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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:

Align module - off target

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Hello,
This is happening every session...
I "find object" in KStars (say, M1), slew and align to it, start guiding and shooting.
After a while, because of a not so perfect guiding, the target drifts off center.
I go back to Align - hit " Capture & Solve". Align module does some minor adjustments (still showing M1 as the target) but it's still off center!
Now, if I again go to the "find object", select M1, slew to it and align - then it's perfectly centered!

Looks like a bug?
Just reporting.
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
Last edit: 10 months 1 week ago by maxthebuilder.
10 months 1 week ago #68322

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Replied by S on topic Align module - off target

I'm experiencing the same thing all the time. Allignment after an imaging session says target is within 30 arcsec after platesolve (using align and center), but the target is clearly halfway to the corner and not aligned at all. Goto a nearby star and goto back to target again and allign works just fine again. I'm using eqmod and dither in the autoguider and Kstars updates everything. Kstars also had the mount centered even when it is not.
10 months 1 week ago #68328

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Not sure. I would first do a 'slew to target' to make sure the actual pointing coordinates (of the star map) are spot-on, and only then align. After all, also stuff like dither will move your pointing, and actually change your pointing location.
openSUSE Tumbleweed KStars git INDI git
GPDX+EQMOD, CEM60EC, ASI2600/1600/290mini+EFW+EAF
10 months 1 week ago #68338

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Replied by S on topic Align module - off target

This seems counter intuitive to me. If the last allignment/plate solve was too a certain target, then this should still be the target after some imaging. I don't see a benefit of the target "driftigt" due to guiding and dithering, but maybe I'm missing something?
Is it possible to put allignments into the scheduler to circumvent drifting too far? For example realign every hour or so....
10 months 1 week ago #68375

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Might be worth removing the mount model and redoing the model using the tool in Ekos? Sounds like your model might be off?
10 months 1 week ago #68385

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Replied by Ken Self on topic Align module - off target

It seems that you and the OP have differential flexure so that the guide scope is driftng away from the imaging scope. Since its the guide scope determing the pointing during guiding it is moving the imaging scope off target - that is, the coordinates of the mount are now different. No different to slewing (slowly) to a target that is close by the one you started on. So the alignment module is going to align you to where the mount coordinates are now since that is what it understands to be the target.
Using the last target coordinates is not a good idea. You could have slewed intentionally to a completely different target.
The real solution is to fix the differential flexure.
A temporary solution is to repoint the mount to the original coordinates before aligning or, better still, load and slew to the first image taken.
-- Ken
RPi3 Ubuntu Server 20.04, Windows 10 AMD64, AAEON UP Core Ubuntu Desktop 20.04
Avalon M-Uno, EQ6 Pro, Atik420, ASI1600MM-C, ASI120MM-S, DBK21AU04, ZWO EFW, Optec TCFSi
Vixen R150S, GSO RC8, ST80
The following user(s) said Thank You: maxthebuilder
10 months 1 week ago #68410

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These two points make perfect sense - thanks!

I am not sure but I think I didn't have this issue before I replaced a ZWO Mini guide scope with a much heavier and taller Orion.
I will be receiving an OAG soon - will see if it makes a difference.
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
Last edit: 10 months 1 week ago by maxthebuilder.
10 months 1 week ago #68417

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Replied by S on topic Align module - off target


Yes thanks a lot, great explaining :-)

I'm pretty sure the alignment module still writes that it is centered on the last goto target (e.g. NGC 7023). If it actually wrote "star" or "empty sky" or something when it puts the target off-center it would make sense. I will take a snapshot next time it happens, maybe my memory is wrong....

My guiding is pretty awful (~1.5 " RMS with much larger peak-to-peak values), so I will also be getting an OAG soon. Which one are you getting?
Last edit: 10 months 1 week ago by S.
10 months 1 week ago #68418

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ZWO
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
10 months 1 week ago #68421

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Replied by Ken Self on topic Align module - off target

I think your memory is correct. I've had the align module name the spot where I'm pointing with the nearest known object (e.g. NGC2573 when I'm pointing at the SCP). In other cases I've had it label the coordinates as "star" or "empty sky" when I've moved slighly off target on a nebula or open cluster to get better framing. Or even if I've drifted off target similar to your situation due to a tracking problem. So I guess there is some subtle algorithm that makes a best guess of the target name.
-- Ken
RPi3 Ubuntu Server 20.04, Windows 10 AMD64, AAEON UP Core Ubuntu Desktop 20.04
Avalon M-Uno, EQ6 Pro, Atik420, ASI1600MM-C, ASI120MM-S, DBK21AU04, ZWO EFW, Optec TCFSi
Vixen R150S, GSO RC8, ST80
Last edit: 10 months 1 week ago by Ken Self. Reason: quoting
10 months 1 week ago #68424

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Replied by S on topic Align module - off target

I managed to capture schreenshots of this:

Indi1_after_capture.png shows that after some captures, kstars is drifted off target (but the captured images were not that much off target).

Indi2_after_capture+solve.png: shows what it looks like after pressing "capture & solve". The field is now alligned with the off-target position in kstars, but the alignment module writes that it is still alligned at NGC 7023. The Ra+Dec are different than the initial position used for NGC 7023.

Indi3_after_goto_capture+solve.png: shows what it looks like after a goto to NGC 7023 and a "capture & solve". Nicely centered again.

The confusing part is the the alignment module reports NGC 7023 at two different Ra+Dec. It should report "empty sky" or similar for the wrong position of NGC 7023. Even better would be to have a 3rd option like "Slew to latest target" so that one does not have to do a GOTO in kstars.
10 months 6 days ago #68456
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