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
    Name or NavList Code:
    Email:
       
    Reply
    Re: Submarine celestial through periscope
    From: Frank Reed
    Date: 2023 Mar 13, 13:16 -0700

    Andrés,

    In your post earlier today, you included this images with "cones of position" terminating at points on the celestial sphere. Where is that from? It's clearly a professional illustration from a book dating back some decades. But it appears to me that the creator of the image has thoroughly misunderstood the concept. The cones are backwards.

    I was getting ready to go digging for some of my old artwork on this concept, and then I noticed that you actually referenced one of my old webpages, https://navlist.net/cones/, on this concept dating back 17 years (so shockingly long ago that I grabbed my calculator to make sure that 2023-2006 actually equals 17!). A two-star fix understood as two circles of position on the Earth's surface can be extended off the surface of the Earth as two cones of position, but the "pointy ends" of those cones are at the Earth's center. The old diagram that you found with the cones' pointy ends on the stars on the "celestial sphere' really doesn't even make sense as a visual aid. It's an oddity!

    Frank Reed
    Clockwork Mapping / ReedNavigation.com
    Conanicut Island USA

    File:

       
    Reply
    Browse Files

    Drop Files

    NavList

    What is NavList?

    NavList is a community devoted to the preservation and practice of celestial navigation and other methods of traditional position-finding. We're a group of navigators, navigation enthusiasts and hobbyists, mathematicians and physicists, and historians interested in all aspects of navigation but primarily those techniques which are non-electronic.

    To post a message, if you are already signed up as a NavList member, start a new discussion or reply to any posted message and use your posting code (this is a simple low-security password assigned when you join). You may also join by posting. Your first on-topic messsage automatically makes you a member, and a posting code will be assigned and emailed to you for future posts.

    Uniquely, the NavList message boards also permit full interaction entirely by email. You can optionally receive individual posts or daily digests by email, and any member can post messages by email (bypassing the web site) by sending to our posting address which is "NavList@NavList.net". This functionality is similar to a traditional Internet mailing list: post by email, read by email, reply by email. Most members will prefer the web interface here for posting and replying to messages.

    NavList is more than an online community... more about that another day.

    © Copyright notice: please note that the rights to all messages and posts in this discussion group are held by their respective authors. No messages or text or images extracted from messages may be reproduced without the explicit consent of the message author. Email me, Frank Reed, if you have any questions.

    Join / Get NavList ID Code

    Name:
    (please, no nicknames or handles)
    Email:
    Do you want to receive all group messages by email?
    Yes No

    A NavList ID Code guarantees your identity in NavList posts and allows faster posting of messages.

    Retrieve a NavList ID Code

    Enter the email address associated with your NavList messages. Your NavList code will be emailed to you immediately.
    Email:

    Email Settings

    NavList ID 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