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On 3/3/2017 12:43 AM, Steve E. Bryant wrote:
> Dear NavList,
>
> According to news sources, Venus is entering retrograde motion today,
> March 2, 2017.  Apparently, whether the “v correction” is negative or
> not is not one of the ways to realize that Venus is entering retrograde
> motion.
>
> How can one tell, by using the Nautical Almanac, whether a planet is in
> retrograde motion or not?

The Nautical Almanac makes it clear in its explanation section the
hourly increase in the GHA of the Sun AND PLANETS is 15d precisely  and
Aires 15d 2'.46 (15d2' 26".6). If retrograde motion is measured against
a star field when the V correction falls below 2'.46 the planet is in
retrograde. The planets V corrections are a three-day averages (as are
the planets SHAs) and stated in tenths of an arc minute, so that narrows
it down to May 1. 2, or 3. For all practical purposes you can ignore
SHAs and compare the rate of change of Aires and the planet's GHA. When
the difference becomes a hair under 2'.46d , you have it as close to the
day and time as you can come with the NA IMHO.

According to my almanac, the V correction for Venus becomes 0 in early
June. Thens its back to prograde motion.

   

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