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A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Lunars: 10/27/2013
From: Paul Hirose
Date: 2013 Nov 03, 10:22 -0800
From: Paul Hirose
Date: 2013 Nov 03, 10:22 -0800
One must "turn up the gain" to .01″ or higher to see a difference
between 40 feet height of eye and 45 feet 10 inches:
At 40 feet:
83°23′12.394″ center to center, unrefracted
1′41.625″ refraction
At 45 feet 10 inches:
83°23′12.394″ center to center, unrefracted
1′41.603″ refraction
Only the refraction (which is the decrease in separation angle
between the body centers) is different. That's calculated from a
troposphere model, but in the real world I believe small temperature
gradients around the observer will have greater effect. In any event,
the slight change in refraction is insignificant compared to the
irregularity of the Moon's limb, which surely exceeds a tenth of an arc
second.
When I added 1000 feet to altitude, the unrefracted separation angle
increased only .081″.
The above values are intended to show the sensitivity of the angles to
variation of height. I don't mean to imply my software is that accurate
in absolute terms.
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