TITLE: GCN CIRCULAR NUMBER: 7634 SUBJECT: Swift-BAT trigger 309665 is not a GRB DATE: 08/04/20 13:32:43 GMT FROM: Hans Krimm at NASA-GSFC H.A. Krimm (CRESST/GSFC/USRA) and L. Vetere (PSU) report on behalf of the Swift Team: The Swift-BAT trigger (trigger=309665) at 04:12:47 UT on 20 April 2008, tentatively labelled GRB 080420 (GCN 7632, Vetere et al.), is not due to a GRB or any other astrophysical source. This trigger is due to a cosmic ray shower event in the instrument. All events occurred in the same 100 microsec window.