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INDI Library v1.9.0 Released (23 Apr 2021)

Major INDI Library release v1.9.0 bring significant internal changes championed by @pawel-soja to modernize core INDI Library drivers and clients. New drivers for DeepSkyDad Flat Panel & Pegasus devices plus further improvements to PCM8 drivers.

Manual Rotator - Plate solve - Angle of rotation

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Hi,

I am fairly new to Kstars and Ekos and I must say I love it. Every aspect of it including the RPi4 setup and connecting to equipment, planning and etc. etc.
However there's one missing feature that has caused more heart ache for me and at least 3 others that I know off who have gone back to laptop based setup using SGP and NINA. Its the manual rotation feature.

In NINA and SGP, the user can select manual rotator and request the plate solver to check the actual angle of the FOV against the desired FOV rotation, then SGP/NINA reports the rotation required say 5.5 deg. clockwise or counter clockwise, the user then manually rotates the focuser and selects ok and the plate solver solves again and reports the required rotation. This is done until the required tolerance is met, In my case I've set it to 0.5 deg.

This is critical in my setup because, I use a 1" sensor at 550mm focal length and for most targets (eg:M45) it just fits in the FOV and because we have to pack up and setup over different nights and swap between targets, getting back to the original rotation as close as possible is important so as to not destroy the edges of the stacked image and minimize the crop.

We could use a automatic rotator but the equipment is too expensive and we have been using manual rotation successfully in SGP/NINA.

Could you please consider the feature

- Vin
90mm APO
HEQ5 Pro
ZWO 290MM
ZWO183MM, QHY 183C
Pegasus PPB
ZWO ASI EAF
RPi4 Astroberry
6 months 3 days ago #64771

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I swear I saw this request before? I replied that it would be nice to add, but requires some effort. Right now, the FOV shows you the rotation, so you can just capture & solve and check the rotation and adjust accordingly. You want a dialog that tells you how much to move in what direction?
Jasem Mutlaq
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5 months 3 weeks ago #65331

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Hi Jasem,
I originally asked the question if this can be done and if there was a workflow to achieve this, and as you mentioned using the plate solved info in kstars I gave it a try a couple of times and could not get the rotations to match between different setups and pack ups. I hence added this to the wishlist if this feature could be added in future release.

The workflow is being able to set a target angle of rotation and when plate solving the result compares to this original target angle and denotes which way and how much to rotate by. The process is repeated until the tolerance is met.
Thanks in advance.
90mm APO
HEQ5 Pro
ZWO 290MM
ZWO183MM, QHY 183C
Pegasus PPB
ZWO ASI EAF
RPi4 Astroberry
5 months 3 weeks ago #65358

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Thanks, I've added it to our issue tracker: invent.kde.org/education/kstars/-/issues/56
Jasem Mutlaq
Support INDI & Ekos; Get StellarMate Astrophotography Gadget.
How to Submit Logs when you have problems?
Add your observatory info
The following user(s) said Thank You: Vinodh Ravi
5 months 2 weeks ago #65377

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I have asked the exact same thing not too long ago! You were probably thinking of me, Jasem!

For the original poster: the workaround I have been using, while the feature is added is this:

- Load and solve an image from the previous session with the exact orientation that you are happy with
- As soon as the Plate solver solves it and reports an angle, take note of it - it will soon be overwritten by the new picture coming from the camera, that will have a different angle
- Go to KStars, set a custom field of view with your focal length and sensor dimension; put the same angle that you saw on your "load and slew" plate solve
- This will show the exact rectangle, with the exact rotation on KStars
- When the new images from the camera are solved, compare the solved rectangle to the custom one
- If they differ, and they'll likely will if you changed the rotation of the camera from session to session, turn the manual rotator CW (or CCW) and solve again
- Check the two rectangles again: is the one from the solver closer or further away from the custom one? If it's closer, your initial guess for direction was correct; if not, reverse direction
- Keep solving until the two rectangles match as closely as you can get them - you can also read the angle computed by the solver and see how much different it is from the one you got from the initial "load and slew" of your reference image

With this method, I have been able to get them as close as a tenth of degree off. In my case, taking dithering into account, it's good enough as I don't have to crop much the edges that don't overlap completely, as I dither pretty aggressively anyway.

