[IAUC] CBET 3946: 20140829 : SUPERNOVA 2014ch = PSN J15583110+1251596

[quai en eps.harvard.edu]

                                                  Electronic Telegram No. 3946
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 2014ch = PSN J15583110+1251596
     A. J. Drake, S. G. Djorgovski, M. J. Graham, A. Mahabal and R. Williams,
California Institute of Technology; J. L. Prieto, Princeton University; M.
Catelan, Pontificia Universidad Catolica de Chile; and S. M. Larson and E.
Christensen, Lunar and Planetary Laboratory, University of Arizona, report the
Catalina Real-time Transient Survey discovery of an apparent supernova in
unfiltered Catalina Sky Survey (CSS) images:

 SN       2014 UT       R.A. (2000.0) Decl.       Mag.      Offset
 2014ch   May 30.34   15 58 31.03  +12 51 58.6   17.4     0".9 E, 1".0 N

After receipt of Drake's report, an independent discovery of this object was
reported by T.-m. Zhang, National Astronomical Observatories of China (NAOC),
with W.-x. Li, J. Mo, and X.-f. Wang, Tsinghua University (THU), at mag 17.5
on unfiltered CCD images taken on May 29.23 UT using the 0.6-m NAOC Schmidt
telescope in the course of the THU-NAOC Transient Survey (TNTS), the position
of the new object given as R.A. = 15h58m31s.10, Decl. = +12d51'59".6 (equinox
2000.0), noted as 7".3 east and 3".4 north of the center of the assumed host
galaxy (SDSS J155830.61+125156.1).  Nothing is visible at this position on a
digitized image from the Palomar Sky Survey.  The TNTS images are posted at
URL http://www.thca.tsinghua.edu.cn/~wangxf/TNTS/PSNJ15583110+1251596.png.
The variable was designated PSN J15583110+1251596 when it was posted by Wang
at the Central Bureau's TOCP webpage and is here designated SN 2014ch based
on the spectroscopic confirmation reported below.  Additional CCD magnitudes
for 2014ch:  2014 Mar. 23, [20.0 (TNTS); May 22.35, [19.0 (CSS); 25.20, 19.1
(TNTS); 27.22, 18.3 (TNTS); June 2.379, 17.0 (J. Brimacombe, Cairns, Australia;
remotely using a 51-cm RCOS telescope at the New Mexico Skies observatory near
Mayhill, NM, U.S.A.; position end figures 31s.10, 58".8; images posted at URL
https://www.flickr.com/photos/43846774@N02/14253307260/); 5.832, 16.6 (G.
Masi; remotely using a 43-cm telescope at Ceccano, Italy; position end figures
31s.06, 59".1); 6.365, 16.7 (Brimacombe; position end figures 31s.11, 58".5);
15.185, 16.5 (Brimacombe; position end figures 31s.07, 58".5).  Masi adds that
several co-added low-resolution spectrograms (dispersion 3.45 nm/pixel) of
2014ch were obtained on June 5.94 using a 36-cm telescope (+ 100 lines/mm
grating) at Ceccano, showing the Si II absorption around 638 nm, suggesting
that the variable is a type-Ia supernova.

     D. D. Balam, Dominion Astrophysical Observatory, National Research
Council of Canada; M. L. Graham, Las Cumbres Observatory Global Telescope,
University of California at Santa Barbara; and E. Y. Hsiao, Las Campanas
Observatory, report that a spectrogram (range 369-700 nm, resolution 0.3 nm)
of PSN J15583110+1251596 = SN 2014ch, obtained on June 4.38 UT with the
1.82-m Plaskett Telescope of the National Research Council of Canada, shows it
to be a type-Ia supernova near maximum light.  Cross-correlation with a
library of supernova spectra using the "Supernova Identification" code
(Blondin and Tonry 2007, Ap.J. 666, 1024) indicates that 2014ch is most
similar to the peculiar type-Ia supernova 2003fg at 2 days post-maximum light.

     J.-j. Zhang, Yunnan Observatories (YNAO); and X.-f. Wang, Tsinghua
University, report on an optical spectrogram (range 340-870 nm) of PSN
J15583110+1251596 = SN 2014ch that was obtained on June 4.81 UT with the
2.4-m telescope (+ YFOSC) at the LiJiang Gaomeigu Station of YNAO.  The
spectrum shows that 2014ch is a type-Ia supernova a few days before maximum
light.  Cross-correlation with a library of supernova spectra using the
"Supernova Identification" code (SNID; Blondin and Tonry 2007, Ap.J. 666,
1024) shows that 2014ch matches with SN 2003kf at -7 days.  Adopting a
redshift of 0.044 for the host galaxy from the SNID fit, they measure a
velocity of the Si II 635.5-nm absorption feature to be about 12400 km/s.
The weak absorption feature at 629.0 nm is likely due to the C II 658-nm line.


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

                         (C) Copyright 2014 CBAT
2014 August 29                   (CBET 3946)              Daniel W. E. Green