Welcome to the NavList Message Boards.

NavList:

A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding

Compose Your Message

Message:αβγ
Message:abc
Add Images & Files
    Name or NavList Code:
    Email:
       
    Reply
    Re: Thomas Jefferson and Lunar Obs.
    From: George Huxtable
    Date: 2005 Mar 26, 23:36 +0000

    In my recent contribution on this topic, I wrote-
    
    "This method presumes that Moon GHA was tabulated with sufficient accuracy
    and at small enough time intervals. This wasn't really true for the early
    Nautical Almanacs; mine, for 1767, provides Moon GHA only to an accuracy of
    one arc-minute, and at 12 hour intervals. Contrast this with lunar
    distances, which were tabulated to the arc-second (even if such precision
    was largely illusory), and at 3-hour intervals. I don't have easy access to
    the almanacs from 1803, which are relevant to Lewis and Clark's expedition,
    but expect that some Nav-L reader can kindly advise me how precise the
    predictions for Moon GHA were then."
    
    I referred to the Moon and star motion in terms of hour angle and GHA,
    because that's a familiar concept to modern navigators. But of course when
    referring to predictions in early almanacs they were always in terms of
    Right Ascension, not GHA. Sorry about that confusion. The same question
    arises, for the Almanacs around 1803. How precisely was the Moon's Right
    Ascension tabulated, and at what time intervals?
    
    George.
    
    
    ================================================================
    contact George Huxtable by email at george@huxtable.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.
    ================================================================
    
    
    

       
    Reply
    Browse Files

    Drop Files

    NavList

    What is NavList?

    Get a NavList ID Code

    Name:
    (please, no nicknames or handles)
    Email:
    Do you want to receive all group messages by email?
    Yes No

    A NavList ID Code guarantees your identity in NavList posts and allows faster posting of messages.

    Retrieve a NavList ID Code

    Enter the email address associated with your NavList messages. Your NavList code will be emailed to you immediately.
    Email:

    Email Settings

    NavList ID Code:

    Custom Index

    Subject:
    Author:
    Start date: (yyyymm dd)
    End date: (yyyymm dd)

    Visit this site
    Visit this site
    Visit this site
    Visit this site
    Visit this site
    Visit this site