TITLE:   GCN CIRCULAR
NUMBER:  31475
SUBJECT: GRB 220117B: Nanshan/NEXT optical upper limit
DATE:    22/01/18 03:25:24 GMT
FROM:    Dong Xu at NAOC/CAS  <dxu@nao.cas.cn>

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

We observed the field of GRB 220117B detected by Swift (Melandri et al., 
GCN 31468) using the NEXT-0.6m telescope located at Nanshan, Xinjiang, 
China. Observations automatically started at 20:07:36 UT on 2022-01-17, 
i.e., 128 s after the BAT trigger, and a series of 40 s, 60 s, 90 s 
frames were obtained in the Sloan r-band.

No uncatalogued optical transient is detected in our stacked images at 
the Swift-XRT position (GCN 31468), down to limiting magnitudes of 
r~18.5, calibrated with the nearby PanSTARRS field.