GCN Circular 41679
Subject
GRB 250903A: TRT optical counterpart detection
Event
Date
2025-09-03T18:46:15Z (10 days ago)
From
J. An <jiean0813@foxmail.com>
Via
Web form
J. An (NAOC), K. Noysena, K. Chanchaiworawit, S. Tinyanont (NARIT), S.Y. Fu (HUST), L.B. He, X. Liu, Z.P. Zhu, S.Q. Jiang, D. Xu (NAOC) report on behalf of a large collaboration:
We observed the field of GRB 250903A detected by SVOM/ECLAIRs (Maiolino et al., GCN 41677), using the 0.7-m telescope of the Thai Robotic Telescope network (TRT), located at New South Wales, Australia (SBO). Observations started at 17:34:50 UTC on 2025-09-03, i.e., ~10 min after the SVOM/ECLAIRs trigger. A series of R-band frames were obtained.
An uncatalogued and varying optical source is detected within the SVOM/ECLAIRs error circle (Maiolino et al., GCN 41677), at coordinates
R.A. (J2000) = 23:47:11.67
Dec. (J2000) = -75:58:00.21
with an uncertainty of ~ 0.8 arcsec.
Preliminary photometry shows the source has R ~ 19.0 mag at 13.35 min post-trigger, calibrated with Legacy Survey DR10 catalog and not corrected for Galactic extinction.
We think the source is the optical counterpart of GRB 250903A.