GCN Circular 41665
Subject
GRB 250831A (SVOM trigger sb25083102): KAIT confirmation of stellar flare
Event
Date
2025-09-03T04:11:08Z (a month ago)
From
Weikang Zheng at UC Berkeley <weikang@berkeley.edu>
Via
email
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 GRB 250831A (SVOM trigger
sb25083102; Xie et al., GCN 41614) starting at 09:32:33, 180 seconds
after the burst. Observations were performed in 3 x 3 tiling mode,
and a set of clear (roughly R) filter images were obtained. The first
image covered the proposed flare star G 272-61 (Wu et al., GCN 41615;
Magnani et al., GCN 41616; Xie et al., GCN 41618; Li et al., GCN
41654) was at 09:36:55, 442 seconds after the burst. Although the
star was saturated in KAIT images, photometry with a large aperture
clearly shows the magnitude decreased from 9.2 mag to 10.2 mag (faded
by 1.0 mag) about 2 hours later. This is similar to the light curve
reported by SVOM/VT, confirming this event is due to a stellar flare.