TITLE:   GCN CIRCULAR
NUMBER:  5762
SUBJECT: GRB 061028: Swift detection of a burst
DATE:    06/10/28 01:52:38 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott@lheamail.gsfc.nasa.gov>

T. Sakamoto (NASA/ORAU), S. D. Barthelmy (GSFC),
A. P. Beardmore (U Leicester), D. N. Burrows (PSU),
M. M. Chester (PSU), H. A. Krimm (GSFC/USRA),
V. Mangano (INAF-IASFPA), C. B. Markwardt (GSFC/UMD),
F. E. Marshall (NASA/GSFC), T. Mineo (INAF-IASFPA),
D. M. Palmer (LANL) and M. Stamatikos (NASA/ORAU) report on behalf of
the Swift Team:

At 01:26:22 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 061028 (trigger=235715).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA,Dec 97.212, +46.270 {06h 28m 51s, +46d 16' 12"} (J2000)
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).   This is a 128-sec image trigger and as is typical
the BAT lightcurve does not show any significant emission. 

The XRT began observing the field at 01:29:40 UT, 198 seconds after the
BAT trigger. XRT found a bright, fading, uncatalogued X-ray source
located at RA(J2000) = 06h 28m 54.5s, Dec(J2000) = +46d 17' 55.4", with an
estimated uncertainty of 5.0 arcseconds (90% confidence radius). 
This location is 110 arcseconds from the BAT on-board position, within
the BAT error circle. The initial flux in the 2.5s image was
1.5e-09 erg/cm2/s (0.2-10 keV). 

UVOT took a finding chart exposure of 100 seconds with the White
(160-650 nm) filter starting 208 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 19.4 mag. The 8'x8' region for the list of sources
generated on-board covers 100% of the XRT 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 0.16.