TITLE: GCN CIRCULAR NUMBER: 24931 SUBJECT: GRB 190630B: KAIT Optical Afterglow Confirmation DATE: 19/07/01 05:41:45 GMT FROM: Weikang Zheng at UC Berkeley WeiKang Zheng and Alexei V. Filippenko (UC Berkeley) report on behalf of the KAIT GRB team: The 0.76-m Katzman Automatic Imaging Telescope (KAIT), located at Lick Observatory, responded to the Swift GRB 190630B (Krimm et al., GCN 24913; Cummings et al. GCN 24918) starting at 310s after the burst. Observations were performed with a sequence in the clear (roughly R), V, and I filters, and the exposure time was 60 s per image. Further analysis on our reported afterglow candidate (Zheng & Filippenko, GCN 24914) shows that the candidate position is within the enhanced XRT error circle (Page et al., GCN 24919), and its brightness faded more than 2 magnitude during our ~2 hours observing range. We therefore confirm this is the optical afterglow of GRB 190630B. A preliminary KAIT clear band light curve is available at: http://w.astro.berkeley.edu/~zwk/grb/GRB190630B/GRB190630B_kait.jpg