TITLE: GCN CIRCULAR NUMBER: 43565 SUBJECT: EP260128a: J band upper limit by SYSU 80cm infrared telescope DATE: 26/01/30 04:42:48 GMT FROM: linp@mail2.sysu.edu.cn Pu Lin, Jin-Ji Li, Hao-Nan Yang, Zhong-Nan Dong, Yan Yu, Jia-Qi Lin, Wei-Sen Huang, Chun Chen, Duo-Le Cao, 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 EP260128a (Zhou et al., GCN 43549) using the Sun Yat-sen University 80cm infrared telescope with 167 x 20 s exposures in J band. The calculated position is RA = 128.32533 deg, DEC = -10.27565 deg J2000, from EP/FXT observation (Zhou et al., GCN 43554). Our observations began at 2026-1-29 20:00:00 UTC, 20.33 hours after the EP trigger. We do not detect any counterpart at the position of the optical afterglow (H. L. Li et al., GCN 43551, J. A. Quirola-Vasquez et al., GCN 43552, R. A. J. Eyles-Ferris et al., GCN 43553, L.B. He et al., GCN 43555), down to a 5-sigma depth of J~ 18.5 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/43565. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...