GCN Circular 21261
S. W. K Emery (UCL-MSSL), P. A. Evans (U Leicester), A. Y. Lien (GSFC/UMBC), K. L. Page (U Leicester) and B. Sbarufatti (INAF-OAB/PSU) report on behalf of the Swift Team: At 10:32:44 UT, the Swift Burst Alert Telescope (BAT) triggered on noise near NGC5949 (trigger=758168). Swift slewed immediately to the location. The BAT on-board calculated location is RA, Dec 232.221, +64.871 which is RA(J2000) = 15h 28m 53s Dec(J2000) = +64d 52' 14" with an uncertainty of 4 arcmin (radius, 90% containment, including systematic uncertainty). As is typical for image triggers, there is nothing in the real-time light curve. The XRT began observing the field at 10:39:26.2 UT, 401.6 seconds after the BAT trigger. No source was detected in 391 s of promptly downlinked data. UVOT took a finding chart exposure of 150 seconds with the White filter starting 404 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 19.6 mag. The 8'x8' region for the list of sources generated on-board covers 100% of the BAT error circle. The list of sources is typically complete to about 18 mag. No correction has been made for the expected extinction corresponding to E(B-V) of 0.03. Given that this is a low significance detection in BAT (5.9 sigma) and that there is no XRT source, we think this is a non-astrophysical fluctuation in the BAT image that happens to be close the NGC5949 source.