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.