[IAUC] CBET 1780: 20090426 : SUPERNOVA 2008iy

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                                                  Electronic Telegram No. 1780
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
M.S. 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
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SUPERNOVA 2008iy
     M. Catelan, Pontificia Universidad Catolica de Chile; A. J. Drake,
S. G. Djorgovski, A. Mahabal, R. Williams, and M. J. Graham, California
Institute of Technology; E. C. Beshore and S. M. Larson, Lunar and
Planetary Laboratory, University of Arizona; and E. Christensen, Gemini
Observatory, report the CRTS (cf. CBET 1766) discovery of a supernova in
unfiltered Catalina Sky Survey (CSS) images:

    SN       2008 UT        R.A. (2000.0) Decl.      Mag.
    2008iy   Sep. 28.12   16 08 37.23  + 4 16 26.7   17.8

The CSS light curve, containing 184 observations between 2005 Apr. 4 and
2009 Apr. 16, shows the explosion occurred between 2007 June 18 and 2007
Oct. 13.  The rising part of the light curve is seen to last approximately
a year.  Additional follow-up was obtained with the Palomar 1.52-m reflector
with Gunn filters, yielding the following magnitudes:  2008 Oct. 29.12, g =
18.3, r = 17.2, i = 17.8, z = 17.2; 2009 Mar. 17.33, 18.5, 17.6, 18.2, 17.6;
Apr. 18.24, 18.7; 17.8; 18.3; 17.8.
     Confirming spectra (range 380-900 nm) were obtained using the SMARTS
1.5-m telescope on 2009 Mar. 27 and Apr. 20 UT and reveal Balmer lines
(strong H-alpha, H-beta, H-gamma) and He I lines (587.6, 706.5 nm).  H-beta
exhibits a P-Cyg-like profile.  No significant evolution is seen between the
two spectra.  The spectra closely resemble those of the slowly evolving
type-IIn supernova 2007rt at 500 days past explosion (Trundle et al. 2009,
http://lanl.arxiv.org/abs/0904.0119).  Based on the redshift (z = 0.041) and
the Palomar photometry, the peak absolute Gunn r magnitude was about -18.8.
     Archival GALEX data from 2008 June 5 show a well-detected source at
this location in Medium Imaging Survey (MIS) far-ultraviolet (FUV; 135-175 nm)
and near-ultraviolet (NUV; 175-300 nm) images, at the following magnitudes:
[NUV] = 19.93 +/- 0.04; [FUV] = 21.18 +/- 0.09.  Five-sigma detection limits
in MIS images are about 22.6 for FUV and about 22.7 for NUV.  No source is
seen in any earlier All Sky Imaging Survey (AIS) images (5-sigma detection
limits in AIS images are about 19.9 for FUV and about 20.8 for NUV), including
2004 May 17, indicating a brightening in AIS/NUV by at least 1 magnitude.
Co-added images from the Sloan Digital Sky Survey (all filters) reveal the
presence of a possible host galaxy near magnitude r = 23, corresponding to an
absolute r magnitude of about -13 at the redshift of 2008iy.


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                         (C) Copyright 2009 CBAT
2009 April 26                    (CBET 1780)              Daniel W. E. Green