Thursday, October 6, 2022

Today's Problem Solving

I have one of these
It is a Meade 9x60mm right angle illuminated reticle polar finder.  The reticle which I cannot easily photograph is two concentric circles joined by 24 lines representing hours of Right Ascension.  There were instructions with it when I bought it 10 or 15 years ago, but of course they have wandered away.  (Any scientific equipment should have instructions engraved in the side for that reason.  Okay, this might be a problem with a linear accelerator or the James Webb Telescope.)

Polaris is not exactly at 90 degrees north celestial latitude.  It is closer to 89.25 degrees.  So how will I use this to improve accuracy of pointing the polar axis to True North?  

I measured the degrees of arc of the outer circle by looking at a round object 13" diameter at 20 meters.  A little arithmetic tells me it is just about exactly one degree in diameter.  The inner circle is just a bit smaller.  I suspect about 3/4 degree in diameter.

It turns out that gamma Ursa Minor is at 89 degrees north.  I am pretty sure that if gamma Ursa Major is on the outer circle and Polaris on the inner circle I am aligned.  I just need to adjust azimuth and altitude until these two stars are on the outer and inner circles. 
The lines from each star to north are about 165 degrees apart with Polaris clockwise from gamma Ursa Minor.

 This is not how Meade intended it to work but I am pretty sure it will be close enough. 

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