[IAUC] CBET 4194: 20151121 : SUPERNOVA 2015as IN UGC 5460 = PSN J10081137+5150409

Vie Nov 20 21:18:10 ART 2015

                                                  Electronic Telegram No. 4194
Central Bureau for Astronomical Telegrams
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SUPERNOVA 2015as IN UGC 5460 = PSN J10081137+5150409
     Ken'ichi Nishimura, Ebetsu, Hokkaido, Japan, reports the discovery of
an apparent supernova (mag 16.0) on three unfiltered 15-s CCD exposures taken
on Nov. 15.778 UT with a 0.35-m reflector.  The new object is located at R.A.
= 10h08m11s.37, Decl. = +51d50'40".9 (equinox J2000.0); due to the diffuse
nature of the host galaxy's center (UGC 5460), Nishimura could not measure
the offset easily.  The discovery image was posted by Nishimura at website
URL http://yubeotsu.web.fc2.com/u5460.jpg.  The type-IIn supernova 2011ht
also appeared in UGC 5460 (cf. CBET 2851).  The variable was designated PSN
J10081137+5150409 when it was posted at the Central Bureau's TOCP webpage and
is here designated SN 2015as based on the spectroscopic confirmation reported
below.  Additional approximate CCD magnitudes (unfiltered unless otherewise
noted) for 2015as:  2012 Nov. 10.772, [17.5 (Nishimura); 2015 Nov. 16.205, V
= 15.5 (S. Kiyota, Kamagaya, Japan; remotely with an iTelescope 0.32-m f/8.0
CDK astrograph at Nerpio, Spain; position end figures 11s.57, 40".8; image
posted at URL http://meineko.sakura.ne.jp/ccd/PSN_J10081137+5150409.jpg);
16.715, 15.3 (Kunihiro Shima, Fujimi-machi, Nagano, Japan; 45-cm f/4.6
reflector + FLI ML-8300 camera; position end figures 11s.53, 40".2).

     L. Tartaglia, A. Pastorello, S. Benetti, E. Cappellaro, N. Elias-Rosa, P.
Ochner, G. Terreran, L. Tomasella, and M. Turatto, Osservatorio Astronomico
di Padova, Istituto Nazionale di Astrofisica, report that an optical
spectrogram (range 340-820 nm; resolution 1.4 nm) of PSN J10081137+5150409 =
SN 2015as, obtained on Nov. 17.17 UT with the Asiago 182-cm Copernico
Telescope (+ AFOSC) in the framework of the Asiago Transient Classification
Program (Tomasella et al. 2014, A.N. 335, 841), shows that this a type-II
supernova, a couple of weeks after explosion.  The expansion velocity, as
deduced from the position of the minimum of H-alpha, is about 9700 km/s.  The
spectrum, along with Balmer lines, show strong Ca II H and K, Fe II, and the
relatively weak He I 587.6-nm feature.  The authors note that 2015as was also
detected with AFOSC about one week before the discovery by Nishimura, in the
course of routine imaging observations of UGC 5460:  on Nov. 9.175 UT, they
estimate AB magnitude r = 17.59 +/- 0.02 for PSN J10081137+5150409 = 2015as.
Classifications were done with GELATO (Harutyunyan et al. 2008, A.Ap. 488,
383) and SNID (Blondin and Tonry 2007, Ap.J. 666, 1024).  The Asiago
classification spectra are posted at website URL http://sngroup.oapd.inaf.it.


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

                         (C) Copyright 2015 CBAT
2015 November 21                 (CBET 4194)              Daniel W. E. Green