GCN Circular 4355
H. Krimm (GSFC/USRA), S. Barthelmy (GSFC), J. Cummings (GSFC/NRC) and C. Markwardt (GSFC/UMD) on behalf of the Swift-BAT team: The Swift-BAT trigger (trigger=172767) at 00:39:49 UT on 15 Dec 2005 (reported in GCN Circular 4352, Holland et al.) is not due to a GRB or any other astrophysical source. Using the full event-by-event data from the recent telemetry downlink, all 42 events in the trigger occurred within a single 100 microsec bin. This trigger was due to a cosmic shower event in BAT.