S.Q. Jiang, Z.P. Zhu, S.Y. Fu, J. An, X. Liu, T.H. Lu, D. Xu (NAOC), X. Gao (Urumqi No.1 Senior High School), J.Z. Liu (XAO) report:
We observed the optical afterglow of GRB 231111A detected by Swift (Melandri et al., GCN 34981) using the HMT-0.5m telescope located at Nanshan, Xinjiang, China. Observations started at 14:18:35 UT on 2023-11-11, i.e., 75 s after the Swift/BAT trigger, and we obtained a serise of 3x20, 3x40, 4x60, 4x90, 4x120, 4x200 s frames without any filter.
The optical afterglow has been decaying during our observations from m(r)~16.04 mag @85 s post-burst to m(r)~18.77 mag @2734 s post-burst, roughly in a powerlaw with a decay index of ~ -0.7, calibrated with the nearby PanSTAR field in the Sloan r-filter and the magnitude is not corrected for Galactic extinction.