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On 9/12/2014 5:36 PM, Samuel L wrote:
> It would be nice to be able to speed up my sight reductions. It now
> takes around 15 minutes to complete one. That is; from sitting down to
> drawing the LOP on a UPS.

Short of plotting, I can do the reduction on a TI-30XA in less than five
minutes using its 3 memories.

Essentially I enter the decimal portion of the hour past the whole hour
into memory 1. The GHA at the whole hour into memory 2, and the
declination at the hour into memory 3.

I can then use memory 1 (mem1) x 15 to calculate the additional GHA, add
it to the whole hour GHA in mem2, then store that in mem2.

Same procedure for declination (mem3), being careful to use the correct
sign for d for increasing or decreasing declination.

At this point I have GHA and declination for the time of observation in
mem2 and mem3 respectively.

Now I can recall mem2 (GHA) and subtract AP west longitude for LHA,
which I now store in mem2 replacing GHA.

Replace mem1 fractional hour with AP latitude and your ready for the
cosine formula, which should take a matter of seconds with practice. It
is so fast I do it twice to make sure I haven't blundered.

The result is the HC, which I then store in mem2 (replacing LHA) and
calculate azimuth.

For even more fun, a few keystrokes will swap out mem2 with mem3, and
mem3 with mem2. Then use the azimuth cosine formula in the exact same
order (memory slot recall wise) employed for the azimuth and viola--it's
a time sight.

> Another BIG problem is that the font size of
> the Almanac and HO 249  I'll probably go blind, not from the Sun, but
> from straining my eyes.

I'm at the age that drug-store reading glasses draped around my neck are
a permanent part of my attire. Bifocal sunglasses are available which
are very handy for boaters. I also carry an inexpensive magnifying glass
in my sea bag. Or, perhaps we can convince Reader's Digest or Celestaire
to come out with a "large-print" version of the NA ;)

   

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