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    Accuracy of 1767 almanac
    From: Peter Monta
    Date: 2013 Aug 3, 20:47 -0700

    Geoff South's post got me wondering---how accurate were the Nautical
    Almanac lunar distances?  Let's take the 1767 almanac as an example.
    Maskelyne's preface claims one degree of longitude, or 2' of lunar
    distance, while Wikipedia says the early almanacs were good to 0.5'.
    
    Annoyingly, the time coordinate is apparent time; but after sorting
    that out, and typing in a couple of weeks of data, it looks from the
    attached plot as though it's a little worse than 0.5'.  Peak errors
    are hitting 1.0' in just this short sample (taken from January,
    February, October, and November to cover the equation-of-time
    extremes).
    
    Are there transcriptions of the complete data sets for some or all of
    these almanacs?
    
    I'll attach the code and data in case there's interest in running it
    on other data sets.
    
    I've run across several discussions of all this in the navlist
    archives (from e.g. March 2008).  Sorry for any duplication.
    
    Cheers,
    Peter
    
    

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