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Jim, you wrote:
"I tend to use the 2X monocular mainly because using the 12X inverting
scope is such a bear to use. Even though I don't get the precision the
average seems to work out well and even with the 2X, the spread in the
sights is normally around +/- 0.2'."

Wow. That's very good. Now you've got me envious.  I don't get results
that good with a 2X scope, but then again, the sextants I use have all been
banged around quite a bit. Can you remind me again what type of sextant you
use? Is it a SNO-T? I tried Alex's SNO-T last year and was very impressed
with it. Say, where IS Alex anyway??

And you wrote:
"Besides sextant range, what other criteria does your online program
use for predicted usable lunars?"

I believe you're referring to the predicted lunar distances, right?

If you select the "Visible at DR Only" option, then distances are listed
only when both bodies are higher than 5 degrees. For star and planet lunars,
the Sun must be more than 5 degrees below the horizon. For Sun-Moon lunars,
the true LD must be greater than 25 degrees. And before someone suggests
that these limits are too restrictive or whatever, I would note that the
"Visible Only" box can be left unchecked. So, for example, if you want to
shoot a Moon-Venus lunar in daylight, it's no problem.

If you select the "Usable Only" option, then the true LD must be greater
than 10 degrees and less than 125 degrees. Also the rate of change of the
lunar distance has to be greater than 20 minutes of arc per hour (when
you're dealing with one of the lunar stars that's well off the ecliptic,
like Altair, the Moon's motion can actually be perpendicular to the lunar
distance so that measuring the LD cannot yield a useful value for GMT). And
here, too, if these restrictions seem too restrictive in any way, just
de-select the option.

 -FER
http://www.HistoricalAtlas.com/lunars


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