GCN Circular 30273
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 210619B (D'Avanzo et al., GCN 30261) starting at ~8.05 hours after the Swift trigger. A total of 60x60s images were obtained in the clear (roughly R) filter. The optical afterglow (D'Avanzo et al., GCN 30261; Lipunov et al., GCN 30262; Jelinek et al., GCN 30263; Kong, GCN 30265; Pellegrin et al., GCN 30268; Perley, GCN 30271) was clearly detected in each single image. We measured its brightness of 18.5 +/- 0.1 mag at 8.05 hours after burst, and decayed to be 18.8 +/- 0.1 mag at 11.07 hours after burst, calibrated to the Pan-STARRS1 catalog.