Re: [ap-gto] Re: 1st PEC curve


Sep 7, 2011

 


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#33121 Sep 7, 2011

I've just done a 300s exposure, which this time shows elongated stars, so things aren't perfect yet.



Thanks

Peter



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#33123 Sep 7, 2011

Peter,



PEC is not the only source of star elongation. Polar alignment errors, refraction, and flexure also contribute to

tracking errors. So star elongation in a 5-minute exposure probably doesn't necessarily mean the source is uncorrected

periodic error.



-Ray Gralak

Author of Astro-Physics Command Center (APCC)

Author of PEMPro: www.ccdware.com

Author of Astro-Physics V2 ASCOM Driver: www.gralak.com/apdriver

Author of PulseGuide: www.pulseguide.com

Author of Sigma: www.gralak.com/sigma



> -----Original Message-----

> From: ap-gto@yahoogroups.com [mailto:ap-gto@yahoogroups.com] On Behalf Of PeterN

> Sent: Wednesday, September 07, 2011 7:25 AM

> To: ap-gto@yahoogroups.com

> Subject: [ap-gto] 1st PEC Curve

>

>

>

> I recently adjusted the RA backlash to my AP1200 mount. I have been using it for about

> 16months and felt there was a little to much "wobble" in RA. This is the first time I have

> used PemPro to program the PEC. I have uploaded some screen shots into the photos section

> under Ellinbank Observatory.

> The raw curve after 3 cycles is labelled PEC. My concern is that it doesn't seem smooth and

> there appears to be only coarse correlation between curves. The resultant curve uploaded to

> the mount was pec curve, it has a peak to peak of 3.9 arc", about double the original factory

> curve. The picture 400s is a 400 second exposure, which shows nice round stars.

> I have a concern that the peak-peak is a bit high as well.

> The resultant wobble in the mount is very small now. From the curves, do you think I have made

> it a bit too tight??

> Comments would be welcome.

> Thanks

> Peter

>

>

>

>



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#33136 Sep 7, 2011

In a message dated 9/7/2011 9:37:06 AM Central Daylight Time,

pnelson@... writes:



> I've just done a 300s exposure, which this time shows elongated stars, so

> things aren't perfect yet.

>

> Thanks

> Peter

>



You may have drift also. In 5 minutes you can get significant drift just

from atmospheric refraction effects. And of course polar alignment has to be

spot on.



You can monitor drift using the Maxim guider graph. This will allow fine

tweeking of the polar alignment.



Rolando



Rolando



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



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#33146 Sep 8, 2011

Hi Rolando,



Thanks for your reply.

I wonder could you comment on the PEC curves I posted in the photos section of yahoo, in

the folder Ellinbank Observatory.

Should my individual curves be basically sinusoidal and very nearly identical to each other.

Or should they be like the ones I obtained, which vary from each other?

Thanks

Peter



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#33151 Sep 8, 2011

In a message dated 9/8/2011 4:03:37 AM Central Daylight Time,

pnelson@... writes:



> Hi Rolando,

>

> Thanks for your reply.

> I wonder could you comment on the PEC curves I posted in the photos

> section of yahoo, in

> the folder Ellinbank Observatory.

> Should my individual curves be basically sinusoidal and very nearly

> identical to each other.

> Or should they be like the ones I obtained, which vary from each other?

> Thanks

> Peter

>



Sorry, I don't see any such folder in the files section. Maybe if you

posted a link??



In any case, if you have a question, it is more useful for you to

communicate with Howard or George at AP, our technical staff. You can send them your

data and they can analyze it toot sweet ;^))



Posting things like this on the user group always sounds great, and if I or

Howard are reading the posts we can sometimes help that way, but it is

faster to just call and talk with them. It is probably a simple thing that can

be fixed without you having to send anything in for further analysis.



Rolando



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


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