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On 2020-01-12 17:46, Jim Rives wrote:
> I think this may have been easier if I actually took altitudes for the sun 
and the moon, but there was no horizon.  I'd love to be able to use 
Stellarium, or some other tool, to get the altitudes so I can mess with this 
frequently and actually get fluent it the methods.

If you can run a Windows app, my Lunar program can generate simulated
altitude observations of either limb (or body center), including
refraction (corrected for temperature and pressure) and dip if desired.
For example,

Sun
  28°33.60' computed unrefracted center altitude
    -16.26' unrefracted semidiameter
      1.65' refraction
  28°18.99' apparent lower limb altitude
      0.00' dip
  28°18.99' apparent altitude + dip
152°22.92' predicted azimuth

I did not turn on the dip feature because the computation was run for my
location, where the height above sea level would result in an immense
dip value!

Expected lunar distance is also computed, which is a big convenience if
you shoot a star lunar since the sextant can be preset. It also predicts
the position angle (with respect to the zenith) from the Moon to the
other body. That gives the sextant orientation (about the line of sight
to the Moon) to bring both bodies into coincidence.

http://sofajpl.com/lunar4_4/index.html

The installer is just a zip file which you extract into any convenient
folder on your system. Default behavior is that it creates a new folder
which contains all the application files. Other than that, it does not
modify your system. If you want a shortcut to the executable on your
desktop, you must make it by hand.

As installed, the program cannot do anything useful. It needs a JPL
solar system ephemeris, and one is not included. It's my belief that
users should learn to do that themselves. You need only decide which
ephemeris you want, download a couple ASCII files (one is the ephemeris
itself, the other a "header"), and transform the files into a binary
ephemeris. A function built into my program does that last step. There
are instructions on the web site.

The program is really designed for my own needs, but as a courtesy I
offer it free to the public.

   

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