Good morning Hy

I'm as well facing different results from the new polar alignment. One time it worked like magic and didn't touch the scope for 3 nights, and it was one of my best images, but a few days ago (in a different location up the north US), I spent 2 hours trying to perform polar alignment and I was getting different results each time I'm close to the match, and I had to stop with 50" error. To be fair, I will try again tonight and will share my results.

PS: During the last session I also tried the PHD polar drift align, but also it has variable inconsistent results

Forgot to mention that both sessions were done using my portable setup WO Z61, iOptron SmartEQ Pro+, Pi 4 Kstars/Indi, MyFocuserPro2, ZWO OAG with ASI120MM guide, ASI183MM Pro, ZWO EFW (LRGBHaS2O3)

Mohamed,

My understanding is that 50" error is very good. I agree that there is some noise in the polar alignment system, possibly due to the software, mount, or seeing. In my experience, with my setup, this noise seems to be less than an arc minute. I stop adjusting once I have the error less than an arc minute or so.

Hy

Hy

I know and was happy to reach the 50" total error, but guiding, later on, was giving me 3-4 degrees of error. This didn't happen the time before (it was flawless)

I have a question that could e basic ut worth checking, as I use OAG, in both PHD & Internal guider, I enter my scope parameters as guide scope parameters ()and the camera is the guide camera), but I was thinking that I only look into a small portion of the scope FOV periphery and not the whole aperture. Does this affect the guider calculations?

I believe that only your focal length, and the guide-camera's pixel size matter.
I don't believe the aperture matters, though I also believe the aperture you used is the correct one.
Hy

Question. Is the all-sky polar alignment process sensitive to cone error?

my understanding of the principle of operation is, that the algorithm is not depending on a perfect alignment of the scope or camera in relation to the mount axis. The algorithm will always find the point in the sky around which the axis of the mount revolves, i.e. the MOUNT will be polar aligned. Whether your scope is parallel to the mount axis or not is a different question. So even with a pefectly polar aligned mount axis you could still have a cone error. But the PA algorithm should not be affected by this.
Probably Hy can comment on this as I just derive this from my theoretical understanding.

A  quick question, apologies if it has been covered earlier in this long thread:

My CEM70 is often persnickety about doing the rotations in the polar alignment assistant, so I usually check "Manual rotation". When I get the nice triangle in the PAA, the alt-az adjustments don't move the star along the legs of the triangle, but in some other directions. Is it expecting that the mount has returned to the zero position before clicking "Refresh"? That would be a bit odd, since it's plotting the triangle on the third image, which is at 60° RA from zero, and I'm prompted to select a star there. (I don't know if clicking on a new star even works once you've clicked "Refresh".)

My CEM70 has <em>also</em>  been rather persnickety about parking and returning to home position in the past, I know that Jasem looked into this for iOptron mounts at least once but I'm rather chary about letting it smack into the tripod again to discover if the problem still exists so I have the "park afterwards" checkbox off too.

@Dirk, @Andrew:  I would agree with Dirk that is should be unaffected by cone error. 

@Rick: The refresh should be done in the same mount position as the last capture. That is, the mount is only moved twice.
It captures the first image, it slews in RA, it captures the 2nd image, it slews a 2nd time in RA, it captures the third image.
At this point the refresh/correction procedure is done, with no further mount movements, except of course, for adjusting the alt and az knobs
to correct the mount's polar alignment.

I agree that I believe you can't change your star selection after you click refresh, probably best to select the star when it asks before it even changes to that screen.

Hy

Huh! Wonder why it's whacked for me, then. Something about the CEM70? Well, it's not really an issue. I use the PAA as a backup and quantitative assessment of my iPolar solution now anyway.

However, I was just reading up on the no-polaris alignment and was gobsmacked. That is quite the feature, my friend. Can't wait to try it out -- it literally opens new horizons for me, i.e. in my tree-cave back yard I may be able to move around until I have a patch of sky that includes a target, rather than just using the tiny slice from which I can see Polaris.

I tried aligning from way back under the trees, no northern visibility at all. Lined up the tripod by aligning the center post with a leg on a heading of 000° using my trusty 50-year-old Boy Scout compass (magnetic declination is negligible here). Slewed to visible sky at about 130° az and 35° altitude. Ran the PAA, the azimuth was so far off the triangle didn't even fit in the camera frame. Wound up running it for three or four cycles overall, PAA said 40", PHD Guiding Assistant said 2'. I'll take that!

Star still wasn't tracking the triangle, however. No matter, since the helpful circle guided me to the correct adjustments quite easily, so long as I didn't go too fast. Racking the azimuth more or less followed the hypotenuse, but not quite. Altitude was of course about perpendicular to that. Mount was pretty close to level by the bubble in the base. Does sensor orientation matter? My camera was at some completely random rotation since I was mostly just playing around.

Chris and Hy, this is the nuts. Terrific work, and it will make a big difference to my imaging. Even when I don't have good targets in my available slice of sky in the back yard, I can use that time to debug hardware and workflow instead of infringing on valuable remote-site dark-sky time. Bravo!

Duplicated