A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Frank Reed
Date: 2009 Dec 13, 19:45 -0800
Peter Monta, you wrote:
"Maybe it's cheating a little bit, but the clearing is done for me by
the planetarium program when calculating the "known" lunar position.
A real sight reduction would do this in reverse, I guess."
Nah. Not any more. If you're going to allow computers into the game, and obviously there's no way to do any of what you're doing without one, then this approach is perfectly acceptable. It's "real sight reduction" --just computationally laborious!
And you wrote:
"Differential refraction across the lunar image is currently unaccounted
for, but it should be really small---I'll check it."
A more sophisticated algorithm could handle this easily. Though you may not be able to see it, the output from that astrometry software is a transformation table that gives the RA and Dec for any point in the image. Even if the Moon is severely flattened, as it would be when very low in the sky, the transformation table would account for that. In general, though, for altitudes above about 12 degrees, refractional flattening of the Moon is insignificant.
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