TITLE: GCN CIRCULAR NUMBER: 37348 SUBJECT: GRB 240828B: GWAC-F50A optical upper limit DATE: 24/08/30 06:14:43 GMT FROM: Liping Xin at NAOC, SVOM <xlp@nao.cas.cn> SVOM/GWAC-F50A team：L.P.Xin(NAOC), Y.G.Yang(HNU), X.H.Han, X.M.Lu, R.S.Zhang, Y.Xu, Y.J.Xiao, P.P.Zhang, H.B.Cai, Y.L.Qiu, H.L.Li,C.Wu, L.Lan, W.J.Xie, J.Y.Wei(NAOC),J.Wang,X.G.Wang(GXU) SVOM JSWG: Jian-Yan Wei (NAOC, China), Bertrand Cordier (CEA, F), Shuang-Nan Zhang (IHEP, CN), Stephane Basa (LAM, F), Jean-Luc Attéia (IRAP, F), Arnaud Claret (CEA, F), Zi-Gao Dai (USTC, CN), Frederic Daigne (IAP, F), Jin-Song Deng (NAOC, CN), Andrea Goldwurm (APC, F), Diego Götz (CEA, F), Xu-Hui Han (NAOC, CN), Cyril Lachaud (APC, F), En-Wei Liang (GXU, CN), Yu-Lei Qiu (NAOC, CN), Susanna Vergani (Obs.Paris, F), Jing Wang (NAOC, CN), Chao Wu(NAOC, CN), Li-Ping Xin (NAOC,CN), Bing Zhang (UNLV, CN) We began to observe GRB 240828B (Le Provost et al., GCN 37318) detected by SVOM/ECLAIRs, with GWAC-F50A telescope at Xinglong station,China,at 16:45:50(UT), August 28,2024, about 3.55 hours after the burst. The weather was not good. After stacking 20*100 seconds, no any new sources were detected in our stacked image within the X-ray afterglow error circles (Page et al. GCN 37334) down to a limit magnitude of 18.5 mag in R band at the mid-time of 3.83 hours post the burst, calibrated to several nearby USNO B1.0 stars. We acknowledge the excellent support from observation assistant Yangtong Zheng and Winlong Dong. View this GCN Circular online at https://gcn.nasa.gov/circulars/37348. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...