{
  "submitter": "J. An <jiean0813@foxmail.com>",
  "eventId": "GRB 250903A",
  "bibcode": "2025GCN.41679....1A",
  "body": "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:\n\nWe 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. \n\nAn uncatalogued and varying optical source is detected within the SVOM/ECLAIRs error circle (Maiolino et al., GCN 41677), at coordinates\n\nR.A. (J2000) = 23:47:11.67\nDec. (J2000) = -75:58:00.21\n\nwith an uncertainty of ~ 0.8 arcsec.\n\nPreliminary 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.\n\nWe think the source is the optical counterpart of GRB 250903A.",
  "submittedHow": "web",
  "subject": "GRB 250903A: TRT optical counterpart detection",
  "createdOn": 1756925175384,
  "circularId": 41679,
  "format": "text/plain"
}