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 double reflection: angles halved
    From: David Pike
    Date: 2021 Feb 15, 17:22 -0800

    David - I sent my proof a bit ago, but damn, yours is about 10 times simpler!  Love it!

    Except I was too slick.  You have to consider direction of bending.  A better argument is:

    Letting clockwise be positive, starlight is bent (180-2v) - (180-2u) = Minus Theta, so Theta = 2(v-u)

    For triangle ABC, (90-v) + (90+u) + Phi = 180, or Phi =  v-u,  so Theta = 2 Phi.  Got there in the end. Sorry.  DaveP  

       
    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