Welcome to the NavList Message Boards.


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

Compose Your Message

Add Images & Files
    Re: Celestial predictions. was:[NAV-L] Old style lunar
    From: Alexandre Eremenko
    Date: 2004 Dec 12, 01:13 -0500

    I think you misundertood what Frank was saying.
    (I also did not understand his first message,
    but then he explained)
    On Sat, 11 Dec 2004, George Huxtable wrote:
    > >>It's no longer necessary to do this algorithmically.
    > >> Just open a  virtual
    > >>almanac page.
    > >From George-
    > That's all very well, but in practical terms, what does a mariner,
    > given an
    > on-board  laptop, do to obtain positions by such methods
    > as Frank
    > advocates, when at sea?
    The mariner is supposed to download NASA database
    BEFORE she goes to sea. This database constitutes
    an almanac for several hundred years.
    THIS, of course replaces Meeus algorithm.
    The whole thing occupies only 10MB, which is nothing
    for a modern laptop.
    But I recommend to have a backup. (What if the disc crashes).
    (Or even better, to carry a spare copy of paper almanac:-)
    Much cheaper and more reliable than a spare laptop.
    > In practical terms, there's no requirement for position
    > accuracy to be to
    > an arc-second.
    > Meeus' algorithms do all that's necessary to obtain on-board
    > positions to quite sufficient accuracy for any maritime application, lunar
    > distances included..
    I suppose if you take ALL terms in Meeus you will
    also obtain 1 arcsec accuracy. But this is many hours of
    I think this discussion was not about
    "practical navigator's needs".
    At least my original question was not.
    I just wanted to write my own long term almanac (independent
    of Frank's site, and of the web in general), partially for fun
    of doing it, partially to be able to answer all sorts of
    questions about Tiho Brahe and maybe even Hipparchus observations.
    And also to be able to reduce my balcony sights quickly.
    P.S. If I will ever do CelNav in sea, I don't want to depend
    on such a fragile device as computer for my main tool:
    the almanac.

    Browse Files

    Drop Files


    What is NavList?

    Join NavList

    (please, no nicknames or handles)
    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 Settings

    Posting Code:

    Custom Index

    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