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Re: additional planet corrections...
From: Bill Murdoch
Date: 1999 Nov 23, 7:13 PM
From: Bill Murdoch
Date: 1999 Nov 23, 7:13 PM
As Chuck said the additional correction for Mars and Venus is for parallax. It is needed because those planets can be close to the earth and the observer may not on a line between the center of the earth and the planet. You can find that in section 13 of the Explanation in the back of the almanac. "...but additional corrections for parallax (page A2) are required for Venus and Mars." Be aware that from 1952 to 1984 the additional corrections for Venus allowed for parallax and for phase. The phase correction was required because the tabulated position for Venus was for the planet's center of disk. From 1985 onwards the tabulated position of Venus was for its center of light. Old text books (and some newer ones) still discuss the phase correction, but is no longer needed. See B.D. Yallop, NAO Technical Note Number 55, The Phase Correction of Venus. Bill Murdoch Bill Murdoch
