TITLE: GCN CIRCULAR NUMBER: 40054 SUBJECT: EP250321A: J band upper limit by SYSU 80cm telescope DATE: 25/04/04 15:32:10 GMT FROM: Yan Yu <yuyan35@mail2.sysu.edu.cn> Yan Yu, Jin-Ji Li, Jia-Qi Lin, Wei-Sen Huang, Zhong-Nan Dong, Pu Lin, Hao-Nan Yang, Hao-Ran Zhang, Chun Chen, P H Thomas Tam, Rong-Feng Shen, Bin Ma(Sun Yat-sen University) report on behalf of the SYSU 80cm telescope team: We observed the field of EP250321A (EP GCN 39800; MASTER-OAFA GCN 39803; Zhu et al., GCNs 39809; Swift-XRT GCN 39811) using the Sun Yat-sen University 80cm infrared telescope with 90 x 20 s exposures in J band. The calculated position is RA. = 179.2625 deg, DEC = 17.3628 deg J2000, from EP observation. Our observations began at 2025-3-22 13:25:00 UTC, 31.25 hours after the EP trigger. We do not detect any counterpart at the position of the optical afterglow (Fu et al., GCN 39804; Perez-Garcia et al., GCNs 39805; Brivio et al., GCNs 39807; Becerra et al., GCNs 39810; Pérez-Fournon et al., GCN 39812; Lee et al., GCN 39815; Ghosh et al., GCN 39816; Han et al., GCN 39817; Jin et al., GCN 39822; Zhu et al., GCN 39827; Gill et al., GCN 39831; Zheng et. al, GCN 39832; Pankov et al., GCN 39836; Bochenek et. al, GCN 7939837; Zhu et. al, GCN 39854), down to a 5-sigma depth of J~ 17.6 Vega magnitudes. View this GCN Circular online at https://gcn.nasa.gov/circulars/40054. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...