TITLE: GCN CIRCULAR NUMBER: 42807 SUBJECT: GRB 251122A / EP251122a: WFST optical observations DATE: 25/11/22 17:50:46 GMT FROM: ylhua@pmo.ac.cn Tian-Rui Sun, Yan-Long Hua (PMO), Chao Wu (NAOC), Jin-Jun Geng, Xue-Feng Wu, Jun-Jie Wei,, Yi-Fang Liang, Ding-Fang Hu, Guan-Xiao Li, Yuan-Tai Yang, Xu Kong, Ji-An Jiang report on behalf of the WFST team: Following the detection of GRB 251122A / EP251122a by SVOM/ECLAIRs (Lin et al., GCN 42800) and by the Einstein Probe (Wang et al., GCN 42799), we conducted follow-up observations with the Wide Field Survey Telescope (WFST Collaboration; arXiv:2306.07590) at the Lenghu Astronomical Observation Base in Qinghai Province, China. WFST began i-band imaging at 2025-11-22T15:45:51 UTC, approximately 1.85 hours after the trigger. The afterglow is clearly detected in the i band, with a preliminary magnitude derived from 10 × 150 s exposures: i = 21.89 ± 0.12 (AB) The photometric calibration was performed using nearby stars from the ATLAS-REFCAT2 catalog, in the AB magnitude system. The reported magnitude is not corrected for Galactic extinction. We thank the staff of WFST and the Lenghu observation station for supporting these observations. View this GCN Circular online at https://gcn.nasa.gov/circulars/42807. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...