TITLE: GCN CIRCULAR NUMBER: 12106 SUBJECT: Swift-BAT trigger 456532 is not astrophysical DATE: 11/07/03 00:07:53 GMT FROM: Scott Barthelmy at NASA/GSFC B. Sbarufatti (INAF-OAB/IASFPA), S. D. Barthelmy (GSFC), D. N. Burrows (PSU), M. M. Chester (PSU), J. R. Cummings (NASA/UMBC), S. T. Holland (CRESST/USRA/GSFC), J. A. Kennea (PSU), N. P. M. Kuin (UCL-MSSL), C. J. Saxton (UCL-MSSL), M. H. Siegel (PSU) and E. Troja (NASA/GSFC/ORAU) report on behalf of the Swift Team: At 23:47:50 UT, the Swift Burst Alert Telescope (BAT) triggered (trigger=456532). Swift slewed immediately to the calculated location: RA, Dec 318.634, -46.745, which is RA(J2000) = 21h 14m 32s Dec(J2000) = -46d 44' 42" The lightcurve does not show anything significant and the peak in the image plane is of marginal significance (less than 7 sigma). The XRT began observing the field at 23:49:22.2 UT, 92.0 seconds after the BAT trigger. No source was detected in 230 s of promptly downlinked data. UVOT took a finding chart exposure of 124 seconds with the U filter starting 254 seconds after the BAT trigger. No credible afterglow candidate has been found in the initial data products. The 2.7'x2.7' sub-image covers 25% of the BAT error circle. The typical 3-sigma upper limit has been about 19.2 mag. Data from the list of sources generated on-board are not available at this time. No correction has been made for the expected extinction corresponding to E(B-V) of 0.04. Given the above low significances and non-detections, we conclude that this trigger is not due to anything astrophysical, and is just a chance coincidence of noise in the rate and image domains. Burst Advocate for this burst is B. Sbarufatti (boris.sbarufatti AT brera.inaf.it). Please contact the BA by email if you require additional information regarding Swift followup of this burst. In extremely urgent cases, after trying the Burst Advocate, you can contact the Swift PI by phone (see Swift TOO web site for information: http://www.swift.psu.edu/too.html.)