TITLE: GCN CIRCULAR NUMBER: 45173 SUBJECT: GRB 260618B: EP-FXT follow-up observation upper limit DATE: 26/07/16 11:58:22 GMT FROM: Yinuo Ma <mayn@bao.ac.cn> Y. N. Ma (NAOC), A. Li (BNU), Y. L. Qiu, H. L. Li, L. P. Xin (NAOC), Y. L. Hua (PMO), M. J. Liu (NAOC), X. H. Tang (Tsinghua Univ.), W. D. Zhang (NAOC) on behalf of SVOM and EP missions: EP-FXT performed a follow-up observation of GRB 260618B detected by Fermi (Fermi GBM team, GCN 44979; Gupta et al., GCN 44983; Veres et al., GCN 45010) and Konus-Wind (Ridnaia et al., GCN 45038). The follow-up observation started at 2026-07-15T10:43:17 (UTC), about 26.7 days after the Fermi trigger, with a total exposure time of around 2.9 ks. No significant X-ray source was detected at the position of the reported optical candidate (Li et al., GCN 45001; Shi et al., GCN 45014; Li et al., GCN 45151). The upper limit for the 0.5-10 keV band is about 5.0e-14 ergs/cm^2/s (90% C.L.). Launched on January 9, 2024, EP is a space X-ray observatory to monitor the soft X-ray sky with X-ray follow-up capability (Yuan et al. 2022, Handbook of X-ray and Gamma-ray Astrophysics). View this GCN Circular online at https://gcn.nasa.gov/circulars/45173. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...