Re: PEC for an AVX not sure what I really need to do
Thu Aug 8, 2019 12:24 am (EST) . Posted by:
"Ara Jerahian" jerahian
I’m going to illustrate PEM (Periodic Error Motion), PEC
(Periodic Error Correction), guiding and how they are related with an analogy.
Imagine yourself driving on a long straight road. Think of the lane you are in as your directional guide (guide star) and your eyes as the guide camera. Every few seconds, you nudge the steering wheel to correct for minor variations in your direction due to the road, your tires, etc. Thinks of these as corrections due to “seeing.”
Now, let’s say you’re driving an old Chevy Malibu, which is somewhat out of alignment. If you let go of the steering wheel, the car will inevitably always pull to the left. This is intrinsic to the car (mount), so think of this as its PEM. When you’re driving in a lane and know your car’s position relative to it, you’re adjusting your steering wheel to correct for both the minor perturbations in the road (seeing) as well as your misalignment (PEM). You know this because you are having to adjust the steering wheel more to the right than you are to the left. If you recorded your adjustments, you would find a certain frequency of your adjustments to the right are there to accommodate the left-veering misalignment. If you had software in the car that automatically adjusted for it veering left based on your recording, that would be your PEC (taking your mount in to a mechanic to simply get it perfectly aligned is too costly :) ) So, now when you drive with your guide camera eyes, you only have to make adjustments to accommodate for the imperfections of the road and other non-harmonic perturbations, which is why you still largely should guide.
So, to answer your question, without your guide camera and guide star, you would never find out that you were making more corrections to the right to accommodate PEM intrinsic to your mount. You need software like PEMPro or the new free CPWI software from Celestron to do this. You can use your primary 8SE and 294MC for the guiding during PEC training if you don’t have a separate guide camera or guide scope. You can find the manual for CPWI here (https://celestron-site-support-files.s3.amazonaws.com/support_files/CPWI%20Software%20Manual_ENG_F.pdf), and training PEC is described on pages 13-14.
I hope that helps!
- Ara
> On Aug 7, 2019, at 8:11 PM, goldtr8@charter.net [celestronVX] <celestronVX@yahoogroups.ca> wrote:
>
> Simply I have an AVX mount and would like to do the PEC correction to improve my tracking. I understand the concept of how it works but no idea how to physically do the PEC.
>
> My setup is an AVX mount with an 8SE and I use an ASI294MC camera. I can not understand how what I need to do to get this data. From what I have read so far it seems like I need a guide camera and if I need that then what is the point of PEC.
>
> I would expect that I would do an alignment and then center on a star. Then I would use the camera which is using the OTA to track a star and trigger PEC recording the the hand controller. However, I know I am missing something and the "lights" in my brain have not come on on what I really need to do.
>
> So if someone can point me to instructions on the WWW it would be appreciated.
>
Imagine yourself driving on a long straight road. Think of the lane you are in as your directional guide (guide star) and your eyes as the guide camera. Every few seconds, you nudge the steering wheel to correct for minor variations in your direction due to the road, your tires, etc. Thinks of these as corrections due to “seeing.”
Now, let’s say you’re driving an old Chevy Malibu, which is somewhat out of alignment. If you let go of the steering wheel, the car will inevitably always pull to the left. This is intrinsic to the car (mount), so think of this as its PEM. When you’re driving in a lane and know your car’s position relative to it, you’re adjusting your steering wheel to correct for both the minor perturbations in the road (seeing) as well as your misalignment (PEM). You know this because you are having to adjust the steering wheel more to the right than you are to the left. If you recorded your adjustments, you would find a certain frequency of your adjustments to the right are there to accommodate the left-veering misalignment. If you had software in the car that automatically adjusted for it veering left based on your recording, that would be your PEC (taking your mount in to a mechanic to simply get it perfectly aligned is too costly :) ) So, now when you drive with your guide camera eyes, you only have to make adjustments to accommodate for the imperfections of the road and other non-harmonic perturbations, which is why you still largely should guide.
So, to answer your question, without your guide camera and guide star, you would never find out that you were making more corrections to the right to accommodate PEM intrinsic to your mount. You need software like PEMPro or the new free CPWI software from Celestron to do this. You can use your primary 8SE and 294MC for the guiding during PEC training if you don’t have a separate guide camera or guide scope. You can find the manual for CPWI here (https://celestron-site-support-files.s3.amazonaws.com/support_files/CPWI%20Software%20Manual_ENG_F.pdf), and training PEC is described on pages 13-14.
I hope that helps!
- Ara
> On Aug 7, 2019, at 8:11 PM, goldtr8@charter.net [celestronVX] <celestronVX@yahoogroups.ca> wrote:
>
> Simply I have an AVX mount and would like to do the PEC correction to improve my tracking. I understand the concept of how it works but no idea how to physically do the PEC.
>
> My setup is an AVX mount with an 8SE and I use an ASI294MC camera. I can not understand how what I need to do to get this data. From what I have read so far it seems like I need a guide camera and if I need that then what is the point of PEC.
>
> I would expect that I would do an alignment and then center on a star. Then I would use the camera which is using the OTA to track a star and trigger PEC recording the the hand controller. However, I know I am missing something and the "lights" in my brain have not come on on what I really need to do.
>
> So if someone can point me to instructions on the WWW it would be appreciated.
>
celestronVX@yahoogroups.ca
