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Bi-monthly release with minor bug fixes and improvements

EQMod misbehaving in KStars

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Hello,

this is an issue I have since I am using INDI / KStars, and never found a good answer for it.
The issue is that the EQMod alignment model of my EQ6 mount is going all over the place. The problem is especially visible near the meridian.
I get movements that are in opposite of the intended direction, and the mount position disappears and shows up 180 degrees away at the opposite side of the globe!
This is also causing me exceeding the mounts limits, making restarting the INDI al over again (unparking doesn't help)

As alternative I tried to change to a Shoestring cable but I have no idea how to do an alignment starting using it.

What am I doing wrong?



EDIT: also, why is there almost always an offset from the mouse pointer included from the center when I use center and track from the right-click menu? (seen at 1m07) Is this centering happening on where I clicked center and track instead of the point I right-clicked for the menu?
Last edit: 5 years 5 months ago by Jurgen Kobierczynski. Reason: Additional question below video
5 years 5 months ago #30447

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Replied by alacant on topic EQMod misbehaving in KStars

Hi
Maybe try the latest indi-eqmod or upgrade to the bleeding packages? Details of that problem were discussed here:
www.indilib.org/forum/mounts/1883-eqmod-...scope-pier-side.html
HTH
Last edit: 5 years 5 months ago by alacant.
5 years 5 months ago #30450

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I've noticed similar problems with n-star alignment especially near the meridian and when sync points are relatively close to each other which often happens with slew to target cycle. I switched to using nearest star mode, which is a bit less accurate, but at least works consistently. It's at the bottom of alignment tab in Eqmod.
5 years 5 months ago #30451

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I tried release 3.0.0 nightly build just moments ago.
no more issues noticed, using N-Star, also found good setting for solving, and the issue with the offset with the right-click menu Center and Track was solved as well

Now if there was a good way to do astrophotography indoor behind windows, I would be really happy :P
The following user(s) said Thank You: Eric
Last edit: 5 years 5 months ago by Jurgen Kobierczynski.
5 years 5 months ago #30490

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Unfortunately, the main problem was still not solved, but I was able to pinpoint the problem, so let me describe what is happening:

My normal routine is to first align the telescope using the Synscan controller using a single star alignment procedure, starting the mount from the home position. This implies the mount on a DEC position of +90:00:00 at that moment before I aligned. After this alignment I connect the mount to INDI using a serial/USB cable on the Synscan controller set in PC Direct mode. Then I will sync KStars using a Capture & Solve. The results in a alignment point close to the telescope position at that moment the solve was done. When I slew the telescope to another position this will not move DEC position of the telescope past the 90:00:00 mark. The only location where I risk moving DEC beyond +90:00:00 is when I am near NCP & Polaris, which is OK for most situations.

The routine where I want to go is that I don't have to do an initial alignment using the Synscan controller. This in order to move to using a Shoestring cable. Unfortunately the DEC position of the mount at startup is 90:00:00. When I sync KStars using a Capture & Solve I get an alignment point where the RA and DEC positions of the solve and the telescope are radically different: the DEC position of a solve may be at +15:00:00 while the DEC position of the mount is still at +90:00:00. This is no problem when I afterward move DEC position of the mount not above +15:00:00, but when I do this results in the mount thinking I am beyond the NCP resulting in showing. Unfortunately this didn't happen in the second Youtube movie I did because I aligned at the 01m09 mark in the movie just above M2 which was located at DEC -00:01:18. The DEC position of the mount was at that moment +87:40:29. Then I went to Mars at DEC -19:47:59, M30 at DEC -23:05:38, Helix at DEC -20:43:59. I never went send KStars above DEC -00:01:18, so the DEC mount position never went above +90:00:00.

What I am missing is a way to align the mount not having to rely on using a Synscan controller and not having to move the mount at all. I was looking at several settings of the EQMod alignment module, like the N-Star or Nearest Point of the alignment mode, the Math plugins Inbuilt Math Plugin and the SVD Math Plugin, the Align Method EQMod Align and the Alignment Subsystem, nothing seems to accomplish what I want which is the alignment of the mount itself.
Last edit: 5 years 5 months ago by Jurgen Kobierczynski.
5 years 5 months ago #30506

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I was reading the EQMod documentation located here: eq-mod.sourceforge.net/docs/eqmod_alignment_models.pdf
Reading the documentation of EQMod I discovered that in using a single sync point I essentially made use of a single Nearest Point Transformation mapping, while the mount still was pointing to Home = NCP. Thus I get huge dRA = 246372.652" and dDE = 315550". The operation does only subtraction, it is like I was pointing near the NCP, yet there was no scaling, so I didn't noticed scaling issues, only when I went above the first sync point I ended up on the other side of the globes. It's all user error.

The right way of aligning instead is first sync on the NCP, then track to different positions on the sky, solve and sync on all these positions.
The following user(s) said Thank You: Eric, Christian Deppe
Last edit: 5 years 5 months ago by Jurgen Kobierczynski.
5 years 5 months ago #30509

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Replied by Eric on topic Re:EQMod misbehaving in KStars

Thanks for taking the time to explain this.

-Eric
5 years 5 months ago #30511

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I am using an EQMod cable, not the SynScan controller in PC Direct mode. I usually first do a polar alignment using plate solving since I move my mount outside and back inside every time I image at home. But in September I left it outside for a week and din't do polar alignment apart from at the start of the fist night. Plus I switched off both the raspberry pi running KStars/Ekos and the mount so the alignment model was lost.

The point is: I never bother doing an alignment first. I simply right click on an object that I want to image and select EQMod Mount -> Slew. Then I go to the alignment tab and select the "Slew To Target" option under Solver Action. This almost always gets me within 30" of the object that I want to image. When it doesn't work I usually accidentally clicked on "Sync" in the KStars popup which is directly above "Slew" and this messes up the mount such that I always need to park it, switch it off (including stopping Ekos), back on and then I can proceed again.
The following user(s) said Thank You: Greg, Christian Deppe
5 years 5 months ago #30512

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