TITLE: GCN CIRCULAR NUMBER: 40171 SUBJECT: GRB 250419A: KAIT optical afterglow observations DATE: 25/04/19 06:04:42 GMT FROM: Weikang Zheng at UC Berkeley <weikang@berkeley.edu> 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 SVOM GRB 250403A (Wang et al., GCN 40168) with a set of clear (roughly R) images starting at 1.47 hours after the trigger. We clearly detected the optical afterglow (López et al., GCN 40169; Xin et al., GCN 40170) in our single image. The afterglow is measured at 18.0 +/- 0.2 mag (Vega) at 1.47 hours after the trigger. It remained to be similar brightness for about 40 minutes then decayed after that. Observation is on going. View this GCN Circular online at https://gcn.nasa.gov/circulars/40171. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...