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Asiago spectroscopic classification of the SN impostor SNhunt275

ATel #7042; N. Elias-Rosa, S. Benetti, L. Tomasella, E. Cappellaro, P. Ochner, A. Pastorello, L. Tartaglia, G. Terreran, M. Turatto (INAF Osservatorio Astronomico di Padova)
on 10 Feb 2015; 16:31 UT
Distributed as an Instant Email Notice Transients
Credential Certification: Enrico Cappellaro (enrico.cappellaro@oapd.inaf.it)

Subjects: Optical, Transient

Referred to by ATel #: 7409, 7514, 7515, 7517, 7541

The Asiago Transient Classification Program (Tomasella et al. 2014, AN, 335, 841) reports the spectroscopic observation of PSN J09093496+3307204 (= SNhunt275) in NGC 2770. The observation was performed with the Asiago 1.82m Copernico Telescope (+AFOSC; range 340-820 nm; resolution 1.4 nm), equipped with the CCD Andor IKON L936.

  
 
Name                                | Date (UT)    |  z         |   Type       |     
PSN J09093496+3307204 (= SNhunt275) |  20150209.93 |  0.0064    |  SN impostor |      

We revise the transient coordinates that, based on our frames, are RA=09:09:35.12 +/- 0.02 DEC=+33:07:21.3 +/- 0.2 (J2000.0).

The Halpha line shows a broad emission (FWHM~6800 km/s) with, on top, a narrow line with P-Cygni profile. The marginally resolved emission has FWHM~900 km/s while from the absorption an expansion velocity of ~950 km/s is derived.

We also measured the following Sloan magnitudes: u=21.2, g=20.1, r=19.5, i=19.4. Assuming a distance modulus of 32.48 (from NED) the absolute magnitude of the transient is then r ~ -13.

We remark that examination of archive HST images shows a source that appears coincident with the transient position. Using the Dolphot package (Dolphin 2000 PASP, 112, 1383) the source was measured at apparent mag=22.8, 21.5,22.5 (filter F606W) on 20080209, 20080330, 20090225 respectively (WFPC2 Prog.Id 11161 PI: A. Soderberg).

The spectral appearance and the evidence of erratic variability strongly remind the SN/impostors 2000ch (Wagner et al. 2004 PASP 116, 326, Pastorello et al. 2010 MNRAS 408, 181) and 2009ip (before the explosion of June 2012, Pastorello et al. 2013 ApJ 767,1).

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.