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: Davis MK III Index Error
    From: Brad Morris
    Date: 2015 May 10, 23:25 -0400

    Of course, Fred, that method works too, albeit with some arithmetic involved.

    I've found that the superimposition method works just fine for me, allowing me to simultaneously adjust my index error and my side error to zero.   Set the index arm vernier to zero. Adjust until the images are superimposed.  Viola, zero index error.   No math. No arithmetic.  No fussing over on or off the arc. 


    On May 10, 2015 11:12 PM, "Fred Hebard" <NoReply_Hebard@fer3.com> wrote:
    Isn’t the usual method is to touch one image to another, measuring the semi-diameter?

    Fred Hebard

    On May 10, 2015, at 10:11 PM, Brad Morris <NoReply_Morris@fer3.com> wrote:

    Hello Herman

    Superimposing the sun's image onto itself or the moon's image onto itself is a highly effective method of determining the index error. 

    Just watch that you don't blind yourself by observing the sun without shades!  That pain you feel in your eye is a warning!  (Slight humor should be noticed here!)


    On May 10, 2015 5:07 PM, "Herman Dekker" <NoReply_Dekker@fer3.com> wrote:

    Thanks for the info.
    There is no free sight around possible in the backyard. It is dark now, so I used Venus, that works. The index error is now back from 55' to zero, as long as it stays with a plastic sextant. Is a high cloud with a sharp edge usable for index error? This is just an idea, as nothing else is possible?

    Frank can you explain: What is the Sun test on the Moon?



    View and reply to this message

    View and reply to this message

    View and reply to this message

    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