A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Jim Rives
Date: 2020 Jan 10, 17:20 -0800
Here's an excel sheet with the data I have been using. And a picture of the graph I did before running the regression in excel. I wanted to see whether the line I drew on the chart would be considered a good fit. I got the same exact LDobs at 18:00:00 using both methods, as Frank was confident I would.
Frank, I knew the Lunar was going to solve for GMT, not local time. But I was under the impression that knowing GMT and Local Apparent Time (from shooting a noon sight, for instance) I'd be able to find local time... correct?
Anyway... my confusion about Stellarium's altitude was resolved... it is to the center of the body. I am entering the refraction tables in the Almanac with the Stellarium altitudes for each body at 18:00:00, with the atmosphere on, and not adjusting for SD.
Let me know if you have any questions. I am probably going on the slowest clearing of a Lunar ever. I'm saving Frank's web-based solution as a final check of my answer.