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    Re: Exercise Lunar Distance with Mercury
    From: Antoine Cou�tte
    Date: 2009 Sep 23, 03:07 -0700

    Frank,
    
    
    Thank you very much for your quite interesting feedback and comments.
    
    
    May I ask one question here regarding Lunars with "significantly phase angled 
    planets" (i.e. Venus and Mercury)? Since phase angle can be fully accounted 
    for in Body Coordinates Computation, what would you think of shooting such 
    "Inferior Planets Lunars" through observing this Planet through carefully 
    selecting one of your "opaque" glasses on your sextant (i.e. brightness 
    reducing glass, sorry I do not remember the name of such glasses in English, 
    and I think that you would select the one with the least efficiency if you 
    have one installed), so that it would reduce the ?Planet to a "light 
    pinpoint" ?
    
    This method might also take good care of "getting rid" of additionnal 
    observation inaccuracies due to the Planet semi-diameter because if you 
    swing-kiss the Planet center of light instead of some Planet limb, you then 
    can just ignore Planet Semi-diameter value (i.e. make it equal to Zero) in 
    your computational data processing.
    
    The reason I am asking this is simply because you have indicated more than 
    once that you do not seem as confident with Planet Lunars than with Stars 
    Lunars. The "slightly opaque glass" trick would aim to reducing the planet 
    into a light pinpoint mostly similar to a star light pinpoint. The only 
    remaing difference between Star and Planet Lunars would then essentially be 
    correctly handling horizontal parallax correction for the Planet, an effect 
    which on some occasions can reach 0.4' for Venus.
    
    
    Thanking you for your kind Attention, I am remaining
    
    most Sincerely Yours, and
    
    thank you again for the Navlist site which I am truly enjoying more and more
    
    
    Antoine
    
    
    Antoine M. "Kermit" Couette
    
    PS : Did you have the opportunity to cross-check the results I published and 
    commented in thread "NavList 9816" (also found in "Navlist 9868")?
    
    In NavList 9816 I did reduce Lunars in an "UNCONVENTIONAL WAY". Instead of 
    reducing them to the center of the Earth (to further compare them to 
    published/computed geocentric Lunar Center/Body Center distances) I choose 
    here to directly compare Sextant readings (corrected only for Instrument 
    error) with computed sextant readings derived from an assumed knowledge of 
    the environment, whether UT, Observer's position, Lunar Sextant Distance 
    corrected for instrument error, and Lunar/Body sextant heights.
    
    
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