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antoine.m.couette@club-internet.fr wrote:
> Instead of
> reducing the observed sextant distance between limbs into a gecocentric
> Centers distance, Arago first only and simply reduces the sextant
> distance into the topocentric apparent distance between refracted
> centers. And then from CT (Connaissance des Temps) he works "backwards"
> - as we would say - starting from its published (geocentric) equatorial
> coordinates into "CT derived" topocentric apparent distances between
> centers at two times (hopefully supposed to be) around the observation
> time.

My method is similar. I assume the topocentric separation angle and
altitudes are linear functions of time, latitude, and longitude. Those
last three quantities are the unknowns in three linear equations, which
I solve. Of course the functions are not exactly linear, so the solution
merely gives improved estimates of the unknowns. This is repeated until
the result converges to the desired accuracy.

About a year ago I described the method in more detail, and solved a
real lunar:
http://www.fer3.com/arc/m2.aspx?i=107273&y=200902
http://www.fer3.com/arc/m2.aspx?i=107274&y=200902


> One question though : are short limb distances still a limitation
> nowadays with the powerful computation software available on line ?

I have never tested my program with such an observation. If you have
one, I'll try it.

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