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

Bi-monthly release with minor bug fixes and improvements

Polar alignment... what am I missing

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If you can not fit the line in your FOV, you will have to do it more than once gradually reducing the error.
You will be clicking on a suitable reference star. It should be bright enough to easily distinguish while in the image refresh step. If you begin the refresh cycle and can not clearly see your chosen star, either increase the exposure time or select a new star. Do not select a new star once you've begun making adjustments. While refreshing, adjust your Alt/Az bolts and follow the reference star and attempt to bring it to the end of the line where the crosshair resides.
The following user(s) said Thank You: Yannic Delisle
4 years 6 months ago #42925

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Stupid question here, but are you pressing 'Next' *after* you've selected your alignment star in your second screenshot?

I've only ever used a single click in this stage to select a star.

After you've pressed 'Next' the PAA brings up a different panel (which you haven't shown a screenshot of) in which you can tell the guide camera to loop while you adjust the altaz bolts to bring the star to the crosshairs, so you can monitor in realtime (albeit with a slight lag) your progress towards the crosshairs.
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4 years 6 months ago #43016

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Hello,

Yes, I did follow the steps. My issue is that I am so far away from the NCP that it is not in the FOV where the crosshair might already be but I cannot see it. Double clicking center the crosshair on the star I double click on, so even after proceeding with the alignment on this new star, I am of course way out of wack (1°+) .

So, as per Jasem comment "double clicking in any FITS viewer image would center the crosshair around that point. I just added code to disable this when polar aligning to prevent confusion. Should be in 3.3.5"
"Some people are so poor, all they have is money"
SW Black Diamond 80ED | SW150MAK | Newton SW 200/1000 | Orion 50mm Guider with Helical Focuser |Sirius EQ-G Rowan Belt Mode
Canon 1000D moded | ZWO ASI185MC | Baader Mark III Zoom
INDI | Stellarmate on RPI3B+ | Stellarium | Pixinsight
4 years 6 months ago #43102

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The crosshair does not terminate at the NCP. Indeed, NCP does not even have to be visible. It is merely a vector representing the magnitude of your error. Click once to choose any suitably bright star you like and begin from there, moving that reference star in the direction of the vector. If the error is large you may not fit the entire vector in the frame, even if you choose a star far on the opposite side of the frame. In that case, correct as much as possible and repeat the process from the beginning. The crosshair is your goal, do not worry about double clicking anything to generate one over your reference star.
The following user(s) said Thank You: Jasem Mutlaq
4 years 6 months ago #43120

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Quick update on this. I got the chance to go out last night and was able to test this.

On the first try I was 6° out (!!) and had a hard time getting closer and closer just using my screen but I wanted badly to avoid using the polar scope and see if I could manage using only the PA routine. After a couple of tries, getting closer each time, lo and behold, the crosshair appeared in the field of view. I was able to refine the PA and stopped doing the PA routine when I reached 55'' ... not sure if I should have tried getting closer to 0'' I hear that it can be good to not be perfectly aligned when doing astrophotography.

I realized that it is much easier when you are close to the NCP from the start and can see the other side of the vector ;)

In summary, being close to the NCP helps a lot. It is challenging when you are in the field on a portable setup to be closely aligned on the first try so I guess I will still use the polarscope just to put polaris in the FOV and then do the routine to achieve perfect PA.

"Some people are so poor, all they have is money"
SW Black Diamond 80ED | SW150MAK | Newton SW 200/1000 | Orion 50mm Guider with Helical Focuser |Sirius EQ-G Rowan Belt Mode
Canon 1000D moded | ZWO ASI185MC | Baader Mark III Zoom
INDI | Stellarmate on RPI3B+ | Stellarium | Pixinsight
Last edit: 4 years 6 months ago by Yannic Delisle.
4 years 6 months ago #43523
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That's great.
I can't wait to give this a try again in the (hopefully) near future.
SkyWatcher ED80 Pro
Skywatcher HEQ5 Pro with Rowan Belt Mod with EQDIR cable
ZWO ASI294MC Pro imaging camera
QHY5L-II-C guide camera on 50mm guidescope
DeepSkyDad AF3 autofocuser
Raspberry Pi 4 4GB running Kstars/Ekos
4 years 6 months ago #43525

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Good job! 55" is pretty good. I once got as close as 12" and others have reported even better PA. But with subs of up to 20 minutes I haven't seen any noticeable field rotation or other guide errors when being around 1' = 60" off.


