TITLE: GCN CIRCULAR NUMBER: 36710 SUBJECT: EP240618a: TRT optical upper limit DATE: 24/06/20 02:58:48 GMT FROM: S. Tinyanont at National Astronomical Research Institute of Thailand <samaporn@narit.or.th> S. Tinyanont, R. Anutarawiramkul, P. Butpan (NARIT), S.Q. Jiang, J. An, X. Liu, S.Y. Fu, Z.P. Zhu, Z. Fan, W.X. Li, N.C. Sun, Y.N. Wang, D. Xu (NAOC) report on behalf of a large collaboration: We observed the field of EP240618a (Sun et al., GCN 36690) using the 0.7-m telescope of the Thai Robotic Telescope network (TRT), located at Sierra Remote Observatory, California, USA. Observations started at 07:37:06.059 UTC on 2024-06-18, i.e., 1.89 hr after the EP trigger, and 15 x 120 s R-band frames were obtained. No uncatalogued optical transient is detected in the stacked R-band image within the 30-arcsec EP/FXT error circle (Sun et al., GCN 36690), down to a 5-sigma limiting magnitude of R ~ 20.3, calibrated with Pan-STARRS sources in the field. Also there is no apparent brightening for any catalogued source within the EP/FXT error circle. View this GCN Circular online at https://gcn.nasa.gov/circulars/36710. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...