TITLE: GCN CIRCULAR NUMBER: 44533 SUBJECT: GRB 260511A: TRT optical counterpart detection DATE: 26/05/11 06:45:10 GMT FROM: sqjiang at NAOC <sqjiang@bao.ac.cn> S.Q. Jiang (NAOC), K. Noysena, K. Chanchaiworawit, S. Tinyanont (NARIT), S.Y. Fu (HUST), J. An, L.B. He, X. Liu, Z.P. Zhu, D. Xu (NAOC) report: We observed the field of GRB 260511A detected by Fermi GBM (GCN 44529) and SVOM (GCN 44532) 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 Sloan r-band. An uncatalogued and varing source is detected near the SVOM MXT error circle at coordinates R.A. (J2000) = 13:11:35.94 (197.8997 deg) Dec. (J2000) = -33:48:16.3 (-33.8045 deg) with an uncertainty of ~ 1.0 arcsec. The source had r ~ 17.9 mag at a median time of 2026-05-11T06:19:37.771, calibrated with Legacy DR10 and not corrected for Galactic extinction. No NEO would be at the above position at the observational time by checking MPC. We thus think the source could be the optical counterpart of GRB 260511A. View this GCN Circular online at https://gcn.nasa.gov/circulars/44533. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...