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    The Online Nautical Almanac
    From: George Huxtable
    Date: 2004 Jul 13, 20:18 +0100

    Omar Reis has replied as follows, to my copying to him Frank Reed's note
    indicating that proper-motion of stars appears to have been omitted from
    his Online Almanac.
    
    =====================
    
    As for the proper motion issue, Mr Reed is right.
    Currently, my calculations do not include the
    effects of proper motion for stars.
    
    The average proper motion of the stars that
    can be seen with the naked eye is 0.1" per year.
    (or 5" in 50 years). Proper motion for stars is
    generaly very small.
    
    Of course some stars are faster than the average.
    The Smithsonian Astrophysical Observatory
    Star Catalog states that Arcturus proper motion
    components are:
    
    RA: -0,0776 arcsec/year
    DEC: -1,999 arcsec/year
    
    In 50 years, the 2"/year in declination
    add to 100", or 1.6'. It's significant, I must
    admit. I'm still acessing how the issue impacts
    the rest of the catalog.
    
    I would like to remember that the Online Almanac was
    never intended to be used as a historic research tool.
    It's purpose is to serve as a celestial navigation tool
    for our epoch. The 100 years date range specifies
    this scope.
    
    I will be releasing a note about the issue
    when I finish the investigation. Thanks again for
    forwarding the message from your discussion
    group.
    
    Best regards
    Omar
    
    ====================
    
    I take it from that message that Omar hasn't (yet) promised to amend his
    almanac to include star proper-motions. I hope he will, though.
    
    George.
    
    ================================================================
    contact George Huxtable by email at george---.u-net.com, by phone at
    01865 820222 (from outside UK, +44 1865 820222), or by mail at 1 Sandy
    Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK.
    ================================================================
    
    
    

       
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