TITLE: GCN CIRCULAR NUMBER: 36018 SUBJECT: GRB 240402B: GWAC-F50A optical upper limit DATE: 24/04/03 22:56:22 GMT FROM: Liping Xin at NAOC, SVOM <xlp@nao.cas.cn> L.P.Xin(NAOC), Y.G.Yang(HNU), C.WU(NAOC), Y.L.Qiu(NAOC), J.Wang(GXU/NAOC), L.H.Li(NAOC), C.Wu(NAOC), E.W.Liang(GXU), X.H.Han (NAOC), X.M.Lu(NAOC), R.S.Zhang(NAOC), Y.Xu(NAOC), Y.J.Xiao(NAOC), P.P.Zhang(NAOC), L.Lan(NAOC), J.Y.Wei(NAOC) on behalf of the SVOM/GWAC team: We began to observe X-ray transient LXT 240402A (Xu et all., GCN 36106) detected by LEIA, which was also detected by GECAME-C as GRB 240402B (Xue et al., GCN 36107), with GWAC-F50A telescope, at Xinglong station, China, at 19:22:13 (UT), 03. April. 2024, about 34.57 hours after the burst. The weather was not good. After stacking 5*200 seconds, no any new sources were detected in our stacked image down to a limit magnitude of 18.0 mag in R band comparing to several nearby USNO B1.0 stars. We acknowledge the excellent support from observation assistant Yangtong Zheng. View this GCN Circular online at https://gcn.nasa.gov/circulars/36018. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...