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IAUC 7421: 2000cf; 2000cg; 2000ch

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                                                  Circular No. 7421
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 617-495-7244/7440/7444 (for emergency use only)

SUPERNOVA 2000cf IN MCG +11-19-25
     T. Puckett, Mountain Town, GA; and A. Sehgal, Woodinville, WA,
report their discovery of an apparent supernova (mag 16.9) on an
unfiltered CCD frame (limiting mag 20.5) taken with the Puckett
Observatory automated 0.60-m supernova patrol telescope on May 9.23
UT.  SN 2000cf is located at R.A. = 15h52m56s.19, Decl. =
+65o56'12".7 (equinox 2000.0), which is 3".1 east and 4".3 north of
the center of MCG +11-19-25.  The new object was also present on an
unfiltered CCD frame taken on May 10.05, but it was not present on
a frame taken on Mar. 7.36, and it does not appear on Palomar Sky
Survey images taken on 1994 June 1 (limiting mag about 21.0) or
1955 May 17 (limiting mag about 20.0).

SUPERNOVA 2000cg IN UGC 10121
     Y. Sato and W. D. Li, University of California at Berkeley, on
behalf of the Lick Observatory Supernova Search (cf. IAUC 6627,
7126), report the discovery with the 0.8-m Katzman Automatic
Imaging Telescope of an apparent supernova on unfiltered images
taken on May 6.4 (mag about 18.6) and 9.4 UT (mag about 19.0,
limiting mag about 20.5).  The new object also appeared on an image
taken on Apr. 27.4 UT (mag about 18.6).  SN 2000cg is located at
R.A. = 15h59m45s.52, Decl. = +18o48'13".0 (equinox 2000.0), which
is 4".0 west and 9".0 north of the nucleus of UGC 10121.
Unfiltered images of the field taken on 2000 Apr. 1.4 (limiting mag
about 19.0) and 1998 July 21.3 (limiting mag about 20.0) showed
nothing at this position.

SUPERNOVA 2000ch IN NGC 3432
     A. V. Filippenko, University of California at Berkeley,
writes:  "The descriptions of the 'variable star' in NGC 3432 (cf.
IAUC 7415, 7417, 7419) strongly suggest that it is a subluminous
type-IIn supernova similar to SN 1997bs in NGC 3627 (cf. IAUC 6627)
and SN 1999bw in NGC 3198 (cf. IAUC 7152).  The progenitors of
these subluminous objects may be very massive, powerful stars such
as luminous blue variables (e.g., SN 1961V, cf. Goodrich et al.
1989, Ap.J. 342, 908; SN 1997bs, cf. Van Dyk et al. 1999, A.J. 118,
2331).  If so, the 'explosion mechanism' might not be core collapse,
and the star may survive (e.g., SN 1961V, cf. Filippenko et al.
1995, A.J. 110, 2261).  Indeed, the 'explosion' is actually just a
super-outburst of the luminous variable.  Some of these outbursts
last longer than others, and that of the object in NGC 3432 seems
to have been short-lived."

                      (C) Copyright 2000 CBAT
2000 May 10                    (7421)            Daniel W. E. Green

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