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    Re: Off Center Sextant Scope Observations
    From: Fred Hebard
    Date: 2007 Nov 26, 17:19 -0500

    I'll take a look George.
    On Nov 24, 2007, at 5:14 PM, George Huxtable wrote:
    > Fred Hebard wrote-
    > | As I recall when determining index error using the sun, the point of
    > | contact varies with up and down location in the telescope.
    > ==================
    > Response from George.
    > How interesting! When Fred says "As I recall ...", is he going just
    > by a dim
    > recollection, or is it a real, reproducible effect, that he can see
    > whenever
    > he tries to repeat it? To me, it appears to defeat the laws of
    > optics as I
    > understand them, but that doesn't lead me to deny that Fred saw
    > what he saw.
    > It  makes it worth examining more closely to discover why.  Could
    > it result,
    > perhaps, from a mirror that wasn't exactly flat, so the reflection
    > angle
    > varies slightly when you use a different part? Or a shade with a
    > bit of
    > ripple in it? Tell us more, Fred.
    > George.
    > contact George Huxtable at george@huxtable.u-net.com
    > or at +44 1865 820222 (from UK, 01865 820222)
    > or at 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK.
    > >
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