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SALT Spectroscopy of PSN J06120295-2149353 in NGC 2196: Uncertain Classification

ATel #5783; Saurabh W. Jha, Viraj Pandya (Rutgers), Jeffrey M. Silverman (UT Austin), and Brent Miszalski (SALT/SAAO)
on 21 Jan 2014; 21:54 UT
Credential Certification: Saurabh Jha (saurabh@physics.rutgers.edu)

Subjects: Optical, Request for Observations, Supernovae, Transient

Referred to by ATel #: 5796

We obtained SALT (+ RSS) spectroscopy of PSN J06120295-2149353 in NGC 2196 (Zheng et al. 2014, ATel #5779) on 2014 January 20.98 UT, covering the range 350-940 nm. The spectrum shows a blue continuum with weak, broad features near 460 nm and 550 nm. Cross-correlation of the spectrum with a library of supernova spectra using SNID (Blondin & Tonry 2007, ApJ, 666, 1024) does not yield a clear template match at the host redshift (z=0.0077, Springob et al. 2005, ApJS, 160, 149).

The most plausible SNID matches are with type-Ic SN spectra (including SN 1994I, but also broad-lined SN Ic like SN 1997ef, SN 2002ap, and SN 2006aj) at phases about 5 days before maximum light (though these fit best with z ~ 0.04, indicating either lower ejecta velocities in the NGC 2196 supernova, or that it is in the background).

Another possibility is a type-Iax classification (Foley et al. 2013, ApJ, 767, 57) with a reasonable SNID match to pre-maximum spectra of SN 2008A (McCully et al. 2013, arXiv:1309.4457), at the redshift of NGC 2196.

Finally, and least likely, SNID also gives matches to normal SN Ia near maximum light, but only at z ~ 0.18. We disfavor this interpretation, given the SN brightness would then imply M_R ~ -21.6.

If the object is in NGC 2196, its absolute magnitude is M_R ~ -14.3, with no sign of host extinction in the spectrum. If this young transient does not brighten significantly, it is quite faint for a SN (though perhaps not for a SN Iax). This raises the possibility that the source may actually be a foreground variable star in the Galaxy.

We encourage further observations of this object; the classification should become secure if supernova spectral features emerge.