC/UMD), D. Morris (PSU), K. Page (U. Leicester),
D. Palmer (LANL),
on behalf of the Swift team:

At 06:18:10 UT, Swift-BAT triggered and located GRB 050826
(trigger=152113).  The spacecraft slewed immediately.  The BAT
on-board calculated location is RA,Dec 87.729, -2.680 {+05h 50m 55s,
-02d 40' 46"} (J2000), with an uncertainty of 3 arcmin (radius, 90%
containment, stat+sys).  The BAT light curve shows two peaks (T+10
sec and T+30 sec) with a total duration of 45 sec.  The peak count
rate was ~800 counts/sec (15-350 keV), at ~10 sec after the trigger.

Observations by the Swift X-Ray Telescope (XRT) began at 06:19:56 UT
(106 seconds after the BAT trigger) with the XRT in the auto
state. The on-board detection algorithm failed to find a centroid,
suggesting a very faint source.  More information will be available
around 11:00 UT, after the next Malindi pass.

The UVOT began observing the field of GRB 050826 at 06:19:55 UT, 105 s
after the BAT trigger.  The UVOT image covers the whole of the 3
arcmin BAT error circle. A comparison of the parameterised UVOT
finding chart, based on a 100 sec V-band image, with the DSS image
reveals no new source brighter than ~19th mag.