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Re: Baily's Beads and the lunar distance
From: Brad Morris
Date: 2017 Feb 8, 21:18 -0500
From: Brad Morris
Date: 2017 Feb 8, 21:18 -0500
Hi Frank
I remember our discussions on this point quite well. No intention to steal any thunder whatsoever. I saw Baily's Beads and immediately flashed on our earlier conversation.
I jotted down some thoughts and tried to get a sense of the scale of the problem. I quickly realized that the limb shape was not in my grasp, so I thought to bound the problem at a theoretical maximum. So deepest and tallest came to mind, with a little proportional arithmetic. That yielded the theoretical maximum it could ever be, with the understanding that it was clearly less.
From the chart provided, it appears that we can see a 5 arc second peak to valley around the top, by the "N" designation. It could just as easily be 4, I make no serious claim with a mark one eyeball.
You wrote
Few of the manual methods for clearing lunars have ever included these small elements. Indeed, few of the modern computer methods have included these factors. Needless to say, my online clearing tool on my website at reednavigation.com/lunars/ has included all these small corrections for over a decade. Everything larger than an arcsecond in the clearing process has been accounted for, I believe, except the lunar profile (topography) correction which can amount to as much as two or three seconds.
You can be rightly proud of your tool Frank. No question about it, it's darn good.
I only hope that perhaps this conversation will finally kick start the topography correction!
Brad
