[IAUC] CBET 907: 20070326 : SUPERNOVA 2007ax IN NGC 2577

[IAUC mailing list]

                                                  Electronic Telegram No. 907
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
M.S. 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS en CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
CBAT en CFA.HARVARD.EDU (science)
URL http://cfa-www.harvard.edu/iau/cbat.html


SUPERNOVA 2007ax IN NGC 2577
     S. Blondin, M. Modjaz, R. Kirshner, and P. Challis, Harvard-Smithsonian
Center for Astrophysics; and T. Matheson, National Optical Astronomy
Observatory, report that a spectrogram (range 350-740 nm) of 2007ax (cf.
CBET 904), obtained by M. Calkins on Mar. 26.21 UT with the F. L. Whipple
Observatory 1.5-m telescope (+ FAST), shows it to be a type-Ia supernova
around maximum light.  Cross-correlation with a library of supernova spectra
indicates that 2007ax is most similar to the subluminous type-Ia supernova
1991bg at 3 days past maximum.  Adopting a recession velocity of 2074 km/s
for the host galaxy (from "The Updated Zwicky Catalog", available online at
http://tdc-www.harvard.edu/uzc/), the maximum absorption in the Si II line
(rest 635.5 nm) is blueshifted by roughly 10000 km/s.  Assuming that the
galaxy is in the Hubble flow and that the supernova suffers negligible
extinction, the discovery magnitude of 17.2 corresponds to an absolute
magnitude of roughly -15, which is roughly 2 magnitudes fainter than SN
1991bg at the same phase.


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      superseded by text appearing later in the printed IAU Circulars.

                         (C) Copyright 2007 CBAT
2007 March 26                    (CBET 907)               Daniel W. E. Green