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Circular No. 8227 Central Bureau for Astronomical Telegrams INTERNATIONAL ASTRONOMICAL UNION Mailstop 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 0081-0304 Phone 617-495-7440/7244/7444 (for emergency use only) COMET C/2003 U1 (LINEAR) L. Manguso and H. Stange, Lincoln Laboratory, Massachusetts Institute of Technology, report the discovery of a comet with a definite halo but no tail on LINEAR images (discovery observation below). Following posting on the NEO Confirmation Page, two other CCD observers have also commented on the cometary appearance: J. E. McGaha (Tucson, AZ, 0.30-m reflector; faint 10" coma elongated in p.a. 240 deg on Oct. 20.3 UT) and J. Young (Table Mountain, CA, 0.6-m reflector; coma of diameter 6" and mag 17.5 with a tail about 16" long in p.a. 276 deg). 2003 UT R.A. (2000) Decl. Mag. Oct. 19.37824 5 27 58.79 - 3 17 53.0 18.2 The available astrometry, the following preliminary parabolic orbital elements, and an ephemeris appear on MPEC 2003-U25. T = 2003 Nov. 1.971 TT Peri. = 276.587 Node = 321.837 2000.0 q = 1.80838 AU Incl. = 164.381 1937 UB (HERMES) J. L. Margot, University of California, Los Angeles; M. C. Nolan, V. Negron, A. A. Hine, D. B. Campbell, and E. S. Howell, National Astronomy and Ionosphere Center; L. A. M. Benner, S. J. Ostro, and J. D. Giorgini, Jet Propulsion Laboratory; and B. G. Marsden, Minor Planet Center, write: "Arecibo (2380-MHz, 12.6-cm) radar observations on Oct. 18 and 20 UT show that the recently rediscovered (IAUC 8223) near-earth-object 1937 UB has a strongly bifurcated appearance. Our images show two separate components of roughly equal sizes, consistent with an orbiting binary pair. The range-Doppler separation between components was 150 m at 1.5 Hz on Oct. 18.2 and 600 m at 0.7 Hz on Oct. 20.1. The Doppler broadening of each component was 0.8 Hz on Oct. 18 and 0.6 Hz on Oct. 20. Preliminary estimates of the diameters, based on visible range extents, are 300-450 m. Upper limits to the spin period of each component are 13-21 hr for the above size range. Additional data are needed to provide an unambiguous orbital solution and to verify whether the system is in a doubly synchronous configuration. Radar and lightcurve observations throughout this apparition would be extremely valuable." (C) Copyright 2003 CBAT 2003 October 20 (8227) Daniel W. E. Green
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