TITLE: GCN CIRCULAR NUMBER: 44551 SUBJECT: GRB 260511B: TRT optical observation DATE: 26/05/11 14:21:35 GMT FROM: sqjiang at NAOC <sqjiang@bao.ac.cn> S.Q. Jiang (NAOC), K. Noysena, K. Chanchaiworawit, S. Tinyanont (NARIT), L.B. He, X. Liu, Z.P. Zhu, J. An, D. Xu (NAOC), S.Y. Fu (HUST) report: We observed the field of GRB 260511B detected by SVOM (Godet et al., GCN 44543) and Fermi (Fermi GBM team, GCN 44542), using the 0.7-m telescope of the Thai Robotic Telescope network (TRT), located at New South Wales, Australia (SBO). Observation started at 2026-05-11T12:52:30.855 UT, i.e., 1.867 hrs post-burst, and a series of R-band frames were obtained. The optical counterpart (Wu et al., GCN 44547; Sasada et al., GCN 44549) is clearly detected in our images with a brightness of R = 16.82 +/- 0.01 at a median time of 1.875 hrs since trigger, calibrated with Pan-STARRS DR2 stars in the field and not corrected for Galactic extinction. View this GCN Circular online at https://gcn.nasa.gov/circulars/44551. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...