TITLE:   GCN CIRCULAR
NUMBER:  31998
SUBJECT: GRB 220430A: Nanshan/HMT optical upper limit
DATE:    22/05/06 04:52:43 GMT
FROM:    Dong Xu at NAOC/CAS  <dxu@nao.cas.cn>

S.Q. Jiang (NAOC), Z.P. Zhu (NAOC,HUST), S.Y. Fu, X. Liu, D. Xu (NAOC), 
X. Gao
(Urumqi No.1 Senior High School), J.Z. Liu (XAO) report:

We observed the field of GRB 220430A detected by Swift (Ambrosi et al., 
GCN 31972) and AGILE (Ursi et al., GCN 31975) using the HMT-0.5m 
telescope located at Nanshan, Xinjiang, China. Observations started at 
13:58:51 UT on 2022-04-30 (i.e., 5.6 min after the BAT trigger), and 
3x20, 3x40, 4x60, 12x90 s unfiltered frames were obtained.

No optical source is detected in our stacked image at the XRT position 
(Osborne et al., GCN 31973), down to a limiting magnitude of ~19.2, 
calibrated with the Gaia DR2 stars.