Re: Mach2 - Elongated stars


yanzhe liu
 

Ray,

Where is ASCOM driver log? I dont use APCC, I use SGPro.

Yanzhe

On Sun, Mar 7, 2021 at 10:45 AM Ray Gralak <iogroups@...> wrote:
Hi Yanzhe,

Can you zip and post your PHD2 logs, as well as APCC/AP V2 ASCOM driver logs?

There might be something useful there.

-Ray

> -----Original Message-----
> From: main@ap-gto.groups.io [mailto:main@ap-gto.groups.io] On Behalf Of yanzhe liu
> Sent: Sunday, March 7, 2021 10:12 AM
> To: main@ap-gto.groups.io
> Subject: Re: [ap-gto] Mach2 - Elongated stars
>
> Roland,
>
> I will check my mount serial number later as I just packed everything due to rain forecast.
>
> My camera's orientation was 0/180 degree, so I assume top to bottom elongation would be DEC.
>
> I dont have any picture of my setup, I just tore it down since it will be rainy this week. My setup is
> FSQ106+OAG+16803, image scale is 3.5".
> I was imaging Rosetta Nebula, after it was just past meridian for 2-3 hours.
>
> I used PHD2 drift for PA, it reported <5' PA error, I am waiting for polemaster adapter so I can confirm I get good PA
> next time.
>
> DEC was out of balance because my setup was rear end heavy, if it was in balance position then I could not rotate
> my CCD in all directions. My guess is that the DEC balance was off by less than 1lb. In the next test, I can balance
> DEC to see if the issue still exists.
>
> My suspicion is that if DEC balance is off, then DEC might creep under gravity, even PA is perfect. So you might
> see DEC continually drift  then gets corrected by PHD2 periodically.
>
> Yanzhe
>
> On Sun, Mar 7, 2021 at 9:35 AM Roland Christen via groups.io <chris1011=aol.com@groups.io> wrote:
>
>
>       Couple of questions:
>
>
>       1 - what's the mount's serial number
>       2 - which axis is the elongation
>       3 - which direction was the scope pointing (RA-Dec)
>       4 - what scope and focal length or what is the arc sec per pixel.
>       5 - do you have a picture of your setup?
>
>
>
>       One comment about balance - it should be easy for you to completely balance the scope with the clutches
> loose. Can you estimate how many lb out of balance your scope is in Dec? Normally i would not think this would
> have any effect, but doesn't hurt to check this.
>
>
>
>       Roland Christen
>       Astro-Physics Inc.
>
>
>
>
>       -----Original Message-----
>       From: yanzhe liu <liuyanzhe@...>
>       To: main@ap-gto.groups.io
>       Sent: Sun, Mar 7, 2021 12:44 am
>       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.
>
>       --
>       Roland Christen
>       Astro-Physics
>
>
>
>
>
>






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