TITLE: GCN CIRCULAR NUMBER: 42811 SUBJECT: GRB 251122A / EP251122a: Xinglong 2.16m optical observation DATE: 25/11/23 08:45:24 GMT FROM: Yinuo Ma <mayn@bao.ac.cn> Y. N. Ma, L. P. Xin, Y. L. Qiu, C. Wu, J. Wang, X. H. Han, P. P. Zhang, H. L. Li, Z. H. Yao, J. Zheng, J. Y. Wei (NAOC) report on behalf of SVOM follow-up team: We observed the field of GRB 251122A triggered by SVOM/ECLAIRs (Lin et al., GCN 42800) and EP/WXT (Wang et al., GCN 42799; Yin et al., GCN 42808; Wang et al., GCN 42809) using the 2.16m telescope located at Xinglong observatory, China, equipped with the BFOSC camera. We obtained 7*200s frames in R-band, starting at 14:17:55 UT on 2025-11-22, about 20.8 minutes after the trigger. The optical counterpart (Wu et al., GCN 42801; Lipunov et al., GCN 42802; Cheng et al., GCN 42803; Saccardi et al., GCN 42804; Cotter et al., GCN 42805; Li et al., GCN 42806; Sun et al., GCN 42807) was detected in the stacked image in R band. The magnitude is: mid time (min) | exposure time (s) | band | mag | mag err ---------------|-------------------|------|--------|-------- 32.9 | 7*200 | R | 22.7 | 0.1 The photometry calibration was performed with nearby USNO-B1.0 1040-0024912 as the reference star. Our photometry was not corrected for Galactic extinction. We thank the staff at Xinglong observatory for their excellent support. View this GCN Circular online at https://gcn.nasa.gov/circulars/42811. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...