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: Accuracy of ephemeris
    From: Bill Lionheart
    Date: 2017 Oct 16, 21:02 +0100

    Good point. Just an idea: how about we video the view through the
    sextant with the index arm fixed as the body moves above the horizon,
    then calibrate the pixel to arc correspondence. Video rate is 25 Hz at
    least. Would that buy is some more accuracy at very little expense
    (video cameras are so cheap they fit them in phones after all).
    
    Not that we need that accuracy at sea on the time scale of a passage,
    just doing this for fun.
    
    Bill
    
    On 16 October 2017 at 15:28, John D. Howard  wrote:
    >  Bill,
    >
    > The "Gold Standard" is the data put out by the Jet Propulsion Lab.  They
    > have a public website called Horizions that you can access ( some of ) their
    > data.
    >
    > The limit on cel nav ( IMHO ) is time.  We only record our time to the
    > second and the Nautical Almanac only shows data to the second but that is
    > .25 minutes of arc.  Untill we record the sight to the hunderth or even the
    > thousands of a second we canot get better than .25 MOA - hard to do using a
    > hand held sextant.
    >
    > John H.
    >
    > View and reply to this message
    
    
    
    --
    Professor of Applied Mathematics
    University of Manchester
    http://www.maths.manchester.ac.uk/bl
    

       
    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