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    Re: On LOPs
    From: Steven Tripp
    Date: 2002 Apr 16, 12:40 +0900

    On 4/16/02 11:39 AM, "Herbert Prinz"  wrote:
    > Steven,
    > Could  you please explain to us why the size of the confidence ellipse would
    > depend in part on the angles that the three LOPs cross at? This is news to me.
    > Could you post the formula you are using so we can study this dependency?
    As I wrote in my other message, the formulas came from the Almanac, but I
    don't have them at hand here.
    The intuitive explanation is that there is more "noise" in small angles than
    in large angles.  Imagine the extreme case of two lines (one horizontal, one
    not) crossing at one degree.  One mile of error in the horizontal line will
    cause the intersection point to move up or down one mile.  But it will also
    move left or right 57 miles (have I done the math right?).  When two lines
    cross at 90 degrees a small amount of error will not have the same effect
    and the intersection will not move so much.  One mile of error will move the
    intersection one mile.
    Steve Tripp

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