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

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                                                  Circular No. 8293Central Bureau for Astronomical TelegramsINTERNATIONAL ASTRONOMICAL UNIONMailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)CBAT@CFA.HARVARD.EDU (science)URL http://cfa-www.harvard.edu/iau/cbat.html  ISSN 0081-0304Phone 617-495-7440/7244/7444 (for emergency use only)SUPERNOVA 2004ab IN NGC 5054     L. A. G. Monard, Pretoria, South Africa, reports his discoveryof 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 ofthe center of the galaxy NGC 5054.  Nothing was visible at thislocation on images taken by Monard on 2003 Dec. 29.10 (limiting mag18.5) and 2004 Feb. 1.15 (limiting mag 18.0) or on Digitized SkySurvey images.  A confirming unfiltered CCD image taken by T.Vanmunster (Landen, Belgium) with a 0.35-m reflector on Feb. 24.13shows SN 2004ab at mag 14.5.     T. Matheson, P. Challis, and R. Kirshner, Harvard-SmithsonianCenter for Astrophysics, report that spectra of SN 2004ab, obtainedby 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 CerroTololo 4-m telescope (range 330-940 nm), show it to be a highlyreddened type-Ia supernova about a week past maximum.  Adopting theNASA/IPAC Extragalactic Database recession velocity of 1741 km/sfor the host galaxy, the supernova expansion velocity is 10400 km/sfor Si II (rest 635.5 nm).  The spectra show a strong narrow Na I Dabsorption at the velocity of the host galaxy with an equivalentwidth of 0.33 nm.  The dust maps of Schlegel et al. (1998, Ap.J.500, 525) indicate a relatively low value for Galactic reddening ofE(B-V) = 0.082.  The spectral-feature age of the supernova (Riesset 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 BinaryAstronomy; 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. 14.9UT, on six direct images (two sets of three images taken 20 minapart in time) made with the Hubble Space Telescope (+ ACS/HRC), ofa satellite of minor planet (17246) 2000 GL_74 (V about 18.5).  Thesatellite is clearly separated from the primary in five images.  OnJan. 14.9195, the satellite was at separation 0".16 (projectedseparation 230 km) in p.a. 280 deg.  Using the average albedo ofthe Koronis family (about 0.21), to which (17246) belongs, the sizeof the primary is estimated to be 4.5 km.  The brightnessdifference is about 2 mag, giving an estimated diameter of thesecondary of about 2 km.                      (C) Copyright 2004 CBAT2004 February 24               (8293)            Daniel W. E. Green

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