TITLE: GCN CIRCULAR NUMBER: 31295 SUBJECT: GRB 211223C: BOOTES-4/MET optical upper limit DATE: 21/12/24 09:15:36 GMT FROM: Youdong HU at IAA-CSIC Y.-D. Hu, T.-R. Sun, A. J. Castro-Tirado, E. Fernandez-Garcia, M. D. Caballero-Garcia, R. Sanchez-Ramirez, M. A. Castro Tirado (IAA-CSIC), C. Perez del Pulgar, A. Castellon, I. Carrasco (Univ. de Malaga), S. Guziy (Univ. of Nikolaev) and D. R. Xiong, Y. F. Fan, J. M. Bai, C. J. Wang, Y. X. Xin, X. H. Zhao (Yunnan Observatories of CAS) on behalf of a larger collaboration, report: Following the detection of GRB 211223C by Swift (Evans et al. GCNC 31288), the 0.6m BOOTES-4/MET robotic telescope at Lijiang Astronomical Observatory (China) automatically responded to this burst starting on Dec. 23 at 21:58:25 UT (~7.5 hours after trigger). No new source is detected within the BAT error region in the co-added image (60 x 20 s, clear filter) down to 20.1 mag. We thank the staff at the Lijiang observatory for their excellent support.