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INDI Library v1.9.3 Released (11 Nov 2021)

Bimonthly Stable INDI Library release introduces new drivers and fixes for existing ones. Some highlights:

Polar Alignment problems in Stellarmate 1.61 and KStars 3.5.6 stable (EQMod Mount?)

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Dear All,
Just to share about some problems I experienced when using StellarMate to hopefully help to avoid that other might invest as much time I had to (OS v1.6.1+ KStars v3.5.6 & INDI v1.9.3 Stable release).

The problem are the alignment errors reported by the Polar Alignment turned out to be wrong for my setup. It guided me but the results were apparently wrong and following guiding consequently a nightmare. Some days later I had a chance to examine what happened more closely.

Quick Read. Recommendatition is to deactivate the tickbox "Meridian Flip - Flip if HA>" in the mount tab while executing polar alignment for EQMod Mount. At least this seems to cause the problem for me and I could recreate it in tests.

More details:

After having trouble with polar alignment (wrong results) after updating from 3.5.5 to3.5.6 some days ago I downloaded the latest StellarMateOS_1.6.1.img.xz from the website to ensure I got a good base. I have been lazy though and re-imported my settings (from a 3.5.5 install)

I then ran the following tests:

3.5.2 stable
I started with this version to do a polar alignment with a version that worked fine in the past. I mechanically moved alt/az until I achieved a deviation of 0'22"
I made some test exposures and the guiding worked all fine. So the reported deviation of the ideal polar alignment is likely in a realistic corridor.

After this I did not touch the mount, i.e. the results oft the tests below vary only by the KStar versions and software settings

3.5.6 stable:
Polar Alignment made some crazy movements also with the freshly flashed card. The resulting error was calculated by the polar alignment to be 1°48'05'.
This is not realistic and a contradiction to the results reported for the exact same hardware setup by the 3.5.2 version just before. But I found in the status messages and the analyze file that the mount was initiating twice a meridian flip. The images I saw during the procedure were either showing star trails or appear to have been the same for all 3 positions. I could re-create this problem in several runs. I recorded an analyze file, if this is of interest.

3.5.6 stable - deactivated Meridian Flip
Next thing I tried was to deactive Meridian flip in the mount tab (unticked "Meridian Flip - Flip if HA>", I use the EQMod Mount driver for an EQ 6R). I then initiated the polar alignment again.  Now the resulting error was calculated by the polar alignment to be 3'31'.
Much better but still not in line what the v. 3.5.2 reported. Maybe the algorithm had been changed in the meantime?

3.5.6 stable - reactivated Meridian Flip
Now I reactivated the Meridian flip in the mount tab again. I then initiated the polar alignment. The resulting error was calculated by the polar alignment to be 1°'47'48'.

With some more runs I could confirm the behaviour was dependent on the setting of the Meridian Flip (Tick box "Flip if HA>" ) in the mount tab.

I hope this helps others to avoid such problems even I have no real solution but feels more like a workaround. I will for now deactive the Meridian flip when doing polar alignment to be able to use version 3.5.6 with my setup.

It would be great if someone could share if the polar alignment code to determine the alignment error has ben changed from 3.5.2 to 3.5.6 which would explain the deviation of the results.

And maybe the development team might extract an idea what might be the root cause for this behaviour which was not in place for me up to 3.5.4 stable. In 3.5.5 I was affected by the FOV bug that blocked polar alignment completely so I cannot judge on 3.5.5

Thanks!

Kind regards,
Alex
Standard setup: EQ6R, Williams Megrez 72- ASI 533MC -ZWO EAF, 50 mm viewfinder - ASI 120MM
The following user(s) said Thank You: Bruce
1 month 2 weeks ago #78097

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Thank you so much for posting this!  How did it ever occur to you to try disabling the Meridian Flip flag?

It is that which is the issue causing the west-east-west-east slewing in my EQ6R-Pro mount during polar alginment that I posted here .  Once I disabled median flip the alignment now executes normal and completes.  Now that I can get an alignment done I can add that I too am seeing a much larger error value than what I was prior to the update.  Curious.
 
The following user(s) said Thank You: Alexander Weis, Simon McNally
1 month 2 weeks ago #78103

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Thanks for reporting it. Indeed, we do not have a mechanism in place temporarily disabling the meridian flip during polar alignment. Could you please be so kind and post the logs so that we can investigate it further?

Just one quick thought: if you add a delay of a couple of minutes to the meridian flip, the problem should no longer occur. The problem is - as far as I understand it - that a slew during PA happens to be very close, but before the meridian. And during the capturing etc following it, the mount crosses the meridian. If you have a certain delay for the MF larger than the time between two slews of PA, everything should be fine.
TSA-120 + epsilon-160 + FSQ-85 + GSO 150/750 | Avalon Linear + M-zero | ASI 1600mm pro + 6200mm pro | KStars/INDI on Raspberry Pi 4/Intel NUC
The following user(s) said Thank You: Alexander Weis
1 month 2 weeks ago #78115

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Hi Wolfgang,
Thanks for taking this up. Please find an analyze file attached.

I tried to activate logs and also activated the debugger. But the log directory is empty. I hope the analyze file gives you enough insights. I could download the session file if this help as well.

The current setting of my "Flip if HA>" if activated is 0.27 hours. I don't remember when and why I set it, but in the past PAA used to work ok and still does with Kstars 3.5.2 as I could confirm last night. Relevant with regards to your hint is that the setting is different to 0.

