GCN Circular 37931
Subject
GRB 240821A: Keck/LRIS spectroscopic observations
Date
2024-10-28T17:21:08Z (16 days ago)
From
Weikang Zheng at UC Berkeley <weikang@berkeley.edu>
Via
legacy email
WeiKang Zheng, Thomas G. Brink, Alexei V. Filippenko (UC Berkeley), and Yi
Yang (Tsinghua Univ., Beijing), report on behalf of the KAIT GRB team:
We observed the location of the GRB 240821A optical afterglow
(Quirola-Vasquez et al., GCN 37319) with the Low Resolution Imaging
Spectrometer (LRIS; Oke et al. 1995) with the Keck I 10 m telescope by
centering on the slit the host-galaxy counterpart from the Legacy Survey as
noticed by Quirola-Vasquez et al. (GCN 37319). Observations were performed
on Sep. 2, 2024, and consisted of 4 x 1200 s exposures with the 600/4000
grism and 400/8500 grating. The spectrum has low signal-to-noise ratio
owing to the faintness of the host galaxy. We detect and confirm the
emission line at 8123 Ang reported by Saccardi et al. (GCN 37369) and
Schneider et al. (GCN 37731) from VLT/X-shooter data. The [N II] 6584 and
possibly [O II] 3727 emission lines reported by Schneider et al. (GCN 37731)
are marginally detected. These results confirm the host-galaxy redshift of
z = 0.238.
The data presented herein were obtained at the W. M. Keck Observatory,
which is operated as a scientific partnership among the California
Institute of Technology, the University of California, and the National
Aeronautics and Space Administration. The Observatory was made possible by
the generous financial support of the W. M. Keck Foundation. The authors
wish to recognize and acknowledge the very significant cultural role and
reverence that the summit of Maunakea has always had within the indigenous
Hawaiian community. We are most fortunate to have the opportunity to
conduct observations from this mountain.