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    Re: venus
    From: Herbert Prinz
    Date: 2004 Oct 10, 15:09 -0400

    Michael Dorl wrote:
    > 89.50 west 42.85 north
    > altitude 290 meters
    > temperature 5 degrees C
    > tick.usno.navy.mil time 6-13-06 CDT 11-13-06 Greenwich
    I agree with Frank Reed that the near limb was illuminated, but my own computation
    for it agrees better with George Huxtable's value for that limb. George observes
    correctly that the Moon is about to overtake Venus, which is consistent with the
    GHAs he posts, but then slips in picking the far limb.
    My distances for date and location above, 11:14:10 ET deltaT = 64.4 are
    center Moon / center Venus geoc.                               17? 00' 42.4"
    near limb Moon / center Venus topoc. no atmosphere  16? 06' 01"
    near limb Moon / center Venus topoc. 5?C/1010mbar 16? 05' 08"
    I can post intermediate results from my computations, if Michael Dorl finds that
    helpful for debugging his program. I would have to recompile mine with some traces
    for that purpose. Frank and I should probably also compare work. 0.4' seems too
    much of a difference. I notice that my results disagree with HORIZONS between 2 and
    8 seconds of arc, either because I am using DE200 and they are using DE406, or
    maybe a different refraction model (At least I hope it's nothing more severe.)
    Herbert Prinz

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