Spectroscopic classification of SN 2021J with Faulkes Telescope North/FLOYDS

ATel #14300; M. R. Siebert, R. J. Foley (UC Santa Cruz)
on 4 Jan 2021; 17:50 UT
Distributed as an Instant Email Notice Supernovae
Credential Certification: Ryan Foley (foley@ucsc.edu)

Tweet

We report the classification of SN 2021J with the FLOYDS spectrograph on the 2-m Faulkes Telescope North on UT 2021 Jan 4. The target was supplied by ALeRCE using the ZTF data stream. The classification was performed with SNID (Blondin & Tonry, 2007, ApJ, 666, 1024).

 
Name         | IAU Name | RA (J2000)  | Dec (J2000)  |   z    | Type   |  Phase   | Notes
 
ZTF21aaabvit | AT2021J  | 12:26:27.03 | +31:13:20.59 | 0.0024 |  Ia    |  -14 d   | (1) 
 

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 has some host-galaxy contamination, but still has distinct supernova features. In particular, we identify Si II 6355 with a minimum blueshifted by -16,300 km/s. The spectrum is consistent with some very young SNe Ia (e.g., SN 2002bo at -14 days), although with some color mismatch. The continuum is relatively flat (in f_lambda) from 4000-10,000 A, slightly increasing to the blue. There is no obvious Na D absorption in the spectrum, although narrow H alpha and Ca H&K absorption, presumably from the host galaxy, are present. There is therefore no obvious dust extinction from indirect indicators. Assuming a Cepheid distance to NGC 4414 (also the host to SN Ia 1974G and SN IIb 2013df), mu = 31.1 mag (Freedman et al., 2001, ApJ, 553, 47), and Milky Way reddening of A_g = 0.064 mag (Schlafly & Finkbeiner, 2011, ApJ, 737, 103), the current brightness (g = 16.1 mag) corresponds to an absolute magnitude of M_g = -15.1 mag. This luminosity is consistent with a young Type Ia supernova.