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    Re: Lunar Distances with Alex's SNO-T
    From: Bill B
    Date: 2006 Dec 02, 23:15 -0500

    Bill, you wrote:
    > "Point being, I seriously doubt the lasers you refer to meet the standards  of
    > both monochromatic and collimated light. "
    
    Frank replied:
    > They're real lasers. They produce monochromatic, coherent light --no
    > cheating on the terminology. All lasers have some beam spread, and you can
    > counteract it, up to the diffraction limit, using a telescope...
    
    Ok. I'm buying into that.  Been shopping.  Found a straight-line laser for
    $5 after rebate at Ace.  It's nice as the height in relation to the eyepiece
    doesn't matter much, and very easy to center on eye-side scope lens, but it
    does not produce the fine spike that a point source produces.
    
    Borrowed a friend's "Taiwan Tom" level laser complete with tripod and all
    the niceties, but the off/on knob is on the front so one cannot center the
    beam up with the scope.
    
    Finally, after realizing batteries for my aging Compaq pen/pointer gimme
    would be $12 and considering that a poor investment as the dot is more of an
    ellipse than a circle, I ferreted out a laser pointer/led light/pen at Wal
    Mart for the princely sum of $2.88!  It works very well, with a fine
    vertical diffraction line.
    
    Refining rigs to mount it now, as well as producing a circle to mount on the
    eye end of the scope with a tiny hole to be sure I am shooting down the
    center of the scope.  Centering the spot on the glass/mirror section of the
    horizon mirror is simple trial and error and can be done satisfactorily by
    eye.
    
    Using George's suggesting on how to determine the distance between the
    horizon mirror and index mirror working points, I set up the rigs for trial
    runs. The distance was only 40 ft, but the results were right on (probably
    beginner�s luck.)
    
    Last sun IE check was 0.788' on the arc.  When matching the predetermined
    mirror distance, the sextant reading was just a hair below 0.8' on the arc.
    
    I'm looking forward to more stringent tests as greater distances.
    
    Thanks for the idea Frank.
    
    Alex
    
    You ready to grab some sextants, a pair of FRS radios and go play?
    
    Bill
    
    
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