×

INDI Library v2.0.6 is Released (02 Feb 2024)

Bi-monthly release with minor bug fixes and improvements

Stellar Solver strange result

  • Posts: 269
  • Thank you received: 53
Pointing at the SCP in telescope home positionI requested polar alignment. The solve worked fine but the calculated error is bizarre.
As the screen shot shows the difference between solve and telescope coords is about 1h RA and and 2arcmin Dec.
But the error calculated is RA 639636" (177.67 deg or 11h 50m) and Dec -324126" (90d 2m)
And you can see the tool is asking me to rotate 639 degrees in RA
Extract from log atatched but it doesn't add much
I'm guessing thisis a southern hempisphere near-the-pole issue. Never have a problem anywhere else in the sky.
Could possibly be related to the million degree rotation issue for the away-from-pole case?
But posting it separately in case it is a red herring
3 years 2 months ago #66247
Attachments:

Please Log in or Create an account to join the conversation.

  • Posts: 2876
  • Thank you received: 809
That is an odd amount of error, can you post an example image that produces this much error?
3 years 2 months ago #66249

Please Log in or Create an account to join the conversation.

  • Posts: 269
  • Thank you received: 53
Next clear night (hopefully tonight) I'll save from FITS viewer.
Intersting that the RA and Dec erros are close to 180 and 90 degrees respectively.
I only just noticed also that the RA error in arcseconds has been replicated as the amount to slew in RA in degrees.
3 years 2 months ago #66250

Please Log in or Create an account to join the conversation.

  • Posts: 2876
  • Thank you received: 809
This might possibly be an issue with the Ekos Polar Alignment routine, not with StellarSolver. but it is too soon to tell.
3 years 2 months ago #66251

Please Log in or Create an account to join the conversation.

  • Posts: 269
  • Thank you received: 53
Hi Ron
Its a bit of Polar Alignment and a bit of the delta calculation.
I did a solve at the pole and saved the image. Converted to JPEG to attach

The solve coordinates look reasonable. My home position is not perfect and there is some cone error so some difference, especially in RA so close to the pole, is expected.

Bing close to the pole the solution coords are about 12h different from scope coords due to pier side.
But the calculated delta for RA is 323952" which is 90 degrees or 6 hours in RA
Using the polar alignment tool at the same place in Manual mode gives roughly the same solver result (difference due to normal sky rotation) but it then asks to move the mount 319680 DEGREEs rather than seconds. Even though I left the slew angle at 30 degrees.



I then performed a PA with auto slewing set to 15 degrees:



After the initial solve as part of PA it got delta RA of 622876" (173 deg, 11.53h) and delta Dec -324189" (-90 deg)
It correctly logged that it would rotate to RA 21h 56m from the telescope currrent RA of 22h 56m which is 15 degrees west as expected
I stopped the proces after it had slewed more than about 45 degrees and it reparked the mount.
After parking I did another solve but now the telescope coords had an RA of 11h (i.e pierside was now different from before - maybe just due to passage of time) and a delta RA of 354857" (98 deg, 6.57h)

So in a nutshell the solver is returning the correct coords at image center
The delta calculation is doing strange things in RA
I think the message from Polar Align with manual slew is a bit of a red herring. It is a log message so the user can slew any amount they want to.
The Polar align with auto slew is really making a mess of both RA and Dec deltas and slewing some indeterminate amount. I had thought it was using the same bit of code as the solving process but apparently not.
3 years 2 months ago #66269

Please Log in or Create an account to join the conversation.

  • Posts: 1208
  • Thank you received: 559
Ken (@kengs): The issue where PAA asks you to rotate your mount some crazy number of degrees was my fault.
I hadn't tested manual rotation well. Sorry about that.
(BTW, it shouldn't have affected your results, just a bad message).

I sent Jasem a fix for his review just now.
invent.kde.org/education/kstars/-/merge_requests/202

Also, the issue with a big number in the Err field during PAA was fixed a week or so ago.
That text box should not be filled at all in PAA.
Hy
3 years 2 months ago #66317

Please Log in or Create an account to join the conversation.

  • Posts: 269
  • Thank you received: 53
Thanks Hy
Yes - when I was trying out manual rotation it worked correctly when I just rotated as much as I wanted to.
3 years 2 months ago #66319

Please Log in or Create an account to join the conversation.

  • Posts: 114
  • Thank you received: 5
I have this same thing, but on Astroberry, but hopefully see this fix. I also have another problem with the solver I have posted elsewhere, still trying to resolve where it is. Essentially after solving first time when I do a Meridian Flip is never solves the same place. I shift to a different nearby star that is fixed distance away. At the end of the session when it automatically parks is shows 177 deg AZ and 77 deg ALT. When i shutdown the server and restart it come back to the correct 180/90.
3 years 2 months ago #66330

Please Log in or Create an account to join the conversation.

Time to create page: 0.369 seconds