Quote:
Originally Posted by gregmc
As a check for your altitude adjustment, use an inclinometer (mobile app or some other way to check accurate angles to horizontal).
When at the home position with the OTA pointing at the Pole, check to see if the angle is exactly the same as the latitude for that location (mobile's GPS reading)
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The trouble with digital inclinometers is that they need to be accurately zero’d and even then, most report accuracy in the +- 0.1 to 0.5 degrees range. Not all that encouraging if you want to use it for PA levels of accuracy.
The other problem is that we have no visual guide for dead-centering the pole and we also have to make some allowance for atmospheric refraction around the pole so that inclinometers are at best an approximation. The degree of refraction is a function of height and several other things but, for example, at 10 degrees, it can be as high as 5-6 minutes of arc. At say 27 degrees it would be in the vicinity of 3 minutes.