TITLE: GCN CIRCULAR NUMBER: 37062 SUBJECT: GRB 240805B: Optical detection with 1.6m Mephisto DATE: 24/08/06 08:26:44 GMT FROM: Brajesh Kumar at SWIFAR, YNU <brajesh@ynu.edu.cn> Guowang Du (SWIFAR, YNU), Yuan Fang (SWIFAR, YNU), Yangwei Zhang (SWIFAR, YNU), Xuhui Han (NAOC), Pinpin Zhang (NAOC), Liping Xin (NAOC), Chao Wu (NAOC), Brajesh Kumar (SWIFAR, YNU), Baokun Sun (SWIFAR, YNU), Yuanpei Yang (SWIFAR, YNU), Xinzhong Er (SWIFAR, YNU), Xiangkun Liu (SWIFAR, YNU), Xiaowei Liu (SWIFAR, YNU) We did simultaneous multi-band photometric observations of GRB 240805B (Williams et al., GCN 37043) using 1.6m Multi-channel Photometric Survey Telescope (Mephisto) of Yunnan University located at Lijiang Observatory. The observations were started at (UTC) 2024-08-05 15:46:50 and multiple frames were obtained in uvgriz bands. In our preliminary analysis the OT candidate (Moskvitin et al., GCN 37055) is detected in r, i and z bands with the following magnitudes: MJD Filter Mag (AB) 60527.65751 r 20.3+-0.2 60527.66333 i 18.2+-0.04 60527.65751 z 17.8+-0.08 60527.66333 u >21.1 60527.65751 v >21.2 60527.66333 g >20.9 -----------------------------------------------------------------------------------------------------Mephisto (Multi-channel Photometric Survey Telescope) is a 1.6m wide-field multi-channel telescope, the first of its type in the world, capable of imaging the same field of view in three optical bands simultaneously. It provides real-time, high-quality colors of stellar objects. The on-site telescope assemblage and commissioning were carried out in September 2022. The first light in all three channels was achieved on 2023 December 21. ----------------------------------------------------------------------------------------------------- View this GCN Circular online at https://gcn.nasa.gov/circulars/37062. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...