Spectroscopic Classifications of Optical Transients with Keck I + LRIS
ATel #13892; G. Dimitriadis, M. R. Siebert, R. J. Foley (UCSC)
on 24 Jul 2020; 16:49 UT
Distributed as an Instant Email Notice Supernovae
Credential Certification: Georgios Dimitriadis (gdimitri@ucsc.edu)
Subjects: Optical, Supernovae
We report the classification of the optical transients from spectroscopic observations with the LRIS spectrograph on the Keck I telescope, made on 2020 Jul 24 UT. The targets were supplied by ATLAS, ASAS-SN, and ZTF. The classifications were performed with SNID (Blondin & Tonry, 2007, ApJ, 666, 1024).
Name | IAU Name | RA (J2000) | Dec (J2000) | z | Type | Phase | Notes
ATLAS20njn | SN2020kre | 13:10:29.87 | -01:18:51.10 | 0.136 | Ia-CSM | +50 | (1)
ATLAS20pyr | AT2020nap | 12:07:08.82 | +16:55:16.21 | 0.022 | II | +20 | (2)
ASASSN-20ho | AT2020nub | 02:03:56.09 | -23:18:50.07 | 0.017 | IIn | | (3)
ZTF20abmdfcy | AT2020psv | 00:21:17.97 | +21:04:15.73 | 0.093 | Ia | -1 | (4)
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) The transient was initially classified as a Type Ia supernova, on 2020 May 27 UT. The new spectrum reveals a broad H-alpha component (FWHM of 2,600 km/s). The spectrum is consistent with a Type Ia-CSM supernova, 50 days after maximum brightness. (2) We measure an H-alpha velocity of -8,600 km/s. (3) The H-alpha has two velocity components with FWHMs of 820 and 3340 km/s, respectively. There are many narrow Fe II emission lines, as well as other species. The spectrum is similar to some LBVs, but its luminosity, < -18.5 mag, suggests it is more likely a SN IIn, with a spectrum similar to SN 1995G (Pastorello et al., 2002, MNRAS, 333, 27) or SN 2006gy (Smith et al., 2010, ApJ, 709, 2), but without developed absorption features yet. (4) We measure an Si II velocity of -11,700 km/s.
