[IAUC] CBET 2826: 20110925 : SUPERNOVA 2011ft NEAR UGC 11021 = PSN J17524298+2904106

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                                                  Electronic Telegram No. 2826
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 2011ft NEAR UGC 11021 = PSN J17524298+2904106
     Pavel Balanutsa and Vladimir Lipunov report that the MASTER-Net auto-
detection system at Tunka (http://observ.pereplet.ru) detected an apparent
supernova (mag 17.1) on a 180-s unfiltered CCD exposure (limiting mag 19.4)
taken on Aug. 30.70 UT.  The new object is located at R.A. = 17h52m42s.98,
Decl. = +29d04'10".6, (equinox 2000.0; uncertainty 0".2), which is 46" east
and 38" north of the galaxy UGC 11021.  Nothing is visible at this position
on a MASTER/Tunka reference image from June 22.75 (limiting mag 19.0).  The
variable was designated PSN J17524298+2904106 when posted at the Central
Bureau's TOCP webpage and is here designated SN 2011ft based on the
spectroscopic report below.  The discovery image is available at website
URL http://observ.pereplet.ru/images/SN110830/MASTER110830.png.

     J. L. Prieto, Princeton University, reports that a low-resolution optical
spectrogram (range 370-920 nm; resolution 0.7 nm) of PSN J17524298+2904106 =
SN 2011ft was obtained on Aug. 30.98 UT with the du Pont 2.5-m telescope (+
WFCCD) at Las Campanas Observatory in Chile.  The spectrum shows broad He I
absorption features consistent with a type-Ib supernova.  Cross-correlation
with a library of supernova spectra using SNID (Blondin and Tonry 2007, Ap.J.
666, 1024) shows that the spectrum is most similar to that of normal type-Ib
supernovae at approximately 2-3 weeks after maximum light.  The redshift
derived from the supernova features is consistent within the uncertainties
with the redshift of UGC 11021 (z = 0.0173; Springob et al. 2005, Ap.J.
Suppl. 160, 149).  It is interesting to note that the supernova is 60" from
the center of its host galaxy, which implies a projected separation of about
22 kpc, assuming a distance of 75 Mpc to UGC 11021 (via NED, from the
Virgo-infall recession velocity and h = 0.73).  Furthermore, the spiral host
galaxy (class type Sb in the RC3 catalogue) is seen almost edge-on, and the
supernova lies well outside a linear extrapolation of the optical disk, at a
projected distance from the disk of about 7 kpc.  This location implies that
the supernova either exploded in the halo of UGC11021 or in a low-luminosity
dwarf-galaxy companion.  All these properties resemble the Ca-rich type-Ib
supernova 2005E (Perets et al. 2010, Nature 465, 322), although 2011ft was
two magnitudes brighter (absolute mag approximately -17) at discovery.


NOTE: These 'Central Bureau Electronic Telegrams' are sometimes
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                         (C) Copyright 2011 CBAT
2011 September 25                (CBET 2826)              Daniel W. E. Green