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> -----Original Message-----
> From: Navigation Mailing List
> [mailto:NAVIGATION-L@LISTSERV.WEBKAHUNA.COM]On Behalf Of Jared Sherman
>
> Surely the range from 68.6-84.6 minutes isn't allowably precise for you
> though? 

Jared, That was the range of values for the months where the minutes values
exceeded 60'.  As you anticipated, each month's value is a single digit
precise to 0.1'.  Oh wait, I just spotted the VBG!  :)

----------
However, now that I look more closely at those star SHA/Declination tables
on pages 268-273, almost none of the other stars have a similar situation.
In the 2004 NA only 18 out of 2,076 SHA entries exceed 59.9'!  I would have
thought that based on random chance alone a far greater proportion would
range over two adjacent whole degree values.  What causes this seeming
coincidence?

One way to think of the problem is this:
- Assume that the whole minutes portion does not exceed 84.9 (in fact
Polaris is the largest such value in 2004: 84.6)
- There are 84 x 10 = 840 possible values for the minutes portion, ranging
from 00.0' to 84.9'.
- The proportion of values larger than 59.9 in the range of numbers from
00.0' to 84.9' is (84.9-59.9)/84.9 = 25/84.9 = 0.29, or 29%.
- There are 12 months in a year and 173 stars, for a total of 2,076 entries.
- Based on random chance alone, 0.29 * 2,076 = 602 entries would be 60' or
more.

But given that SHA changes in very small increments for each star, then I
have not correctly stated the odds of a star having an SHA that ranges over
two whole degree portions.

At this point in my thinking I run out of gas, in part because I'm beat
after teaching a marine radio course all day and the Carlsberg Light is
kicking in, and in part because my understanding of probability math is
weak.

What am I missing?

Jim

   

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