[IAUC] CBET 4125: 20150729 : SUPERNOVA 2015O = PSN J18134923+1314159

[quai en eps.harvard.edu]

                                                  Electronic Telegram No. 4125
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 en eps.harvard.edu (alternate cbat en iau.org)
URL http://www.cbat.eps.harvard.edu/index.html
Prepared using the Tamkin Foundation Computer Network


SUPERNOVA 2015O = PSN J18134923+1314159
     Further to CBET 4049, T. W. Ross, W. Zheng, and A. V. Filippenko,
University of California at Berkeley, report the LOSS discovery of a possible
supernova in PGC 1426131 on unfiltered KAIT images:

 SN      2015 UT         R.A. (2000.0) Decl.      Mag.      Offset
 2015O   June 22.378   18 13 49.23  +13 14 15.9   18.3    5".0 E, 6".0 S

A finding chart is viewable via website URL http://tinyurl.com/nrdnsd2.  The
variable was designated PSN J18134923+1314159 when it was posted at the
Central Bureau's TOCP webpage and is here designated SN 2015O based on the
spectroscopic confirmation reported below.  Additional approximate unfiltered
CCD magnitudes for 2015O:  June 21 UT, [18.0 (KAIT); 22.865, 17.9 (G. Masi;
remotely using a 43-cm telescope at Ceccano, Italy; position end figures
49s.14, 16".6); 23.43, 18.3 (KAIT).

     G. Hosseinzadeh, I. Arcavi, S. Valenti, C. McCully, and D. A. Howell, Las
Cumbres Observatory Global Telescope Network and University of California at
Santa Barbara, report that a spectrogram of PSN J18134923+1314159 = SN 2015O,
obtained on June 27.54 UT with the FLOYDS robotic spectrograph (range 320-1000
nm, resolution 2 nm) mounted on the 2-m "Faulkes Telescope North" at Haleakala
Observatory in Hawaii, shows it to be a type-II supernova.  The spectrum
displays a blue continuum with broad H-alpha and H-beta emission at redshift
z = 0.056.  This redshift puts the supernova at an absolute V magnitude of
around -18.5, which is quite luminous for type-II events, especially if young,
as indicated by the blue continuum.

     W. Zheng, P. Kelly, M. Graham, I. Shivvers, and A. V. Filippenko,
University of California at Berkeley, report that a CCD spectrogram (range
350-1050 nm) was obtained of PSN J18134923+1314159 = SN 2015O on July 16.7 UT
with the 10-m Keck I telescope (+ LRIS spectrograph) at Keck Observatory.  The
spectrum shows a clear P-Cyg profile of H-alpha.  Cross-correlation with a
library of supernova spectra using the "SuperNova Identification" code (SNID;
Blondin and Tonry 2007, Ap.J. 666, 1024) indicates a similarity with a number
of type-IIP supernovae at about three weeks after explosion.  The redshift
derived from SNID is 0.056, consistent with the value derived from the narrow
H-alpha emission line.


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

                         (C) Copyright 2015 CBAT
2015 July 29                     (CBET 4125)              Daniel W. E. Green