[IAUC] CBET 4169: 20151115 : SUPERNOVA 2015X IN UGC 3777 = PSN J07164258+2951227

Dom Nov 15 01:30:53 ART 2015

                                                  Electronic Telegram No. 4169
Central Bureau for Astronomical Telegrams
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SUPERNOVA 2015X IN UGC 3777 = PSN J07164258+2951227
     Further to CBET 4049, A. Hughes, W. Zheng, and A. V. Filippenko,
University of California at Berkeley, report the LOSS discovery of a supernova
in UGC 3777 on unfiltered KAIT images:

 SN       2015 UT        R.A. (2000.0) Decl.      Mag.      Offset
 2015X    Feb. 23.216   7 16 42.58  +29 51 22.7   17.2    3".6 W, 5".1 S

A finding chart was posted by the discoverers at the following website URL:
http://astro.berkeley.edu/~zwk/findingchart/PSN_J07164258+29512272.jpg.  The
variable was designated PSN J07164258+2951227 when it was posted at the
Central Bureau's TOCP webpage and is here designated SN 2015X based on the
spectroscopic confirmation reported below.  Additional approximate CCD
magnitudes for 2015X:  Feb. 19 UT, [18.5 (KAIT); 24.18, 17.0 (KAIT); 23.787,
16.5 (G. Masi; remotely using a 43-cm telescope at Ceccano, Italy; position
end figures 42s.64, 23".0); 24.808, 17.4 (N. James, Chelmsford, Essex,
England; position end figures 42s.60, 23".2; UCAC-4 reference stars; image
viewable via website URL http://tinyurl.com/q9adjdv); Mar. 11.87, V = 16.8
(M. Martignoni, Magnago, Italy; 25-cm f/10 Schmidt-Cassegrain reflector;
position end figures 42s.61, 23".2).

     L. Tomasella, S. Benetti, E. Cappellaro, N. Elias-Rosa, P. Ochner, A.
Pastorello, L. Tartaglia, G. Terreran, and M. Turatto, Osservatorio
Astronomico di Padova, INAF, report that an optical spectrogram (range 340-820
nm; resolution 1.2 nm) of PSN J07164258+2951227 = SN 2015X, obtained on Mar.
9.84 UT with the Asiago 182-cm Copernico Telescope (+ AFOSC) in the framework
of the Asiago Transient Classification Program (Tomasella et al. 2014, AN 335,
841), shows that this a young type-II supernova.  A good match is found with
early spectra of the type-II supernovae 1999gi (Leonard et al. 2002, A.J. 124,
2490) and 1999em (Elmhamdi et al. 2003, MNRAS 338, 939), if a redshift of
0.01072 is assumed for the host galaxy, UGC 3777 (de Vaucouleurs et al. 1991,
RC3.9; via NED).  Classification was done with GELATO (Harutyunyan et al.
2008, A.Ap. 488, 383) and SNID (Blondin and Tonry 2007, ApJ, 666, 1024).  The
Asiago classification spectra are posted at URL http://sngroup.oapd.inaf.it.

     W. Zheng, P. Kelly, K. Clubb, and V. Filippenko, University of
California, Berkeley, report that a CCD spectrogram (range 350-1000 nm) of
PSN J07164258+2951227 = SN 2015X was obtained on Mar. 18.214 UT with the
Shane 3-m reflector (+ Kast spectrograph) at Lick Observatory.  The spectrum
shows that 2015X is a type-II supernova.  Using the redshift (z = 0.010) of
the host galaxy, UGC 3777, cross-correlation with a library of supernova
spectra using the "SuperNova Identification" code (SNID; Blondin and Tonry
2007, Ap.J. 666, 1024) indicates a best match with SN 2004et about one week
after maximum brightness.

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

                         (C) Copyright 2015 CBAT
2015 November 15                 (CBET 4169)              Daniel W. E. Green