[vsnet-grb-info 3957] GRB 061102: Swift detection of a burst

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  5776
SUBJECT: GRB 061102: Swift detection of a burst
DATE:    06/11/02 01:20:42 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott at lheamail.gsfc.nasa.gov>

S. T. Holland (GSFC/USRA), S. D. Barthelmy (GSFC),
M. M. Chester (PSU), N. Gehrels (NASA/GSFC), C. Gronwall (PSU),
J. A. Kennea (PSU), F. E. Marshall (NASA/GSFC),
K. M. McLean (LANL/UTD), K. L. Page (U Leicester),
D. M. Palmer (LANL), A. M. Parsons (GSFC), M. Stamatikos (NASA/ORAU)
and R. L. C. Starling (U Leicester) report on behalf of the Swift
Team:

At 01:00:31 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 061102 (trigger=236430). Swift slewed immediately to the
burst. The BAT on-board calculated location is RA,Dec 148.405,
-17.066 {09h 53m 37s, -17d 03' 58"} (J2000) with an uncertainty of 3
arcmin (radius, 90% containment, including systematic uncertainty). 
The BAT light curve shows a weak pulse ~15 sec long. The peak count
rate was ~500 counts/sec (15-350 keV) at ~5 sec after the trigger. 

The XRT began observing the field at 01:02:11 UT, 100 seconds after the
BAT trigger. XRT found an uncatalogued fading X-ray source
located at RA(J2000) = 09h 53m 37.7s, Dec(J2000) = -17d 01' 28.1", with an
estimated uncertainty of 6.1 arcseconds (90% confidence radius). 
This location is 150 arcseconds from the BAT on-board position, within
the BAT error circle. The initial flux in the 2.5s image was
6.0e-10 erg/cm2/s (0.2-10 keV). 

UVOT took a finding chart exposure of 100 seconds with the White
(160-650 nm) filter starting 110 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 3-sigma
upper limit is approximately 18.5 mag. No correction has been made
for the expected extinction corresponding to E(B-V) of 0.04.