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Equipment Discussions >> Mounts

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powerstroke01
sage


Reged: 06/19/07

Loc: Western Sierra Nevada Foothill...
Whats going on here in pempro????
      #5706351 - 02/28/13 10:44 PM

Im lost. I thought my y axis was my RA. But i dont know now!
This is with my Hypertuned G11 with Ovision worm.
Heres the x axis


And the y axis


Edited by powerstroke01 (02/28/13 10:46 PM)


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orlyandico
Post Laureate
*****

Reged: 08/10/09

Loc: Singapore
Re: Whats going on here in pempro???? new [Re: powerstroke01]
      #5706367 - 02/28/13 11:00 PM

It looks like your X axis is the RA because the X axis shows the obvious sinusoidal shape of periodic error. the DEC axis would not show that shape.

If you went through the calibration wizard, pempro should correctly identify the RA axis.


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powerstroke01
sage


Reged: 06/19/07

Loc: Western Sierra Nevada Foothill...
Re: Whats going on here in pempro???? new [Re: orlyandico]
      #5706377 - 02/28/13 11:10 PM

Ive got another question.
Heres my refined graph. Is that right that my periodic error should double?


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orlyandico
Post Laureate
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Reged: 08/10/09

Loc: Singapore
Re: Whats going on here in pempro???? new [Re: powerstroke01]
      #5706385 - 02/28/13 11:15 PM

it should not double. what is probably happening is that the periodic error correction curve is not the inverted PE curve.

this should not happen! pempro should be smart enough.. are you using direct PEC curve upload or training via the ST4 port?

regardless, what you can do is refine curve, invert it manually, then train that. the PE should go right down.

but a caution, once you're below around 2" p-p it's hard to improve things, because measuring the PE becomes hard (the atmospheric seeing is generally 2" range and makes consistent measurement of the PE difficult).


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korborh
professor emeritus
*****

Reged: 01/29/11

Re: Whats going on here in pempro???? new [Re: orlyandico]
      #5706415 - 02/28/13 11:38 PM

Atmospheric seeing is random so it should not appear with a period in the freq spectrum. A slow 2" PE can still be measured in bad seeing.

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WadeH237
Pooh-Bah


Reged: 02/24/07

Loc: Snohomish, WA
Re: Whats going on here in pempro???? new [Re: korborh]
      #5706528 - 03/01/13 01:53 AM

PEMPro has an option to invert the curve. No need to try to alter it manually. The instructions even say to do this in the event that the PE doubles after applying the curve.

Also, my Celestron mounts all use X as the RA axis. I haven't checked on the AP yet, but I suspect that it's the same.


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orlyandico
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Reged: 08/10/09

Loc: Singapore
Re: Whats going on here in pempro???? new [Re: WadeH237]
      #5706629 - 03/01/13 06:02 AM

The x vs y for the ra is all down to camera orientation....

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Ray Gralak
Vendor (PEMPro)


Reged: 04/19/08

Re: Whats going on here in pempro???? new [Re: powerstroke01]
      #5706851 - 03/01/13 09:38 AM

Quote:

Im lost. I thought my y axis was my RA. But i dont know now!
This is with my Hypertuned G11 with Ovision worm.





If you run the calibration wizard then PEMPro will de-rotate the RA axis to show as the X-axis. You can override this behavior in the Settings menu, but I recommend you keep the de-rotation enabled.

-Ray Gralak


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Ray Gralak
Vendor (PEMPro)


Reged: 04/19/08

Re: Whats going on here in pempro???? new [Re: powerstroke01]
      #5706865 - 03/01/13 09:47 AM

Quote:

Ive got another question.
Heres my refined graph. Is that right that my periodic error should double?




It depends... if the blue curve is the PE after applying the initial PEC curve, then it looks like it needs to be inverted and reloaded into the mount. This can happen if the calibration wizard's last step (step 4) wasn't done or that the manufacturer's implementation for PEC cell values is inverted from what PEMPro uses.

-Ray


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WadeH237
Pooh-Bah


Reged: 02/24/07

Loc: Snohomish, WA
Re: Whats going on here in pempro???? new [Re: orlyandico]
      #5706967 - 03/01/13 10:45 AM

Quote:

The x vs y for the ra is all down to camera orientation....




There are two considerations.

There is the X and Y position of the guide star in the image. This is dependent on the camera orientation. I generally don't associate X or Y image directions with the mount's axes. I have a camera rotator, so my camera's orientation changes depending on my target and framing.

When I think of X and Y in the context of guiding and periodic error, I think of the mount's axes. All the mounts that I have worked with have the RA axis on X, and the dec axis on Y. This is what I thought that the OP was talking about.

-Wade


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orlyandico
Post Laureate
*****

Reged: 08/10/09

Loc: Singapore
Re: Whats going on here in pempro???? new [Re: WadeH237]
      #5706981 - 03/01/13 10:53 AM

thanks Wade, Ray. i didn't know that X is RA canonically.. I just can spot the RA from the wiggles

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powerstroke01
sage


Reged: 06/19/07

Loc: Western Sierra Nevada Foothill...
Re: Whats going on here in pempro???? new [Re: Ray Gralak]
      #5707008 - 03/01/13 11:12 AM

Quote:

Quote:

Ive got another question.
Heres my refined graph. Is that right that my periodic error should double?




It depends... if the blue curve is the PE after applying the initial PEC curve, then it looks like it needs to be inverted and reloaded into the mount. This can happen if the calibration wizard's last step (step 4) wasn't done or that the manufacturer's implementation for PEC cell values is inverted from what PEMPro uses.

-Ray


Thanks Ray! I did invert the curve and the pe was MUCH better. I still need to play with it some more.
And thats good to know about the axis!
Thanks again.


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