S.Y. Fu, T.H. Lu, S.Q. Jiang, X. Liu, Z.P. Zhu, D Xu (NAOC), S.W. Luo, M.M. Yang, Z. K. Feng (GYZO, NAOC) report:
We observed the field of GRB 230606A detected by Swift (Lien et al., GCN 33921) with the GOT-0.5m telescope located at Gaoyazi, Xinjiang, China. We obtained 20x180 s frames in the Sloan r-band and 15x180 s frames in the Sloan z-band, starting at 16:25:45 UT on 2023-06-06, i.e., 16.18 hr after the Swift/BAT trigger.
No optical source is detected in our stacked images at the enhanced XRT position (Goad et al., GCN 33924), and preliminary photometric results are as follows:
T_mid-T0 (hr) Filter Upper_Limit (3-sigma)
16.74 r >20.9
18.05 z >18.1
calibrated with the nearby PanSTARRS field and not corrected for Galactic extinction.