TITLE: GCN CIRCULAR NUMBER: 9740 SUBJECT: Swift-BAT trigger 358760 is most likely not a GRB DATE: 09/07/31 17:30:56 GMT FROM: Scott Barthelmy at NASA/GSFC T. Sakamoto (GSFC/UMBC), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), E. E. Fenimore (LANL), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC/UMD), D. M. Palmer (LANL), A. M. Parsons (GSFC), G. Sato (ISAS), M. Stamatikos (GSFC/ORAU), B. Sbarufatti (INAF-IASFPA), J. Tueller (GSFC), T. N. Ukwatta (GWU) (i.e. the Swift-BAT team): Using the data set from T-61 to T+242 sec from the recent telemetry downlink, we report further analysis of trigger #358760 (Subrufatti, et al., GCN Circ. 9739). The BAT ground-calculated position is RA, Dec = 189.693, -15.363 deg, with an uncertainty of 3.3 arcmin, (radius, sys+stat, 90% containment). This is 2.7 arcmin from the flight position. The partial coding was 100%. This is only a 5.5 sigma detection in the image domain. The mask-weighted lightcurve shows a very marginal detection in the 25-100 keV band in a single 64 msec time bin and nothing in the other two energy bands. There is also a weak cosmic ray shower during this 64-msec bin. Given this very maginal evidence, we do not think this trigger is due to a GRB. It is very probably a noise fluctution coupled with a weak CR Shower. However, we can not rule out a GRB origin.