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Bill N.

As I went over my texts with a fine-tooth comb, it would appear that phase
has been built into GHA and declination for the past two decades.  The
additional corrections are, as you stated, for parallax.

Thank you for clearing up my confusion.

Bill B.

> 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.

   

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