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 index error measurement
    From: Frank Reed CT
    Date: 2006 Nov 3, 23:03 EST
    Jim Martin, you wrote:
    "According to "Nicholls concise guide" vol.1, a close by object
    or straight line should not be used to determine index error,because it
    does not allow for sextant parallax and atmospheric refraction. I can
    give the textbook explanation if it is of interest."
     
    Sextant parallax, yes. That's an important issue for index correction. But refraction, no. The only time terrestrial refraction would make a difference is if you're comparing sight lines to two objects at distances differing by a good fraction of a mile. I can't think of any instance where this would matter for standard index correction observations.
     
    -FER
    42.0N 87.7W, or 41.4N 72.1W.
    www.HistoricalAtlas.com/lunars

    --~--~---------~--~----~------------~-------~--~----~
    To post to this group, send email to NavList@fer3.com
    To unsubscribe, send email to 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