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A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Photographic lunars
From: UNK
Date: 2009 Dec 13, 01:40 -0800
From: UNK
Date: 2009 Dec 13, 01:40 -0800
Douglas Denny writes: > The error difference using the Moon in you photographic lunar method could > most likely be horizontal parallax and other errors. Does the method of > translation of photographic star/Moon distance into RA and Dec incorporate > clearing the distance? 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. > Further - Of course it must clear the distance with only arc seconds of error. > Refraction errors maybe? Differential refraction across the lunar image is currently unaccounted for, but it should be really small---I'll check it. Could also be tripod jitter, bad estimate of lunar position, or residual problems with the star positions. Differential refraction across the star field would be partially (mostly) compensated for by the distortion terms in the camera/lens model. This image is fairly high in the sky, though (about 55 degrees altitude), so that's more benign than something at 20 degrees. Cheers, Peter ------------------------------------------- [Sent from archive by: pmonta-AT-gmail.com] -- NavList message boards: www.fer3.com/arc Or post by email to: NavList@fer3.com To , email NavList+@fer3.com
