CEM120 EC2
C11 f/7 (1956mm focal length)
ASI1600MM Pro
Lodestar X2 in OAG
KStars internal autoguider via the CEM120 mount.

Guiding and dithering worked well in the previous versions of Kstars, but I had connection issues with KStars 3.5.3.
So now I downloaded the latest Stellarmate with Kstars 3.5.4 - which solved all the recent connection issues I had with Kstars 3.5.3.

Everything was running great, with nice accurate guiding (0.5") until dithering.  I had kept all the settings at default since this was a new installation of KStars.
As soon as dithering finished - the DEC would swing wildly 50 to 100 arc seconds!
I had never seen this behavior before.

Has anyone seen such behavior, and if so, what can I try to fix it?



 

What's the KStars build number? In KStars --> About --> About KStars

I've had some similar issues in KStars 3.5.3 stable using PHD2 for guiding. The other night it happened five times.... see attached. I'm not sure what part of EKOS, PHD2, EQ6-R, etc. is causing the issue.

Ron

  

Jasem, the version I was using came with the newest Stellarmate this week.
Build: 2021-07-05T21:4831Z

I only had a couple of hours last night, and so after the forth failed dither, I didn't want to waste the perfect night, so I stopped dithering and thus couldn't try and figure out what was going on. Tonight should be a better night, and I will try again and see if I can figure out what is happening. I will also try PHD2 and see if that does it too.

Other than this weird issue - everything else did well - INCLUDING the strange Nexdome issue I had with the shutter disconnects. That seemed to have resolved too!

Incidentally, we pushed an update to KStars that included also a fix for dithering, but it's a fix to the "randomness" and not something else. So it's worth testing this out as well if you update Stellarmate.

I'm updating my RPi with the newest version and hope to try it out after Tropical Storm Elsa gets out of my area. My primary areas of attention will be auto-focusing during a session (polynomial under capture tab), twilight calculation (under scheduling), and guiding after dithering.

Ron

Jasem, the update is only for non guided dithering, here the issue seems with guided dithering.

I'll test it tonight. I would use unguided dithering a lot - since that would work best with an EC2 mount.

The update was pushed on kstars git repo yesterday evening in the 3.5.5 beta path. Are you building from source? I don’t know if it is already available as a nightly build.

Well - I'm not sure why - but so far tonight the dithering is fine!   Strange!
Guiding is dead on - under 0.25 arc seconds, and the dithering hasn't caused the crazy DEC excursions.
I'm using 10 second guide exposures (OAG guider with Lodestar x2).

 

 


 

This looks a lot like the issues I had with my CEM60EC.  The issue had been that after the dither two threads were trying to do guide exposures, terminating each other fast.  So the guide cycle had changed (in my case) from ~5s to 1.8s - and the EC mount doesn't like that, and started doing insane moves.  See this post and follow-ups.
However, Jasem had fixed that in a commit 3 weeks ago, so I'd expect that is taken care of....  Still it might be worth checking the logfile for exposure aborts...

 

I recently updated to SM 1.5.9 with KStars 3.5.4 Stable.
Had three nights shooting with this setup.
On two occasions I had really bad guiding runaways.
Not with DEC. With RA.
It went up through the roof to 15-20".
Never had this before.
It settled quite fast in both occasions so I lost just three frames.

Just reporting.