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: Lat/Lon by "Noon Sun" & The Noon Fix PROVE IT
    From: George Huxtable
    Date: 2009 May 1, 23:50 +0100

    Jim Wilson wrote, about his solution to the second simulated data-set that 
    was provided-
    
    You're right. So, I did George's second set, with the altitude-time lines
    fit by eyeball only. LAN is at 12-35-40.
    
    Latitude: 55°36.4'N, Longitude: 9°20.8'W
    
    The time between maximum altitude and LAN looks to be about a minute
    short, but there's no way the given data can get to that.
    
    ====================================
    
    The original data for the second test-set, which was time-coded as 
    39930.595727
    was -
    latitude 55º 37.2' N, so Jim's result was out by 0.8' (to the South)
    longitude 10º 58.2'W, so he was out by all of 97.4 ' (to the East) or 55 
    miles!
    
    This is such an immense discrepancy (getting on for 10 standard deviations 
    out from the computer curve-fitting prediction, though that was for a 
    somewhat different data-set) that I suspect something must have gone wrong, 
    either with Jim's analysis or with the data that (with Dave Walden's kind 
    help) I provided. It needs looking at more seriously. The first thing to 
    check is to make sure that we were talking about the same time-coded data 
    set, in which the first altitude of the time series (at 12:12) was at 
    10.5200 (10º 31.2').
    
    I'll need to get out a bit of graph-paper, but it's late now, so it has to 
    wait 'til the morning.
    
    ================
    
    I'm sorry that Jim had to wait for that result. I've been away for a few 
    days in Whitby, North Yorkshire, but it had a navigational connection. They 
    were having a bit of civic junketing about a nice exhibition, at the Captain 
    Cook Museum, about Cook's time in Canada, which had some of his original 
    manuscript charts of Newfoundland on display. Also the original wooden 
    "little midshipman", the half-size figure which stood outside Norie's 
    original London shop, clutching an immense Hadley quadrant, (with somewhat 
    dubious optical detail), which has been loaned from the Dickens museum. If 
    you're a Dickens fan (I'm not) you might be familiar with the fictional 
    instrument maker in "Dombey and Son" (1844), whose trademark was based on 
    that same figure.
    My involvement was a very marginal one in a bit of the research that went 
    into the exhibition.
    
    George.
    
    contact George Huxtable, at  george@hux.me.uk
    or at +44 1865 820222 (from UK, 01865 820222)
    or at 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK.
    
    
    --~--~---------~--~----~------------~-------~--~----~
    Navigation List archive: www.fer3.com/arc
    To post, email NavList@fer3.com
    To unsubscribe, email NavList-unsubscribe@fer3.com
    -~----------~----~----~----~------~----~------~--~---
    
    
    

    File:


       
    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