TITLE: GCN CIRCULAR NUMBER: 41481 SUBJECT: GRB 250821A: KAIT optical upper limit DATE: 25/08/21 23:35:44 GMT FROM: Weikang Zheng at UC Berkeley <weikang@berkeley.edu> WeiKang Zheng (UCB) 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 250821A (Dichiara et al., GCN 41462) starting at 12:02:57, Aug. 21 UT, ~1.28 hours after the burst. A set of 9x60s clear (roughly R) filter images were obtained under twilight conditions. We do not detect any new optical counterpart candidate within the Enhanced XRT error circles (Beardmore et al., GCN 41472) in the co-add image. Our upper limit is about 20.0 (Vega) mag at a mid time of 1.30 hours after the burst. Our result is consistent with the optical upper limit reported by other groups (Strausbaugh et al., GCN 41466; Oates et al., GCN 41471; Lipunov et al., GCN 41478). View this GCN Circular online at https://gcn.nasa.gov/circulars/41481. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...