Re: Teaching the Mount Permanent Error Memory


Hap Griffin
 

----- Original Message -----
From: "hewholooks" <hewholooks@...>
To: <ap-gto@...>
Sent: Wednesday, March 26, 2008 5:40 PM
Subject: [ap-gto] Re: Teaching the Mount Permanent Error Memory


That was easy - for both of us. Thanks Roland.

As a followup question - what does PEMpro do for us that simply
training the mount's PEM with an autoguider cannot.

Hunter
By simply training your mount using an autoguider, the autoguider follows the perturbations of the guide star caused by seeing and so these random errors are etched into your PEM training along with the true periodic error of the mount. PEMPRo allows you to capture date from multiple rotations of the worm gear and creates a smoothed curve from that, thus cancelling out the seeing induced errors (if you use lots of rotations) and therefore only trains in movements that counteract the true periodic error of the mount. I started with about 4.5 arc-seconds peak to peak errors and after capturing 10 interations of the worm gear and creating a smooth curve from that data, my PE is now only about 1 arc-second peak to peak...which is to say that it is now within the measurable error caused by seeing.

Hap Griffin
www.hapg.org

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