Supernova 2014dt in M61 = Psn J12215757+0428185

S. Nakano, Sumoto, Japan, reports the discovery by K. Itagaki (Teppo-cho, Yamagata) of an apparent supernova (mag 13.6) in NGC 4303 = M61 on an unfiltered CCD frame (limiting magnitude 19.0) taken on Oct. 29.838 UT using a 0.50-m f/6.8 reflector at Takanezawa station, Tochigi-ken. The new object is located at R.A. = 12h21m57s.57, Decl. = +4d28'18".5 (equinox 2000.0; reference stars from UCAC4 catalogue), which is 33".9 east and 7".2 south of the nucleus of the galaxy NGC 4303 (position end figures 54s.90, 25".7). Itagaki posted his discovery image at website URL http://www.k-itagaki.jp/images/4303.jpg. The variable was designated PSN J12215757+0428185 when it was posted at the Central Bureau's TOCP webpage and is here designated SN 2014dt based on the spectroscopic confirmation reported below. Additional CCD magnitudes for 2014dt: 2008 April 5.596, 19.5 (Itagaki; 0.60-m f/5.7 reflector at Yamagata); 2014 Oct. 30.507, 13.2 (E. Guido, M. Nicolini, and N. Howes; iTelescope 0.10-m f/5 astrograph near Mayhill, NM, USA; position end figures 57s.61, 17".8; UCAC-3 reference stars; images posted at website URL http://bit.ly/1rVHdBj; animation at URL http://bit.ly/13jRhPf compares the current image with a 1991 infrared plate from the Digitized Sky Survey); 30.515, B = 14.36, V = 13.65, R_c = 13.42, I_c = 13.15 (S. Kiyota, Kamagaya, Japan; remotely with iTelescope 0.5-m f/6.8 astrograph + FLI PL-11002M camera near Mayhill, NM, USA; image posted at URL http://meineko.sakura.ne.jp/ccd/PSN_J12215757+0428185.jpg); 31.154, 13.0 (G. Masi and P. Catalano; remotely with a 43-cm telescope near Ceccano, Italy; position end figures 57s.58, 18".6); 31.169, B = 14.62, V = 13.70, R_c = 13.51, I_c = 13.28 (A. Vagnozzi and U. Munari; 0.51-m telescope operated by the ANS Collaboration at Stroncone, Italy).