Ekos plate solving. No go?

[Steenamaroo]

Hi all,

Hoping someone might be able to offer some advice regarding successful polar alignment/plate solving in Ekos.
I previously had no issue but had a real fight on my hands tonight, and I don't know why.

I have a QHY5LII on SVBony SV106 (50/190).
Kstars + Ekos is on an Astroberry install on a PI4, all up to date.

What changed?
My previous setup was Ubuntu Mate with a year old install of Ekos/Kstars.
I switched to Astroberry this week which brought all the software up to date.

 

I have downloaded all the required fits files so tonight's attempts were split between astrometry online, and internal.
I found that internal would work maybe one time out of ten, and I don't think online worked once.

I'm told that there may not be enough stars although, from previous experience, this isn't the case.

Tracking is working well, the image is in good enough focus, and the stars are all clearly visible and it was a nice clear night.

Interestingly when reading online for help I found many people saying not to bother trying to solve/align at the pole star, as it will most likely fail.
Prior to this evening, I had never solved or carried out alignment anywhere but at the pole star!

Regardless, I did move over and try a range of other areas with no real change to the results.

If you got this far, thanks for reading.
Hopefully there's some setting or option that I've overlooked.

Edited February 15, 2022 by Steenamaroo

[Steenamaroo]

I should add, when it does work it tells me focal length is 188, so I'm confident the specs I'm inputting for the guidescope are correct, or close enough.

[wimvb]

Platrsolving near the pole is not a problem, I do it every time that I need to polar align. Have you tried uploading one of the images to astrometry.net? Maybe that will give you some clues.

The  internal solver can be a bit sensitive to fov, which needs to be near or larger than 1 degree.

Hope this helps.

[david_taurus83]

Platesolving near the pole prior to issuing a goto command can be problematic as the mount could end up with the wrong side of pier being reported. This has happened to me and this is probably why people will say this.

Platesolving near the pole for polar alignment though is absolutely fine as that's what EKOS, Sharpcap, ASIAir all do.

[alacant]

12 hours ago, Steenamaroo said:

the image is in good enough focus,

Hi

Post -a link to- the .fits? We can then see if we can solve it. That may narrow the debugging.

 

Edited February 15, 2022 by alacant

[AstroMuni]

11 hours ago, Steenamaroo said:

I should add, when it does work it tells me focal length is 188, so I'm confident the specs I'm inputting for the guidescope are correct, or close enough.

Are you platesolving with guidescope? What is your main scope?

Per se there is nothing wrong in doing it this way IF both guide and main have been aligned to same point. Using guidescope for PA should work even if its not aligned with main, but when it comes to actual imaging, it could lead to the main object not being correctly positioned in FOV.

Edited February 15, 2022 by AstroMuni

[Steenamaroo]

Hi folks. Thanks for the replies.
@alacant- Seems so obvious, now that you've said it. 😂
I'll save some images next time I'm trying...Next time the sky is clear.

@AstroMuni- Yes, I'm trying to polar align and platesolve using the guidescope and QHY camera, which is what I've always done.
Main scope, guide scope, and finder scope, are all pretty well trained on the same point.
I have imaged before with this rig - Not much, admittedly, but enough to know.

My main scope is a 130pds, since you asked, but it's not a part of the platesolving/polar alignment chain.

Edited February 15, 2022 by Steenamaroo

[Steenamaroo]

@wimvb- That's reassuring. Thank you for the info.
I didn't try uploading to astrometry.net myself - That would have been too obvious. 😂
Will certainly do that next time. Thank you.

"The  internal solver can be a bit sensitive to fov, which needs to be near or larger than 1 degree."
That's interesting. I'm not sure what I can do about that, if anything?

@david_taurus83- Reassuring to hear about near-pole alignment, and potential go-to issues.
That makes more sense, hearing your explanation.
Thank you.

[Steenamaroo]

If it's useful information, my guidescope info is shown as follows.
Nothing here has changed since it worked well.

Focal 190 (188)
Aperture 50
F/D 3.8
FOV 86.8 x 65.1

[AstroMuni]

16 minutes ago, Steenamaroo said:

- Yes, I'm trying to polar align and platesolve using the guidescope and QHY camera, which is what I've always done.
Main scope, guide scope, and finder scope, are all pretty well trained on the same point.
I have imaged before with this rig - Not much, admittedly, but enough to know.

My main scope is a 130pds, since you asked, but it's not a part of the platesolving/polar alignment chain.

Next time try doing platesolving with main scope as well to see if it has the same problem.

[Steenamaroo]

Fair enough. It might reveal something interesting.
Thanks for the suggestion.

[AstroMuni]

49 minutes ago, Steenamaroo said:

Fair enough. It might reveal something interesting.
Thanks for the suggestion.

On the days platesolving hasnt worked for me its generally due to very high level clouds that reduce the number of stars its able to recognise. They are hard to spot but when comparing images from a previous night, its obvious. In my case I use the ASI224mc as my main camera on a 130/650 scope. The guidecam is ASI120mm on the Astro essentials 32mm guidescope. I prefer using the internal Ekos Stellarsolver to external ones. I run Ekos from my Linux based laptop and the RPi just runs the INDI server & drivers.

