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Hello, Richard Bash -

And welcome to the NavList.

The "d" at the bottom of the Nautical Almanac columns for the sun and
planets is the rate of change per hour of the declinations of those
bodies.

Because the moon's declination changes so fast, its rate of change is
given in a separate column alongside the declination column. There the
"d" heads the column.

The other "d" (the one Mary Blewitt is referring to in connection with
249 Table 5) is the amount of change in the computed altitude (Hc) as
the declination increases one degree - i.e. from a left declination
column to a right declination column in 249.

Hewitt Schlereth


On 1/29/10, FrankReed@historicalatlas.com  wrote:
>
>
> Unfortunately, a copy of the message copied below was sent out to some
> NavList email recipients with scrambled headers and the subject obscured.
> For those of you who did not get a scrambled version, sorry for the
> duplication:
>
> "Hello. I am living in Hot Springs, Arkansas, and am studying
> celestial on my own. Have several books, including Bowditch.
>
> I am unclear about the so-called "d correction." It seems the d
> number in the dailt pages of the Nautical Almanac should really
> be called a "d factor" or something similar. Mary Blewitt's
> book says to use this d factor to get into Table 5 of H.O. 249.
>
> My confusion stems from no one else mentioning Table 5 (except
> H.O. 249 itself).
>
> Can/would someone explain to me, at the 8th grade level, about
> the d factor for sun, moon and planet shots.
>
> Thanks in advance. E-mail is fine (dickbash[at]bashlaw.com). You
> have a fine resource here. Hope I am accepted as a list member.
>
>
> Regards,
>
> Richard Bash
> Hot Springs, AR"
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