GCN Circular 41927
Subject
GRB 250917B: KAIT optical upper limit
Event
Date
2025-09-21T08:31:40Z (a day ago)
From
Weikang Zheng at UC Berkeley <weikang@berkeley.edu>
Via
email
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, automatically responded to the Swift triggered
GRB 250917B (Caputo et al., GCN 41848; see also Fermi GBM Team,
GCN 41846) starting at 06:29:01 UT, 77 seconds after the burst.
A set of 10x20s, 10x40s and 50x60s clear (roughly R) filter images
were obtained. We do not detect any new uncataloged source around
Swift-XRT sources 1, 5 or 6 (Kennea et al., GCN 41851) neither in
single image nor in coadd images. We estimate the limiting mag of
~21.5 (Vega) at a mid time of 45 minutes after the burst in our
coadd image.