GCN Circular 3825

S. Barthelmy (GSFC), J. Cummings (GSFC/NRC),
H. Krimm (GSFC/USRA),  C. Markwardt (GSFC/UMD)
on behalf of the Swift-BAT team:

The Swift-BAT trigger (trigger=150993) at 17:15:20 UT on 18 August 2005
is not due to a GRB or any other astrophysical source.  The BAT-derived
notices were not distriuted to the GCN list because automated checking
determined that this trigger did not meet the criteria for real-time
distribution.  The spacecraft did not slew immediately to the source
because the merit value of this long image-trigger was less than the target
in the planned observing program.  But about an hour later, the planned target
had a lower merit and the spacecraft slewed and initiated the full response
of the XRT and UVOT instruments.  These XRT and UVOT notices were 
distributed to the world because the information was no longer available
to allow for automated blocking.  Please note that all of the GCN notices
with trigger=150993 (at or near BAT location 268.33,-35.06 J2000)
are related to an invalid trigger response from BAT.