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    Calculating Horizontal Parallax
    From: Sean C
    Date: 2014 Apr 2, 14:08 -0700

    After some searching, I found a formula for calculating horizontal parallax:

    sin(HP)= radius of Earth / distance to body

    I seem to be able to reliably reproduce the corrections for Venus in the NA using the above formula and the formula for PA. I'm obtaining the AU distance from MICA. I have two questions, though:

    1) Is a figure of 6,378 km for the radius of Earth sufficient for most calculations?

    2) What level of precision is necessary for accurate results? For instance, I've been using 0.0000426 AU for the radius of Earth. Also, MICA gives distances to nine decimal places. Is it necessary to use all of them?

    Thanks in advance for any insights!

    -Sean C.
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