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: Refraction, sunset, and HO229 beginner question
    From: Jim Theriot
    Date: 2004 Jul 22, 09:46 -0500

    Bill said:
    
    > The idea struck me that at sunrise and sunset I could get a LOP without a
    > sextant.  One barrel of my binoculars, a heavy-duty neutral-density
    filter,
    > a watch, Nautical Almanac and HO229 tables would suffice.
    
    I was struck by a possibly similar idea -- I am not sure if it's the same
    idea,
    because Bill's comments are mostly about use of almanac and tables, not
    about
    the basic principle.  My idea was simply that for any observation you make
    with watch and sextant where the object appears on the horizon, the same
    observation could be made with watch only (or watch and binoculars).  Then
    you run the computations, using using zero for the sextant reading, making
    all
    the appropriate corrections (but using zero for the sextant index error
    correction!), and you should get identical results.  Possibly that's what
    Bill was getting at.
    
    Furthermore, it seems that on a moonless night you might be able to get
    a LOP from the setting of a star or planet more easily using this method,
    since you don't have to see the horizon, you only need to note the instant
    at which the star or planet blinks out.
    
    I wanted to test this theory on a sailing trip a couple of months ago (I
    live inland, not in sight of a 'real' horizon), but weather and
    circumstances
    prevented it.
    
    Regards,
    Jim
    
    
    

       
    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