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SN 2012eo in pgc 68367 - 27 agosto 2012

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SN 2012eo (A.R. 22 14 37.82, Dec. +32 57 18.7), scoperta il 27 agosto 2012 nella galassia pgc 68367 (offset 9W 2N), magnitudine 17.2, tipo Ia (ATEL 4370).

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

                                                  Electronic Telegram No. 3220

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 2012eo IN PGC 68367 = PSN J22143782+3257187
F. Ciabattari, E. Mazzoni, and R. Simonetti, Borgo a Mozzano, Italy,
report their discovery of an apparent supernova (mag 17.2) on unfiltered CCD
images (limiting mag 19) obtained on Aug. 27.99 and 29.04 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. = 22h14m37s.82, Decl. = +32d57'18".7
(equinox 2000.0; astrometry with respect to UCAC-2 stars), which is 9" west
and 2" north of the center of the galaxy PGC 68367. The variable was
designated PSN J22143782+3257187 when it was posted at the Central Bureau's
TOCP webpage and is here designated SN 2012eo based on the spectroscopic
confirmation reported below.  Additional magnitudes for 2012eo (via
unfiltered CCD unless noted otherwise):  1986 Sept. 30, [20.3 (Palomar Sky
Survey, F plate, via Digitized Sky Survey; reported by Ciabattari); 1989
Sept. 7, [20.3 (Palomar Sky Survey, J plate, via DSS; reported by Ciabattari);
2012 Aug. 7, [19.5 (Ciabattari); Aug. 15.60, [18.2 (D. Denisenko, V. Lipunov,
V. Yurkov, and E. Sinyakov; 0.40-m f/2.5 MASTER-Amur robotic reflector +
16-megapixel camera); Aug. 15.60, [19.8 (D. Denisenko, V. Lipunov, N. Budnev,
O. Gress, K. Ivanov, V. Poleshchuk, and S. Yazev; 0.40-m f/2.5 MASTER-Tunka
robotic reflector + 16-megapixel camera); Aug. 20.731, 17.0 (D. Denisenko,
V. Lipunov, V. Yurkov, and E. Sinyakov; pre-discovery; MASTER-Amur images
posted at http://master.sai.msu.ru/static/OT/PSNJ22143782+3257187-MASTER-Amur.jpg);
Aug. 23.67, 16.9 (D. Denisenko, V. Lipunov, N. Budnev, O. Gress, K. Ivanov,
V. Poleshchuk, and S. Yazev; MASTER-Tunka telescope; pre-discovery; the
MASTER-Tunka prediscovery and reference images are posted at website URL
Aug. 29.388, 16.7 (L. Elenin, Lyubertsy, Russia; and I. Molotov, Moscow;
remotely taken at with a 0.45-m f/2.8 telescope at the ISON-NM Observatory
near Mayhill, NM, USA; position end figures 37s.86 +/- 0".11, 18".1 +/- 0".12;
NOMAD reference stars; limiting mag about 19.9; image posted at website URL
http://spaceobs.org/images/TOCP/PSNJ22143782+3257187-20120829.png); Aug.
30.319, R = 17.2 +/- 0.2 (Joseph Brimacombe, Cairns, Australia; remotely
using a 51-cm RCOS telescope + STL11K camera + red filter at the New Mexico
Skies Observatory near Mayhill; position end figures 37s.83, 18".7; image
posted at website URL http://www.flickr.com/photos/43846774@N02/7897019644/);
Aug. 30.942, 16.6 (D. Grennan, Dublin, Ireland; 0.35-m Schmidt Cassegrain
reflector; position end figures 37s.83 +/- 0".33, 18".6 +/- 0".25;
image posted at website URL http://www.webtreatz.com/images/J22143782+3257187.jpg);
Sept. 7.084, 18.2 (Federica Luppi and Luca Buzzi, Varese, Italy; 0.38-m f/6.8
reflector; position end figures 37s.80, 18".4; reference stars from CMC-14
catalogue; image posted at http://www.astrogeo.va.it/pub/TOCP/PSN_P68367.jpg);
Sept. 10.908, R_c = 18.1 (Massimiliano Martignoni, Magnago, Italy; 0.25-m
f/10 Schmidt-Cassegrain reflector; position end figures 37s.75, 17".9).

S. Benetti, L. Tomasella, E. Cappellaro, A. Pastorello, M. Turatto, and
S. Valenti, Osservatorio Astronomico di Padova, Istituto Nazionale di
Astrofisica, report that a spectrogram of PSN J22143782+3257187 = 2012eo,
obtained on Sept. 10.89 UT with the 1.82-m Copernico telescope (+ Afosc
spectrograph; range 350-820 nm, resolution 1.3 nm), suggests that 2012eo is
a type-Ia supernova.  Adopting for the host galaxy (PGC 68367) a redshift z =
0.028546 (Huchra et al. 2012, Ap.J. Suppl. 199, 26; via NED), comparison
with a library of supernova spectra via GELATO (Harutyuyan et al. 2008, A.Ap.
488, 383) shows that 2012eo is a type-Ia event similar to several type-Ia
supernovae at two weeks after maximum light.  The expansion velocity,
measured from the Si II 635.5-nm minimum, is about 13100 km/s, which places it among
the high-velocity gradient type-Ia supernovae (Benetti et al. 2005, Ap.J. 623,
1011).  The spectrum also shows an intense Na I D interstellar absorption
(EW about 0.31 nm).

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

(C) Copyright 2012 CBAT
2012 September 13                (CBET 3220)              Daniel W. E. Green