TITLE: GCN CIRCULAR NUMBER: 29546 SUBJECT: GRB210222B: BOOTES-1 optical afterglow detection DATE: 21/02/22 23:16:50 GMT FROM: Youdong HU at IAA-CSIC Y.-D. Hu, E. Fernandez-Garcia, A. J. Castro-Tirado, M.D. Caballero-Garcia, M. A. Castro Tirado (IAA-CSIC), C. Perez del Pulgar, A. Castellon, I. Carrasco, A. Reina (Univ. de Malaga) and F. Rendon (IAA-CSIC and INTA-CEDEA) on behalf of a larger collaboration, report: Following the Swift trigger of GRB 210222B (Gropp et al. GCNC 29545), the 0.3m BOOTES-1B robotic telescope in Mazagon (Huelva), southern Spain, automatically responded to this burst. Images were taken starting at 22:40:53 UT (~3.5 min after trigger). In the first 10s image, the afterglow reported by UVOT (Gropp et al. GCNC 29545) is detected with magnitude of 15.6 +/- 0.15 (clear filter). Further observations are ongoing. We thank the staff at INTA-CEDEA for their excellent support.