GCN Circular 38150
Subject
EP241109a: KAIT photometry and 3 m Shane spectroscopy from Lick observatory
Event
Date
2024-11-10T00:34:38Z (8 months ago)
From
Weikang Zheng at UC Berkeley <weikang@berkeley.edu>
Via
email
WeiKang Zheng, Ryan Chornock, Natalie LeBaron, Xinze Guo, William Wu
Alexei V. Filippenko (UCB), and Xuhui Han, Pinpin Zhang (NAOC) report
on behalf of the KAIT GRB team:
The 0.76-m Katzman Automatic Imaging Telescope (KAIT), located at
Lick Observatory, automatically responded to EP241109a (Li et al.,
GCN 38140) starting at 06:09 UT, 7 minutes after the trigger. A set
of images with 20s exposure time were obtained in B, V, R I and
clear (roughly R) filters. Observations lasted for about 3.5 hours.
We detected the flare star reported by Perez-Garcia et al. (GCN
38141) in all our images. Photometry of the star show that its
brightness decreased from the start of our observation in all filters,
especially in B band which decreased by nearly 3 mag. The light curves
became flat after about 2.5 hours after trigger in all bands.
A spectrum was also taken with the Kast spectrograph on the 3 m Shane
telescope at Lick Observatory. Observations was performed at about
2.3 hours after the trigger, covering the 3500-10,000 A wavelength
range, with an exposure time of 300s. The spectrum shows a red
continuum flux overlapped with strong Balmer emission lines as well
as Ca II H&K and TiO emission lines, consistent with a typical dMe star
spectrum. The flux below ~4000A show a bit excess, which might be caused
by the flare, compared with the typical dMe star spectrum at quiescent
time.
Based on the above photometry and spectroscopy results, we therefore
confirm that this EP241109a event is truly associated with this stellar
flare.