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A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Lat/Lon by "Noon Sun" & The Noon Fix PROVE IT
From: James N Wilson
Date: 2009 Jun 7, 18:19 -0700
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From: James N Wilson
Date: 2009 Jun 7, 18:19 -0700
Dave:
Sorry to take so long to reply, but I've had to untangle myself several
times from being wrapped around the axle. Translating what I do graphically into
mathematics has proved elusive. My analytic geometry is rusty, but I think the
problem is a wrong assumption somewhere.
One of the benefits of the graphic approach is that the exact value of hs
doesn't need to be matched. By taking several measurements, the needed value is
bracketed. I've belatedly remembered that in conjuring up this method, I
initially calculated two values of Dhs for two values
of DWT, thus establishing the different slope of the
adjusted hs vs WT line, and bracketing the selected value. I discarded that
idea in the interest of simplification, although I think it would be needed for
the moon. When I did a check on one of George's problems, a one minute change in
DWT resulted in a three second difference in the time
of meridian passage. So, I think that the simplification is justified.
I still wish I could translate this into mathematics, because that would
allow me to examine lots of cases. I'll keep trying.
Sorry about the lapse. I recollect a joke about that: "As we get older, the
first thing to go is our memory, and I forget what the second one is."
Jim Wilson
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