GCN Circular 41236

X. Liu (NAOC), K. Noysena, K. Chanchaiworawit, S. Tinyanont (NARIT), L.B. He, Z.P. Zhu, S.Q. Jiang, J. An, D. Xu (NAOC), S.Y. Fu (HUST) report on behalf of a large collaboration:

We observed the field of GRB 250805A (Ambrosi et al, GCN 41233

), using the 0.7-m telescope of the Thai Robotic Telescope network (TRT), located at Cerro Tololo Inter-American Observatory, Chile. Observations started at 06:27:50.5 UTC on 2025-08-05, i.e., ~ 0.3 hr after the Swift/BAT trigger, and 10 x 200 s frames were obtained in the Sloan r- and i- bands.

No new optical source is detected in the co-added r- and i-band images within the Swift/XRT error circle (Kennea et al, GCN 41234

). The limiting magnitudes are as follow:

Tmid(s)	band	upper limit(3sigma)
2746.99	i	20.7
3545.62	r	20.8

The magnitudes are calibrated against Legacy Survey DR10 and are not corrected for Galactic extinction.