# NavList:

## A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding

Message:αβγ
Message:abc
 Add Images & Files Posting Code: Name: Email:
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
manuscript charts of Newfoundland on display. Also the original wooden
"little midshipman", the half-size figure which stood outside Norie's
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.

--~--~---------~--~----~------------~-------~--~----~
To post, email NavList@fer3.com
To unsubscribe, email NavList-unsubscribe@fer3.com
-~----------~----~----~----~------~----~------~--~---

File:

Browse Files

Drop Files

### 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)