TITLE:   GCN CIRCULAR
NUMBER:  36833
SUBJECT: EP240703b: TRT optical upper limits
DATE:    24/07/05 15:25:56 GMT
FROM:    S. Tinyanont at National Astronomical Research Institute of Thailand <samaporn@narit.or.th>

S. Tinyanont, R. Anutarawiramkul, P. Butpan (NARIT), X. Liu, S.Q. Jiang, J. An, S.Y. Fu, Z.P. Zhu, D. Xu, Z. Fan, W.X. Li, N.C. Sun, Y.N. Wang (NAOC) report on behalf of a large collaboration:

We observed the field of the fast X-ray transient EP240703b (Peng et al., GCN 36810) using the 0.7-m telescope of the Thai Robotic Telescope (TRT) network, located at Spring Brook Observatory, Australia. Observations started at 09:09:53 UTC on 2024-07-04, i.e., 1.16 day after the EP trigger, and 5 x 360 s  frames in the R- & I- bands were obtained, respectively.

No uncatalogued optical transient is detected in the stacked image within the 3-arcmin EP/WXT error circle, down to a 5-sigma limiting magnitudes of R ~ 21.3 and I ~ 20.4, calibrated with SkyMapper sources in the field.