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Re: Lat/Lon by "Noon Sun" & The Noon Fix PROVE IT
From: George Huxtable
Date: 2009 May 1, 23:50 +0100
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 , email NavList-@fer3.com -~----------~----~----~----~------~----~------~--~---