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Sean,

The first correction using the NA Moon altitude correction table corrects for refraction, mean parallax, lower limb semi-diameter, and augmentation. Because of the eccentricity of the Moon's orbit there needs to be an additional correction to compensate for the difference from the mean. This is done in part two of the NA Moon correction table. For lower limb just add the L column correction using the daily page HP value. For upper limb add the U column correction using the daily page HP value then subtract 30'.

As a check try using the Pub 208 Moon altitude correction tables. If absolute precision isn't needed then use the Pub 208 Moon altitude correction table for bubble observations then adjust by the semi-diameter of the Moon from the daily pages.

Hopefully I explained this right. If not then someone else will weigh in to better explain.

Greg Rudzinski

Sample Plots and a Question
From: Sean C
Date: 2013 Jun 13, 20:34 -0700
All:

Here is a link to a PDF of some plots I did recently using those postscript plot sheets and a homemade reduction form for HO 229:

https://db.tt/Zg4zzpcU

After looking over some of my plots I realized I don't fully understand the corrections given in the Nautical Almanac for the Moon. I looked up the explanation in the Almanac, but didn't find it satisfactory. So my question: Is the first correction (from the upper table) a combination of refraction and semi-diameter and the second (from the lower table) for parallax in altitude?

I set the form up that way because that's the way I understood the corrections for Mars and Venus to be handled. (Correct me if I'm wrong, please!)

Thanks,
Sean C.

PS:

If anyone wants that reduction form, I have it saved as an Excel spreadsheet. I can email it or post it here. :)
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