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    Re: Sextant accuracy (was : Plumb-line horizon vs. geocentric horizon)
    From: Bill B
    Date: 2005 Feb 13, 21:48 -0500

    > Of course my optics laboratory is close at hand (my optics lab is my
    > kitchen...), so I decided to do some simple testing with my own pair of
    > detector arrays. I drew various shapes on an index card taped on a wall: pairs
    > of dots, pairs of thick black lines, pairs of thin red lines, pairs of blue
    > dots, etc. Then I moved away from the card until I couldn't see the difference
    > between the pairs anymore. The specific geometry and colors made some
    > difference (lines are easier to split than dots) but in every case I got a
    > resolution of 1.2 to 1.7 minutes of arc. Next I did similar patterns cut into
    > a piece of aluminum foil taped over a flashlight and turned out all the
    > lights. The results were in the same range.
    Was the range similar before or after corrections for irradiation? 

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