T.H. Lu, S.Q. Jiang, S.Y. Fu, X. Liu (NAOC), Z.P. Zhu (NAOC, HUST), D.
Xu (NAOC), X. Gao (Urumqi No.1 Senior High School), J.Z. Liu (XAO) report:
We observed the field of GRB 230228A detected by Swift (Dichiara et al.,
GCN 33378) using the NEXT-0.6m telescope located at Nanshan, Xinjiang,
China. We obtained 12x200 s frames in the Sloan r-band and 12x200 s
frames in the Sloan z-band, starting at 14:37:32 UT on 2023-02-28 (i.e.,
8.77 hr after the BAT trigger).
No optical source is detected in our stacked images at the enhanced XRT
position (Evans, GCN 33379), and preliminary photometric results are as
T_mid-T0 (hr) Filter Upper limit(3-sigma)
9.86 r >20.6
9.14 z >19.5
calibrated with the nearby PanSTARRS field and not corrected for