Hope this helps!
Last edit: 5 months 2 weeks ago by Matteo Gaetan.
5 months 2 weeks ago #65392

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Thanks Jasem, cant thank enough for the excellent work you do !

Thanks endlessky, It makes sense and will give it a try this week if the sky clears up, have you tried this workflow with mosaics ? many a times I set the job up on scheduler but do the second panel next night and this is when the rotation matters the most, as you would know the difference in rotation between the panels contributes to excessive crop and the only way I know to counteract it is to do more panels.
90mm APO
HEQ5 Pro
ZWO 290MM
ZWO183MM, QHY 183C
Pegasus PPB
ZWO ASI EAF
RPi4 Astroberry
5 months 2 weeks ago #65405

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I worked on this last night, and think I've got a good workflow. This video shows it in action (I'm manually changing the rotation of the CCD simulator in the video). It works off of the "Rotator" option in "Alignment Options".

Gayle H Riggsbee Observatory
Charlotte Amateur Astronomers Club

CGX
AT72EDII w/Homemade Moonlite Compatible Arduino Focuser
AT8RC w/Moonlite CSL 2.5" w/Moonlite Stepper v3
ZWO ASI1600MC-Pro
ZWO ASI1600MM-Pro
ZWO ASI174MM-Mini
ZWO OAG
ZWO EFW
AT2FF
The following user(s) said Thank You: Jasem Mutlaq, Matteo Gaetan
5 months 2 weeks ago #65441
Attachments:

    manualrotator.mp4

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What about those who don't have a rotator? Would we be able to rotate the camera manually and still use the interface that tells us which direction to turn and how many degrees we are from target?

Thanks!
5 months 2 weeks ago #65445

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That's exactly what this change does. If you have the "Rotator" option checked in the "Alignment Options", but don't have an automatic rotator attached, it will pop up this dialog when your rotation is outside the set threshold. If you do have an automatic rotator, this dialog won't show, since it can rotate for you.
Gayle H Riggsbee Observatory
Charlotte Amateur Astronomers Club

CGX
AT72EDII w/Homemade Moonlite Compatible Arduino Focuser
AT8RC w/Moonlite CSL 2.5" w/Moonlite Stepper v3
ZWO ASI1600MC-Pro
ZWO ASI1600MM-Pro
ZWO ASI174MM-Mini
ZWO OAG
ZWO EFW
AT2FF
The following user(s) said Thank You: Matteo Gaetan, Vinodh Ravi
5 months 2 weeks ago #65446

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Fantastic! Thank you, this is exactly what I needed!
5 months 2 weeks ago #65453

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This is great, thank you! This would solve most of the issues with manual rotation and give the user the ability to reduce rotational errors. Just one thing to mention

1.Once the rotation is complete and within tolerance, it would be necessary to check the image center and plate solve again to ensure the user didn't accidentally move the center point. This happens at times and causes the image to shift in the horizontal or vertical directions. [plate solve steps would be : Solve the loaded image send reference co-ordinates and rotation to Ekos --> calculate deviation and center the image and slew to target and be within required accuracy. --> Check rotation and report required rotation [as per your video] --> Once the rotation is within tolerance ---> Plate solve to check center of image and reslew to center and be within tolerance.
90mm APO
HEQ5 Pro
ZWO 290MM
ZWO183MM, QHY 183C
Pegasus PPB
ZWO ASI EAF
RPi4 Astroberry
5 months 2 weeks ago #65460

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Each click of "Take a new image" does a plate solve (it's how we check the rotation). It will ensure we are centered every time.
Gayle H Riggsbee Observatory
Charlotte Amateur Astronomers Club

CGX
AT72EDII w/Homemade Moonlite Compatible Arduino Focuser
AT8RC w/Moonlite CSL 2.5" w/Moonlite Stepper v3
ZWO ASI1600MC-Pro
ZWO ASI1600MM-Pro
ZWO ASI174MM-Mini
ZWO OAG
ZWO EFW
AT2FF
The following user(s) said Thank You: Matteo Gaetan, Vinodh Ravi
5 months 2 weeks ago #65466

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