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A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Are we most likely not where we are?
From: Bill Murdoch
Date: 2002 Apr 15, 09:27 EDT
From: Bill Murdoch
Date: 2002 Apr 15, 09:27 EDT
In a message dated 4/15/2002 12:06:50 AM Eastern Daylight Time, hprinz@ATTGLOBAL.NET writes:
I am not so sure about that. I think it may be true if the errors are random, but not if they are not. Let’s say I have three bodies at 300, 000, and 060 degrees (the horizon is dirty to the south), and a sextant with an (unknown to me) 5 arcminute error. I reduce my sights, get a nice small cocked hat and am actually 5 miles to the same side of all three LOPs. It seems to me that my most probable position is outside the cocked hat. Now these are non-random errors, but those are the pretty normal (at least for me).
Bill Murdoch
Themost probable position (MPP) is, by definition (!), inside the cocked hat.
I am not so sure about that. I think it may be true if the errors are random, but not if they are not. Let’s say I have three bodies at 300, 000, and 060 degrees (the horizon is dirty to the south), and a sextant with an (unknown to me) 5 arcminute error. I reduce my sights, get a nice small cocked hat and am actually 5 miles to the same side of all three LOPs. It seems to me that my most probable position is outside the cocked hat. Now these are non-random errors, but those are the pretty normal (at least for me).
Bill Murdoch
