Electronic Telegram No. 1975
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
M.S. 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
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CBAT@CFA.HARVARD.EDU (science)
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COMET P/2009 SK280 (SPACEWATCH-HILL)
     R. E. Hill, Lunar and Planetary Laboratory, reports his discovery of
a comet with the Mount Lemmon Survey's 1.5-m f/2 reflector on Oct. 15.4 UT.
Four coadded 30-second exposures showed a small condensed nucleus with a
20"-30" fanshaped tail in p.a. 240 deg.  The comet's appearance was similar
on four further coadded exposures an hour later.  Prediscovery Spacewatch
observations (all showing asteroidal appearance) by T. H. Bressi, J. V. Scotti
and R. S. McMillan on Sept. 17, 25 and 29 were then identified at the Minor
Planet Center, those on the last two nights having previously been linked under
the designation 2009 SK280 and published on MPS 297945.  The two discovery
observations are therefore

     2009 UT             R.A. (2000) Decl.       Mag.   Observer
     Sept.25.28819   01 44 47.49   +04 15 40.7   20.1   Spacewatch I
     Oct. 15.36043   01 32 40.70   +03 54 44.8   19.8   Hill

     On Oct 16.3 Scotti, using the Spacewatch II 1.8-m f/2.7 reflector,
detected a 0'.39 tail in p.a. 239 deg, while Hill at Mount Lemmon described a
20"-30" tail in p.a. 230 deg and W. H. Ryan (Magdalena Ridge, 2.4-m f/8.9
reflector) a tail in p.a. 225 deg.

     The hitherto unpublished astrometric observations are given in detail
on MPEC 2009-U02, together with the following elliptical orbital elements and
an ephemeris:

     T = 2009 Apr. 22.2398 TT         Peri. = 324.1478
     e = 0.127467                     Node  =  36.4871   2000.0
     q = 4.178926 AU                  Incl. =  16.7109
       a =  4.789418 AU    n = 0.0940329    P =  10.5 years



NOTE: These 'Central Bureau Electronic Telegrams' are sometimes
      superseded by text appearing later in the printed IAU Circulars.

                         (C) Copyright 2009 CBAT
2009 October 16                  (CBET 1975)              Brian G. Marsden