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[Nml] index error adjustment...


Subject: [Nml] index error adjustment...
From: Russell Sher (rsher@XXX.XXX)
Date: Tue Jan 26 1999 - 09:25:42 EST


Hi - With all the talk on sextants, perhaps I can squeeze in a question
about index error adjustment;
I have an instrument which has two right-angle shaped brackets for assisting
with index glass adjustment - With the instrument held horizontally, these
calibrating brackets are placed on the arc so that both the reflected and
true images are seen. The relative heights of these are adjusted into
co-incidence with the adjusting screw to give perpendicularity. When I
removed these brackets and eye-balled the arc directly, after performing the
adjustment, I noticed that there was still some error - In other words,
these two methods are possibly not as reliable as each other- OR is this a
case of parallax error, or the way which I am viewing the arc? Celestaire
(www.celestaire.com) market calibrating cylinders for the same purpose -
does anyone have any experience with these? Any comments etc.

regards
Russell
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