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IAUC 8453: 2004gs; 2004gd, 2004ge, 2004gf,, 2004gl

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IAUC number

                                                  Circular No. 8453
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)
URL http://cfa-www.harvard.edu/iau/cbat.html  ISSN 0081-0304
Phone 617-495-7440/7244/7444 (for emergency use only)

SUPERNOVA 2004gs IN MCG +03-22-20
     Further to IAUC 8452, S. Park and W. Li report the LOSS
discovery of an apparent supernova (mag 17.1) on an unfiltered KAIT
image taken on Dec. 12.43 UT.  SN 2004gs is located at R.A. =
8h38m23s.18, Decl. = +17o37'39".8 (equinox 2000.0), which is 9".8
west and 12".7 south of the nucleus of MCG +03-22-20.  A KAIT image
taken on Dec. 4.42 already showed a hint of the new object
(limiting mag about 19.5), while an image taken on Nov. 24.45
showed nothing at this position (limiting mag about 19.0).
     N. Morrell, G. Folatelli, and M. Hamuy, Carnegie Supernova
Project, report that a CCD spectrogram (380-920 nm) of SN 2004gs,
obtained on Dec. 13.25 UT with the Las Campanas 2.5-m du Pont
telescope (+ WFCCD Spectrograph), shows it to be a type-Ia
supernova near maximum light.  The expansion velocity, derived from
the blueshift of the minimum of Si II 635.5-nm, is 11600 km/s
(assuming a recession velocity of 7988 km/s for the host galaxy as
given in the NED database).  SN 2004gs shows an enhanced Si II
597.2-nm absorption line.  No evidence for Na I D 589.3-nm can be
seen (with an upper limit of 0.05 nm), which suggests little or no
dust absorption in the host galaxy.

SUPERNOVAE 2004gd, 2004ge, 2004gf, AND 2004gl
     Further to IAUC 8452, A. V. Filippenko and R. J. Foley write
that inspection of CCD Keck I spectra, also obtained on Dec. 12 UT,
shows that SN 2004gd (IAUC 8443) is of type IIn, strongly
resembling SN 1985G (Pastorello et al. 2002, MNRAS 333, 27).
Prominent, relatively narrow (FWHM 1000 km/s) hydrogen-Balmer
emission lines are superposed on broader bases and exhibit narrow
P-Cyg absorption components with minima displaced by about 700 km/s
from the emission-line cores.  Similar absorption features are seen
in the Fe II multiplets and other lines; they are probably produced
by a dense circumstellar shell.  SN 2004ge (IAUC 8443) is of type
Ic, shortly after maximum brightness; the shape of its continuum
argues that it is heavily reddened, and the equivalent width of the
narrow interstellar Na I D absorption line at 589 nm is about 0.2
nm.  SN 2004gf (IAUC 8444) is of type II, probably within a few
weeks past explosion, based on the blue continuum; the H_alpha line
is vastly dominated by the emission component (FWHM = 2200 km/s),
although all other lines (Balmer, Fe II, O I, Ca II) show more
typical P-Cyg profiles.  SN 2004gl (IAUC 8446) is of type Ia, three
weeks past maximum brightness; the redshift of the host galaxy,
measured from narrow emission lines in the nucleus, is 0.0393.

                      (C) Copyright 2004 CBAT
2004 December 13               (8453)            Daniel W. E. Green

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