TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4721 SUBJECT: Swift-BAT trigger 180931 is not a GRB DATE: 06/02/09 22:17:14 GMT FROM: Scott Barthelmy at NASA/GSFC S. Barthelmy (GSFC), L. Barbier (GSFC), J. Cummings (GSFC/ORAU), E. Fenimore (LANL), N. Gehrels (GSFC), D. Hullinger (GSFC/UMD), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), D. Palmer (LANL), A. Parsons (GSFC), T. Sakamoto (GSFC/ORAU), G. Sato (ISAS), J. Tueller (GSFC) on behalf of the Swift-BAT team: The Swift-BAT trigger (trigger=180931) at 19:08:55 UT on 09 Feb 2006 is not due to a GRB or any other astrophysical source. This trigger is due to a cosmic ray shower event in the instrument.