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
    or...
       
    Reply
    Re: Lunar distances
    From: Eric Haberfellner
    Date: 2002 Jan 25, 11:38 PM

    I am not an expert on Lunars, but I believe that Lechter gives a complete
    solution. He states:
    
    "In discovering a way to solve it [GMT by lunar distance] using only the
    Nautical Almanac and the ordinary sight reduction tables I had on board
    (H.O. 214), I experienced one of the great intellectual triumphs of my life.
    On the 25th day of the passage, with 500 miles to go, I was able to prove
    beyond all doubt that my clock was correct, within one minute of GMT, so my
    longitude was gound within 30 miles or so - ample precision for the upcoming
    landfall"
    
    This was in 1963. Did the Nautical Almanac still have Lunar distance tables
    at that time? I will have to dig into this material to figure out what
    information he actually uses from the Nautical Almanac. I don't have time
    right now.
    
    He has some equations, and gives complete examples.
    
    Eric Haberfellner
    
    -----Original Message-----
    From  Navigation Mailing List
    [mailto:NAVIGATION-L{at}LISTSERV.WEBKAHUNA.COM]On Behalf Of Chuck Griffiths
    Sent: Friday, January 25, 2002 12:09 PM
    To: NAVIGATION-L{at}LISTSERV.WEBKAHUNA.COM
    Subject: Re: Lunar distances
    
    
    george---.u-net.com wrote:
    
    ...There's no escaping the fact that lunar distances are a complex business.
    If
    there existed accessible textbooks on the subject, I could have simply
    referred the reader to those. The only modern one I am familiar with is
    C.H.Cotter, "A History of Nautical Astronomy" (London, 1968), which is very
    hard to find.
    
    If any reader knows of other useful textbooks on lunars, please say. Eric
    Haberfellner tells me of  "Self-Contained Celestial Navigation with H.O.
    208" by John S. Letcher, Jr., published by International Marine Publishing
    Company in 1977.
    
    He says- "This book (to my suprise) has a chapter on "Time by Lunar
    Distance" and a chapter on "Time by Lunar Lines of Position". This would
    make it one of the few "modern" books that deals with this subject."...
    
    
    Which brings to mind the following:
    
    I'm curious whether anyone has an old enough edition of Bowditch to still
    have
    tables for clearing lunar distances. I believe that the tables and
    explanations
    were included until the mid-60's. What did these tables provide solutions
    for?
    
    My related question: Has anyone cataloged the tables and articles that have
    been
    removed from Bowditch over the years? I have to say, the 1995 edition,
    compared
    to  the 1977 edition, seems to have left out a lot of good information e.g.,
    correct plotting of high angle sights and the history of sight reduction
    techniques. If you start adding up just the few things that I'm aware of
    that
    have been taken out over the years - tables for clearing lunar distances,
    Ageton's tables, better explanations spherical trig, it seems like a
    collection
    of the "lost" Bowditch articles and tables would be a pretty nice reference
    to
    own.
    
    Chuck Griffiths
    
    
    
    
    
    
    **********************************************************************
    This e-mail and any files transmitted with it are confidential and may
    be legally privileged or otherwise exempt from disclosure under
    applicable law. This e-mail and its files are intended solely for
    the individual or entity to whom they are addressed and their content
    is the property of Smiths Aerospace.  If you are not the intended
    recipient, please do not read, copy, use or disclose this communication.
    If you have received this e-mail in error please notify the e-mail
    administrator at postmaster{at}si.com and then delete this e-mail, its
    files and any copies.
    
    This footnote also confirms that this e-mail message has been scanned
    for the presence of known computer viruses.
    ***********************************************************************
    

       
    Reply
    Browse Files

    Drop Files

    NavList

    What is NavList?

    Join NavList

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

    You can also join by posting. Your first on-topic post automatically makes you a member.

    Posting Code

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

    Email Settings

    Posting 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