TITLE: GCN CIRCULAR NUMBER: 38758 SUBJECT: GRB 250101A: SVOM/C-GFT early optical observations DATE: 25/01/01 16:31:19 GMT FROM: Chao Wu at NAOC <cwu@nao.cas.cn> SVOM/C-GFT team: Chao WU (NAOC), Zhe Kang (CHO), Liping Xin(NAOC), Xuhui Han(NAOC), Pinpin Zhang (NAOC), Xiaomeng Lu (NAOC), Zhenwei Li (CHO), You Lv (CHO), Ruosong Zhang (NAOC), Yujie Xiao(NAOC) SVOM JSWG: Jian-Yan Wei (NAOC), Bertrand Cordier (CEA), Shuang-Nan Zhang (IHEP), Stéphane Basa (LAM), Arnaud Claret (CEA), Zi-Gao Dai (USTC), Frédéric Daigne (IAP), Jin-Song Deng (NAOC),Olivier Godet (IRAP), Andrea Goldwurm (APC), Diego Götz (CEA), Xu-Hui Han (NAOC), Cyril Lachaud (APC), En-Wei Liang (GXU), Yu-Lei Qiu (NAOC), Susanna Vergani (Obs.Paris), Jing Wang (NAOC), Chao Wu (NAOC), Li-Ping Xin (NAOC), Shao-Lin Xiong (IHEP), Bing Zhang (UNLV) We observed the field of GRB 250101A detected by Swift/BAT (Page et al., GCN 38752) on 2025-01-01T13:24:07 UT, ~ 77s after the trigger with C-GFT in the commissioning phase. A series of g, r and i band images were obtained with exposure time of 10s. The optical counterpart (Page et al. GCN 38752, Li et al. GCN 38753, Mohan et al. GCN 38754, Zhu et al. GCN 38755, Budnev et al., GCN 38756 ) was clearly detected in band g,r and i. The results are, (T-T0)_mid(s) mag mag_err band ------------------------------------- 82 18.38 +/- 0.26 i 172 17.37 +/- 0.08 g 262 16.83 +/- 0.05 r The photometry was calibrated with nearby PS1 star. Observations will be continued. We thank the observation assistant Guangsheng Zhang at Jilin observatory for their excellent support. Chinese Ground Follow-up Telescope of SVOM mission is located at Jilin, Changchun Observatory, National Astronomical Observatories, CAS. It has FOV of 1.28 deg x 1.28 deg with a 4k*4k CMOS detector mounted on the primary focus of 1.2-meter-aperure telescope. View this GCN Circular online at https://gcn.nasa.gov/circulars/38758. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...