[IAUC] CBET 2898: 20111103 : SUPERNOVA 2011ho IN NGC 3847 = PSN J11441295+3330581

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                                                  Electronic Telegram No. 2898
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 2011ho IN NGC 3847 = PSN J11441295+3330581
     S. Howerton, Arkansas City, KS, U.S.A.; A. J. Drake, S. G. Djorgovski, A.
Mahabal, M. J. Graham, and R. Williams, California Institute of Technology; J.
L. Prieto, Princeton University; M. Catelan, Pontificia Universidad Catolica
de Chile; R. H. McNaught and G. Garradd, Australian National University; E. C.
Beshore and S. M. Larson, Lunar and Planetary Laboratory, University of
Arizona; and E. Christensen, Gemini Observatory, report the discovery of an
apparent supernova in public images from the Catalina Sky Survey (CSS).

 SN       2011 UT        R.A. (2000.0) Decl.      Mag.      Offset
 2011ho   Oct. 28.49   11 44 12.95  +33 30 58.1   18.7    12".8 W, 5".8 N

This variable was designated PSN J11441295+3330581 when it was posted on the
Central Bureau's TOCP webpage and is here designated SN 2011ho based on the
spectroscopic confirmation reported below.  Further unfiltered CCD magnitudes
for 2011ho:  June 11.21 UT, [19.0 (CSS); Oct. 30.495, 18.3 (Joseph Brimacombe,
Cairns, Australia; position end figures 13s.10, 59".2; image posted at website
URL http://www.flickr.com/photos/43846774@N02/6297040020/).

     R. J. Foley, Harvard-Smithsonian Center for Astrophysics; and D. Kasen
and A. V. Filippenko, University of California, Berkeley, report that a CCD
spectrum (range 310-1020 nm), obtained on Oct. 31 UT with the Keck I 10-m
telescope (+ LRIS), shows that PSN J11441295+3330581 = SN 2011ho is a type-Ia
supernova near maximum brightness.  The spectrum exhibits a large Si II
597.2-nm/635.5-nm ratio, indicating a cooler photosphere and a lower
luminosity.  The spectrum is similar to that of SN 1986G at -3 days (Phillips
et al. 1987, PASP 99, 592), but it also resembles spectra of the more typical
type-Ia supernovae 1992A and 2004eo at a similar epoch.  After removing the
recession velocity of 9520 km/s (obtained from the Sloan Digital Sky Survey),
the minimum of the Si II 635.5-nm feature is blueshifted by 11700 km/s.

     G. H. Marion, Harvard-Smithsonian Center for Astrophysics (CfA), on
behalf of the CfA Supernova Group, reports that a spectrum (range 340-740 nm)
of PSN J11441295+3330581 = 2011ho was obtained on Nov. 3 UT by P. Berlind with
the F. L. Whipple Observatory 1.5-m telescope (+ FAST).  Cross-correlation
with a library of supernova spectra using the "Supernova Identification" code
(SNID; Blondin and Tonry 2007, Ap.J. 666, 1024) shows that 2011ho is a
1991bg-like type-Ia supernova near maximum light.  Good fits can be found to
several templates of normal and 1991bg-like type-Ia supernovae within three
days of maximum.  The presence of a strong feature from Si II 597.2-nm and
the reported brightness of 2011ho are consistent with a subluminous, or
1991bg-like, type-Ia supernova.  Using an estimated redshift of z = 0.031829
for NGC 3847 as reported in NED (de Vaucouleurs et al. 1991, RC3.9C), the
velocity of the Si II 635.5-nm and 597.2-nm features are estimated to be
10700 km/s and 10500 km/s, respectively.


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

                         (C) Copyright 2011 CBAT
2011 November 3                  (CBET 2898)              Daniel W. E. Green