As your problems seem to have started after a software install, I am guessing some config has changed in that process. What would help us is if you post the solver settings esp the Options profiles that you have chosen eg: 4-ParallelSmallScale. And I am guessing you have downloaded all the recommended Index files for your FOV onto your RPi.

Edited February 15, 2022 by AstroMuni

[Steenamaroo]

Thanks again @AstroMuni
I'm afraid I can rule out cloud - Last night was one of the rare clear nights while I was out.

Here are some screenshots of my settings.
The only thing I toggled throughout the evening was Solving Method Internal Solver / Online Astrometry.

[wimvb]

1 hour ago, Steenamaroo said:

The  internal solver can be a bit sensitive to fov, which needs to be near or larger than 1 degree."
That's interesting. I'm not sure what I can do about that, if anything?

You are fine with the guidescope you have (fov is in arc minutes, 86>60)

but change the options profile in the stellarsolver settings. I believe that in my configuration I have the first option, but would need to check that to be sure.

[Steenamaroo]

Ok, something else to try. Thank you.
I'll try everything suggested here next time there's a clear sky.
Not looking great for tonight but who knows...I'll keep an eye out.

[Same old newbie alert]

On 15/02/2022 at 13:32, Steenamaroo said:

Hi folks. Thanks for the replies.
@alacant- Seems so obvious, now that you've said it. 😂
I'll save some images next time I'm trying...Next time the sky is clear.

@AstroMuni- Yes, I'm trying to polar align and platesolve using the guidescope and QHY camera, which is what I've always done.
Main scope, guide scope, and finder scope, are all pretty well trained on the same point.
I have imaged before with this rig - Not much, admittedly, but enough to know.

My main scope is a 130pds, since you asked, but it's not a part of the platesolving/polar alignment chain.

I can understand polar aligning with the guidescope but, I don't understand why you want to platesolve with the guider.. surely you want to frame the target with the imaging camera, or are you platesloving again afterwards?

[Steenamaroo]

Hi,
I'm not sure I understand?

For imaging I'm using a DSLR so framing a shot would be manual rotation of the DSLR plus a few nudges of the mount control to get it just right.
The guidescope and main scope are trained on the same point, so there shouldn't really be a difference whether I solve for mount position (and goto) with one or the other, right?

I'm a beginner...Do people point their guide scopes at more star-rich areas than the imaging target when needed?

Edited February 16, 2022 by Steenamaroo

[Same old newbie alert]

Are the guidescope and imaging scope trained on the same area within pixels, obviously not if you're talking about rotating the camera.. fair enough if you're taking images of small targets that don't fill the fov but shoot a nebulae that fills the frame and stack those, do a meridian flip or add some more data to it from another night, and as it's all about signal to noise and you will see those rotation differences and stacking artifacts within your data, sure you can crop but you're losing those hard earned photons.. nudging the mount??that's the beauty of platesloving,  if you have the camera angle set the same( you should be getting that info on the platesolve results) and tell the mount to point at X latitude, with y longitude you can plateslove those coordinates and it will nudge the mount into position within pixels, and depending on your tolerance that you have it set to.. mine often solves within 4 to 6 pixels which is pretty cock on... So multiple nights imaging data can be stacked and a minimal amount of stacking artifacts as a result.. platesloving replaces your star alignment, but to a far more accurate level . So using the info data that it kicks out can give you a far more accurate level of alignment, on multiple nights

[wimvb]

6 hours ago, Steenamaroo said:

The guidescope and main scope are trained on the same point,

How accurate is this? If you want the best accuracy in your image framing, then the imaging camera should be used. The guide scope and camera can be used for polar alignment, but I would always use the imaging camera for framing.

[Steenamaroo]

Alright, that's good info. Thanks folks.
 

To be honest I've never imaged over multiple sessions but I understand you'd want the greatest accuracy possible if you were doing that, so using the main scope in that case makes sense.
For now, though, I'd just like to get solving working via guide scope as it did before, for goto convenience and/or single evening imaging.
Last night was clouded out but I will be back after the next clear sky.

[alacant]

On 15/02/2022 at 16:32, Steenamaroo said:

some screenshots of my settings

Hi

How about the 'Mount' tab. Any clues there? Maybe post that one too?

[Steenamaroo]

Not sure there's anything helpful in there but attached none the less.
The current coordinates aren't meaningful, of course, as I just booted up to grab that screenshot.

[alacant]

5 minutes ago, Steenamaroo said:

there's anything helpful

Assuming you have entered the camera pixel size correctly, we can eliminate pixel scale being wrong.

[Steenamaroo]

I can't see where I'd input that information, but I know I have never entered that manually so you might be on to something.

[Steenamaroo]

Oh, I see it now.
Looks like it's all auto-filled and not editable.