Spectroscopic classification of transients with the Lick Shane telescope
ATel #15047; K. W. Davis, D. O. Jones, M. J. Bustamante-Rosell, M. R. Siebert, R. J. Foley (UCSC)
on 18 Nov 2021; 21:23 UT
Distributed as an Instant Email Notice Supernovae
Credential Certification: Samaporn Tinyanont (stinyanont@ucsc.edu)
Subjects: Optical, Supernovae
We report the following classifications from spectroscopic observations with the KAST spectrograph on the Shane telescope obtained on 2021 November 15 UT. The targets were supplied by ATLAS, ALeRCE (selected from the ZTF data stream), 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
ATLAS21bjxx | AT2021aatr | 09:10:11.475 | +35:15:39.50 | 0.059 | Ia | +25d |
ZTF21acnfsun | AT2021adwh | 10:00:58.399 | +03:28:02.13 | 0.15 | Ia | -2d | (1)
ZTF21acontmk | AT2021aegy | 02:22:58.989 | +35:39:45.19 | 0.107 | Ia | -5d | (2)
ATLAS21bmkw | AT2021aele | 03:35:32.578 | -28:30:51.67 | 0.077 | Ia | -5d | (3)
ZTF21acpkzcc | AT2021aess | 03:33:48.126 | -19:29:44.63 | 0.007 | LBV | | (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) We measure a Si II velocity of -9,600 km/s.
(2) The spectrum has a low signal-to-noise ratio, but is consistent with a SN Ia.
(3) Some matches to SN 1991T-like SNe Ia.
(4) An marginally resolved H-alpha emission line is detected. We measure a H-alpha FWHM velocity of 700 km/s. Using a Tully-Fisher distance modulus to the host galaxy, NGC 1359, of 32.95 mag (Tully et al., 2009, AJ 138 323) and correcting for Milky Way extinction, the current absolute magnitude is M_r = -14.4 mag and rising. The relatively low absolute magnitude, slow rise (1.7 mag over 6 days), and narrow H-alpha line indicate that AT2021aess is likely not a supernova, but a non-terminal LBV eruption (i.e., a "supernova impostor") or possibly a luminous red nova.
