AstroNote 2020-3

ePESSTO+, the advanced Public ESO Spectroscopic Survey for Transient Objects (Smartt et al. 2015 2015A&A...579A..40S), reports the following supernova classifications.

Targets were supplied by the ATLAS survey (Tonry et al. 2018 2018PASP..130f4505T), and the Zwicky Transient Facility ZTF (Kulkarni 2018 2018ATel11266....1K) - data stream processed through the Lasair broker (Smith, Williams, Young et al. 2019 2019RNAAS...3a..26S).

Observations were performed on the ESO New Technology Telescope (NTT) at La Silla on the night of 2020 Jan 02, using EFOSC2 and Grism 13 (3985-9315A, 18A resolution). Classifications were done using SNID (Blondin & Tonry 2007 2007ApJ...666.1024B) and astroDASH (Muthukrishna et al. 2019 2019arXiv190302557M).

The classification spectra and additional details can be obtained from http://www.pessto.org (via WISeREP) and the IAU Transient Name Server.

The classified objects are listed in the Related Objects table below.

AT2019yzs lies in the nucleus of a bright, interacting galaxy system with a strong blue continuum. We detect nebular emission lines including H-alpha, [NII], [SII], [OII], and strong higher order Balmer series absorption. [OIII] and H-beta are present but much weaker. The widths of the emission and absorption lines are consistent with the 18A resolution. Attempts to subtract the host galaxy light result in a blue continuum with the emission features still present. We identify a broad spectral feature around 4100A at low significance, although cannot robustly identify it. We thus cannot rule out a SN, TDE, or AGN origin for this transient. We encourage high resolution spectral follow up.