Re: Mach2 - Elongated stars


yanzhe liu
 

My setup is FSQ106+OAG+16803. The same setup has been used for a while with a different mount, so it is unlikely the collimation or fan issue.

Yanzhe

On Sun, Mar 7, 2021 at 8:25 AM Ray Gralak <iogroups@...> wrote:
> One issue bothering me is that I got slightly elongated stars across the entire image (15min Ha sub).

Can you describe your imaging setup? (Telescope, camera, image scale, etc.)

Is it possible the issue is optical (collimation) or caused by vibrations from the camera's fan?

-Ray

> -----Original Message-----
> From: main@ap-gto.groups.io [mailto:main@ap-gto.groups.io] On Behalf Of yanzhe liu
> Sent: Saturday, March 6, 2021 10:44 PM
> To: main@ap-gto.groups.io
> Subject: [ap-gto] Mach2 - Elongated stars
>
> Testing new mach2 for a couple of nights. It works great out of the box and I am very pleased.
>
> One issue bothering me is that I got slightly elongated stars across the entire image (15min Ha sub).
> The exact same telescope/CCD were used with another mount and stars were round, I am wondering what I should
> check (I think there was due to some setup issue, but I could not figure it out).
> - Used OAG for guiding, so there should not be any flexure.
> - CCD orientation was 0/180 degree. The stars were elongated top to bottom.
> -  I did polar alignment with PHD2 drift align. PA error should be < 5'. The field rotation of each sub is ~0.01 degree,
> much larger than the other system (but elongated stars do not look like field rotation, they were same across the
> image)
> - Both RA and DEC guiding curves looked smooth, had similar RMS. DEC correction was mainly to one direction.
> - DEC balance was slightly off, camera heavy. Is Mach2 DEC sensitive to this? Will the guiding/image be affected?
>
> I dont think any of the above is of particular concern, except DEC balance. Any comment/help is appreciated.
>






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