Electronic Telegram No. 4198
Central Bureau for Astronomical Telegrams
Mailing address:  Hoffman Lab 209; Harvard University;
 20 Oxford St.; Cambridge, MA  02138; U.S.A.
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Prepared using the Tamkin Foundation Computer Network


SUPERNOVA 2015au IN NGC 7300 = PSN J22305942-1359561
     G. Bock, Runaway Bay, Queensland, Australia, reports his discovery of an
apparent supernova (red mag 17.7) on a 30-s unfiltered CCD image (limiting
mag 17.5) taken by himself on Nov. 10.49 UT with a 35-cm Meade LX200R f/7
reflector (+ ST10 camera) at his Runaway Bay Observatory in the course of the
Backyard Observatory Supernova Search.  The new object is located at R.A. =
22h30m59s.42, Decl. = -13d59'56".1 (equinox J2000.0; reference stars from
USNO-B and UCAC4 catalogues), which is 7" west and 18" north of the nucleus of
the galaxy NGC 7300.  Nothing is visible at this position on Digitized Sky
Survey red and infrared images (limiting red magnitude > 19).  The variable
was designated PSN J22305942-1359561 when it was posted at the Central
Bureau's TOCP webpage and is here designated SN 2015au based on the
spectroscopic confirmation reported below.  The type-Ia supernova 1996ca also
appeared in NGC 7300 (cf. IAUC 6523).

     S. Mattila, University of Turku; J. Harmanen, Turku and Nordic Optical
Telescope; M. Dennefeld, Institut d'Astrophysique de Paris and University
Pierre et Marie Curie; T. Kangas, University of Turku; T-.W. Chen, Max Planck
Institut fuer Extraterrestriche Physik; R. Cartier, University of Southampton;
C. Inserra, Queen's University of Belfast (QUB); M. Fraser, Institute of
Astronomy, Cambridge; A. Gal-Yam, Weizmann Institute of Science; E. Kankare,
K. Maguire, S. J. Smartt, and K. W. Smith, QUB; M. Sullivan, University of
Southampton; S. Valenti, University of California, Davis; O. Yaron, Weizmann
Institute of Science; D. Young, QUB; and I. Manulis, Weizmann Institute of
Science, report -- on behalf of the PESSTO collaboration (cf. website URL
http://www.pessto.org) -- that an optical spectrogram (range 399-932 nm) of
PSN J22305942-1359561 = SN 2015au, obtained on Nov. 19.01 UT at the 3.6-m New
Technology Telescope (+ EFOSC2) at La Silla Observatory, shows it to be a
type-IIb supernova.  Adopting a recession velocity of 4876 km/s for the host
galaxy, NGC 7300 (Mathewson et al. 1992, Ap.J. Suppl. 81, 413; via NED), the
best fit to the 2015au spectrum found by GELATO (Harutyunyan et al. 2008,
A.Ap. 488,383; publicly available at website URL https://gelato.tng.iac.es)
is with the spectrum of the type-IIb supernova 2000H roughly a week after
maximum light.


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

                         (C) Copyright 2015 CBAT
2015 November 23                 (CBET 4198)              Daniel W. E. Green