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Do you need to redo a APPM model after collimation?

Pete Mumbower
 

I made a APPM model for my 1100GTO (nonAE) last week and ended up redoing the collimation on my 8"RC this afternoon. Just wondering if I need to redo my model? The scope has not been taken off the mount since the last model run. I made adjustments to the primary/secondary/focuser. I should note that I have a custom decoupler plate on the rear cell that separates the focuser and everything from the primary cell that usually causes issues for these import RCs.

Thanks,
Pete
Roland Christen
 

If you don't remove the scope then you should be ok with the model that you have.

Rolando


-----Original Message-----
From: Pete Mumbower <pmumbower@...>
To: main@ap-gto.groups.io
Sent: Mon, Mar 27, 2023 1:52 pm
Subject: [ap-gto] Do you need to redo a APPM model after collimation?

I made a APPM model for my 1100GTO (nonAE) last week and ended up redoing the collimation on my 8"RC this afternoon. Just wondering if I need to redo my model? The scope has not been taken off the mount since the last model run. I made adjustments to the primary/secondary/focuser. I should note that I have a custom decoupler plate on the rear cell that separates the focuser and everything from the primary cell that usually causes issues for these import RCs.

Thanks,
Pete

--
Roland Christen
Astro-Physics
Nick Iversen
 

If you move the secondary then stars will move on the sensor so your positioning will be off by a very small number of pixels. It is unlikely to affect guiding or tracking since those corrections hardly change from pixel to pixel
Brian Valente
 

>>>If you move the secondary then stars will move on the sensor so your positioning will be off by a very small number of pixels. It is unlikely to affect guiding or tracking since those corrections hardly change from pixel to pixel

Yes, I agree with this 

Unless your collimation issues were severe, you should be able to continue using your existing model

 

On Tue, Mar 28, 2023 at 3:22 PM Nick Iversen <inoddy@...> wrote:
If you move the secondary then stars will move on the sensor so your positioning will be off by a very small number of pixels. It is unlikely to affect guiding or tracking since those corrections hardly change from pixel to pixel



--

Pete Mumbower
 

Thanks everyone for the confirmation. Last night the model did work very well after the collimation. Though today I had to take apart the entire tube to adjust the primary retaining ring due to some mirror flop. So I know for sure I need a new model now! Just wish my dome was faster, it takes a couple of hours to do a medium model!
nmrdude
 

Hey something to be aware of if you've not found already is the Point Ordering Strategy menu. One choice is to minimize dome movements!  Takes my setup with dome about 40 minutes to do a 86 point model.  Mount slew at 900x..
I plan to replace with a larger model shown here next opportunity..
Nick Iversen
 

I haven't used a model so I have no experience. I was wondering if doing a sync or recal after a secondary mirror adjustment would fix up the minor positioning error.

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