TITLE: GCN CIRCULAR NUMBER: 31417 SUBJECT: GRB 220107B: Nanshan/NEXT optical upper limits and host galaxy candidate DATE: 22/01/09 04:04:47 GMT FROM: Dong Xu at NAOC/CAS S.Q. Jiang, S.Y. Fu (NAOC), Z.P. Zhu (NAOC, HUST), X. Liu, D. Xu (NAOC), X. Gao (Urumqi No.1 Senior High School), J.Z. Liu (XAO) report: We observed the field of GRB 220107B detected by Fermi (Arimoto et al., GCN 31409; Veres & Meegan, GCN 31414) and AstroSat (Suresh et al., GCN 31412), using the NEXT-0.6m telescope located at Nanshan, Xinjiang, China. We obtained 6x300 s frames in the Sloan r-band and 5x300 s frames in Sloan z-band, starting at 21:30:31 UT on 2022-01-08. No optical source is detected in our stacked images at the Swift-XRT position (Gropp et al., GCN 31411). Preliminary photometric results are as follows: Tmid-T0 (hr) Filter Upper Limit(5-sigma) 26.97 r >21.3 27.44 z >19.3 calibrated with the nearby PanSTARRS field. In addition, from Legacy Survey there exists a faint source at the border of the Swift-XRT error circle at coordinates R.A. (J2000) = 14:25:37.66 and Dec. (J2000) = +20:10:17.01, and magnitudes of g ~ 24.62, r ~ 24.51, z ~ 23.32 as well as a photo_redshift = 1.13 +/- 0.23. The source is not present in SDSS and PanSTARR, and might be the host of the burst.