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Re: Lat/Lon by "Noon Sun" & The Noon Fix PROVE IT
From: George Huxtable
Date: 2009 Apr 25, 23:37 +0100
From: George Huxtable
Date: 2009 Apr 25, 23:37 +0100
With Dave Walden's kind help, here are 20 sets of simulated data from "around noon", adapted for Jim Wilson's special method of analysis, though anyone else is welcome to have a go. The aim is to deduce the position, which I have not (yet) disclosed, that on 21 Dec 2008, at 12.40 GMT, is somewhere between 55º 30'N and 56º 30'N in latitude, and between 9º W and 11ºW in longitude. The Sun dec. has been taken as -23.442º and the equation of time 1min 44 sec (the Sun transiting at Greenwich that much before noon GMT). The vessel has a Northerly component of speed of 10 knots +/- 1 knot variation (rms), but you are not asked to deduce that. You can presume that all necessary corrections have been made to the sextant observations, without additional error. Each set comprises 13 altitude observations. The first 5 were taken at times 1 minute apart from 12:10 to 12:14, then a gap, then a set of 3, 5 minutes apart, from 12:35 to 12:45. Then a variable gap again, waiting for falling altitudes to start to match the values that were seen on rising. From time T (which time is given in a column to the right) to time T+4, there are 5 more altitudes given, at 1 minute intervals. In a previous posting I had said that time T would be the the first moment that the altitude, observed at whole-minute intervals, fell below its previous value at 12:14. In fact, it's turned out that instead, the comparison was made with the altitude (which isn't printed) at 12:15, rather than at 12:14. I doubt if this will upset Jim's analysis, but if it does, or if he needs any other change in the simulation of data, perhaps he will say. Each data set has, in the rightmost column, an identifier code attached to relate each test set with its solution. Sorry for the delay. 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 -~----------~----~----~----~------~----~------~--~---
File: 108048.noon3d.doc
File: 108048.noon3d.rtf