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: "Attainment of Precision" article (1964)
    From: Thomas Kleemann
    Date: 2009 Jul 08, 23:58 +0200

    Nicol�s de Hilster schrieb:
    > frankreed{at}HistoricalAtlas.com wrote:
    >> If you want a really good value for IC, shoot the Sun or the Moon 
    limb-to-limb ... it's usually more effective than the standard sea horizon 
    test (but the standard test is usually quite sufficient and it's the one that 
    should always be taught).
    >>   
    > And can you explain how this is done? 
    
    You shoot a set of two sextant readings, where the double reflected sun 
    and the directly observed one are showing an eight-like figure with 
    their touching limbs. After the first shoot you exchange the two images, 
    so that the lower becomes the higher and vice versa.
    
    Now you have got two readings - one on the arc and one off the arc,
    e.g. 31' on, 32' off.
    
    - substract them and the index error is half the difference (-0.5' in 
    the above example)
    
    - add them and divide by four will get you the semidiameter (15.75'),
    which you can compare to the almanach to check the precision of your 
    measurement.
    
    Thomas.
    
    --~--~---------~--~----~------------~-------~--~----~
    Navigation List archive: www.fer3.com/arc
    To post, email NavList@fer3.com
    To unsubscribe, email NavList-unsubscribe@fer3.com
    -~----------~----~----~----~------~----~------~--~---
    
    

       
    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