[vsnet-grb-info 2826] GRB 060204C: Swift-BAT detection of a burst

[GCN Circulars]

TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  4663
SUBJECT: GRB 060204C: Swift-BAT detection of a burst
DATE:    06/02/04 21:30:36 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <Scott at lheamail.gsfc.nasa.gov>

D. Grupe (PSU), S. Barthelmy (GSFC), D. Burrows (PSU),
A. Cucchiara (PSU), J. Cummings (GSFC/NRC), N. Gehrels (GSFC),
S. Hunsberger (PSU), J. Kennea (PSU), C. Markwardt (GSFC/UMD),
F. Marshall (GSFC), D. Morris (PSU), D. Palmer (LANL), T. Sakamoto (GSFC)
on behalf of the Swift team:

At 20:33:43 UT, Swift-BAT triggered and located GRB 060204C (trigger=180274).
The spacecraft slewed immediately.  The BAT on-board calculated location is
RA,Dec 92.727d,+70.171d {06h 10m 54s,+70d 10' 14"} (J2000), with an
uncertainty of 3 arcmin (radius, 90% containment, stat+sys).
This is a 64-sec image trigger, and as such, there is little that can be
determined from the TDRSS lightcurve.

The S/C slewed immediately and the XRT began taking data at 20:36:19 UT, 
157 sec after the BAT trigger.  The XRT on-board centroid algorithm did not 
converge and no prompt position is available, however, the XRT 
lightcurve suggests the possibility of a decaying source in the field of view.
We are waiting for down-linked data to determine the presence of the source.

UVOT took a finding chart exposure of nominal 200 seconds with the V filter
starting 156 seconds after the BAT trigger.  No afterglow candidate
has been found in the initial data products.  Image catalog data
are not available at this time.  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 18.0 mag.  No correction
has been made for the expected extinction of about 0.6 magnitudes.
No afterglow candiate was found in a second B finding chart taken
at T+363 sec.

Given that the star tracker had been out-of-lock for only 2 minutes prior
to this trigger, it is very unlikely there is a problem with the attitude
of this position solution, so we believe this location to be valid.