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Re: Artificial horizon
From: Frank Reed
Date: 2026 Sep 6, 09:59 -0700
From: Frank Reed
Date: 2026 Sep 6, 09:59 -0700
Josh Carty you asked:
"How woud I apply corrections for altitudes, the "pre-clearing" step, in lunars? Historically at sea they used +12/-20 (LL/UL). Part of that is a conventional EASY (lazy?!) dip value. No dip with an AH, so what would you use?"
Great minds think alike. I answered a very similar question by email a few days ago.
For the pre-clearing step in lunars, as always you do the index correction and then divide by two. Assuming Sun overlap and Moon overlap altitudes, there's nothing more to do --no +12/-20 corrections since those corrections are dip +/- SD. Naturally you still have to add the exact SDs of Sun and Moon for the lunar distance angle itself in that "pre-clearing" step.
Frank Reed
