GCN Circular 31218
A. de Ugarte Postigo (Obs. Cote d���Azur), D.A. Kann, C. Thoene, J.F. Agui Fernandez, M. Blazek (HETH/IAA-CSIC) and A. Guijarro (CAHA) report: We observed the optical afterglow of GRB 211211A (Fermi team GCN31201; D���Ai et al. GCN31202; Zheng and Filipenko GCN 31203) with CAFOS, mounted on the 2.2m telescope, at the Calar Alto Observatory (Almer��a, Spain). The observation started at 04:54 UT (15.73 hr after the GRB) and consisted of 30x90s in i-band. The optical afterglow is well detected at a magnitude (AB) of i = 20.83+/-0.05, as compared to field stars from the SDSS catalogue. This magnitude confirms the plateau or very shallow decay phase undergone by the afterglow light curve since the early detection (Zheng and Filipenko GCN 31203) already noted by Jiang et al. (GCN 31213) and consistent with the observations of Strausbaugh & Cucchiara (GCN 31214) and Ito et al. (GCN 31217).