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: Sextant experiment
    From: Peter Monta
    Date: 2021 Jun 13, 09:38 -0400
    Hi Modris,

    My sextant SNO-M shows constant difference between these two average index corections.


    How much difference are you seeing?  Can you see it by placing the two solar images in contact, then slowly rolling the sextant 180 degrees (without touching the micrometer assembly)?  A difference of, say, 0.3' or larger would be visible this way, but smaller differences would need multiple trials as you describe.

    I don't have a good guess as to how much flexing might be expected from a metal frame, or whether the flexing couples more into side error than into the main angle.  Still, if you're seeing more than a few arcseconds of difference, it might be from something actually flopping around (which could be subtle, e.g. play in the index bearing) rather than from ordinary elastic flexure.

    It strikes me that sextant calibration, when it was done at all, would have been done horizontally.

    Cheers,
    Peter

       
    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