GCN Circular 39486
Subject
EP250226a / GRB 250226A: TRT optical counterpart observation
Date
2025-02-26T08:35:09Z (11 days ago)
From
Dong Xu at NAOC/CAS <dxu@nao.cas.cn>
Via
Web form
J. An, S.Q. Jiang, X. Liu, S.Y. Fu, Z.P. Zhu, D. Xu (NAOC), S. Tinyanont, R. Anutarawiramkul, P. Butpan (NARIT), Z. Fan, W.X. Li, N.C. Sun, Y.N. Wang (NAOC) report on behalf of a large collaboration:
We observed the field of EP250226a detected by EP/WXT (Jiang et al., GCN 39482), which is very likely the same event of GRB 250226A detected by Fermi/GBM (Fermi GBM team, GCN 39479), using the 0.7-m telescope of the Thai Robotic Telescope network (TRT), located at Cerro Tololo Inter-American Observatory, Chile. We obtained several 300 s frames in the Sloan-r filter.
An uncatalogued and decaying optical source is detected within the EP/FXT error circle (Jiang et al., GCN 39482) at coordinates
R.A. (J2000) = 14:57:03.63
Dec. (J2000) = +20:58:32.31
with an uncertainty of about 1.0 arcsec. The source has r ~ 17.7 mag at 21.8 min after the EP trigger, calibrated with PanSTARRS DR2 stars and not corrected for Galactic extinction.
We think that the source is the optical counterpart of EP250226a / GRB 250226A.