TITLE: GCN CIRCULAR NUMBER: 40135 SUBJECT: GRB 250407A: Continued KAIT/Nickel optical observations DATE: 25/04/11 07:26:26 GMT FROM: Weikang Zheng at UC Berkeley <weikang@berkeley.edu> Asia deGraw, Gracelynn Jost, 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, continued the observation of GRB 250407A optical afterglow (Zheng et al., GCN 40116; Ducoin et. al, GCN 40117; Pérez-Fournon et. al, GCN 40125; Pankov et al., GCN 40133) at 03:35 UT, Apr. 09, namely ~1.55 days after burst. A set of clear (roughly R) filter images were obtained. Compared to our earlier observations (Zheng et al., GCN 40116), the reported afterglow had faded to ~20.8 +/- 0.3 mag (Vega) measured in our coadd image. Additional R band images with 600sx5 exposure were obtained with the 1-m Nickel telescopes located at Lick observatory, starting at ~1.55 days after burst. We measure the brightness of R ~ 21.0 +/- 0.2 mag (Vega), similar to the R band magnitude reported by Pankov et al. (GCN 40133) at a slightly later epoch (1.98 days), suggesting that this might be the host galaxy of GRB 250407A as suggested by Ducoin et. al, GCN 40117). View this GCN Circular online at https://gcn.nasa.gov/circulars/40135. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...