GCN Circular 41675
Subject
EP250903a: TRT optical observations
Event
Date
2025-09-03T17:08:34Z (5 days ago)
From
J. An <jiean0813@foxmail.com>
Via
Web form
J. An (NAOC), S. Tinyanont, R. Anutarawiramkul, P. Butpan (NARIT), S.Y. Fu (HUST), L.B. He, X. Liu, Z.P. Zhu, S.Q. Jiang, 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 EP250903a (Zhao et al., GCN 41674), using the 0.7-m telescope of the Thai Robotic Telescope network (TRT), located at New South Wales, Australia (SBO). Observations started at 14:14:31 UTC on 2025-09-03, i.e., ~ 11.5 min after the EP/WXT trigger and a series of frames in the R band were obtained.
No uncatalogued source is detected in our stacked image within or at the border of the EP-FXT error circle, down to a 5-sigma limiting magnitude of R > 20.1 (Vega) at ~ 1.21 hr post-trigger, calibrated with SKYMAPPER DR2 catalog and not corrected for Galactic extinction.
The two relatively bright catalogued sources/stars within or at the border of the EP-FXT error circle do not show variability in brightness. Our result is consistent with that by GOTO (O'Neill et al., GCN 41672).
We note that there are faint galaxies within the EP-FXT error circle from Legacy Survey, so deep follow-ups are encouraged.