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IAUC 8293: 2004ab; S/2004 (17246) 1

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                                                  Circular No. 8293
Central Bureau for Astronomical Telegrams
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
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SUPERNOVA 2004ab IN NGC 5054
     L. A. G. Monard, Pretoria, South Africa, reports his discovery
of a supernova (mag 14.7) on unfiltered CCD images taken on Feb.
21.979 UT.  The new object is located at R.A. = 13h16m58s.18, Decl.
= -16o37'52".7 (equinox 2000.0), which is 2" west and 11" north of
the center of the galaxy NGC 5054.  Nothing was visible at this
location on images taken by Monard on 2003 Dec. 29.10 (limiting mag
18.5) and 2004 Feb. 1.15 (limiting mag 18.0) or on Digitized Sky
Survey images.  A confirming unfiltered CCD image taken by T.
Vanmunster (Landen, Belgium) with a 0.35-m reflector on Feb. 24.13
shows SN 2004ab at mag 14.5.
     T. Matheson, P. Challis, and R. Kirshner, Harvard-Smithsonian
Center for Astrophysics, report that spectra of SN 2004ab, obtained
by P. Berlind on Feb. 24.49 UT with the Mt. Hopkins 1.5-m telescope
(range 370-750 nm) and by J. Huchra on Feb. 24.41 with the Cerro
Tololo 4-m telescope (range 330-940 nm), show it to be a highly
reddened type-Ia supernova about a week past maximum.  Adopting the
NASA/IPAC Extragalactic Database recession velocity of 1741 km/s
for the host galaxy, the supernova expansion velocity is 10400 km/s
for Si II (rest 635.5 nm).  The spectra show a strong narrow Na I D
absorption at the velocity of the host galaxy with an equivalent
width of 0.33 nm.  The dust maps of Schlegel et al. (1998, Ap.J.
500, 525) indicate a relatively low value for Galactic reddening of
E(B-V) = 0.082.  The spectral-feature age of the supernova (Riess
et al. 1997, A.J. 114, 722) is 6 +/- 2 days after maximum light.

S/2004 (17246) 1
     P. M. Tamblyn, Southwest Research Institute (SwRI) and Binary
Astronomy; W. J. Merline, C. R. Chapman, D. Nesvorny, and D. D.
Durda, SwRI; C. Dumas, Jet Propulsion Laboratory; A. D. Storrs,
Towson University; L. M. Close, University of Arizona; and F.
Menard, Observatoire de Grenoble, report the discovery on Jan. 14.9
UT, on six direct images (two sets of three images taken 20 min
apart in time) made with the Hubble Space Telescope (+ ACS/HRC), of
a satellite of minor planet (17246) 2000 GL_74 (V about 18.5).  The
satellite is clearly separated from the primary in five images.  On
Jan. 14.9195, the satellite was at separation 0".16 (projected
separation 230 km) in p.a. 280 deg.  Using the average albedo of
the Koronis family (about 0.21), to which (17246) belongs, the size
of the primary is estimated to be 4.5 km.  The brightness
difference is about 2 mag, giving an estimated diameter of the
secondary of about 2 km.

                      (C) Copyright 2004 CBAT
2004 February 24               (8293)            Daniel W. E. Green

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