TITLE:   GCN CIRCULAR
NUMBER:  31999
SUBJECT: GRB 220430A: Nanshan/NEXT optical upper limit
DATE:    22/05/06 04:58:07 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 NEXT-0.6m 
telescope located at Nanshan, Xinjiang, China. Observations started at 
14:13:38 UT on 2022-04-30 (i.e., 20.39 min after the BAT trigger). We 
obtained 3x40, 6x60, 3x90, 6x200 s frames in the Sloan r-band and 
3x60,3x90,6x200 s frames in Sloan z-band.

No optical source is detected in our stacked image at the XRT enhanced 
position (Osborne et al., GCN 31973), with upper limits as follows

Tmid-T0 (hr) Filter   UpperLimit (3sigma)
    0.953           r         >20.7
    0.923           z         >19.0

calibrated with the nearby PanSTARRS field.