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IAUC 8282: 2004S; 2001em; C/2003 H1

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                                                  Circular No. 8282
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 2004S IN MCG -05-16-21
     R. Martin, Perth Observatory, reports the discovery of an
apparent supernova (mag 16) on red CCD images taken on Feb. 3.542
and 4.560 UT with the 0.61-m Perth/Lowell Automated Telescope in
the course of the Perth Automated Supernovae Search.  SN 2004S was
not visible on an image taken on 2003 Dec. 30.583 (limiting mag 19).
J. Biggs reports the following position for SN 2004S from an
unfiltered images taken around 2004 Feb. 5.65, when the object
appeared at R about 13.6 +/- 0.3:  R.A. = 6h45m43s.50 +/- 0".1,
Decl. = -31o13'52".5 +/- 0".1 (equinox 2000.0), which is 47".2 west
and 2".5 south of the nucleus of MCG -05-16-21.

SUPERNOVA 2001em IN UGC 11794
     C. J. Stockdale, Marquette University; S. D. Van Dyk, Infrared
Processing and Analysis Center, California Institute of Technology;
R. A. Sramek, National Radio Astronomy Observatory (NRAO); K. W.
Weiler, Naval Research Laboratory; N. Panagia, European Space
Agency and Space Telescope Science Institute; M. P. Rupen, NRAO;
and B. Paczynski, Princeton University, report the detection of
radio emission near the position of the type-Ib/c supernova 2001em
(IAUC 7722, 7737) with the Very Large Array (VLA):  "Radio-flux
densities on 2003 Oct. 17.18 UT of 1.151 +/- 0.051 mJy at 8.435 GHz
(wavelength 3.6 cm), and on 2004 Jan. 30.90 of 1.815 +/- 0.099 mJy
at 4.860 GHz (wavelength 6.2 cm), 1.480 +/- 0.052 mJy at 8.460 GHz,
and 1.200 +/- 0.162 at 14.94 GHz (2.0 cm), were observed at R.A. =
21h42m23s.61, Decl. = +12o29'50".3 (equinox 2000.0; +/- 0".2 in
each coordinate).  This is in near coincidence (< 1") with the
reported optical position of SN 2001em (position end figures
23s.66, 50".9; IAUC 7722).  The source appears variable at 3.6 cm
and is mildly non-thermal (alpha = -0.37; S is proportional to
nu**alpha) between 4.9 and 14.9 GHz.  SN 2001em appears to be the
most luminous (currently about 2 x 10**28 erg s**-1 Hz**-1 at 6 cm
for a distance of 90 Mpc) type-Ib/c supernova ever observed at such
a late epoch, about fifty times more radio luminous than SN 1998bw
at a comparable age.  We are continuing to monitor this source with
the VLA."

     Visual total-magnitude estimates:  Jan. 20.23 UT, 13.3 (J. J.
Gonzalez, Asturias, Spain, 0.20-m reflector); 25.86, 13.0 (K.
Yoshimoto, Yamaguchi, Japan, 0.25-m reflector); Feb. 1.23, 12.7

                      (C) Copyright 2004 CBAT
2004 February 5                (8282)            Daniel W. E. Green

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