Next message: Bill: "Re: Venus"
Bill has asked about how to use the Nautical Almanac when measuring
a lunar distance from Venus -- in particular, how to take the phase of
Venus into account.
As several have mentioned, the main pages of the Almanac tabulate the
geocentric apparent position of the "center of light" of Venus (and Mars),
which already takes phase into account, so those can be used directly.
Bill seems to be trying to use the "additional corrections" and argues
(correctly) that those are only good for correcting altitude.
Unless I'm confused, I'm pretty sure the "additional corrections" are
primarily for parallax, and not at all for phase. As such, you would use
them along with refraction in the clearing process to adjust between true
and apparant altitude for Venus.
Hoping I'm not all wet,
-- the other Bill
