Re: Tracking Accuracy

Khalid Baheyeldin


Last night, I tried Full Compensation, Dual Axis. I was using the latest OnStep version and Android app available at the time (that is, the version prior to today's releases with the DF fix).

I did a 6 star align, and was given 192" and 192" as polar alignment error (suspicious that both values are identical). The sequence of the 6 stars were kind of odd, with 2 west of the meridian, two east of it, then one west, then one east. The confusion was because I kept adjusting the list of stars as I was waiting for the clouds to clear out, and forgot to sort them by proximity. Not sure if that makes a difference.

The results are inconclusive when I took 480 second exposures. I did not see much difference between with and without Full Comp Dual.

There was also some breeze.

Other factors that I can think of are:

1. PEC:
There is no PEC. I did not start using this feature yet. There is no sensor in the mount (yet). I can use the Park feature, but want to first get a hand controller so recording PEC is easier (will be awkward with a touch screen).

Lack of PEC will produce a short streak while the star oscillates(*) in place because of the PE of the worm gear.

2. Backlash:
I did adjust backlash values somewhat, but not sure if these are the optimal values. The mount can do precision slews with 30" arc second margin of accuracy.

If the backlash values are inaccurate, they can cause imprecise compensated tracking.

On the next available clear sky window, I plan on trying the newer version of OnStep with the DF fix.

Any other thoughts.

(*) Yes, I have been reading about Quantum Mechanics ...

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