Supernova 2013ee in NGC 3079 = Psn J10015683+5541440

Giancarlo Cortini, Predappio, Italy, reports the discovery of a possible supernova (mag about 15.5) on several unfiltered images (limiting mag about 18.5) taken on July 13.86 UT with a 0.35-m f/5.5 Schmidt-Cassegrain reflector (+ SXVR-H9 CCD camera). The new object is located at R.A. = 10h01m56s.83, Decl. = +55d41'44".0 (equinox 2000.0), which is 56" north and 14" west of the center of the presumed host galaxy, NGC 3079. Norhing is visible at this position on his past images of the same field taken on Feb. 28.75 and 14.90 (limiting mag 19.0) or on Palomar Sky Survey red and blue plates. The variable was designated PSN J10015683+5541440 when it was posted at the Central Bureau's TOCP webpage and is here designated SN 2013ee based on the spectroscopic confirmation reported below. Additional CCD magnitudes for 2013ee: July 14.216, 15.1 (J. Brimacombe, Cairns, Australia; remotely using a 51-cm RCOS telescope + luminance filter at the New Mexico Skies observatory near Mayhill, NM, U.S.A.; position end figures 56s.70, 44".3; images posted at website URL http://www.flickr.com/photos/43846774@N02/9281250965/); 15.825, 15.4 (Gianluca Masi and Francesca Nocentini, remotely using a 43-cm robotic telescope at Ceccano, Italy; position end figures 56s.73, 44".4; a low- resolution spectrogram, with a 100 lines/mm grating and a resolution of 3.35 nm/pixel, taken remotely using a 36-cm telescope at Ceccano, with the source at about 27 deg above the horizon, shows an emission at the wavelength of H-alpha, suggesting a type-II supernova); 15.916, 15.4 (Federica Luppi and Luca Buzzi, Varese, Italy; 0.36-m f/7.1 reflector; position end figures 56s.72, 44".4; reference stars from CMC-14 catalogue; a knot or an H II region is visible in Digitized Sky Survey images at the same position; image posted at URL http://www.astrogeo.va.it/pub/TOCP/PSN_N3079.jpg). L. Tomasella, P. Ochner, A. Pastorello, S. Benetti, E. Cappellaro, M. Turatto, and J. Farinato, Astronomico di Padova, Istituto Nazionale di Astrofisica, report that an optical spectrogram (range 340-820 nm; resolution 1.3 nm) of PSN J10015683+5541440 = SN 2013ee, obtained on July 18.88 UT with the Asiago 1.82-m Copernico Telescope (+ AFOSC), shows that this is a type-II supernova at redshift z = 0.003723 (Hagiwara et al. 2004, MNRAS 353, 1055; via NED). A good match is found with normal type-II supernovae at a couple of weeks after explosion. The expansion velocity deduced from the H-alpha absorption is about 8500 km/s. The Asiago classification spectra are posted at website URL http://sngroup.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). T. Pursimo, Nordic Optical Telescope; M. Dennefeld, Institut Astrophysique de Paris, and Universite Pierre et Marie Curie, Paris VI; and the NEON school students (cf. IAUC 7664) Benjamin Hendricks (LSW, Heidelberg), Jaan Laur (Tartu Observatory), Marijana Smailagic (Belgrade), and Sonia Tamburi (Istituto Nazionale di Astrofisica, Brera), report that a spectrum of PSN J10015683+5541440 = SN 2013ee was obtained at the Nordic Optical Telescope (+ ALFOSC) on July 18.90 UT. The spectrum (range 350-900 nm, resolution 2 nm) shows a strong, broad (22-nm FWHM) H_alpha emission with a P-Cyg profile and several broad features in the blue portion (473, 501, and 513 nm, among others; observed wavelengths). Assuming a recession velocity of 1116 km/s for the parent galaxy, NGC 3079 (Tully et al. 2008, Ap.J. 676, 184; via LEDA), the absorption on the blue side of H_alpha indicates an expansion velocity of 7500 km/s. Although no satisfactory fit could be found via GELATO (Harutyunyan et al. 2008, A.Ap. 488, 383), these features are indicative of a type-II supernova well past maximum.