Spectroscopic Classifications of Optical Transients with the Keck I telescope

ATel #14624; M. R. Siebert, S. Tinyanont, K. Taggart, R. J. Foley (UCSC)
on 13 May 2021; 22:47 UT
Distributed as an Instant Email Notice Supernovae
Credential Certification: Samaporn Tinyanont (stinyanont@ucsc.edu)

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We report the following classifications of optical transients from spectroscopic observations with the LRIS spectrograph on the Keck I telescope. Targets were supplied by ATLAS, PSST, YSE, ZTF, and ALeRCE (selected from the ZTF data stream). All observations were made on 2021 May 12 UT. Classifications were performed with SNID (Blondin & Tonry, 2007, ApJ, 666, 1024).

 
Name         |  IAU Name  | RA (J2000)  |  Dec (J2000) | z      | Type    | Phase | Notes
 
PS20ctq      |  AT2020jev | 09:48:38.87 | +33:25:03.26 | 0.005  | LBV     |       | (1) 
PS21dau      |  SN2021iyt | 10:18:44.41 | +00:03:19.40 | 0.071  | Ibn     |       | (2) 
PS21dhs      |  AT2021jvl | 16:24:39.99 | +23:56:05.41 | 0.159  | II      |       | (3) 
ZTF21aaxtepe |  AT2021krc | 12:26:32.85 | +16:50:50.43 | 0.044  | II      |plateau| (4) 
ZTF21aazqkeq |  AT2021lmt | 15:41:45.04 | -03:54:37.06 | 0.028  | II      | peak  | (5) 
ATLAS21oft   |  AT2021lwl | 18:44:20.89 | +22:43:45.70 | 0.052  | Ia      | -3    | (6) 

Notes: When the redshift is given to 2 significant figures, it is derived from the SN spectrum. Otherwise, the redshift is determined from the host galaxy. (1) We detect strong H-alpha emission with a FWHM of 400 km/s. We also note P-Cygni profiles for the Ca NIR triplet. (2) Previously classified by YSE as a SN with a blue continuum and flash ionization signatures (2021TNSCR1206....1A). Our new spectrum reveals that it is a SN Ibn. For the He 5876 line, we measure a FWHM of 1900 km/s. (3) We measure an H-alpha absorption velocity of -5,500 km/s. (4) The spectrum shows strong H-alpha emission with weak P-Cygni absorption, for which we measure a velocity of -8,500 km/s. (5) As reported in AstroNote 2021-151 (previously classified as "other"), AT2021lmt shows a blue continuum, but now has broad Hydrogen line features, consistent with being a SN II. (6) We measure a Si II 6355 velocity of -12,000 km/s.