[vsnet-grb-info 2804] Swift-BAT trigger 180151 is unknown origin at this time

[GCN Circulars]

TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  4641
SUBJECT: Swift-BAT trigger 180151 is unknown origin at this time
DATE:    06/02/04 00:45:13 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <Scott at lheamail.gsfc.nasa.gov>

A. Retter (PSU), S. Barthelmy (GSFC), J. Cummings (GSFC/NRC),
N. Gehrels (GSFC), S. Hunsberger (PSU), J. Kennea (PSU), H. Krimm (GSFC/USRA)
on behalf of the Swift team:

At 23:55:35 UT, Swift-BAT had an 80-sec image trigger.  And because of an
observing constraint, the spacecraft did not slew to the flight-derived
location; and so there are no immediate XRT or UVOT data products to analyze.
We note that the star tracker was not in lock at the time of the trigger.
Past experience shows that the gyros are able to maintain sufficient tracking
to prevent drift and therefore false triggers, but it is still possible
that this current trigger is a false positive.  We will get the full data set
in about 2 hours and may be able to determine the validity of this trigger
at that time.