TITLE: GCN CIRCULAR NUMBER: 35353 SUBJECT: GRB 231215A : Nanshan/HMT optical observations DATE: 23/12/15 14:32:20 GMT FROM: Dong Xu at NAOC/CAS <dxu@nao.cas.cn> J. An, X. Liu, S.Q. Jiang, S.Y. Fu, T.H. Lu, Z.P. Zhu, D. Xu (NAOC), X. Gao (Urumqi No.1 Senior High School), J.Z. Liu (XAO) report: We observed the field of GRB 231215A detected by Swift (D'Avanzo et al., GCN 35343) using the HMT-0.5m telescope located at Nanshan, Xinjiang, China. Observations started at 11:51:08 UT on 2023-12-15, i.e., 2.06 hr after the BAT trigger. A series of 90, 120, 200 s frames without any filter have been obtained and observations are ongoing. Preliminary analysis of the initial frames shows that the previously reported optical afterglow (e.g., Pankov et al., GCN 35349; Sasada et al., GCN 35351) has decayed to m(r) = 18.3 +/- 0.1 mag at 2.19 hr post-burst, calibrated with the nearby PanSTAR field in the Sloan r-filter and the magnitude is not corrected for Galactic extinction. View this GCN Circular online at https://gcn.nasa.gov/circulars/35353. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...