[IAUC] CBET 4124: 20150728 : SUPERNOVA 2015N IN UGC 11797 = PSN J21431689+4334476

[quai en eps.harvard.edu]

                                                  Electronic Telegram No. 4124
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 2015N IN UGC 11797 = PSN J21431689+4334476
     Further to CBET 4049, S. Stegman, W. Zheng, and A. V. Filippenko,
University of California at Berkeley, report the LOSS discovery of a supernova
in UGC 11797 on unfiltered KAIT images:

 SN       2015 UT        R.A. (2000.0) Decl.      Mag.      Offset
 2015N   July 6.425   21 43 16.89  +43 34 47.6   17.6    36".2 W, 12".9 N

A finding chart was posted via website URL http://tinyurl.com/oxpppeg.  The
variable was designated PSN J21431689+4334476 when it was posted at the
Central Bureau's TOCP webpage and is here designated SN 2015N based on the
spectroscopic confirmation reported below.  Additional approximate magnitudes
for 2015N:  July 4, [18.0 (KAIT); 5.42 UT, 18.3 (KAIT; marginal detection);
7.683, 18.2 (J. Brimacombe, Cairns, Australia; remotely with a 33-cm
telescope at the Savannah Skies Observatory at Chillagoe, Queensland,
Australia; position end figures 16s.91, 47".5; image posted via website URL
http://tinyurl.com/nn62qhx); 7.900, 17.6 (G. Masi and P. Catalano; remotely
using a 43-cm telescope at Ceccano, Italy; position end figures 16s.89,
47".5); 8.722, 17.6 (Brimacombe; position end figures 16s.90, 47".1); 9.655,
17.4 (Brimacombe; position end figures 16s.92, 47".4).

     G. Hosseinzadeh, C. McCully, S. Valenti, I. Arcavi, and D. A. Howell, Las
Cumbres Observatory Global Telescope Network and University of California,
Santa Barbara, report that a spectrogram of PSN J21431689+4334476 = SN
2015N, obtained on July 7.4 UT with the FLOYDS robotic spectrograph (range
320-1000 nm, resolution 2 nm) mounted on the 2-m "Faulkes Telescope North" at
Haleakala Observatory, Hawaii, shows it to be a type-Ia supernova.  Using SNID
(Blondin and Tonry 2007, Ap.J. 666, 1024), they find a good fit to the type-Ia
supernova 2002bo at thirteen days before maximum light at a redshift
consistent with that of the proposed host galaxy (z = 0.019; Seeberger et al.
1994, A.Ap. 286, 17; via NED).  The Si II 635.5-nm and Ca II infrared features
are very broad, corresponding to expansion velocities in excess of 20000 km/s.
The continuum is also quite red, which is consistent with the measured
foreground reddening of E(B-V) = 0.5 mag (Schlafly and Finkbeiner 2011, Ap.J.
737, 103; via NED).

     W. Zheng, P. Kelly, M. Graham, I. Shivvers, and V. Filippenko, University
of California at Berkeley, report that a CCD spectrogram (range 350-1050 nm)
was obtained on July 16.7 UT with the 10-m Keck I telescope (+ LRIS
spectrograph) at Keck Observatory.  The spectrum shows that 2015N is a
type-Ia supernova before maximum.  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 several normal
type-Ia supernovae around maximum light.  Adopting a redshift z = 0.019 for
the host galaxy, UGC 11797, the rest-frame photospheric velocity estimated
from the minimum  of the Si II 635.5-nm feature, is about 14400 km/s.


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

                         (C) Copyright 2015 CBAT
2015 July 28                     (CBET 4124)              Daniel W. E. Green