A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Frank Reed
Date: 2015 Aug 29, 15:43 -0700
Jaap vd Heide, you wrote:
"Steven Webster (Utrecht University) generates precomputed lunar distance tables."
Yes, those are fine. Just as a reminder, you can get all the same data and more, at slightly improved accuracy (see PS), with more display options from my online tools. Here are the hourly lunar distance tables for all available navigational stars and planets for today: reednavigation.com/lunars/[...]. To try out different options, go here and select Predicted Lunars. I don't include prop.log values but the same information is found simply by looking at the hourly rate of change. Rate of change, of course, is only relevant when you're trying historical lunars where the purpose is to get GMT.
Among the options available from my online tools, you can enter your location and the tables will then only list lunars when both bodies are above the horizon. Another option allows you to display lunar distances by Greenwich Apparent Time which was the way they were generated and listed in the heyday of lunars in the original Nautical Almanac from 1767 to 1834.
PS: Steve Wepster's lunar distance tables are consistently off by at least one-tenth of a minute of arc. Easy to correct if you know about it, and only a very small difference, but if you're trying to test your skills, it may matter.