[IAUC] CBET 1305: 20080319 : SUPERNOVA 2008ax IN NGC 4490

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                                                  Electronic Telegram No. 1305
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 2008ax IN NGC 4490
     H. Marion, University of Texas and Texas State University; P. Garnavich,
University of Notre Dame; C. L. Gerardy, Florida State University; R. J.
Rudy, D. K. Lynch, and R. W. Russell, Aerospace Corporation; and C. E.
Woodward, University of Minnesota, observed supernova 2008ax (cf. CBET 1285)
on Mar. 14.5 UT with the Infrared Telescope Facility (+ SpeX instrument
in low-dispersion mode).  The spectrum (wavelength range 0.7-2.4 microns)
shows strong P-Cyg profiles of He I at 1.08 and 2.06 microns and Ca II at
0.85 microns.  The expansion velocity of the 1.08-micron He I line is
11000 km/s.  Paschen-beta is very weak, and analysis with SYNOW synthetic
spectra (Branch et al. 2007, AIP Conf. Proc. 924, 342) indicates that
Paschen-beta is likely contaminated by He I.  The 2008ax spectrum is similar
to the infrared spectrum of supernova 1999ex (Hamuy et al. 2002, A.J. 124,
417) near maximum.  SN 1999ex was a type-Ib/c event, and 2008ax -- with its
weak hydrogen and dominant He I -- appears as a type-Ib supernova in the
near-infrared.


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                         (C) Copyright 2008 CBAT
2008 March 19                    (CBET 1305)              Daniel W. E. Green