TITLE: GCN CIRCULAR NUMBER: 41417 SUBJECT: GRB 250818B: KAIT optical observations DATE: 25/08/18 21:38:07 GMT FROM: Weikang Zheng at UC Berkeley WeiKang Zheng (UCB), Xuhui Han (NAOC), Pinpin Zhang (NAOC) and Alexei V. Filippenko (UCB) report on behalf of the KAIT GRB team: The 0.76-m Katzman Automatic Imaging Telescope (KAIT), located at Lick Observatory, observed the field of GRB 250818B (Wang et al., GCN 41405) with a set of 90x60s images in the clear (roughly R) filters, at a mid time of 8.0 hours after the trigger. We clearly detected the optical afterglow (Kumar et al., GCN 41406; Yao et al, GCN 41409) in the coadd image with a brightness of 19.9 +/- 0.2 mag (Vega).