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IAUC 8388: 2004dv; 2004dj, 2004du

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IAUC number

                                                  Circular No. 8388
Central Bureau for Astronomical Telegrams
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
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SUPERNOVA 2004dv IN MCG -01-6-12
     Further to IAUC 8387, M. Ganeshalingam and W. Li report the
LOSS discovery of an apparent supernova (mag about 18.5) on an
unfiltered KAIT image taken on Aug. 13.49 UT.  The new object was
also marginally detected on earlier images taken on July 21.49,
27.45, and Aug. 8.44 (all with limiting mag about 18.5-19.0).  SN
2004dv is located at R.A. = 1h58m52s.76, Decl. = -8o10'11".5
(equinox 2000.0), which is 12".5 east and 17".5 south of the
nucleus of MCG -01-6-12.  A KAIT image taken on 2003 Sept. 11.36
showed nothing at this position (limiting mag about 20.0).

SUPERNOVAE 2004dj AND 2004du
     W. Li and A. V. Filippenko, University of California, Berkeley
(UCB); and S. D. Van Dyk, Infrared Processing and Analysis Center,
California Institute of Technology, report:  "We have identified a
progenitor candidate for the type II-P supernova 2004dj (cf. IAUC
8377, 8378, 8384, 8385) in multiband images obtained at the Nordic
Optical Telescope (NOT) by Larsen and Richtler (1999, A.Ap. 345,
59), under good (0".8) seeing conditions.  This star, with V = 21.1
and V-I = +1.4, is 0".3 southwest of the radio position of the
supernova (cf. IAUC 8379).  Assuming little reddening toward the
supernova, other than Galactic (Schlegel et al. 1998, Ap.J. 500,
525), and assuming a true distance modulus of 27.48 mag (Freedman
et al. 2001, Ap.J. 553, 47), this corresponds to an extinction-
corrected absolute V magnitude of -6.5 and an unreddened V-I color
of +1.3.  The color and magnitude are consistent with a red
supergiant with initial mass of about 17 solar masses.  A brighter
object to the northeast, Sandage's 'star' 96 (cf. IAUC 8385), is
within 0".5 of the reported optical position of SN 2004dj (cf. IAUC
8377) but is 1".0 west and 1".2 south of the radio position.  The
profile of 'star' 96 appears nonstellar in the I-band NOT image.
We consider it less likely that 'star' 96 is the progenitor of this
supernova and suggest that definitive identification of the
progenitor will only be possible when high-resolution images of SN
2004dj become available."
     Filippenko, R. J. Foley (UCB), and Li add that inspection of
CCD spectra (range 320-930 nm), obtained by C. Fassnacht and J.
McKean (University of California, Davis) on Aug. 13 UT with the
Keck-I 10-m telescope (+ LRIS), shows that SN 2004du (IAUC 8387) is
a young type-IIn supernova.  Very weak, narrow H_alpha emission is
superposed on a featureless, extremely blue continuum.  There is a
hint of H_beta and He I 587.6-nm emission, as well.

                      (C) Copyright 2004 CBAT
2004 August 15                 (8388)            Daniel W. E. Green

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