Supernova 2015A in NGC 2955 = Psn J09411555+3553174

S. Nakano, Sumoto, Japan, reports the discovery by K. Itagaki (Teppo-cho, Yamagata, Japan) of an apparent supernova (mag 16.6) on an unfiltered CCD frame (limiting magnitude 18.5) taken remotely on Jan. 9.636 UT using a 0.50-m f/6.8 reflector at the Takanezawa station, Tochigi-ken. The new object is located at R.A. = 9h41m15s.55, Decl. = +35d53'17".4 (equinox 2000.0; reference stars from UCAC4 catalogue), which is 12".5 west and 21".2 north of the nucleus of the galaxy NGC 2955. Itagaki has posted his discovery image at the following website URL: http://www.k-itagaki.jp/images/2955.jpg. The variable was designated PSN J09411555+3553174 when it was posted at the Central Bureau's TOCP webpage and is here designated SN 2015A based on the spectroscopic confirmation reported below. Additional CCD magnitudes for 2015A: 2006 Oct. 27.807, 19.5 (Itagaki; 0.60-m f/5.7 reflector); 2015 Jan. 2.580, 18.0 (Itagaki); 10.466, 16.4 (T. Noguchi, Chiba-ken, Japan; 0.23-m f/6.3 Schmidt- Cassegrain reflector; position end figures 15s.52, 17".8; image posted at website URL http://park8.wakwak.com/~ngc/images/PSNinNGC2955.jpg; communicated by Nakano); 10.652, V = 15.95, R_c = 15.67, I_c = 15.45 (S. Kiyota, Kamagaya, Chiba, Japan; 25-cm Schmidt-Cassegrain telescope + Apogee F47 camera); 11.818, 15.9 (G. Masi and P. Catalano; remotely using a 43-cm telescope at Ceccano, Italy; position end figures 15s.53, 17".4). T. Nakaoka, T. Ui, K. S. Kawabata, K. Takaki, and M. Kawabata, Hiroshima University; and M. Yamanaka, Konan University, obtained a low-resolution optical spectrogram (range 480-900 nm) of SN 2015A = PSN J09411555+3553174 on Jan. 10.8 UT with the 1.5-m Kanata telescope (+ HOWPol) at Higashi-Hiroshima Observatory. A comparison with a library of supernova spectra using GELATO (Harutyunyan et al. 2008, A.Ap. 488, 383) suggests that the spectrum is consistent with that of the type-Ia supernova 1989B at 6 days before B-band maximum. After correction for the recession velocity of the host galaxy, it exhibits absorption lines at 488, 528, 542, 575, 610, and 807 nm, which are identified as an Fe II multiplet, S II at 545.4 and 564.0 nm, Si II at 597.2 and 635.5 nm, and the Ca II infrared triplet. The spectrum also shows a weak O I 777.4-nm absorption line. The line velocities of Si II 635.5-nm and the Ca II infrared feature reach 12000 and 18000 km/s, respectively. L. Tomasella, S. Benetti, E. Cappellaro, N. Elias-Rosa, P. Ochner, A. Pastorello, G. Terreran, L. Tartaglia, and M. Turatto, Osservatorio Astronomico di Padova, INAF, report that an optical spectrogram (range 340-1000 nm; resolution 1.2 nm) of SN 2015A = PSN J09411555+3553174, obtained on Jan. 10.94 UT with the Asiago 182-cm Copernico Telescope (+ AFOSC) under the Asiago Transient Classification Program (Tomasella et al. 2014, AN 335, 841), shows that 2015A is a type-Ia supernova. Assuming a recessional velocity of 7013 km/s (de Vaucouleurs et al. 1999, RC3.9; via NED) for the host galaxy, NGC 2955, a good match is found with several type-Ia supernovae at a few days before B-band maximum light. An expansion velocity of 12200 km/s is derived from the minimum of the Si II 635-nm line. Classification was done with GELATO (Harutyunyan et al. 2008, A.Ap. 488, 383) and SNID (Blondin and Tonry 2007, ApJ. 666, 1024). The Asiago classification spectra are posted at website URL http://sngroup.oapd.inaf.it.