Spectroscopic Classifications of Optical Transients with Keck I + LRIS

ATel #13965; S. Tinyanont, M. R. Siebert, G. Dimitriadis, R. J. Foley (UCSC)
on 23 Aug 2020; 21:24 UT
Distributed as an Instant Email Notice Supernovae
Credential Certification: Georgios Dimitriadis (gdimitri@ucsc.edu)

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We report the classification of the optical transients from spectroscopic observations with the LRIS spectrograph on the Keck I telescope, made on 2020 Aug 23 UT. The targets were supplied by Gaia, YSE and ATLAS. The classifications were performed with SNID (Blondin & Tonry, 2007, ApJ, 666, 1024).

 
Name         | IAU Name  | RA (J2000)  |  Dec (J2000)  |   z   |  Type  |   Phase   | Notes
 
Gaia20dgj    | AT2020pju | 03:37:29.92 | -24:30:04.14  | 0.005 |   LBV  | post-peak |  (1) 
PS20gji      | AT2020qmo | 00:41:33.69 | +01:26:14.78  | 0.042 |   II   | post-peak | 
PS20gse      | AT2020rii | 16:36:04.01 | +33:12:35.44  | 0.087 |   Ia   |    +9d    |  (2) 
ATLAS20xio   | AT2020rkt | 02:24:58.87 | -05:15:42.27  | 0.103 |   Ia   |    +5d    |  (3) 
ATLAS20xni   | AT2020rmg | 01:09:07.23 | -15:59:49.76  | 0.040 |   Ia   |    -7d    |  (4) 
PS20gsy      | AT2020rmy | 20:40:37.59 | -03:31:17.88  | 0.138 |   Ia   |    -3d    |  (5) 
PS20guq      | AT2020rvq | 16:21:34.06 | +32:34:02.86  | 0.131 |   Ia   |    -7d    |  (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) The spectrum is similar to both LBV outbursts ("SN impostors") and low-luminosity SNe II. With a distance modulus of 29.9 mag to NGC 1385 (Tully et al., 2013, AJ, 146, 86), we find that the transient was discovered at M = -12.6 mag. Assuming extinction of <1 mag, this is more consistent with an LBV outburst than a bone fide supernova, but we cannot rule out that possibility. (2) We measure an Si II velocity of -10,300 km/s. Significant host galaxy extinction (Na I D EW = 1.57 Angstrom). (3) We measure an Si II velocity of -10,700 km/s. (4) We measure an Si II velocity of -13,600 km/s. (5) We measure an Si II velocity of -10,700 km/s. (6) We measure an Si II velocity of -12,200 km/s.