TITLE: GCN CIRCULAR NUMBER: 36863 SUBJECT: GRB 240713A: NOT optical upper limits on three EP/FXT candidates DATE: 24/07/14 14:32:50 GMT FROM: Dong Xu at NAOC/CAS <dxu@nao.cas.cn> J. An, S.Q. Jiang, X. Liu, Z.P. Zhu, S.Y. Fu, L.B. He, D. Xu (NAOC), J.P.U. Fynbo (DAWN/NBI), N. Koivisto (NOT) report on behalf of a large collaboration: We observed the field of GRB 240713A detected by SVOM/ECLAIRs (Schanne et al., GCN 36854) and by Fermi/GBM as a sub-threshold event (Burns et al., GCN 36856) using the 2.56-m Nordic Optical Telescope (NOT) equipped with the ALFOSC camera. Due to the constraints of the NOT's FOV and observational time window, we managed to observe three among the ten EP/FXT soft X-ray afterglow candidates (Yang et al., GCN 36859). Observation started at 2024-07-14T03:02:07, i.e., ~ 1.04 day after the SVOM trigger, and a series of 300 s in the Sloan r-band images were obtained. No credible uncatalogued source or apparently brightening catalogued source was found at the positions of the three candidates. Preliminary results are as follows Source | mid time | T-T0(d) | U.L. (5 sigma) ---------------------------------------------------------- EP J233017.4+014339 | 2024-07-14T03:18:18 | 1.0525 | 24.0 EP J233012.2+015001 | 2024-07-14T03:52:33 | 1.0763 | 24.0 EP J233020.4+015231 | 2024-07-14T03:52:32 | 1.0763 | 24.0 calibrated with nearby PanSTARRS stars and not corrected for Galactic extinction. View this GCN Circular online at https://gcn.nasa.gov/circulars/36863. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...