[IAUC] CBET 1788: 20090430 : SUPERNOVA 2009ds IN NGC 3905

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                                                  Electronic Telegram No. 1788
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 2009ds IN NGC 3905
     K. Kinugasa, S. Honda, H. Takahashi, H. Taguchi, and O. Hashimoto,
Gunma Astronomical Observatory; and K. Ayani, Bisei Astronomical Observatory,
write that low-resolution spectra (range 400-800 nm, resolution about 500)
of 2009ds (cf. CBET 1784), were obtained on Apr. 29.6 and 30.5 UT with the
GAO 1.5-m telescope (+ GLOWS).  The spectrum shows it to be a type-Ia
supernova before maximum light.  Adopting the NED recession velocity of
5774 km/s for NGC 3905 (de Vaucouleurs et al. 1991, Third Reference Catalogue
of Bright Galaxies, ver. 3.9), the expansion velocity derived from the Si II
absorption minimum (rest 635.5 nm) is about 13000 km/s.
     P. Challis, Harvard-Smithsonian Center for Astrophysics (CfA), on behalf
of the CfA Supernova Group, reports that a spectrum (range 360-750 nm) of
2009ds, obtained on Apr. 30 UT by M. Calkins with the F. L. Whipple
Observatory 1.5-m telescope (+ FAST), shows it to be a type-Ia supernova.
Cross-correlation with a library of supernova spectra using the "Supernova
Identification" code (SNID; Blondin and Tonry 2007, Ap.J. 666, 1024) indicates
that 2009ds is a normal type-Ia supernova about 7 days before maximum
brightness.
     Further to the information on CBET 1784, S. Nakano reports the following
unfiltered CCD magnitudes for 2009ds:  Apr. 29.455 UT, 16.7 (K. Itagaki,
Yamagata, Japan; position end figures 04s.12, 45".1); 29.494, 15.5 (Y. Hirose,
0.35-m Schmidt-Cassegrain reflector; position end figures 04s.10, 44".3);
29.516, 16.4 (K. Kadota, Ageo, Saitama-ken, Japan; position end figures
04s.14, 45".0).


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                         (C) Copyright 2009 CBAT
2009 April 30                    (CBET 1788)              Daniel W. E. Green