Maybe of interest: Bruce reported in this chain the same problem and he uses a EQ6R as well.
In case it is relevant: I have to slew east due to a roof inhibiting slewing west and use speed 600x. I start PAA in the initial park position. I haven't tried from other positions yet but just confirmed that 3,5,2 still works fine for me with the same settings.

Do you happen to know if the calculation of the PAA error has been refactored which might explain the different results between 3.5.2 and 3.5.6 (with meridian flip being deactivated on the latter)? I saw this entry about a major refactoring of the align section for 3.5.5. Unfortunately I couldn't use PAA in 3.5.5 as I was affected by the FOV bug.
Kind regards,
Alex
Standard setup: EQ6R, Williams Megrez 72- ASI 533MC -ZWO EAF, 50 mm viewfinder - ASI 120MM
1 month 2 weeks ago #78117
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Hi Bruce,
Thanks for your input. Very helpful to know that I'm not alone. Interestingly you are using the exact same mount.

The problems you are describing with rotating forth and back are exactly the same that I observed. Only when I had a bit more patience yesterday to systematically analyze what is happening I noticed that a Meridian Flip is being reported during PAA. So one of the things I tried was to dectivate what I consider is triggering the Meridian Flip in KStars/Ekos after trying a number of other things.

When deactivating the flip in 3.5.6 the error I see as a result from a PAA run is different about 3' to what it gives me in version 3.5.2. Not so far off but hopefully the development team could confirm if there has been a change which could explain thus and maybe the new version is more accurate.

With the alignment adjustments I did based on 3.5.2 I made some test shots (with 3.5.6) of M31 (knowing well that clouds will stop me) and achieved a total RMS in the guiding of around 0.6" which is the range I usually target for. So the 3.5.2 guidance for the polar alignment of the mount has been surely not too bad. I ran out of time to adjust the mount in line with the 3.5.6 PAA results to be able to compare as clouds rolled in....

Kind regards,

Alex
Standard setup: EQ6R, Williams Megrez 72- ASI 533MC -ZWO EAF, 50 mm viewfinder - ASI 120MM
1 month 2 weeks ago #78118

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Hi Wolfgang,

Just curious: are the logs I posted in the topic I linked above of any use here?
1 month 2 weeks ago #78130

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Thanks for the explanation, that makes sense.
I've had my EQ6R-Pro carefully situated in my backyard for quite sometime and since I got such a good PA I've been very very cautious to not disturb it. On those nights that were clear enough I'd first check the PA and it has been holding very well. Then I did an update on Stellarmate and everything (seemingly) went nuts.
Lat night, after seeing your message, I disabled meridian flip and voila: I could use the mount again. Did the PA check and it was off by a lot, just a shade over 3 degrees in Altitude.
I did not do the thorough analysis you did and thus have no idea if that was just coincidence or not (instead just corrected the PA and happily continued).
1 month 2 weeks ago #78131

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Yes, helpful, it indeed shows that the mount detects that a meridian flip is necessary immediately after the first slew had completed. And I'm afraid it shows that the idea I had above won't work, since in your case the HA was +6h, i.e. far beyond 0 of the meridian.
TSA-120 + epsilon-160 + FSQ-85 + GSO 150/750 | Avalon Linear + M-zero | ASI 1600mm pro + 6200mm pro | KStars/INDI on Raspberry Pi 4/Intel NUC
1 month 2 weeks ago #78133

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6h? (!). Ugh, I guess I better pay attention to all the settings after doing an update.
1 month 2 weeks ago #78138

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I think the Idea was to set the value to delay the Flip beyond the movement needed for the polar alignment to supress that the flip is being triggered. But that would not be a value that is helpful for the actual flip in the end. I could though try to start at another angle so the Meridian would not be crossed.

Seems like the code changed on the way between 3.5.2 and 3.5.6 so the condition set for the flip became relevant. But just for the EQ6R?

And this still not explains the difference of about 3 minutes in the reported pointing accuracy when comparing the two versions.

When your mount is permanently placed, do you have the chance to compare to another software as benchmark? I need to set up the mount for every session.

Thanks,
Alex

Gesendet von meinem STF-L09 mit Tapatalk
Standard setup: EQ6R, Williams Megrez 72- ASI 533MC -ZWO EAF, 50 mm viewfinder - ASI 120MM
1 month 2 weeks ago #78144

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I just got some new SDCards, I'll have to burn an original Stellarmate image to give that a try. Weather permitting of course (which it has not been most of this year, ha!).
1 month 2 weeks ago #78148

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I also had this problem and still having it.
Using another EQMod mount - HEQ5.
Starting with 3.5.6 beta I believe. Windows client.
Just one or two times.
Today I updated to 3.5.7 beta (Windows client) and had this again - system was trying to do meridian flip while doing polar alignment.
Rebooted, disabled "Flip if HA>" and this helped.

Never had this with versions prior to 3.5.6.
Thanks!
Max S.

RPI 4 B (4Gb) with SMate
Askar FRA400, TPO RC6, Nikon D5500 full spectrum (with IDAS clip-in filter).
ASI2600MC Pro
ZWO ASI120MM Mini on ZWO 30F4
ZWO ASI224MC-S on Orion 50 mm f/3.2
ZWO EAF x 2
SW AZ-GTi
SW HEQ5
RST-135
1 month 2 weeks ago #78176

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