Wouter
4 years 6 months ago #43535

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Good to know !

I was about to move the star in the middle of the crosshair and remembered that having too perfect of a PA was not recommended (something with natural dithering I think?) I will dig a bit more on the subject ;)

Just to say that the process, when starting not to far from the NPC is quite easy and can achieve perfect PA in minutes... I am grateful that this is now part of Ekos :) I just needed some practice and field experience to enjoy the full beauty of it :)
"Some people are so poor, all they have is money"
SW Black Diamond 80ED | SW150MAK | Newton SW 200/1000 | Orion 50mm Guider with Helical Focuser |Sirius EQ-G Rowan Belt Mode
Canon 1000D moded | ZWO ASI185MC | Baader Mark III Zoom
INDI | Stellarmate on RPI3B+ | Stellarium | Pixinsight
4 years 6 months ago #43538

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FYI Ekos can dither for you as well. In the guide tab, click on the Options button to the lower right of the tab and there you can configure this.
The following user(s) said Thank You: Yannic Delisle
4 years 6 months ago #43540

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I am also a grateful user for the last month of the Ekos Polar Alignment routine, and with my portable setup, have naturally been beginning each session with It. I own a SW AZ-EQ5 which as purchased did not have a polarscope, so I locate Polaris in the finderscope, use it to focus my scope with a Bahtinov mask, and then place it in the finderscope somewhere near where I expect it to be from my experiences from earlier PAs.

I am imaging with a Canon DSLR on an 80mm refractor with focal reducer/field flattened, so the adjustment feedback loop from image capture to display is quite long at ~6 to 10 seconds. If I attempt too large an adjustment between preview images, I can lose the reference star off the screen, but sometimes realise it is actually hidden behind the purple adjustment vector.

Might it be possible for the vector to be set to be 50% transparent so that the reference star would shine through?

In making the final adjustments I place the reference star just under the end of the purple vector where, of course, it remains hidden. Is this right or should the star be placed just visible at the end?

When I run the PA routine again to check the new position, I am satisfied if it measures within 30 arcseconds or so.

[Edit] Note: I just read again the whole of this thread and it seems I am not seeing the ‘crosshair’ on the end of the correction vector. I am running the software on my Raspberry Pi 4 in headless WiFi hotspot mode and controlling it from an iPad using VNC Viewer. I zoom in on the iPad image (two fingers spreading out) to enlarge the adjustment screen. Perhaps this is where the crosshair is being lost? Is there a way of making the adjustment screen ‘full screen’ on the RPi during this adjustment?
Last edit: 4 years 6 months ago by Avocette. Reason: Additional thoughts
4 years 6 months ago #43859

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I enjoy using the paa as well. It took a while to get my procedure down but now I can do it pretty quickly. It sounds like you may be putting the star at the wrong end of the vector. When you are prompted to choose a star the red cross hair should show up, it has a circle in the middle and that is where you should position the star, not sure why you are not seeing it, maybe like you said it is zoomed in, or out too far. After I choose my star I click next, then refresh, then in the upper left hand corner, default zoom, that usually gives a close in look at the vector with cross hair. On my Galaxy tab 8 tablet I have to move the vertical and horizontal sliders around to get the vector and crosshair in the middle of the screen., sometimes it is not visible at all at first and I need to locate it with the sliders then zoom in with two fingers to get a close view, then do the mount adjustments.
Greg, a user here has made a paa video that might be helpful. Skip to the end to see the red crosshair and you might get some ideas there to help you out


Good luck!
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4 years 6 months ago #43860

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Thanks for this - it’s helpful to see someone using the same software, even if on somewhat different hardware, and as you suggest, I spotted a couple of things I will try next time I am out in the dark!
Ed
4 years 6 months ago #43862

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