Re: Teaching the Mount Permanent Error Memory


hewholooks
 

Impressive, Hap. Your autoguiding software doesn't have a lot to do
but correct any errors you may have in your polar alignment.

Hunter

--- In ap-gto@..., "Hap Griffin" <lgriffin@...> wrote:


----- 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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