SN 2012dg (A.R. 18 18 18.80, Dec. +47 41 54.2), scoperta il 26 giugno 2012 nella galassia PGC61709 (offset 6E 8N), magnitudine 17.2, 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. 3162
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
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 2012dg = PSN J18181880+4741542
F. Ciabattari and E. Mazzoni, Borgo a Mozzano, Italy, report their
discovery of an apparent supernova (mag 17.2) on unfiltered CCD images
(limiting magnitude 19.5) obtained on June 26.93 and 27.87 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. = 18h18m18s.80, Decl. = +47d41'54".2
(equinox 2000.0; astrometry with respect to USNO-B1 stars) which is 6" east
and 8" north of the center of the presumed host galaxy. Nothing is visible
at this position on digitized plates of the Palomar Sky Survey from 1990
June 26 (J plate, limiting mag 20.3) and 1991 Aug. 7 (F plate, limiting mag
20.3), or in their images from 2011 Sept. (limiting magnitude 19.0). The
variable was designated PSN J18181880+4741542 when it was posted at the
Central Bureau's TOCP webpage and is here designated SN 2012dg based on the
spectroscopic confirmation reported below.
Additional CCD magnitudes for 2012dg: June 29.314 UT, 17.0 (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.80, 54".0; image posted at website URL
http://www.flickr.com/photos/43846774@N02/7470408806/); 30.963, 16.9 (Federica
Luppi and Luca Buzzi, Varese, Italy, 0.38-m f/6.8 reflector; position end
figures 18s.77, 54".1; reference stars from CMC-14 catalogue; image posted at
URL http://www.astrogeo.va.it/pub/TOCP/PSN_P61709.jpg); July 3.934, R_c = 16.7
(Massimiliano Martignoni, Magnago, Italy, 0.25-m f/10 Schmidt-Cassegrain
reflector; position end figures 18s.77, 53".8).
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 J18181880+4741542 = 2012dg
obtained on June 28.90 UT with the Asiago 1.82-m Copernico Telescope (+ AFOSC;
range 340-820 nm; resolution 2.4 nm), suggests that this is a normal type-Ia
supernova. Adopting for the host galaxy a redshift z = 0.037 (SDSS 2004, via
NED), a comparison with a library of supernovae spectra via GELATO (Harutyuyan
et al. 2008, A.Ap. 488, 383) shows that 2012dg is an event similar to the
type-Ia supernova 1994D (Patat et al. 1996, MNRAS 278, 111) at maximum light.
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 3162) Daniel W. E. Green