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GCN Circular 31612

Subject
ZTF22aaajecp/AT2022cmc: Keck DEIMOS Redshift
Date
2022-02-19T19:46:02Z (2 years ago)
From
Michael J. Lundquist at Keck <mlundquist@keck.hawaii.edu>
Michael J Lundquist, Carlos A. Alvarez, and John O'Meara (W. M. Keck Observatory)

We observed the fast, red optical transient ZTF22aaajecp/AT2022cmc (Andreoni et al., GCN 31590) using the DEIMOS spectrograph at the W. M. Keck Observatory.

We obtained spectroscopy covering the wavelength range 5250-8780 AA, consisting of 3 exposures of 900s each starting at 2022-02-17 15:07 UT.  Data was reduced using the PypeIt data reduction pipeline (Prochaska, J. Xavier et al., 2020).

The spectrum had low S/N, but the transient is detected over the full wavelength range.  We confirm the detection and interpretation of the absorption lines at 6132, 6148 AA as the Mg II 2796, 2803 AA lines and the absorption lines at 5671, 5702 AA as the Fe II 2586, 2600 AA lines as reported by Tanvir et al. (GCN 31602), agreeing with the reported redshift of 1.193.  The Ca II 3934 line is detected at 8629 AA, however we do not clearly identify the Ca II 3969 line at 8706 AA.

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.
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