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: Latitude from date and length of daylight?
    From: Nels Tomlinson
    Date: 2005 Feb 16, 21:34 +1500

    The only problem I can see with this would be in high latitudes, since
    the sunrise and sunset are both very drawn out (if they happen at
    all).  I wonder if that one-degree-ish estimated accuracy holds in the
    high 50's and 60's?
    Here in Juneau (about 58* North), the sun slides along the horizon for
    a while on either end of its arc, and it would be pretty hard to tell
    when it first touches.  The long twilight might fool the light sensor
    on the tag, too?
    On Sun, 13 Feb 2005 18:28:18 -0800 (PST), Frank Reed
    > Jared wrote:
    > "It seemed interesting, that with just a watch and calendar
    > one should be able to get latitude this way. Since most modern watches run
    > to better than a second a day, this would seem to be a reasonable navigation
    > tool."
    > You can get longitude, too. If your watch is running well, as you travel
    > east, sunrises and sunsets will occur at earlier and earlier watch times.
    > This technique of navigation is actively employed on a small device that
    > operates in an area inaccessible to GPS signals --underwater. Do you have
    > $4200 to spare? Then you, too, can be the proud honor of a celestial
    > navigating fish tag. I brought this up briefly on the list over a year ago.
    > Here's a link to their web site and a description of the device:
    > http://microwavetelemetry.com/Fish_PTTs/archival.php
    > They get one-degree-ish estimated accuracy in latitude and longitude by
    > timing sunrise and sunset (based on light levels corrected for depth, which
    > is measured by pressure). This may be one of the last scientifically
    > significant uses of celestial navigation. I guess it was easier than
    > teaching the tuna to use sextants and H.O.229.
    > "Has anyone seen a formula for this, or does anyone want to give it a try?"
    > The easiest way to do it would be trial and error with the standard formulas
    > for sunrise/sunset. Or with an almanac, just interpolate.
    > -FER
    > 42.0N 87.7W, or 41.4N 72.1W.
    > www.HistoricalAtlas.com/lunars

    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