TITLE:   GCN CIRCULAR
NUMBER:  33932
SUBJECT: GRB 230606A: Gaoyazi/GOT optical upper limit
DATE:    23/06/07 02:16:11 GMT
FROM:    Dong Xu at NAOC/CAS <dxu@nao.cas.cn>

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.