Tracking Accuracy

Khalid Baheyeldin

So, after months of work, I have an OnStep controller, as I explained in this post.

I tested it under the stars, and for short exposures, it works well.

But I continue to try to push further to see what the limits are.

The motor is the MPJA NEMA11 with an 18:1 gear head, and 1:1 belt and pulleys to the worm gear.
The worm period for the mount is 480 seconds.

So I took an exposure that is 960 seconds (two rotations), of Albireo (with a known distance between A and B of 34 arc seconds). The result is attached.

There is no PEC yet on this mount (neither with a sensor, nor with parking only).

Look at the two orange stars on the left below center.

There is a large wave which is due to periodic error.

The question is: what are the smaller fluctuations?

Any ideas?

My configuration is posted on the link above.

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