Spectroscopic Classifications of Optical Transients with the Lick Shane telescope

ATel #13766; G. Dimitriadis and R. J. Foley (UCSC)
on 27 May 2020; 21:43 UT
Distributed as an Instant Email Notice Supernovae
Credential Certification: Georgios Dimitriadis (gdimitri@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 ATLAS, PSST, and the Young Supernova Experiment (YSE). All observations were made on 2020 May 27 UT. Classifications were performed with SNID (Blondin & Tonry, 2007, ApJ, 666, 1024).

 
Name       | IAU Name  | RA (J2000)  | Dec (J2000)  |   z   | Type  | Phase | Notes
 
PS20cbx    | AT2020hrw | 13:04:07.10 | +05:33:42.72 | 0.024 |  II   |       | (1) 
PS20cpw    | AT2020ioz | 13:03:47.58 | +20:54:09.01 | 0.06  |  Ia   | +15   | (2) 
ATLAS20njn | AT2020kre | 13:10:29.87 | -01:18:51.04 | 0.136 |  Ia   | -5    | (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) We measure an H-alpha absorption velocity of -7,000 km/s. The light curve has been rising for several weeks, consistent with a SN similar to SN 1987A, although this is somewhat speculative with the limited photometry data. (2) The transient's host galaxy matches SDSS J130347.55+205409.1, a faint galaxy with no cataloged redshift. The best SNID matches are several normal Type Ia supernovae at z ~ 0.06, two weeks after maximum brightness. Given that redshift, the transient peaked at approximately -19.0 in g-band, consistent with the classification. We measure an Si II 6355 velocity of -9,700 km/s. (3) We measure an Si II 6355 velocity of -11,000 km/s. Although the spectrum is somewhat noisy, the relatively weak Si II feature is similar to SN 1991T and other high-luminosity SNe Ia.

We thank the Lick Observatory staff for their dedication and hard work to make these observations possible.