TITLE:   GCN CIRCULAR
NUMBER:  31416
SUBJECT: GRB 220107A: Nanshan/NEXT optical observations
DATE:    22/01/09 03:07:24 GMT
FROM:    Dong Xu at NAOC/CAS  <dxu@nao.cas.cn>

Z.P. Zhu (NAOC,HUST), S.Q. Jiang, 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 220107A detected by Fermi (the Fermi/GBM 
team, GCN Circ. 31399, Kunzweiler et al. GCN Circ. 31400) and Swift 
(DeLaunay et al. GCN Circ. 31402), using the NEXT-0.6m telescope located 
at Nanshan, Xinjiang, China. Observations started at 19:46:36 UT on 
2022-01-08 (i.e., 29.46 hrs after the Fermi GBM trigger), and 10x300 s 
frames were obtained in the Sloan r-filter.

The previously reported optical afterglow (Hosokawa et al. GCN Circ. 
31413, Siegel et al. GCN Circ. 31415) is clearly detected in our stacked 
image, and has decayed to r = 20.22 +/- 0.05, calibrated by nearby SDSS 
stars.