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SN 2012df - 27 giugno 2012

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SN 2012df (A.R. 17 48 18.75, Dec. +52 18 02.3), scoperta il 27 giugno 2012 in una galassia anonima (offset 5E 4S), magnitudine 18.6, tipo Ia.

SN scoperta da F. Ciabattari ed E. Mazzoni con il telescopio Newton da 50cm dell'Osservatorio di Monte Agliale (Lucca).

                                                  Electronic Telegram No. 3161
Central Bureau for Astronomical Telegrams
CBAT Director:  Daniel W. E. Green; Hoffman Lab 209; Harvard University;
 20 Oxford St.; Cambridge, MA  02138; U.S.A.
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SUPERNOVA 2012df = PSN J17481875+5218023
     F. Ciabattari, E. Mazzoni, and G. Petroni, Borgo a Mozzano, Italy, report
the discovery of an apparent supernova (mag 18.6) on unfiltered CCD images
(limiting mag 19.5) obtained on June 27.89 and 28.95 UT with a 0.5-m Newtonian
telescope in the course of the Italian Supernovae Search Project.  The new
object is located at R.A. = 17h48m18s.75, Decl. = +52d18'02".3 (equinox
2000.0), which is 5" east and 4" south of the center of the presumed host
galaxy.  Nothing is visible at this position on Palomar Sky Survey digitized
images from 1993 Aug. 16 (F plate, limiting mag 20.3) and 1995 July 1 (J
plate, limiting mag 20.3).  The variable was designated PSN J17481875+5218023
when it was posted at the Central Bureau's TOCP webpage and is here designated
SN 2012df based on the spectroscopic confirmation reported below.  Additional
CCD magnitudes for 2012df:  June 30.370, 18.2 (Joseph Brimacombe, Cairns,
Australia; remotely using a 51-cm RCOS telescope + STL11K camera + luminance
filter at the New Mexico Skies Observatory near Mayhill, NM, U.S.A.; position
end figures 18s.69, 02".3; image posted at the following website URL:
http://www.flickr.com/photos/43846774@N02/7476712034/); 30.973, 18.2 (Federica
Luppi and Luca Buzzi, Varese, Italy; 0.38-m f/6.8 reflector; position end
figures 18s.71, 01".6; reference stars from the NOMAD catalogue; image posted
at URL http://www.astrogeo.va.it/pub/TOCP/PSN_J17481875+5218023.jpg.

     L. Tomasella, A. Pastorello, S. Valenti, S. Benetti, E. Cappellaro, M.
Turatto, and P. Ochner, Osservatorio Astronomico di Padova, Istituto Nazionale
di Astrofisica, report that a spectrogram of PSN J17481875+5218023 = 2012df,
obtained on June 30.06 UT with the Asiago 1.82-m Copernico Telescope (+ AFOSC;
range 340-820 nm; resolution 2.4 nm), indicates that this is a type-Ia
supernova.  Cross-correlation with a library of supernova spectra via the
"Supernova Identification" code (SNID; Blondin and Tonry 2007, Ap.J. 666,
1024) shows that 2012df is similar to several normal type-Ia supernovae soon
after maximum at a redshift around z = 0.07.

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

                         (C) Copyright 2012 CBAT
2012 July 4                      (CBET 3161)              Daniel W. E. Green