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> Now, about Sun and Moon... what is a preferable way to set images (oil/sky
> image)through view and just what corrections should I use in order to
> finally calculate the departure?

I think these are your choices:

#1.  Bring the sun's image down so it is superimposed over
its reflection in the artificial horizon.  In other words,
the two disks merge into one.  This is likely to be the
most accurate way to make the observation.  To convert Hs
to Ho in this case, first correct for index error in the
usual way, then divide by two, then correct for refraction
(using the Almanac table for stars).  There is no correction
for semidiameter in this case.  For extra refinement, you
could add 0.1' for the sun's parallax if the altitude is less
than about 60 degrees.

#2.  Bring the sun's image down so that its lower limb
just meets the near side of the reflection.  (This is the
reflection of the lower limb, but it appears on the upper
side of the image.)  In other words, the two disks look like
a snowman or a figure 8.  To convert Hs to Ho in this case,
first correct for index error, then divide by two, then
apply corrections for refraction, semidiameter (lower limb),
and parallax using the normal "Sun LL" table.

#3.  Bring the sun's image down so that its upper limb
just meets its own reflection -- another snowman, but
upside down from the case above.  To convert Hs to Ho in
this case, first correct for index error, then divide by
two, then apply corrections for refraction, semidiameter
(upper limb), and parallax using the normal "Sun UL" table.

When observing the moon, my guess is that procedure #2
or #3 (based on whichever limb is visible) will give
a more precise observation than #1, but I can't claim
any experience.  Also, in case #2 and #3, the NA tables
correct for parallax at the same time as for semidiameter,
whereas in case #1 you have to do it separately, and I
don't think the NA makes that easy.

        -- Bill

   

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