SN 2014ac in NGC 5837 - 2014 03 09

Stampa

SN 2014ac (A.R., 15 04 40.09 Dec. +12 37 54.0), scoperta il 9 marzo 2013 nella galassia ngc 5837 (offset 8W 10S), magnitudine 16.6, tipo: Ia (ATEL 5970)

PSN individuata da  S. Leonini, G. Guerrini, P. Rosi, L.M. Tinjaca Ramirez and M. Conti con il telescopio Newton da 53cm dell'Osservatorio di Montarrenti (Siena).

Electronic Telegram No. 3830
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 2014ac IN NGC 5837 = PSN J15044009+1237540
     Simone Leonini, Siena, Italy, reports the discovery of an apparent
supernova (mag about 16.6) by G. Guerrini, M. Conti, P. Rosi, L. M. Tinjaca
Ramirez, and himself on two unfiltered CCD images (limiting mag about 19.0)
taken on Mar. 9.993 UT at the Montarrenti Observatory in the course of an
automatic survey of the Italian Supernovae Search Project using a 0.53-m 
f/8.7
Ritchey-Chretien telescope (+ Apogee Alta U47 CCD camera).  The new object 
is
located at R.A. = 15h04m40s.09 +/- 0s.23, Decl. = +12d37'54".0 +/- 0".2
(equinox 2000.0), which is 8" west and 10" south of the nucleus of the 
galaxy
NGC 5837.  No stellar source is visible at this position on Palomar Sky 
Survey
infrared, red, and blue plates (1997 July 8, F plate; 1991 May 15, J plate;
and 1991 May 15, N plate; limiting mag 19.5).  The discovery image is posted
at URL http://www.astrofilisenesi.it/public/Sne/Uploads/PSN_NGC5837.jpg. 
The
variable was designated PSN J15044009+1237540 when it was posted at the
Central Bureau's TOCP webpage and is here designated SN 2014ac based on the
spectroscopic confirmation reported below.  Additional CCD magnitudes for
2014ac:  2014 Feb. 24, [18.7 (Leonini et al.); Mar. 3, [17.0 (Leonini et 
al.);
Mar. 13.008, 16.7 (Gianluca Masi, Francesca Nocentini, and Patrick Schmeer;
remotely using a 43-cm f/6.8 corrected Dall-Kirkham robotic telescope near
Ceccano, Italy; position end figures 40s.08, 54".0); 13.028, V = 17.3 (M.
Martignoni, Magnago, Italy; 0.25-m f/10 Schmidt-Cassegrain reflector; 
position
end figures 40s.09, 54".3); 13.069, 17.7 (Federica Luppi and Luca Buzzi,
Varese, Italy; 0.60-m f/4.6 reflector; position end figures 40s.08, 54".2;
image posted at website URL 
http://www.astrogeo.va.it/pub/TOCP/PSN_N5837.jpg).

     L. Tomasella, S. Benetti, E. Cappellaro, A. Pastorello, P. Ochner, N.
Elias-Rosa, and M. Turatto, Osservatorio Astronomico di Padova, Istituto
Nazionale di Astrofisica; and S. Ciroi, Dipartimento di Fisica e Astronomia,
Universita' di Padova, report that a noisy optical spectrogram (range 
340-820
nm; resolution 1.3 nm) of PSN J15044009+1237540 = SN 2014ac, obtained on 
Mar.
10.98 UT with the Asiago 1.82-m Copernico Telescope (+ AFOSC), shows it to 
be
a type-Ia supernova.  Adopting for the host galaxy, NGC 5837, a redshift z 0.0287
(Fisher et al. 1995, Ap.J. Suppl. 100, 69; via NED), a good match is
found with several type-Ia supernovae at a few days after maximum.  The
expansion velocity deduced from the Si II 635.5-nm absorption is about 10500
km/s.  The Asiago classification spectra are posted at website URL
http://sngroup.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).

     N. Walton, M. Fraser, N. Blagorodnova, Institute of Astronomy; S.
Taubenberger, Max-Planck-Institut fuer Astrophysik, Garching; M. Dennefeld,
Institut Astrophysique de Paris; S. Benetti and A. Pastorello, Osservatorio
Astronomico di Padova, Istituto Nazionale di Astrofisica (INAF); C. Inserra,
S. Smartt, K. Smith, and D. Young, Queen's University, Belfast; M. Sullivan,
University of Southampton; S. Valenti, Las Cumbres Observatory Global
Telescope; O. Yaron and A. Gal-Yam, Weizmann Institute for Science; C. 
Knapic,
R. Smareglia, and M. Molinaro, Trieste Astronomical Observatory, INAF; and 
I.
Manulis, Weizmann Institute for Science, on behalf of the Public European
Southern Observatory (ESO) Spectroscopic Survey for Transient Objects 
(PESSTO;
see website URL http://www.pessto.org), report that a spectrogram was taken 
of
PSN J15044009+1237540 = SN 2014ac on the ESO's New Technology Telescope at 
La
Silla on Mar. 10, using EFOSC2 and Grism 13 (398.5-931.5 nm; 1.8-nm
resolution).  Cross-correlation of the spectrum with a library of template
spectra using SNID (Blondin and Tonry 2007, Ap.J. 666, 1024) gives a best
match to several normal type-Ia supernovae at the redshift of NGC 5837 (z 0.029) and
around maximum light.


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

                         (C) Copyright 2014 CBAT
2014 March 19                    (CBET 3830)              Daniel W. E. Green