TITLE: GCN CIRCULAR NUMBER: 7780 SUBJECT: Swift analysis of BAT Slew Survey event (Trigger=009) DATE: 08/06/01 22:47:46 GMT FROM: Eleonora Troja at INAF-IASFPA E. Troja (U. Leicester/INAF-IASFPA), S. Barthelmy (GSFC), J. Cummings (GSFC/UMBC), A. Copete (Harvard), J. Grindlay (Harvard), P. Evans (U. Leicester) report: At 01:17:20 UT on 2008-05-31, BAT detected a source during a spacecraft slewing interval (when normal BAT triggering is disabled). This event (ID_Num=009) was detected using the BAT Slew Survey (BATSS) method and classified it as 'Silver plated' -- highly likely to be a GRB. The location is RA(J2000) = 22h 53m 24s Dec(J2000) = +54d 57' 00" with an uncertainty of 7.7 arcmin. This was initially distributed as a GCN/BAT_SLEW_POS Notice at 13:53 UT, 12.6 hrs after the slew. The Swift BAT team performed a further analysis of the event data during this slew. No sign of a source was found at the BATSS position with a 3 sigma upper limit of 0.10 cts/s. A 2 ks ToO observation of the location started at 15:42 UT, 14.4 hrs after the slew. The XRT observation (Photon Counting mode) detected an X-ray source with a count rate of 0.04 cts/s. Its position is RA(J2000) = 22h 53m 08.54s Dec(J2000) = +55d 04m 34.0s with an uncertainty of 4.6 arcsec (90% confidence). This is at the edge of the BATSS error circle. This source shows no indication of fading over the 2 ks interval. We therefore conclude that this event is not a GRB and that the source found by XRT is an unassociated field object.