TITLE: GCN CIRCULAR NUMBER: 15039 SUBJECT: GRB130725B: REM-ROS2 optical observations DATE: 13/07/26 13:48:28 GMT FROM: Dino Fugazza at INAF-OAB D. Fugazza, S. Covino, G. Tagliaferri (INAF-OAB), V. D'Elia (INAF-OAR) report on behalf of the CIBO team: We observed the field of GRB 130725B (Swenson et al., GCN 15029) simultaneously in the optical and near-infrared with the the 60-cm robotic telescope REM at La Silla Observatory (Chile). The observations started at 23:41:40 UT on July 25 2013, about 6.03 hours after the GRB and lasted for about 45 min. We detect the afterglow reported by Siegel et al. (GCN 15032) and Tanga et al. (GCN 15034) with the upgraded ROS2 optical camera. In the NIR with REMIR camera the afterglow was not detected. ROS2 is able to observe simultaneously in the g', r', i', and z' filters and preliminary magnitudes (AB) are: g' = 20.65 ± 0.07 r' = 20.32 ± 0.07 i' = 20.08 ± 0.09 The magnitudes are calibrated against the APASS catalogue.