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SN 2013em in PGC214897 - 27 luglio 2013

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SN 2013em (A.R., 23 02 26.62 Dec. +32 31 31.2), scoperta il 27 luglio 2013 nella galassia pgc 214897 (offset 8W 6S), magnitudine 15.7, tipo: Ia (spettro Asiago odb.)

PSN individuata da Ciabattari, Mazzoni e Petroni con il telescopio Newton da 50cm dell'Osservatorio di Monte Agliale (Lucca).

Electronic Telegram No. 3612
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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URL http://www.cbat.eps.harvard.edu/index.html
Prepared using the Tamkin Foundation Computer Network

SUPERNOVA 2013em = PSN J23022662+3231312
F. Ciabattari, E. Mazzoni, and G. Petroni, Borgo a Mozzano, Italy, report
their discovery of an apparent supernova (mag 16.7) on unfiltered CCD images
(limiting magnitude 20.1) obtained on July 27.04 and 30.93 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. = 23h02m26s.62, Decl. = +32d31'31".2
(equinox 2000.0; astrometry with respect to UCAC-2 stars), which is 8" west
and 6" south of the center of the galaxy PGC 214897. Nothing is visible at
this position on digitized plates of the Palomar Sky Survey from 1989 July 
(F plate; limiting magnitude 20.3) and 1986 Nov. 3 (J plate; limiting mag
20.3). The variable was designated PSN J23022662+3231312 when it was posted
at the Central Bureau's TOCP webpage and is here designated SN 2013em based 
the spectroscopic confirmation reported below. Additional CCD magnitudes for
2013em: 2013 July 9, 19.5 (Ciabattari); 31.094, 16.5 (Federica Luppi and 
Buzzi, Varese, Italy; 0.36-m f/7.1 reflector; position end figures 26s.61,
31".1; reference stars from CMC-14 catalogue; image posted at website URL
http://www.astrogeo.va.it/pub/TOCP/PSN_P214897.jpg); 31.364, 15.7 (L. 
Lyubertsy, Russia, and I. Molotov, Moscow, Russia; remotely taken with a
0.45-m f/2.8 telescope located at the ISON-NM Observatory near Mayhill, NM,
USA; position end figures 26s.69 +/- 0".1, 31".5 +/- 0".1; UCAC-4
stars; limiting magnitude about 20.0; image posted at website URL

P. Ochner, L. Tomasella, S. Benetti, E. Cappellaro, A. Pastorello, and M.
Turatto, Osservatorio Astronomico di Padova, Istituto Nazionale di 
report that an optical spectrogram (range 340-790 nm; resolution 0.9 nm),
obtained on July 31.03 UT with the Asiago 1.22-m Galileo Telescope (+ Boller 
Chivens spectrograph) shows that PSN J23022662+3231312 = SN 2013em is a 
type-Ia supernova. Assuming a recessional velocity of 6597 km/s (z = 
for the host galaxy, PGC 214897 (Huchra et al. 2012, Ap.J. Suppl. 199, 26; 
NED), an expansion velocity of about 10700 km/s is derived from the minimum 
the Si II 635-nm line. The best match is found with several type-Ia
supernovae -- and, in particular, with SN 2005am at a couple of days after
maximum (Brown et al. 2005, Ap.J. 635, 1192). The Asiago classification
spectra are posted at website URL http://graspa.oapd.inaf.it. Classification
was made via GELATO (Harutyunyan et al. 2008, A.Ap. 488, 383) and SNID
(Blondin and Tonry 2007, Ap.J. 666, 1024).

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

(C) Copyright 2013 CBAT
2013 August 2 (CBET 3612) Daniel W. E. Green