Spectroscopic Classifications of Optical Transients with Shane + Kast

ATel #14180; S. Tinyanont, G. Dimitriadis, R. J. Foley (UCSC)
on 16 Nov 2020; 00:18 UT
Credential Certification: Samaporn Tinyanont (st@astro.caltech.edu)

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We report the classification of the optical transients from spectroscopic observations with the Kast spectrograph on the Shane telescope, made on 2020 Nov 15 UT. The targets were supplied by Gaia, YSE, and ZTF (as reported by ALeRCE). The classifications were performed with SNID (Blondin & Tonry, 2007, ApJ, 666, 1024).

 
Name         | IAU Name  | RA (J2000)  |  Dec (J2000) | z     | Type | Phase | Notes
 
ZTF20acjeflr | AT2020wnt | 03:46:37.95 | +43:13:45.25 | 0.032 | I    |       | (1) 
PS20kau      | AT2020xkt | 01:23:30.73 | +11:17:27.51 |       |      |       | (2) 
ZTF20acoplqe | AT2020ytg | 20:48:10.00 | -01:12:40.10 | 0.056 | II   | -4    | (3) 
ZTF20acpkpla | AT2020zgc | 01:24:17.00 | -19:25:54.64 | 0.068 | Ia   | -3    | (4) 
Gaia20ffl    | AT2020zmi | 21:00:11.01 | -04:04:01.24 | 0.020 | Ia   | -10   | (5) 
Gaia20ffs    | AT2020znv | 07:12:18.87 | +38:26:22.27 | 0     | CV   |       | (6) 

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) Assuming the measured redshift and the Galactic extinction correction, the current absolute magnitude is M ~ -19 mag. The spectrum is most similar to "super-Chandrasekhar" SNe Ia such as SNe 2009dc and 2012dn, however it is somewhat similar to SNe Ic and SLSN-I. The C II 6580 line is particularly strong and the S II "W" feature is relatively weak, disfavoring the SN Ic and SLSN interpretations. Additionally, the current luminosity is relatively high for a SN Ic without broad lines, yet low for a SLSN (although it could still be rising). The luminosity is similar to a super-Chandrasekhar SN Ia near peak, however, the ZTF photometry indicate a fading light curve immediately after discovery before a ~25 day rise, which would be unique behavior for such an event. Additional observations are encouraged. (2) Spectrum dominated by galaxy light. (3) We measure an H-alpha velocity of 14,300 km/s. (4) We measure an Si II 6355 velocity of 10,800 km/s. (5) The SN is in similar distance to two potential host galaxies. Our slit went through 2MASX J21001139-0403511, the galaxy to the north-east. We derive a redshift of 0.020 for 2MASX J21001139-0403511, consistent with the 6dF value (Jones et al., 2009). It is possible that the true host is GALEXASC J210010.52-040351.9, which has no listed redshift. Assuming z = 0.020, we measure an Si II 6355 velocity of 18,800 km/s. (6) Blue continuum with H alpha at z = 0