TITLE: GCN CIRCULAR NUMBER: 7452 SUBJECT: GRB 080319B: TORTORA synchronous observation DATE: 08/03/19 17:33:14 GMT FROM: Sergey Karpov at SAO RAS S. Karpov, G. Beskin, S. Bondar, C. Bartolini, G. Greco, A. Guarnieri, D. Nanni, A. Piccioni, F. Terra, E. Molinari, G. Chincarini, F.M. Zerbi, S. Covino, V. Testa, G. Tosti, F. Vitali, L.A. Antonelli, P. Conconi, G. Cutispoto, G. Malaspina, L. Nicastro, E. Palazzi, E. Meurs, P. Goldoni report on behalf of the TORTOREM team: TORTORA wide-field optical camera (12 cm diameter, 20x25 deg FOV, TV-CCD, unfiltered) mounted on REM robotic 60-cm telescope located at La Silla (Chile) observed the field of GRB 080319B (GCN 7427, Racusin et al.) before, during and after the gamma-emission with 0.13 s time resolution. We observe optical emission at the position given by Swift XRT: 1. We did not detect any transient brighter than 8.5m (unfiltered, near B) at T-100 - T+16 s 2. We detect rapidly rising OT (~5 second rise front) and observe it between T+16 and T+30, the peak brightness has been around 5 m 3. Between T+30 and T+36 the observations have been paused due to repointing of REM telescope 4. Since T+36 we continuously observe the transient until it faded below the detection limit (~8.5m) at T+90 s The detailed analysis is in progress. This message may be cited.