TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4426 SUBJECT: Swift-BAT trigger 175653 is probably not a GRB DATE: 06/01/03 04:41:19 GMT FROM: Scott Barthelmy at NASA/GSFC D. Grupe (PSU), S. Barthelmy (GSFC), D. Burrows (PSU), M. Chester (PSU), N. Gehrels (GSFC), C. Gronwall (PSU), S. Immler (GSFC), J. Kennea (PSU), F. Marshall (GSFC), T. Sakamoto (GSFC) on behalf of the Swift team: The Swift-BAT trigger (trigger=175653) at ~04:03 UT on 03 January 2006 is probably not due to a GRB or any other astrophysical source. The background is high while entering the SAA. This was a single-sided trigger criterion which is susceptible to rising backgrounds. The XRT began observing the field in the SAA and attempted to find a centroid of a bright source in the field of view, but failed to find a source. This is consistent with a non-burst origin for this event, but this is not conclusive, as we only succeed in on-board centroids approximately 40% of the time due to faint afterglows. This GCN Notices have the same incorrect trigger time as did the previous burst. This problem is being worked.