TITLE:   GCN CIRCULAR
NUMBER:  37186
SUBJECT: EP240816b: TRT optical upper limit
DATE:    24/08/16 12:34:32 GMT
FROM:    Dong Xu at NAOC/CAS <dxu@nao.cas.cn>


J. An, S.Q. Jiang (NAOC), S. Tinyanont, R. Anutarawiramkul, P. Butpan (NARIT), X. Liu, S.Y. Fu, Z.P. Zhu, S.Y. Gao, 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 EP240816b (Yang et al., GCN 37185) using the 0.7-m telescope of the Thai Robotic Telescope network (TRT), located at Fresno, California, U.S.A. Observations started at 07:10:37 UTC on 2024-08-16, i.e., 5.436 hr after the EP trigger, and 4 x 300 s  frames were obtained in R-band.

No uncatalogued optical source is detected in the stacked image within the 10-arcsec EP/FXT error circle, down to a 5-sigma limiting magnitude of R ~ 20.0, calibrated with PanSTARRS sources in the field.