[vsnet-grb-info 2160] Swift-BAT trigger 150993 is probably not a GRB

[GCN Circulars]

TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  3999
SUBJECT: Swift-BAT trigger 150993 is probably not a GRB
DATE:    05/09/18 20:29:07 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <Scott at lheamail.gsfc.nasa.gov>

D. Grupe (PSU), S. Barthelmy (GSFC), D. Burrows (PSU), N. Gehrels (GSFC),
H. Krimm (GSFC/USRA), J. Kennea (PSU), C. Markwardt (GSFC/UMD),
D. Palmer (LANL), P. Roming (PSU)
on behalf of the Swift team:

The Swift-BAT trigger (trigger=155764) at 19:42:13 UT on 18 Sep 2005
is probably not due to a GRB or any other astrophysical source.
We will have the full data set at 23:45 UT, after which we will issue
a final determination.

The spacecraft slewed immediately and the XRT began observing at 19:43:11 
(at T+58s).  The XRT generated an on-board centroid on a cosmic ray near 
the edge of the field of view.  This position is invalid (GCN 3998).
The spectrum and light curve are ambiguous, and we cannot rule out
the possibility of a weak afterglow in the XRT field of view.
Further analysis will require downloaded data following the next
ground station pass.