TITLE: GCN CIRCULAR NUMBER: 29159 SUBJECT: GRB 201223A: Nanshan/NEXT early optical afterglow detection DATE: 20/12/23 18:58:50 GMT FROM: Dong Xu at NAOC/CAS Z.P. Zhu (NAOC, HUST), S.Y. Fu, M. Zhang, X. Liu, D. Xu (NAOC), X. Gao (Urumqi No.1 Senior High School), J.Z. Liu (XAO) report: We observed the field of GRB 201223A (Gropp et al., GCN 29158) using the NEXT-0.6m optical telescope located at Nanshan, Xinjiang, China. Observations automatically started at 18:01:14 UT on 2020-12-23, i.e., 168 s after the BAT trigger. We obtained a series of 2x40s, 4x60s and 12x90s frames in the Sloan r-filter, and observations are ongoing. An uncatalogued decaying optical transient is detected at the Swift/UVOT position (Gropp et al., GCN 29158), which is thus concluded to be the optical afterglow of burst. The afterglow has r = 15.67 +/- 0.01 mag in our first image, calibrated with nearby PS1 stars. [GCN OPS NOTE(24Dec2020) Per author's request, M. Zhang was added to the author list.]