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    Re: Definition of the twilight intervals
    From: Sean C
    Date: 2015 Aug 25, 08:48 -0700


    However, modern editions of Bowditch's "The American Practical Navigator" do not seem 
    to be consistent with the definition of astronomical twilight.
    In the 2002 online bicentennial edition (the latest to which I have easy access), 
    astronomical twilight is defined as the interval between -0 degr 50 arcmin 
    and -18 degr (table 1516 on p. 227) while the Glossary of Marine Navigation 
    in the same publication defines it as the interval between -12 degr and -18 
    degr (p. 725).
    Whom should one contact to point out this inconsistency?
    Rob van Gent




    Apologies for replying to this so long after you posted it, but I was just browsing through my copy of Bowditch, saw the table you were referring to and was reminded of your question. Bowditch is prepared and published by the National Geospatial-Intlligence Agency (Formerly the National Imagery and Mapping Agency). Their website gives their mailing address as:


    National Geospatial-Intelligence Agency
    Office of Corporate Communications
    Public Affairs Branch, MS N73-OCCAE
    7500 GEOINT Drive
    Springfield, Virginia 22150-7500


    ...and their email address is: publicaffairs -at- nga.mil. Hope that helps.



    Sean C.

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