GCN Circular 18586
P. A. Evans (U Leicester), H. A. Krimm (CRESST/GSFC/USRA), K. L. Page (U Leicester) and B. Sbarufatti (INAF-OAB/PSU) report on behalf of the Swift Team: At 10:28:11 UT, the Swift Burst Alert Telescope (BAT) triggered (trigger=663164) on what appears to be noise during the count rate rise associated with entry into the SAA. The image significance is low (6.5 sigma) and there is no significant peak in the light curve. Thus we believe that this trigger is not due to a GRB or other astrophysical event. The XRT began observing the field at 10:29:46.6 UT, 94.8 seconds after the BAT trigger. Initially XRT centroided on a cosmic ray. Further XRT data were not gathered until 1491 s after the trigger, due to SAA passage. No source was detected in 132 s of promptly-downlinked data.