Electronic Telegram No. 4197
Central Bureau for Astronomical Telegrams
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Prepared using the Tamkin Foundation Computer Network


SUPERNOVA 2015at IN IC 900 = PSN J13344316+0920194
     G. Bock, Runaway Bay, Queensland, Australia, reports his discovery of an
apparent supernova (red mag 16.6) on a 30-s unfiltered CCD image (limiting mag
17.5) taken by S. Parker (Canterbury, New Zealand) on July 11.34 UT with a
30-cm Astro-Tech AT12RC Ritchey-Chretien astrograph (+ ST10 camera) at the
Parkdale Observatory in the course of the Backyard Observatory Supernova
Search.  The new object is located at R.A. = 13h34m43s.16, Decl. = +9d20'19".4
(equinox J2000.0; reference stars from USNO-B and UCAC4 catalogues), which is
2".2 east and 5".8 north of the nucleus of the galaxy IC 900.  Nothing is
visible at this position on Digitized Sky Survey red and infrared images
(limiting red magnitude > 19).  The variable was designated PSN
J13344316+0920194 when it was posted at the Central Bureau's TOCP webpage
and is here designated SN 2015at based on the spectroscopic confirmation
reported below.  G. Masi and P. Catalano remotely obtained unfiltered CCD
iamges of 2015at using a 43-cm telescope at Ceccano, Italy, on Aug. 19.81,
showing the variable at red mag 16.8 with position end figurse 43s.10, 19".1.

     N. Morrell, C. Contreras, M. Phillips, Las Campanas Observatory; G.
Bock, Runaway Bay, Queensland; and M. Stritzinger and C. Gall, Aarhus
University, report -- on behalf of the Carnegie Supernova Project -- on an
optical spectrogram (range 370-920 nm) of PSN J13344316+0920194 = SN 2015at
that was obtained on July 20.0 UT with the Las Campanas 2.5-m du Pont
telescope (+ WFCCD).  The data suggest that 2015at was then a young type-II
supernova soon after explosion.  The spectrum is dominated by a blue, almost-
featureless continuum, with a weak bump consistent with H-alpha.  Prevalent
interstellar absorption features of Na I (equivalent width 0.37 nm) and Ca
II H and K (E.W. 0.19-nm and 0.17-nm, respectively) are also evident, as
well as narrow emission lines associated with a surrounding H II region.
Both the interstellar absorption and narrow emission lines provide a redshift
that is consistent with the value listed in NED for IC 900 (7069 km/s, after
Kent et al. 2008, A.J. 136, 713).


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      superseded by text appearing later in the printed IAU Circulars.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 4197)              Daniel W. E. Green