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    Russian data
    From: Dave Walden
    Date: 2021 Jun 30, 13:11 -0700

    http://iaaras.ru/en/dept/ephemeris/online/

    russian data (and easy access to US and French as well)

    if you get as far as topocentric, you need to think like a russian astronomer.  I.e., coordinates are: 

    long

    rho sin phi

    rho cos phi

    where phi is latitude.

    recall WGS-84 constant:

    earth flattening=1/298.257223563 (or 1-1/f  =  0.996647189)

    then, if u  = atan( 0.996647189 tan phi)

    we have:

    rho cos phi = cos u

    rho sin phi = 0.996647189 sin u

       
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