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    Re: Daytime Venus Lunar
    From: Greg Rudzinski
    Date: 2012 Aug 13, 12:22 -0700

    Kermit,

    I can do one better for you. I have taken a digital photo using a 200 mm lens set at ISO 200, 1/250 sec, f 11 on infinite focus. The minutes of arc per pixel has been previously calibrated at .0975 minutes of arc per pixel. Measured pixels from Venus center to Moon near limb is 403 pixels for a measured angle of 39.3'

    Attached is a rather spectacular result considering how close Venus is to the Moon.

    If you inspect the image it is apparent that Venus is oval and yes I did measure from the center of the oval on the previous sextant measurements.

    Greg Rudzinski

    [NavList] Re: Daytime Venus Lunar
    From: Antoine Couëtte
    Date: 13 Aug 2012 11:26
    Hello again from Mauritius !

    Your Venus Lunar is extremely interesting, Greg, because :

    - Venus is very close from the Moon. Accurately clearing such short distances can no longer be made through "classical" Tables, as it can be done only through Computers. Frank, be so kind as to correct me if I'm wrong. And,

    - Venus phase correction is significant in this example.

    IF NO PHASE CORRECTION, and if assuming that both position and UT are correct, I am computing that you "should" have observed a Sextant Distance of 2°05'980 - hence a difference of 0'18 with your records, Greg - and a cleared distance of 2°56'424. I observe a difference of 0'224 in the cleared distances between Frank's results and mine.

    IF PHASE CORRECTION TAKEN IN ACCOUNT IN THE COMPUTATION, and still assuming that both position and UT are "perfect", then you "should" have observed a sextant distance of 2°05'896 - hence a difference of 0'096 with your record, Greg - and a cleared distance of 2°56'342. I keep observing a still relatively important difference of 0'142 between Frank's results and mine as far as cleared distances are concerned (more on this further down).


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