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    Re: Lunar distance accuracy
    From: Frank Reed
    Date: 2007 Oct 23, 21:39 -0400

    Alex, you wrote:
    "These are all data I have. I will be very grateful if someone points to any
    other hard data or research on the subject."
    
    You may have missed the article by E.J. White from 1889 that I described on
    the list almost a year ago --I know you get busy now and then and don't
    follow the list as closely as you would like. Here's a paragraph from my
    post back then:
    
    "White then details the lunar distance observations he has made in the past
    three years: forty-two lunars in 1887, 1888, and 1889. He lists the time and
    measured distance (only approximately, not enough detail to re-work them
    today) and also lists the error of the resulting longitude in seconds of
    time. We can convert this to an approximate error in the measured lunar by
    dividing by 120. That is, an error of 12 seconds in the longitude is
    approximately equivalent to an error of 0.1 minutes of arc in the measured
    lunar distance. Calculating from his listed numbers, I find he has a
    standard deviation in Greenwich time of about 30 seconds which is equivalent
    to about 0.25 minutes of arc in the lunar distances. If we take his lunars
    in sets of four and average them (which I consider the best approach with
    lunars), the results are generally within 0.1 minutes of arc. I would note
    that these results are very similar to my own experience."
    
    The original post is here:
    http://fer3.com/arc/m2.aspx?y=200611&i=101759
    
    As noted then, I found White's article originally while digging around in
    Google Books. Since it's short, I've also made it available on the web here:
    www.HistoricalAtlas.com/lunars/ejwhite.
    
     -FER
    www.HistoricalAtlas.com/lunars
    
    
    
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