Spectroscopic Classifications of Optical Transients with the Lick Shane telescope

ATel #12351; R. J. Foley
on 3 Jan 2019; 15:03 UT
Distributed as an Instant Email Notice Supernovae
Credential Certification: Ryan Foley (foley@ucsc.edu)

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We report the following classifications of optical transients from spectroscopic observations with the Kast spectrograph on the Shane telescope. Targets were supplied by ZTF. All observations were made on 2019 January 3 UT. Classifications were performed with SNID (Blondin & Tonry, 2007, ApJ, 666, 1024).

 
Name         | IAU Name  | RA (J2000)  | Dec (J2000)  | z     | Type     | Phase    | Notes
 
ZTF18aczrafz | AT2018kss | 06:46:23.87 | +43:49:27.78 | 0.021 | Ia       | 0        | (1) 
ZTF18acvgxtb | AT2018kkt | 12:56:46.74   +21:40:55.90 | 0.001 | outburst |          | (2) 
ZTF18adalarn | AT2018las | 10:59:52.23 | +19:47:41.81 | 0.027 | Ia-pec   | near max | (3) 

Notes: When the redshift is given to 2 decimal places, it is derived from the SN spectrum. Otherwise, the redshift is determined from the host galaxy. (1) There is strong host-galaxy Na D absorption; we measure a Na D EW of 3.3 A. We measure a Si II 6355 velocity of -11,600 km/s. (2) The spectrum is blue with narrow Balmer emission. The H-alpha profile has a narrow (FWHM of ~250 km/s, consistent with the resolution of the spectrograph) and a broad (FWHM ~ 700 km/s) component. H beta, although noisy, appears to have a similarly broad (FWHM ~ 650 km/s) component. The difference-image flux is consistent with an absolute magnitude of -9.7 mag (neglecting any possible host-galaxy extinction). While some characteristics are consistent with a massive-star outburst, the luminosity is currently significantly lower than LBV giant eruptions. (3) Peculiar SN with spectrum similar to SN 2000cx (Li et al., 2001, PASP, 113, 1178) at peak brightness. There are also some matches to SN 2006gz (Hicken et al., 2007, ApJL, 669, 17), however, the matches are only reasonable if the redshift of AT2018las is assumed to be smaller than that of its presumed host galaxy. We measure a Si II 6355 velocity of -13,300 km/s, similar to SN 2000cx a few days before peak.