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Spectroscopic classifications of four transients at Asiago

ATel #4796; L. Tomasella, S. Benetti, E. Cappellaro, A. Pastorello, M. Turatto, P. Ochner (Osservatorio Astronomico di Padova, Istituto Nazionale di Astrofisica), N. Elias-Rosa and A. Morales-Garoffolo (ICE-IEEC/CSIC Barcelona)
on 7 Feb 2013; 15:31 UT
Distributed as an Instant Email Notice Transients
Credential Certification: Stefano Benetti (stefano.benetti@oapd.inaf.it)

Subjects: Optical, Supernovae, Transient

Referred to by ATel #: 4798

We report the spectroscopic confirmation of four transients with observations obtained with the 1.82-m Copernico Telescope in Asiago (+ AFOSC; range 340-820 nm, resolution 1.3 nm).

A spectrogram of PSN J10011200+0019423 obtained on Feb. 06.98 UT shows that it is a peculiar type-Ia event. Adopting for the host galaxy PGC 29001 the redshift z = 0.03451 (SDSS 2004, via NED), the best fit is obtained with peculiar, over-luminous 1991T-like type Ia supernovae, a few days before the maximum light. The expansion velocity, as deduced from the position of the Si-II 635.5nm absorption, is about 11200 km/s.

Optical spectroscopy obtained on Feb. 07.03 UT shows that PSN J09084154+4448496 is a type-Ia supernova. Adopting for the host galaxy UGC4798 the redshift z = 0.026762 (de Vaucouleurs et al. 1991, Third Reference Catalogue of Bright Galaxies, via NED), the best match was found with various type-Ia supernovae and in particular with supernova 2003du (Stanishev et al. 2007, A.Ap. 469, 645) more then one week before the maximum light. The expansion velocity, as deduced from the position of the Si-II 635.5nm absorption is about 13000 km/s.

Optical spectroscopy obtained on Feb. 07.08 UT indicates that PSN J10063402+1425578 is a type-IIn supernova. Prominent narrow but resolved hydrogen Balmer lines are visible in emission, and H-alpha shows a composite profile. The narrow component (FWHM about 400 km/s) is superimposed on a broader one (FWHM about 8000 km/s). From the position of the Balmer line peaks we derive a redshift z~0.03 for the parent galaxy, which is in agreement with z=0.030027 given for the host galaxy UGC 5448 (Mahdavi & Geller, 2004, Ap.J. 607, 202, via NED).

A spectrogram of PSN J15213475-0722183 obtained on Feb. 07.16 UT shows narrow hydrogen Balmer lines in emission (expansion velocity about 900-1000 km/s). The spectral features similar to those of a type IIn SN, combined with the faint absolute magnitude at discovery (-14.5), suggest that the object is a supernova impostor (see also Atel 4795). From the position of the Halpha and Hbeta line peaks we derive a redshift z~0.006 for the parent galaxy, in perfect agreement with z=0.006351 given for the host NGC5917 (Strauss et al., 1992, ApJS 83, 29, via NED).

The Asiago classification spectra are posted at this website: URL http://graspa.oapd.inaf.it ; classification was made via GELATO (Harutyunyan et al. 2008, A.Ap. 488, 383) and SNID (Blondin and Tonry 2007, Ap.J. 666, 1024).