TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  4945
SUBJECT: GRB 060403: Swift detection of a burst
DATE:    06/04/03 13:40:52 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <Scott@lheamail.gsfc.nasa.gov>

P. T. Boyd (NASA/GSFC), S. D. Barthelmy (GSFC), D. N. Burrows (PSU),
J. R. Cummings (NASA/ORAU), N. Gehrels (NASA/GSFC),
C. Gronwall (PSU), S. T. Holland (GSFC/USRA), J. A. Kennea (PSU),
H. A. Krimm (GSFC/USRA), V. La Parola (INAF-IASFPA),
V. Mangano (INAF-IASFPA), F. E. Marshall (NASA/GSFC),
K. L. Page (U Leicester), D. M. Palmer (LANL), P. Romano (INAF-OAB)
and T. Sakamoto (NASA/ORAU) report on behalf of the Swift Team:

At 13:12:17 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 060403 (trigger=203755).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is RA,Dec 282.306, +8.330
{18h 49m 13s, +08d 19' 47"} (J2000) with an uncertainty of 3 arcmin 
(radius, 90% containment, including systematic uncertainty). 
The BAT light curve shows a single FRED-like peak structure
with a duration of about 25 sec.  The peak count rate
was ~2000 counts/sec (15-350 keV), at ~0 sec after the trigger. 

The XRT began taking data at 13:15:59 UT, 222 seconds after the BAT
trigger. The XRT on-board centroid algorithm did not find a source in
the image. However downlinked image data show the presence of a
uncatalogued point source at the following position:  

RA(J2000): 18:49:21.2 
Dec(J2000): +08:19:39.3  

with an error radius of 8 arcseconds (90% containment). This position 
lies 116 arcseconds from the BAT position. 

UVOT took a finding chart exposure of 100 seconds with the White
filter starting 63 seconds after the BAT trigger. No afterglow
candidate has been found in the initial data products. The XRT
position is not covered by the 2.7'x2.7'sub-image.  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 XRT error circle. The
list of sources is typically complete to about 18.1 mag. No
correction has been made for the large, but uncertain expected extinction. 
We note that this is a crowded field.