2010CBET.2317....1L

S. Leonini, Siena, Italy, reports the discovery by S. Leonini and G. Guerrini of an apparent supernova (mag about 17.9) on unfiltered CCD image (limiting mag about 19.8) taken on 2010 June 6.947 UT during the Montarrenti Observatory Supernovae Search program using a 0.53-m f/7.8 Ritchey-Chretien telescope (+ Apogee Alta U47 CCD camera). Confirming images taken on June 9.847 and 9.888 show 2010dy at mag about 17.6. The new object is located at R.A. = 16:10:11.03, Decl. = +0:45:07.5 (equinox 2000.0), which is 9" east and 5" south of the nucleus of the galaxy PGC 1174551. Nothing is visible at this position in their numerous past images, including one taken on 2010 May 19.097 (limiting mag about 19.5), and 2010dy does not appear on Palomar Sky Survey infrared, red, and blue plates (1984 July 17, F plate, limiting mag 20.3; 1987 May 3, J plate, limiting mag 20.3; 1991 June 15, N plate, limiting mag 19.5). The discoverers have posted their discovery image at the following website URL: http://www.jacopobaldi.it/dati/PSN%20in%20PGC1174551.jpg.