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A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Backlash
From: Bill B
Date: 2005 Nov 21, 17:05 -0500
From: Bill B
Date: 2005 Nov 21, 17:05 -0500
Alex > But I do not see any effect of this when I look through the scope. > On the other hand, when I measure the index correction > with stars of with the Sun, I find substantial backlash: > the result depends on whether I rotate clockwise or anti clockwise. > Same happens with star distances. Try this experiment. Touch the Sun's limbs (clockwise or anti-clockwise). Now move the index arm laterally at the arc if you can do that with the SNO-T. Can you see a change in separation or overlap? > The thing which drives me crazy is that it does not ALWAYS happen. > And the amount is different. > Sometimes, especially with Sun, I see no backlash. > The best results are obtained when I measure the IC say > 5 times clockwise and 5 times anticlockwise and then average. > And do the same with star distances. Crazy? Cause and effect? Just why are we trying to do land surveying with these instruments and tables?. For whatever reason, the effect as I perceive it is greater in below zero off the arc (Sun's limbs) reading than above zero on my Astra. Spent several (unhurried) hours in the wonderful 52d F Sun Sunday exploring that from a folding chair. Why? Bill