[vsnet-grb-info 3637] GRB 060825: Swift detection of a burst

[GCN Circulars]

TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  5471
SUBJECT: GRB 060825: Swift detection of a burst
DATE:    06/08/25 03:27:14 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott at lheamail.gsfc.nasa.gov>

G. Sato (GSFC/ISAS), S. D. Barthelmy (GSFC), M. M. Chester (PSU),
N. Gehrels (NASA/GSFC), S. T. Holland (GSFC/USRA),
S. Immler (GSFC/USRA), J. A. Kennea (PSU), H. A. Krimm (GSFC/USRA),
F. E. Marshall (NASA/GSFC), K. M. McLean (LANL/UTD),
K. L. Page (U Leicester) and D. M. Palmer (LANL) report on behalf of
the Swift Team:

At 02:59:57 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 060825 (trigger=226382).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA,Dec 18.102, +55.805 {01h 12m 24s, +55d 48' 18"} (J2000)
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve shows a single bright peak
with some structure and a duration of about 15 sec.  The peak count rate
was ~4000 counts/sec (15-350 keV), at ~1 sec after the trigger. 

The XRT began taking data at 03:01:03 UT, 66 seconds after the BAT
trigger.  The XRT on-board centroid algorithm did not find a source in the
image, however ground analysis of quicklook data reveals a faint uncatalogued
point source at the following coordinates: RA(J2000) = 01h 12m 28.9s,
Dec(J2000) = +55d 47m 46.4s with an error of 5.4 arcseconds radius (90%
confidence). This position is 49 arcseconds from the BAT position. 

UVOT took a finding chart exposure of 100 seconds with the White
(160-650 nm) filter starting 72 seconds after the BAT trigger. No
afterglow candidate has been found in the initial data products. The
2.7'x2.7' sub-image covers 100% of the XRT error circle. The typical
3-sigma upper limit has been about 18.5 mag. The 8'x8' region for the
list of sources generated on-board covers 100% of the BAT error
circle. The list of sources is typically complete to about 18 mag. No
correction has been made for the expected extinction corresponding to
E(B-V) of  0.57.