Electronic Telegram No. 2317
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
CBAT Director:  Daniel W. E. Green; Room 209; Dept. of Earth and Planetary
 Sciences; Harvard University; 20 Oxford St.; Cambridge, MA  02138; U.S.A.
e-mail:  cbat@iau.org; cbatiau@eps.harvard.edu
URL http://www.cfa.harvard.edu/iau/cbat.html


SUPERNOVA 2010dy
     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. = 16h10m11s.03, Decl. = +0d45'07".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.
     Following posting on the Central Bureau's unconfirmed-objects webpage, D.
Milisavljevic and R. Fesen, Dartmouth College, report confirmation of 2010dy,
based on low-dispersion optical spectra (range 500-830 nm) obtained with the
2.4-m Hiltner telescope (+ CCDS) at MDM Observatory on June 10.3 UT.
Comparison with a library of supernova spectra using the "Supernova
Identification" tool (SNID; Blondin and Tonry 2007, Ap.J. 666, 1024) shows
that the spectrum of 2010dy closely matches that of the type-Ia supernova
2002bo around maximum light.  The redshift z = 0.043 determined by SNID
agrees with the redshift of the nearby galaxy catalogued by the Sloan Digital
Sky Survey (SDSS J161010.57+004512.1).


NOTE: These 'Central Bureau Electronic Telegrams' are sometimes
      superseded by text appearing later in the printed IAU Circulars.

                         (C) Copyright 2010 CBAT
2010 June 10                     (CBET 2317)              Daniel W. E. Green