{
  "submitter": "L. B. He at NAOC <helb@bao.ac.cn>",
  "body": "L.B. He (NAOC), K. Noysena, K. Chanchaiworawit, S. Tinyanont (NARIT), S.Y. Fu (HUST), X. Liu, Z.P. Zhu, S.Q. Jiang, J. An, D. Xu (NAOC) report:\n\nWe observed the field of GRB 260421B detected by Fermi (GCN 44360) and SVOM (zhao et al., GCN 44362), using the 0.7-m telescope of the Thai Robotic Telescope network (TRT), located at Cerro Tololo Inter-American Observatory, Chile (CTO).  We obtained a series of frames in the r-band. \n\nAn uncatalogued source is detected within the Fermi error circle at coordinates\nR.A. (J2000) = 12:40:00.5\nDec. (J2000) = -17:44:24.5\nwith an uncertainty of ~ 1.0 arcsec. The source had r = 19.14 +/- 0.07  mag, calibrated with Pan-STARRS DR2 and not corrected for Galactic extinction.\n\nNo NEO would be at the above position at the observational time by checking MPC.\n\nWe thus think the source is the optical counterpart of GRB 260421B.",
  "circularId": 44363,
  "submittedHow": "web",
  "subject": "GRB 260421B: TRT optical counterpart detection",
  "format": "text/plain",
  "eventId": "GRB 260421B",
  "createdOn": 1776749192010
}