GCN Circular 37959

WeiKang Zheng, Thomas G. Brink, Alexei V. Filippenko (UC Berkeley), and Yi
Yang (Tsinghua Univ., Beijing), report on behalf of the KAIT GRB team:


Following the detection of GRB 241030A (Klingler et al., GCN 37956
Not found
 
 
), we
observed its optical counterpart (Klingler et al., GCN 37956
Not found
 
 
; Watson et
al., GCN 37957
Not found
 
 
; Fernández-Rodríguez et al., GCN 37958
Not found
 
 
) with the Low
Resolution Imaging Spectrometer (LRIS; Oke et al. 1995) on the Keck I 10 m
telescope. Observations started at 2024-10-30 06:47 UTC (about 1.0 hr after
the burst), and consisted of 3 x 200 s exposures with the 600/4000 grism
and 400/8500 grating. The spectrum shows a well-detected continuum
throughout the complete range (3400-10,200 Ang). Numerous narrow absorption
lines are present, including Mg II 2796, 2803 Ang doublets at redshifts of
0.456, 0.862, 1.302, and 1.411. We conclude that the redshift of the GRB is
likely to be 1.411, but perhaps larger if the highest-redshift doublet is
not associated with the interstellar medium in the host galaxy.

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.