NavList:

I took Frank's online Lunars course in Nov, 2022. I have recently been reviewing the notes I took during all of the courses that he offers, not just the Lunars course. I live inland where I don't have a true horizon that I can use, so my actual sextant work is limited. I have attempted to measure a lunar distances in the past, but have not tried to clear them - until now.  I made my best effort to obtain a LD on 02-04-2024 at 10:52:50 MST (17:52:50 UT). My sextant is a Davis 25 which only has a 3X scope. I haven't adjusted it in a while, but I try to handle it carefully (no index error, I'm assuming). I have a new appreciation of how hard it is for a novice to shoot a lunar. On my sextant I got a near-limb reading of 69° 06.8'. I couldn't use my sextant to measure the sun and moon altitudes, so I thought I would use Stellarium to get them. The values that I get for the alt sun (apparent) and alt moon (apparent) are a little higher than the displayed values when the effect of the atmosphere is turned off - so this setting seems to eliminate the need to correct for refraction. Is this correct? Also, do I need to do S.D. corrections for the sun and moon, or are the altitudes calculated based on the center of the bodies? If one or two Navlisters could let me know if I'm on the correct path, I would appreciate their responses. I'm going to go ahead and clear my LD as per Frank's method (Thomson Tables) covered in the Lunars class and then check my results with his app. My location is 40.726° N, 111.811° W. I will post my results.

As an aside, I am including 2 screen shots from Stellarium zoomed-in to the sunset at my location yesterday with the sun just touching the horizon, with and without the effect of the atmoshpere. It seems to show what we all know: at the time that we se see the sun just touch the horizon, it is already below the horizon.

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