TITLE: GCN CIRCULAR NUMBER: 18574 SUBJECT: GRB 151107B: Mini-MegaTORTORA limits on simultaneous optical emission DATE: 15/11/10 17:29:27 GMT FROM: Sergey Karpov at SAO RAS S.Karpov, G.Beskin (SAO RAS and Kazan Federal University, Russia), S.Bondar, E.Ivanov, E.Katkova, A.Perkov, N.Orekhova (OJS RPC PSI, Russia), A.Biryukov (SAI MSU and Kazan Federal University, Russia), V.Sasyuk (Kazan Federal University, Russia) The localization of Fermi GBM trigger 468620696 / GRB 151107B (Stanbro et al, GCN Circ. 18570) has been observed by Mini-MegaTORTORA nine-channel wide-field monitoring system (located at Special Astrophysical Observatory near Russian 6-m telescope and belonging to Kazan Federal University) before, during and after the trigger time at 2015-11-07 20:24:52.30 UT. The whole final 1-sigma localization box (as well as 6 more degrees around it) has been covered since 20:19:23 UT (T-329.3 s) and until 20:25:18 UT (T+25.7 s, thus covering the brightest part of first gamma-ray peak) with temporal resolution of 0.1 s in white light. Dedicated real-time transient detection pipeline did not detect any events longer than 0.3 s and brighter than approximately V=10.5 mag. Visual inspection of co-added images with 10 s effective exposure (summation of 100 consecutive frames each) has not revealed any variable source down to V=12.0 mag during that interval. At 20:25:18 UT the system initiated a repointing following the initially distributed GBM coordinates, and since 20:25:55 UT (T+62.7 s, during the continuing gamma-ray activity) till 20:35:59 UT (T+666.7 s) acquired 20x9 deep images with 30 s exposures in white light in a 30x30 degree field of view centered on RA=24.1 Dec=44.8. The whole final 1-sigma localization was still inside the field of view. Quick-look analysis of the acquired data has not revealed any variable object down to roughly V=13.5 mag over that time interval. The analysis is ongoing.