Teaching the Mount Permanent Error Memory


Roland Christen
 

In a message dated 3/26/2008 3:27:38 PM Central Daylight Time,
hewholooks@... writes:


Any autoguiding system (PHD, MaximDL, etc) will
send corrections to the servos to keep the mount tracking accurately,
so will the mount's controller remember the corrections and record the
PEM?
Sure.

Rolando


**************
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Roland Christen
 

In a message dated 3/26/2008 4:40:44 PM Central Daylight Time,
hewholooks@... writes:


As a followup question - what does PEMpro do for us that simply
training the mount's PEM with an autoguider cannot.
It smoothes the curve and takes out the errors of the sky motion.

Rolando


**************
Create a Home Theater Like the Pros. Watch the video on
AOL Home.

(http://home.aol.com/diy/home-improvement-eric-stromer?video=15?ncid=aolhom00030000000001)


hewholooks
 

I was just perusing the updated instruction manual for the keypad and
re-reading the section in the manual concerning permanent error memory
and how to train the servos (page 53 - tools menu).

It states that besides training the PEM manually with crosshair
eyepiece (who does that anymore, anyway?) you can use an ST-4 or STV to
autotrain the mount.

Is there any reason that any other autoguiding system shouldn't be able
to do the same thing? Any autoguiding system (PHD, MaximDL, etc) will
send corrections to the servos to keep the mount tracking accurately,
so will the mount's controller remember the corrections and record the
PEM?

Thanks,

Hunter


hewholooks
 

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

--- In ap-gto@..., chris1011@... wrote:

In a message dated 3/26/2008 3:27:38 PM Central Daylight Time,
hewholooks@... writes:


Any autoguiding system (PHD, MaximDL, etc) will
send corrections to the servos to keep the mount tracking
accurately,
so will the mount's controller remember the corrections and
record the
PEM?
Sure.

Rolando


**************
Create a Home Theater Like the Pros. Watch the video on
AOL Home.

(http://home.aol.com/diy/home-improvement-eric-stromer?video=15?
ncid=aolhom00030000000001)


[Non-text portions of this message have been removed]


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


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