Supernova 2013ai in NGC 2207 = Psn J06161835-2122329

Alain Klotz, Institut de Recherche en Astrophysique et Planetologie (IRAP), Toulouse, reports the discovery by E. Conseil (IRAP) of an apparent supernova (R-band magnitude about 17.4) on images taken on Mar. 1.66 UT with the Zadko 1-m telescope at the Gingin observatory in Australia. The new object is located at R.A. = 6h16m18s.35, Decl. = -21o22'32".9 (equinox 2000.0), which is 51" west and 11" south of the nucleus of NGC 2207; nothing was visible at this position on an image taken on Feb. 6.72. Images have been posted at website URL http://cador.obs-hp.fr/sn_tarot/PSN_J06161835-2122329/. The variable was designated PSN J06161835-2122329 when it was posted at the Central Bureau's TOCP webpage (with the offset in declination given there by mistake as 11" north) and is here designated SN 2013ai based on the spectroscopic confirmation reported below. Additional CCD magnitudes for 2013ai: Feb. 26.66, R = 19.3 (Conseil and Klotz; prediscovery); 28.66, R = 18.6 (Conseil and Klotz; prediscovery); Mar. 3.185, 17.0 (Joseph Brimacombe, Cairns, Australia; stacked images obtained remotely with a 51-cm RCOS telescope + luminance filter at the New Mexico Skies observatory near Mayhill, NM, U.S.A.; position end figures 18s.42, 31".0; image posted at website URL http://www.flickr.com/photos/43846774@N02/8526368927/); 3.890, 16.8 (Federica Luppi and Luca Buzzi, Varese, Italy; 0.38-m f/6.8 reflector; unfiltered; position end figures 18s.38, 32".9; reference stars from the NOMAD catalogue; image posted at URL http://www.astrogeo.va.it/pub/TOCP/PSN_N2207.jpg). M. Fraser and C. Inserra, Queen's University, Belfast; N. Walton and N. Blagorodnova, Institute of Astronomy, Cambridge; M. Nicholl, Queen's University, Belfast; S. Benetti and A. Pastorello, Istituto Nazionale di Astrofisica, Padova Astronomical Observatory; S. Valenti, Las Cumbres Observatory Global Telescope and University of California at Santa Barbara; S. Taubenberger, Max-Planck-Institut fuer Astrophysik, Garching; S. J. Smartt, K. Smith, and D. Young, Queen's University, Belfast; M. Sullivan, University of Southampton; and A. Gal-Yam and O. Yaron, Weizmann Institute for Science, on behalf of the PESSTO collaboration (www.pessto.org), report that they obtained a spectrogram of PSN J06161835-2122329 = SN 2013ai on Mar. 3, using the European Southern Observatory's New Technology Telescope (+ EFOSC2 with Grism#13) at La Silla. The spectrum consists of a blue continuum, with a broad absorption from H_alpha, and is consistent with a young type-II supernova in NGC 2207. Narrow H_alpha emission is also seen in the spectrum, likely arising from the host galaxy.