GCN Circular 40789
Subject
GRB 250617B: Nickel telescope optical observations
Date
2025-06-20T00:49:40Z (2 days ago)
From
Weikang Zheng at UC Berkeley <weikang@berkeley.edu>
Via
email
Eli Gendreau-Distler, Gracelynn Jost, William Wu, WeiKang Zheng and
Alex Filippenko (UC Berkeley) report on behalf of the KAIT GRB team:
We observed the field of GRB 250617B (Page et. al, GCN 40760; The
Fermi GBM team, GCN 40763) with the 1-m Nickel telescope located at
Lick observatory, California. Observations were performed in R band
with 600s x 5 exposure time started at 09:46 UT on June 18. We
clearly detected the optical afterglow (Page et. al, GCN 40760,
Moskvitin et. al, GCN 40761, Jelinek et. al, GCN 40762; Kumar et. al,
GCN 40768; Lipunov et. al, GCN 40769; Grossan et. al, GCN 40771;
Ma et. al, GCN 40772; Schneider et. al, GCN 40774; Antier et. al,
GCN 40775; Corcoran et. al, GCN 40776; Turpin et. al, GCN 40777;
Siegel & Page, GCN 40778; Pankov et al., GCN 40783) in our coadd image
with 21.4 +/- 0.1 mag at a mid time of 13.10 hours after the burst.