TITLE: GCN CIRCULAR NUMBER: 39921 SUBJECT: GRB 250328A: SVOM/C-GFT optical upper limit DATE: 25/03/29 11:16:01 GMT FROM: SVOM_group <svomgroup@bao.ac.cn> Zhe Kang (CHO), J. Malzac(OMP)，M. Brunet(OMP), Liping Xin(NAOC), Xuhui Han(NAOC), Chao WU (NAOC), Pinpin Zhang (NAOC), Xiaomeng Lu (NAOC), Zhenwei Li (CHO), You Lv (CHO), Ruosong Zhang (NAOC), Yujie Xiao(NAOC), Yulei, Qiu(NAOC), Jing Wang(NAOC), Jianyan Wei (NAOC) report on behalf of the SVOM/C-GFT team: We observed the field of GRB 250328A detected by SVOM/ECLAIRs (sb25032803) with C-GFT. Our observations were started on 2025-03-28T17:14:26 UTC, ~17.50 mins fter the trigger. A series of g, r, and i-band images were obtained. No uncataloged optical counterpart candidates were detected within the SVOM/ECLARIRS source error circle (GCN 39910). Additionally, no sources were detected at the positions of the Swift/XRT Source #2 and the location reported by Schneider et al. (GCN 39919) and Schneider et al. (GCN 3920) in our coadded images. The upper limit magnitudes(3sigma) are, (T-T0)_mid(mins) upper_limit(3sigma) band ---------------------------------------------------------------- 22.65 >20.00 i 24.15 >20.20 g 25.63 >20.11 r The photometry was calibrated with UCAC4 catalog. This result is consistent with the report from Xin et al.(39911). We thank the observation assistants Bowen Li 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/39921. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...