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: Coordinate precision
    From: Brad Morris
    Date: 2019 Jul 3, 00:40 -0400
    Frank, Thanks for clarifying Bob's link. 

    That cartoon illustrates something we have talked about in the past.  Just because we have 15 decimal digits on our calculator doesn't mean they make sense.

    At 3 decimal digits (.001° vs .002°), we are discussing just over 100 meters.  That's really good enough for SAR, and plenty good enough for CN.  That value is better than 0.1' , our nominal least significant  digit.  The true value is 0.06' or 3.6".

    At 0.000,000,000,000,001°, its 4 billionths of an inch.  Serious overkill, but hey, your calculator said it, so it must be true.  SAR doesn't need it.  You don't need it.  Its at least 12 orders of magnitude beyond reasonable.


    On Tue, Jul 2, 2019, 9:17 PM Frank Reed <NoReply_FrankReed@fer3.com> wrote:

    Bob Crawley posted a copy of a clever cartoon earlier today. Because of a quirk in the way it was posted, it took interminably long to load, taxing the limits of most web browsers and email clients. Here is a plain vanilla link to it at the source: coordinate precision cartoon.

    Frank Reed

    View and reply to this message

    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