Re: Precise polar alignment of the azimuth axis


Cheng-Yang Tan
 

Actually there is a way to see whether your guide scope is flexing w.r.t. the mount with SharpCap (SC):

Do the PA routine in SC as usual with the scope starting at Park 3. Adjust Alt and Az to get your PA to good or excellent. At this point, your scope should be about 90 deg from Park 3. Then in SC hit the restart button. This time, let SC plate solve with the scope at 90 deg from Park 3. Then once SC is done, send the scope back to Park 3. And without touching Alt or Az,  note what what SC reports. It should still be good or excellent to show that flexure is not a problem.

The above routine is described in SC doc:





I use it all the time to make sure that nothing has moved during PA.

IMO, using the guide scope gives a more accurate PA because of its finer image scale. In my workflow, I do a rough PA with PoleMaster (PM) and the PM scope  and then use SC with the guide scope for the final PA. 

Also SC tells you what your PA error is while PM just asks you to eye ball the alignment between the dot in the square and the circle. I think having a PA error allows you to know how precise your PA is.

cytan

P.S. I've never had any success with drift align with PHD2. I think I'm just not patient enough to wait for drift to get the error to a steady value.



On Tuesday, December 29, 2020, 04:27:13 PM CST, Ray Gralak <groups3@...> wrote:


> Try the Sharpcap polar align app using the Polemaster camera.
> That works for me and allows setups using Sharpcap without a guide camera.

Using the Polemaster camera is the best way to do it.

If a guide camera is used and the entire scope is rotated, there is going to be flexure somewhere, which can affect the calculated polar alignment position.

There is only so much accuracy you are going to get with this method with a guide scope.

-Ray Gralak
Author of PEMPro
Author of APCC (Astro-Physics Command Center): https://www.astro-physics.com/apcc-pro
Author of Astro-Physics V2 ASCOM Driver: https://www.siriusimaging.com/apdriver


> -----Original Message-----
> From: main@ap-gto.groups.io [mailto:main@ap-gto.groups.io] On Behalf Of Greg McCall
> Sent: Tuesday, December 29, 2020 1:53 PM
> To: main@ap-gto.groups.io
> Subject: Re: [ap-gto] Precise polar alignment of the azimuth axis
>
> Hi,
> Re Sharpcap and Polesmaster.
> Try the Sharpcap polar align app using the Polemaster camera.
> That works for me and allows setups using Sharpcap without a guide camera.
>
> Greg
>





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