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If Polar Alignment repeatredly fails, what does that mean and how to fix it?

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What specifically do you mean by "it fails"?
Can you supply a verbose log with all the ekos modules checked?
Please also read the KStars Handbook's Align section:
docs.kde.org/trunk5/en/kstars/kstars/tool-ekos.html#ekos-align

Also, of course, no you don't need to put on an eyepiece.
Please note--you mount's RA axis is what should be pointing roughly to the pole--not necessarily the telescope.
You don't have to go overboard, just stand behind the telescope, look along the RA axis and see if it's roughly right.

Here's an older video a user made on this

I don't think it shows the newer "Plate Solve" adjustment methods (which I recommend) but it should be able to get you started.

Hy
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3 months 3 weeks ago #97024

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Thanks for the video! What I see is nothing like the wealth of information displayed there. I probably need to turn on verbose logging, but even then it probably won't show me all those graphics in the video. It fails first, iIt never gets past the first yellow light for image capture. The solve reports failure.

This afternoon I went out to my back yard, where there is a concrete slab that the scope sits on. I had marked the line on it that I considered true north based on a compass I had. Only last night did I realize I owned a much better compass, the app on my IPhone. This allowed me to scribe a new line that was exaclty true north. Comparing the two lines, I learned that I was about 3 degrees off. I've placed the scope in line with the new line. Good old high school geometry helped me out. I don't know if three degrees was enough to render the PA tool unusable but we'll see.

It may be a whule before I get to it. I have a dying mother 3/4 of a continent away, whom I need to spend some time with. If I get an observing session in before I go, I'll send the results.
3 months 3 weeks ago #97030

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Hi Steve,


Loop your video for the main scope/camera and play with DEC & RA as long as you have Polaris somewhere in the middle of the image. Don't touch your mount and do the same for your guiding scope/camera by loosing/fastening the setscrews.

Try to have both scopes/camera's pointed to Polaris with the same angle. It doesn't have to be completely exact, but try to do it as well as possible so you don't have to change it afterwards. Save this position as Park Position.

This setup should be more than sufficient to successfully perform a polar align. If direction East does not work, I recommend that you choose direction West. It may also help to reduce the default setting of 30° to 20°. It's just a matter of having a few useful stars in view and then the process automatically does the rest.


Good luck !
3 months 3 weeks ago #97031

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Thanks. Is there any reason to prefer the West of East direction? Why is this even an option?
Last edit: 3 months 3 weeks ago by Steve Cohen. Reason: remove incorrect statement
3 months 3 weeks ago #97036

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(I assume you are using the newer Polar Align where the scope does not need to be pointing at the pole)

I usually start near the meridian and typically Declination 60° or so (but the declination is totally unimportant). I start near the meridian because the most important thing is that the polar align RA rotation must not *cross* the meridian (it seems to ignore all safety stops and will happily just keep going and crash the scope into the tripod). So if I happen to start on the east side, the rotation must be to the east and vice versa.

Sometimes there are clouds in one part of the sky, so I polar align on the other side. Some people might also have a tree or a building in the way on one side, so they need to be able to specify the other side.
3 months 3 weeks ago #97037

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Thanks for the explation on East of West side.
3 months 3 weeks ago #97038

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@Hy
Ok, I bumped up the logging as you indicated. I've attached a screenshot of the settings.



There is a problem here. The log file named was not created. Why would this be? Is there a bug so some other setting change I need to make?
-------------------------------------------------------------------------------------------------------------------------------------------
~ » pwd                                                                                                                astronaut@astroarch
/home/astronaut
-------------------------------------------------------------------------------------------------------------------------------------------
~ » ls *.log                                                                                                           astronaut@astroarch
zsh: no matches found: *.log

Anyhow, regardless of the logging problem, here is a screenshot of the results of the polar align



This is actually a big improvement over the previous night's results. The solve still failed with a whopping error as seen in the screenshot, but this time, the "blind image scan" that followed worked quickly. On previous occasions, it went on for minutes without coming to a solution. This, I attribute to my more careful efforts to point true north. Even so, I see none of the information shown in the clip you posted, the blue, green, and yellow lines, which would enable me to fix the alignment. And why is the error so big?
3 months 3 weeks ago #97039
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Steve,
As I mentioned in the other post - the plate-solve error will always be very large close to the Pole.
This is not relevant to the Polar Alignment. It's OK.

That's how I do my Polar Alignment.
-- the scope is pointed to the Pole (i.e. Home or Park position depending on your mount)
-- then just run the Polar Align routine
-- East/West doesn't matter
--- your speed is set to 1x - it needs to be set to Maximum speed!
-- Three images will be captured while the mount does two rotations
-- After that select "Move Star.. Calc Error" (not Platesove) and hit REFRESH button
-- do your alignments
-- Max S
ZWO AM5. RST-135. AZ-GTI. HEQ5. iOptron SkyTracker.
TPO RC6. FRA400. Rokinon 135 and other lenses.
ZWO ASI2600MC. D5500 modified with UVIR clip-in filter.
ZWO ASI120MM Mini x 2. ZWO 30F4 guider. Orion 50mm guider.
ZWO EAF x 2.
3 months 3 weeks ago #97047

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Based on the screenshot, scope focal length is wrong: your input was 300, but the blind solver detected 2000!. So, what's the real focal length of your scope? One thing you must consider it that plate solve is normally "not blind", i.e. the solver is fed with approximate pointing data to speed-up the solve. Moreover, solving success it strongly related to the selection of correct index file, which, in turn, is related to FOV and so to sensor size and scope focal length. If this data is not correct, solver will fail.
The following user(s) said Thank You: Steve Cohen
3 months 3 weeks ago #97050

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@maxthebuilder

>>After that select "Move Star.. Calc Error" (not Platesove) and hit REFRESH button

I do not see either of these options on my screen (see screenshot. Are we using the same Ekos version? Mine is 3.6.7
3 months 3 weeks ago #97074

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the mount needs to complete rotations before you could see that
-- Max S
ZWO AM5. RST-135. AZ-GTI. HEQ5. iOptron SkyTracker.
TPO RC6. FRA400. Rokinon 135 and other lenses.
ZWO ASI2600MC. D5500 modified with UVIR clip-in filter.
ZWO ASI120MM Mini x 2. ZWO 30F4 guider. Orion 50mm guider.
ZWO EAF x 2.
3 months 3 weeks ago #97078

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@Matteo

Grrr. I would think this would be set from optical the train, as it is on other screens. thanks for pointing it out. In any event, I was not able to edit this field before starting. What IS the source of this data on the screen?
3 months 3 weeks ago #97083

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