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Antoine Couëtte wrote:
> Would you be then able to use the very same coordinates I purposely 
published with extra (non significant) digits so that you could independently 
verify my end-results ? If not, please be so kind as to publish your parallax 
as well as GHA Arietis (or Moon GHA) values for the Observation time 
(23h48m29.0s with as earlier TT-UT=+55.7s).

That's not possible due to the way my SofaJpl astronomy DLL works. The
algorithm is:

1. Get the rectangular coordinates of the observer with respect to the
ITRS. This includes the ellipsoidal shape of Earth.

2. To that vector, apply the transpose of the GCRS to ITRS rotation
matrix to obtain the observer position with respect to the GCRS. This
accounts for precession, nutation, polar motion, and Earth rotation.

3. To that vector, add the ICRS position of the center of Earth. The
result is the position of the observer with respect to the solar system
barycenter.

4. Subtract the above from the ICRS position of the Moon. The result is
the position of the Moon with respect to the observer.

5. Apply the GCRS to ITRS rotation matrix, then the ITRS to horizontal
matrix. The result is the position of the Moon in the observer's
horizontal coordinate system. (I have omitted the corrections for light
time and aberration.)

In that procedure the neither GAST nor geocentric position of the Moon
is computed, and there is no parallax correction. I can generate
geocentric coordinates, but the computation is handled as a special case
where the "observer" has zero offset from the geocenter.

Sorry I could not help. But I think it is sufficient that our intercepts
are practically the same.


> Nonetheless the interest of my unchanged habit to publish my retained
"delta-T" values

It is a good habit, not necessary in an ordinary sight reduction, but
helpful when one requests others to duplicate an unusual computation at
high accuracy. If there are anomalies it eliminates the question about
what delta T in the original poster used.

In this case, the automatically computed value from my program
(interpolated from the Astronomical Almanac table) is only a few
milliseconds different.

Did anyone answer your request for the oblateness correction formula in
the Nautical Almanac?

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