Re: APPM requirements


ap@CaptivePhotons.com
 

I use TSX tPoint now with a MyT, and anticipating the 1100 soon.

 

Does this mean that APPM does not have a concept similar to the recalibrate of TSX?

 

I have a (something like) 200 point model, but each time I set up I just run 15-20 points and it recalibrates for the new polar align (etc) and effectively shifts the prior model slightly to line up in some way.

 

It’s handy.  It can be especially handle if there are a fair number of clouds that may make it difficult to get a full model run.

 

It’s not a killer issue since generally there’s plenty of time before full-enough dark to image, but…

 

So no “recalibrate” type run in APPM?

 

 

From: main@ap-gto.groups.io [mailto:main@ap-gto.groups.io] On Behalf Of Jeffc via groups.io
Sent: Wednesday, March 24, 2021 12:26 PM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] APPM requirements

 

Thx Ray for the info... this kinda confirms what I was thinking... create a model after polar aligning.  (I just need to figure out a repeatable routine.  A project for the full moon weekend.)

 

-jeff

 

On Wed, Mar 24, 2021 at 7:39 AM Ray Gralak <iogroups@...> wrote:

Hi Jeff,

> I’ve just wondered about the practicality for a non-permanent setup, and the conditions where APPM is needed for
> unguided imaging… eg the focal length where APPM becomes effective over just the encoders on a polar aligned
> mount..  Or is the benefit simply repeatable pointing accuracy?

A pointing model will improve both tracking and pointing accuracy, including accounting for drift from polar alignment error.

However, if you move the mount you will need to recreate the model from scratch, but that should not take much time. Usually, APPM will do between 2-3 points per minute, so you should easily be able to do a 50-point model (25 points per side) in about 15-25 minutes. You can do this even before the skies are completely dark, thus not losing any imaging time.

The accuracy of a model is roughly related to the square root of the number of points on each side. For example, going from 25 to 100 points per side will roughly double the tracking and pointing accuracy (because 100 is four times 25 and the square root of four is two!).

-Ray

> -----Original Message-----
> From: main@ap-gto.groups.io [mailto:main@ap-gto.groups.io] On Behalf Of Jeffc
> Sent: Tuesday, March 23, 2021 1:54 PM
> To: main@ap-gto.groups.io
> Subject: Re: [ap-gto] APPM requirements
>
> Speaking of “requirements”…
>
> What’s the thought on using APPM with a non-permanent setup?
>
> Fwiw, I’m using the mach2 now with an st8300m + fs128 at about 1040mm focal length and am “visually” seeing
> decent round stars with 5 minute unguided exposures.
>
> I’ve only had the mount for a couple weeks, but I also used the 130GT at 614mm with (iirc) 20 minute exposures
> unguided.
>
> Yes, objects do not land in the center of the chip on a goto , but it is usually close enough such that I can plate solve
> , sync , then goto again (for proper framing).
>
> I’m guessing APPM might help with longer exposures , and also with objects low on horizon affected by
> atmospheric distortion… the latter would be nice to correct for.  At this point I image objects when they are fairly
> high on the sky.
>
> What would be the guidelines for a “portable” setup ?
> Eg
> a) create model at the site but it could be reused for the same location?
>  b) or.. it is necessary to re-create model if the mount is moved.. ie polar alignment is re-done?
>
> I’ve just wondered about the practicality for a non-permanent setup, and the conditions where APPM is needed for
> unguided imaging… eg the focal length where APPM becomes effective over just the encoders on a polar aligned
> mount..  Or is the benefit simply repeatable pointing accuracy?
>
> Thx
>
>
>
>
>       On Mar 23, 2021, at 12:39 PM, Dean Jacobsen <deanjacobsen@...> wrote:
>
>
>
>       Ray's APCC/APPM on-line manual is a great place to start.
>
>       https://www.siriusimaging.com/Help/APCC/index.html
>
>       There is a specific section for APPM that I used to get everything set up.
>       --
>       Dean Jacobsen
>       http://astrophoto.net/wp/
>       Image Gallery - http://astrophoto.net/wp/image-gallery/
>       Astrobin Image Gallery - https://www.astrobin.com/users/deanjacobsen/
> <https://www.astrobin.com/users/deanjacobsen/>
>       Amateur Radio Call Sign - W6DBJ
>
>





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