Electronic Telegram No. 4130
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.
e-mail:  cbatiau@eps.harvard.edu (alternate cbat@iau.org)
URL http://www.cbat.eps.harvard.edu/index.html
Prepared using the Tamkin Foundation Computer Network


SUPERNOVA 2015S IN PGC 1923 = PSN J00312606-4935336
     G. Bock reports the discovery by P. Marples, Loganholme, Queensland,
Australia, of an apparent supernova (red mag 17.1 ) on a 30-s unfiltered CCD
image (limiting mag 17.5) taken by S. Parker (Canterbury, New Zealand) on
July 22.61 UT with a 30-cm Astro-Tech AT12RC Ritchey-Chretien astrograph (+
ST10 camera) at Parker's Parkdale Observatory in the course of the Backyard
Observatory Supernova Search.  The new object is located at R.A. =
0h31m26s.07, Decl. = -49d35'34".6 (equinox 2000.0; reference stars from
USNO-B and UCAC4 catalogues), which is 8".1 east and 10".3 south of the
nucleus of the galaxy PGC 1923 = ESO 194-G24.  Nothing is visible at this
position on Digitized Sky Survey red and infrared images (limiting red
magnitude > 19).  The variable was designated PSN J00312606-4935336 when it
was posted at the Central Bureau's TOCP webpage and is here designated SN
2015S based on the spectroscopic confirmation reported below.  J.
Brimacombe, Cairns, Australia, obtained images of 2015S with a 43-cm
telescope at the Savannah Skies Observatory at Chillagoe, Qld., on July 25.74
that yield mag 17.1 and position end figures 26s.06, 33".7; his images are
posted at website URL https://www.flickr.com/photos/43846774@N02/20020499871/.

     M. Childress, B. Tucker, R. Scalzo, F. Yuan, B. Zhang, A. Ruiter, I.
Seitenzahl, and B. Schmidt, Australian National University (ANU), report n
spectroscopy of PSN J00312606-4935336 = SN 2015S with the Wide Field
Spectrograph (cf. Dopita et al. 2007, Ap. Space Sci. 310, 255) on the ANU
2.3-m telescope at Siding Spring using the B3000/R3000 gratings (wavelength
range 350-980 nm at 0.1-nm resolution).  A 40-minute spectrogram taken on
July 31.60 UT revealed hydrogen Balmer lines in P-Cyg, espeically H-alpha.
The supernova's continuum is relatively blue, indicating a young age.  Using
the code SNID (Blondin and Tonry 2007, Ap.J. 666, 1024), they find good
matches to type-IIP supernovae near peak brightness, with the best match
being to SN 2004et at phase +2 days and a redshift of z = 0.020.  This is
consistent with the redshift of the apparent host galaxy, PGC 1923, which has
redshift z = 0.0219 (Jones et al. 2009, 6dF Galaxy Survey).


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

                         (C) Copyright 2015 CBAT
2015 August 4                    (CBET 4130)              Daniel W. E. Green