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Asiago spectroscopic classification of 2 supernova candidates

ATel #10219; L. Tomasella, S. Benetti, E. Cappellaro, N. Elias-Rosa, A. Pastorello, P. Ochner, M. Turatto (INAF-OAPd), G. Terreran (INAF-OAPd, QUB, Univ. di Padova)
on 28 Mar 2017; 09:21 UT
Distributed as an Instant Email Notice Supernovae
Credential Certification: Stefano Benetti (stefano.benetti@oapd.inaf.it)

Subjects: Optical, Supernovae

The Asiago Transient Classification Program (Tomasella et al. 2014, AN, 335, 841) reports the spectroscopic observation of ATLAS17dek (aka AT2017cki, candidate SN close to the galaxy SDSSJ105613.78+560813.2) and ATLAS17deh (aka AT2017ckj) in SDSS J160943.67+480209.4 at z=0.037.

The observations were performed with the Asiago 1.82 m Copernico Telescope equipped with AFOSC (range 340-820 nm; resolution 1.4 nm).

Survey Name   | IAU Name      | Discovery date (UT) | Discovery mag | Observation (UT)    |  Type         | z    |  phase  | Notes| 
ATLAS17dek    | SN 2017cki    |2017-03-22 09:51:50  |     18.34     |2017-03-27 21:58     |  SN Ia        | 0.04 |  max    | (1)  | 
ATLAS17deh    | SN 2017ckj    |2017-03-26 13:17:45  |     17.81     |2017-03-28 02:29     | core-collapse | 0.037| pre-max | (2)  | 

(1) A good match is obtained with several Type Ia SNe around B-band maximum light. From the position of the minimum of the Si II 635.5nm feature, we infer an expansion velocity of about 11200 km/s for the ejected material, assuming a redshift derived from the match with libraries of SNe Ia spectra (zmed=0.0414 +/- 0.006).

(2) The AFOSC spectrum shows a blue (T about 21500 K) almost featureless continuum, typically seen in young core collapse SNe a few days after explosion. An un-resolved emission identified with He II 468.6 nm is clearly seen. At the given redshift (derived from the narrow He II emission and from the SDSS galaxy spectrum), very faint unresolved emission of Halpha and HeI 587.6 nm are also discernible. Further observations are ongoing.

Classifications were done with GELATO (Harutyunyan et al. 2008, A&A, 488, 383) and SNID (Blondin and Tonry 2007, ApJ, 666, 1024). The Asiago classification spectra are posted at the website http://sngroup.oapd.inaf.it.