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: sextant mirror silvering
    From: Frank Reed CT
    Date: 2006 Nov 9, 03:51 EST
    George H, you wrote:
    "There may be an intended star, reflected as normal in the index
    mirror, which may perhaps be confused with a brighter star, rather
    overhead and somewhat behind the observer's head, seen through the
    holes in the silvering. Can that happen, in practice?"
    I have never seen a sextant that did not have an opaque barrier behind the mirrors, so, no, I don't think it can happen in practice. But on a related note, it can be very confusing when you're trying to see a star that is 100 degrees or more from the Moon. In that case, the image of the index mirror is highly foreshortened as seen from the horizon mirror so you can see a lot of sky behind it. It's not unusual to find a star in that direction, and it can be confusing. As you noted in a follow-up, there's never any 'real' doubt, but it's still a nuisance.
    42.0N 87.7W, or 41.4N 72.1W.

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

    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