NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Greg Rudzinski
Date: 2012 Mar 26, 04:45 -0700
Alan,
The on-line calculator gives a precise calculation using exact latitude and declination but does lose some reduction precision as time from LAN increases beyond 30 minutes. Hansen's tables are less precise using visual interpolation of latitude and declination but seem to reduce ex-meridians better than the calculator formula out to 60 minutes from LAN. Why this is so is not obvious and perhaps there is a further correction in the Hansen tables to extend the useful XM time window.
Greg Rudzinski
[NavList] Re: Ex-meridian On-line Calculator
From: Alan S
Date: 25 Mar 2012 21:58
Greg:
What is the connnection/relationship if any, between what you linked here and Hansen's Improved Ex-Meridian Tables, not so often come upon these days.
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