NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Nitpicking on Moon Height Corrections
From: Peter Hakel
Date: 2013 May 30, 06:13 -0700
Frank,
Thanks for your replies.
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From: Peter Hakel
Date: 2013 May 30, 06:13 -0700
Hi Kermit,
In the attached spreadsheet the Moon parallax (B10) can also be corrected for the oblateness of the Earth by entering the latitude (E8) and azimuth (E9) in the yellow cells of column E. That said, even though it is there for completeness, I myself have never used it. My source for this formula is the Commercial Edition of the Nautical Almanac (attached PDF).
Peter Hakel
http://www.navigation-spreadsheets.com/alt_corr.html
In the attached spreadsheet the Moon parallax (B10) can also be corrected for the oblateness of the Earth by entering the latitude (E8) and azimuth (E9) in the yellow cells of column E. That said, even though it is there for completeness, I myself have never used it. My source for this formula is the Commercial Edition of the Nautical Almanac (attached PDF).
Peter Hakel
http://www.navigation-spreadsheets.com/alt_corr.html
RE : http://fer3.com/arc/m2.aspx/Nitpicking-Moon-Height-Corrections-FrankReed-may-2013-g24194
Frank,
Thanks for your replies.
You wrote :
QUOTE
"It may be worth mentioning that the instructions in the NA also note that there is a small correction for oblateness which is necessarily ignored in the calculation of the Moon's standard correction tables. In the section in the Nautical Almanac Explanation with "methods and formulae for direct computation", there is actually a little procedure outlined for calculating those extra couple of tenths of a minute of arc for the Moon's altitude correction. This is hardly a practical concern, but it's nice that they included it. I've never bothered with that correction or the calculation included in the NA, but it's a nice, short formula. How close is it? How do you results compare with that nice, short formula?"
UNQUOTE
QUOTE
"It may be worth mentioning that the instructions in the NA also note that there is a small correction for oblateness which is necessarily ignored in the calculation of the Moon's standard correction tables. In the section in the Nautical Almanac Explanation with "methods and formulae for direct computation", there is actually a little procedure outlined for calculating those extra couple of tenths of a minute of arc for the Moon's altitude correction. This is hardly a practical concern, but it's nice that they included it. I've never bothered with that correction or the calculation included in the NA, but it's a nice, short formula. How close is it? How do you results compare with that nice, short formula?"
UNQUOTE
Thank you very much for mentioning this information I had been totally unaware of. Certainly it must be quite instructive to take a closer look at such little correction procedure. However, and in spite of careful research into the Copies I have at hand, namely:
- US paper editions 1982 and 1983 (EXPLANATION, Section pages 254-261), and
- PORTUGAL .pdf 2013 edition (INSTRUÇÕES PARA USO DO ALMANAQUE NÁUTICO, pages 257-270),
nowhere have I been able to locate such nice and nifty procedure, whilst you have made my mouth thirsty here. And I bet that when I have implemented it, results will be extremely close to the 3D space computation ones I have published.
- US paper editions 1982 and 1983 (EXPLANATION, Section pages 254-261), and
- PORTUGAL .pdf 2013 edition (INSTRUÇÕES PARA USO DO ALMANAQUE NÁUTICO, pages 257-270),
nowhere have I been able to locate such nice and nifty procedure, whilst you have made my mouth thirsty here. And I bet that when I have implemented it, results will be extremely close to the 3D space computation ones I have published.
Would you then be so kind (yourself or any other NavList Member) as to send me a copy (if scanned document: .pdf format preferred) of such little procedure ? Thank you very much in advance.
*******
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File: 124205.alt_corr.xls
File:
