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Asiago spectroscopic classification of PSN J07285387+3349106 in NGC 2388

ATel #7105; P. Ochner, S. Benetti, A. Pastorello, E. Cappellaro, N. Elias-Rosa, L. Tartaglia, G. Terreran, L. Tomasella, M. Turatto (INAF - Osservatorio Astronomico di Padova), F. Patat (ESO)
on 18 Feb 2015; 23:06 UT
Distributed as an Instant Email Notice Supernovae
Credential Certification: N. Elias-Rosa (nancy.elias@oapd.inaf.it)

Subjects: Optical, Supernovae

The Asiago Transient Classification Program (Tomasella et al. 2014, AN, 335, 841) reports the spectroscopic observation of PSN J07285387+3349106 in NGC 2388. The observation was performed with the Asiago 1.82m Copernico Telescope (+AFOSC; range 340-925 nm; resolution 1.4 nm), equipped with the CCD Andor IKON L936.

Name                  | Date (UT)    |  z         |  Type    | Phase  | 
PSN J07285387+3349106 | 20150218.79  |  0.01379   |  SN Ibn: | young  | 

The spectrum is almost featureless, but with a narrow, strong interstellar Na ID absorption at the redshift of the host galaxy. From the equivalent width of this feature (~6.6A), and following Turatto et al. 2003 (Proc. "From Twilight to Highlight - The Physics of Supernovae" ESO/MPA/MPE Workshop Garching July 29 - 31, 2002), we estimate a reddening value E(B-V) ~ 1. After reddening correction, we infer a black-body temperature of about 15300 K. These characteristics are consistent with those of a very young core-collapse SN. Narrow emission lines (Halpha, [N II] and [S II]) are spatially extended and therefore attributed to the host galaxy background. However, from a closer inspection of the spectrum, unresolved emission lines of He I (including 587.6 nm and 706.5 nm) are detected and are attributed to the transient. For this reason, we tentatively suggest for PSN J07285387+3349106 a Type Ibn classification (Pastorello et al. 2008, MNRAS, 389, 113; Pastorello et al. 2015, MNRAS, accepted, preprint arXiv: 1502.04946). Accounting for the bright apparent magnitude of the transient (m ~ 16.9) at discovery, we would obtain an absolute magnitude M = -20.2.

Classification was 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.