Supernova 2014ac in NGC 5837 = Psn J15044009+1237540

Simone Leonini, Siena, Italy, reports the discovery of an apparent supernova (mag about 16.6) by G. Guerrini, M. Conti, P. Rosi, L. M. Tinjaca Ramirez, and himself on two unfiltered CCD images (limiting mag about 19.0) taken on Mar. 9.993 UT at the Montarrenti Observatory in the course of an automatic survey of the Italian Supernovae Search Project using a 0.53-m f/8.7 Ritchey-Chretien telescope (+ Apogee Alta U47 CCD camera). The new object is located at R.A. = 15h04m40s.09 +/- 0s.23, Decl. = +12d37'54".0 +/- 0".2 (equinox 2000.0), which is 8" west and 10" south of the nucleus of the galaxy NGC 5837. No stellar source is visible at this position on Palomar Sky Survey infrared, red, and blue plates (1997 July 8, F plate; 1991 May 15, J plate; and 1991 May 15, N plate; limiting mag 19.5). The discovery image is posted at URL http://www.astrofilisenesi.it/public/Sne/Uploads/PSN_NGC5837.jpg. The variable was designated PSN J15044009+1237540 when it was posted at the Central Bureau's TOCP webpage and is here designated SN 2014ac based on the spectroscopic confirmation reported below. Additional CCD magnitudes for 2014ac: 2014 Feb. 24, [18.7 (Leonini et al.); Mar. 3, [17.0 (Leonini et al.); Mar. 13.008, 16.7 (Gianluca Masi, Francesca Nocentini, and Patrick Schmeer; remotely using a 43-cm f/6.8 corrected Dall-Kirkham robotic telescope near Ceccano, Italy; position end figures 40s.08, 54".0); 13.028, V = 17.3 (M. Martignoni, Magnago, Italy; 0.25-m f/10 Schmidt-Cassegrain reflector; position end figures 40s.09, 54".3); 13.069, 17.7 (Federica Luppi and Luca Buzzi, Varese, Italy; 0.60-m f/4.6 reflector; position end figures 40s.08, 54".2; image posted at website URL http://www.astrogeo.va.it/pub/TOCP/PSN_N5837.jpg). L. Tomasella, S. Benetti, E. Cappellaro, A. Pastorello, P. Ochner, N. Elias-Rosa, and M. Turatto, Osservatorio Astronomico di Padova, Istituto Nazionale di Astrofisica; and S. Ciroi, Dipartimento di Fisica e Astronomia, Universita' di Padova, report that a noisy optical spectrogram (range 340-820 nm; resolution 1.3 nm) of PSN J15044009+1237540 = SN 2014ac, obtained on Mar. 10.98 UT with the Asiago 1.82-m Copernico Telescope (+ AFOSC), shows it to be a type-Ia supernova. Adopting for the host galaxy, NGC 5837, a redshift z = 0.0287 (Fisher et al. 1995, Ap.J. Suppl. 100, 69; via NED), a good match is found with several type-Ia supernovae at a few days after maximum. The expansion velocity deduced from the Si II 635.5-nm absorption is about 10500 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). N. Walton, M. Fraser, N. Blagorodnova, Institute of Astronomy; S. Taubenberger, Max-Planck-Institut fuer Astrophysik, Garching; M. Dennefeld, Institut Astrophysique de Paris; S. Benetti and A. Pastorello, Osservatorio Astronomico di Padova, Istituto Nazionale di Astrofisica (INAF); C. Inserra, S. Smartt, K. Smith, and D. Young, Queen's University, Belfast; M. Sullivan, University of Southampton; S. Valenti, Las Cumbres Observatory Global Telescope; O. Yaron and A. Gal-Yam, Weizmann Institute for Science; C. Knapic, R. Smareglia, and M. Molinaro, Trieste Astronomical Observatory, INAF; and I. Manulis, Weizmann Institute for Science, on behalf of the Public European Southern Observatory (ESO) Spectroscopic Survey for Transient Objects (PESSTO; see website URL http://www.pessto.org), report that a spectrogram was taken of PSN J15044009+1237540 = SN 2014ac on the ESO's New Technology Telescope at La Silla on Mar. 10, using EFOSC2 and Grism 13 (398.5-931.5 nm; 1.8-nm resolution). Cross-correlation of the spectrum with a library of template spectra using SNID (Blondin and Tonry 2007, Ap.J. 666, 1024) gives a best match to several normal type-Ia supernovae at the redshift of NGC 5837 (z = 0.029) and around maximum light.