Spectroscopic Classifications of SNe 2022nwx, 2022nyu, and AT2022nuh with Keck I + LRIS

ATel #15494; Y. Yang, T. G. Brink, W. Zheng, A. V. Filippenko (UC Berkeley)
on 3 Jul 2022; 15:46 UT
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Credential Certification: Yi Yang (yiyangtamu@gmail.com)

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We report the classification of SN 2022nwx as a Type Ib supernova a few days before peak luminosity. The spectroscopic observation was carried out with LRIS on the Keck-I 10 m telescope on UTC 2022-07-01 12:35 / MJD 59761.524. The transient was flagged and supplied by ANTARES (antares.noao.edu) using the discovery stream from the Zwicky Transient Facility (ZTF; Bellm et al., 2019, PASP, 131, 018002) on 2022-06-29 10:42 with the last nondetection on 2022-06-21 10:47. Using the Supernova Identification code (SNID; Blondin & Tonry 2007, ApJ, 666, 1024), the spectrum of SN 2022nwx shows a good match with the Type Ib SN 1999ex at day -5, and the associated redshift estimated for SN 2022nwx is 0.027±0.007. Cross-correlation adopting GELATO (Harutyunyan et al. 2008, A&Ap, 488, 383; https://gelato.tng.iac.es) also suggests that SN 2022nwx is consistent with the spectrum of the Type Ib SN 2007C at -5.9 days relative to its V-band peak luminosity, with a redshift estimate of SN 2022nwx of 0.02±0.003. We report the classification of SN 2022nyu as a young Type IIP supernova a few days after the explosion. The Keck-I LRIS spectrum was obtained on UTC 2022-07-01 14:47 / MJD 29761.616. The transient was reported by the ATLAS survey (Tonry et al. 2011, PASP, 123, 58) on 2022-06-29 13:45 with the last nondetection on 2022-06-28 14:16. Cross-correlations using SNID and GELATO suggest that the LRIS spectrum of SN 2022nyu matches the spectra of Type IIP SN 2005cs at 4 days and Type IIP SN 1995ad at 11.9 days after the explosion. The redshift determined from the narrow H-alpha emission yields 0.0613±0.0003. We do not find any convincing match to the spectrum of AT 2022nuh, which is a transient reported by ALeRCE using the discovery stream from ZTF at 2022-06-28 09:56 with the last nondetection at 2022-06-28 10:12. The LRIS spectrum of AT 2022nuh was obtained on UTC 2022-07-01 14:57 / MJD 59761.623. It marginally matches the spectrum of the Type Ib SN 2008D at -15.8 days relatively to the B-band peak luminosity and a redshift of 0.09±0.002 according to GELATO cross-correlation. A reddening E(B-V) ~ 0.2 mag is suggested by the matching process.