A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Mark Coady
Date: 2017 Aug 21, 15:27 -0700
I recall that the optimum range for Lunars was 45 -110 degrees, with a note that below 20 degrees there were math problems. I know part of it extended from the accuracy of altitudes taken based on the relation of Sin (LD) and Tan (LD) functions to the Cos of the altitudes.
With these very short lunars, other than with a computer calcualted altitude feature, would this normally be used? even though the denominator around 60 degrees is nice, the numerator starts to demand high precision. It looks as if the altitude accuracy would be in the neighborhood of .1' along with the required lunar distance. Of course if you needed a lunar on the new moon....what else can you do.
Is there perchance and illustration of how the phase method produces an LOP mathamatically? I get the concept in that that relationship can only exist on a specific view cone, but I'm not picking up the first hint on how to specifically calcualte it.
Also, I took a decent shot of the clipse through my 7x scope on my Sextant using my cell phone. Thats an interesting juggling act. Fortunately did not drop either. Anyway, I noticed many camera phone snapshots show the disc as fully and uniformly illuminated.
Is that a function of the lens refraction or reflection in the lenses that is canceled shooting through the filters?