TITLE: GCN CIRCULAR NUMBER: 40986 SUBJECT: GRBs 250702B,C,D,E / EP250702a: J band upper limit by SYSU 80cm infrared telescope DATE: 25/07/06 04:15:00 GMT FROM: lixia76@mail2.sysu.edu.cn Xia Li, Chun Chen, Zhong-nan Dong, Duo-le Cao, Wei-Sen Huang, Jin-Ji Li, Jia-Qi Lin, Pu Lin, Yan Yu, Hao-Nan Yang, Hao-Ran Zhang, Xiang-Tao Zeng, P H Thomas Tam, Rong-Feng Shen, Bin Ma (Sun Yat-sen University) report on behalf of the SYSU 80cm infrared telescope team: We observed the field of GRBs 250702B,C,D,E / EP250702a (H. Q. Cheng et al., GCN 40906; Y. Kawakubo et al., GCN 40910; D. Frederiks et al., GCN 40914; H. Q. Cheng et al., GCN 40917; J. A. Kennea et al., GCN 40919; Chen-Wei Wang et al., GCN 40923; E. Neights et al., GCN 40931) using the Sun Yat-sen University 80cm infrared telescope with 58 x 20 s exposures in J band. The calculated position is RA. = 18:58:45.61, DEC =-07:52:26.9 J2000, from Swift/XRT observation (J. A. Kennea et al., GCN 40919). Our observations began at 2025-7-3 19:36:00 UTC (29.67 hours after the first Fermi trigger, GRB 250702B). We do not detect any optical counterpart (A. Kumar et al., GCN 40908; V.Lipunov et al., GCN 40912; Rosa L. Becerra et al., GCN 40918; I. Pérez-García et al., GCN 40929; Yan-Long Hua et al., GCN 40943; Malte Busmann et al., GCN 40949; M. H. Siegel, GCN 40952) at the position of the near-infrared afterglow (A. Martin-Carrillo et al., GCN 40924; A. J. Levan et al., GCN 40961), down to a 5-sigma depth of J~ 17.5 Vega magnitudes. The SYSU 80cm infrared telescope is operated and managed by the Department of Astronomy, Sun Yat-sen University. View this GCN Circular online at https://gcn.nasa.gov/circulars/40986. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...