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Re: Letcher's Lunars Math
From: Frank Reed CT
Date: 2004 May 31, 22:23 EDT
From: Frank Reed CT
Date: 2004 May 31, 22:23 EDT
Last week, George H wrote:
"Unfortunately, that table handles "distances", angles across the sky, up to 90deg, and no further. I think there would have been no problem in extending the table to 120deg, but
Letcher didn't do that. So once a user gets to correcting for refraction, with a lunar distance greater than 90, he is outside the limits covered by table 15.2. What does he do, then? Thoughtfully, in the caption to that table 15.2, Letcher has provided the expressions that it is based on."
Wow. OK, thanks. Now I see what you were getting at. That strikes me as a very trivial issue considering --as you note here-- that the equation to calculate any value is right there in the caption of the table. The method in Letcher is correct just as it is (except for the potential errors in clearing the distance of up to a few tenths of a minute of arc which Letcher himself describes in the book).
Frank R
[ ] Mystic, Connecticut
[X] Chicago, Illinois
"Unfortunately, that table handles "distances", angles across the sky, up to 90deg, and no further. I think there would have been no problem in extending the table to 120deg, but
Letcher didn't do that. So once a user gets to correcting for refraction, with a lunar distance greater than 90, he is outside the limits covered by table 15.2. What does he do, then? Thoughtfully, in the caption to that table 15.2, Letcher has provided the expressions that it is based on."
Wow. OK, thanks. Now I see what you were getting at. That strikes me as a very trivial issue considering --as you note here-- that the equation to calculate any value is right there in the caption of the table. The method in Letcher is correct just as it is (except for the potential errors in clearing the distance of up to a few tenths of a minute of arc which Letcher himself describes in the book).
Frank R
[ ] Mystic, Connecticut
[X] Chicago, Illinois
