I would check that next time, that could be exactly the source of all your problems.

Yes, that is exactly what I mean. See also nmac's comment.

EDIT Recently I was made aware of this presentation about the importance of balancing your astro gear .

We noticed that the PA was not consistent unless you always start from park and always move in the same direction during the process. Also, one problem was a pin that the az bolts pinch. It was not solid. The HEQ5 mount does not have a pin but a boss instead that is part of the structure so it can't move. But I'd say you have something not screwed down solidly - like the house! Haha - sorry just kidding.

Interesting presentation, I always tried to balance the RA first, I shall try this method next time.

If you were to use phd2 for an evening, you can use the logs to measure your polar error based off the corrected drift. It could serve as an independent test.

I have been asking for this for a long time.. I never really measured PAA against any other method.

Jasem. Based off of what I have seen, the polar error reported by PHD2 agrees almost exactly with the remaining error I have after the PAA routine. At least within ± 10 seconds

Andrew, that's great! Thanks for the confirmation!

I see a variance of around an arc minute or so between polar alignment measurements. Back-of-the-envelope calculations suggest that the variance is within the errors of mid-range mounts. (I'm using a CEM60 and it works very well for the loads I put on it.) It's not going to be perfect, and we shouldn't be obsessed with these measurements. With a 120mm refractor f7.5 imaging scope and an 80mm f4 guide scope, I've achieved 35" RMS on my CEM60 which is better than I expected. I can't get quite as good with a C11 + the same guidescope on the mount, but mount dynamics are quite a bit different for the C11 load - PHD2 reports I'm between 0.5 and 0.8 arcseconds RMS with the C11 which is pretty good.

Recent guidance from the PHD2 folks suggest you should not strive for a perfect polar mount as that can contribute to oscillation in DEC, and instead, a bit of polar misalignment helps to steady DEC . The amount of misalignment depends on the length of sub-exposure and plate scale which determines the amount of rotation you will see in the image. PHD2 tends to settle down at a couple of arcminutes off NCP, but that is likely because I polar align the image axis, not the guide scope which is not perfectly aligned with the image scope.

Bottom line is the EKOS polar alignment works very well,

PHD2 Best Practices is an excellent read, and work really well with EKOS/INDI.

jmh

Interesting. I noticed Trevor on AstroBackyard gets pretty good guiding but he only does polar alignment with a polar scope, so he would probably have a couple of arcmins of error. Maybe the guide scope PA can be avoided on mobile setups.

So in a nutshell, if you are guiding you do not need A perfect alignment, but if you're not guiding you actually do need near perfect to be able to do long exposures.
I was able to reach 5 min un-guided the other day without any apparent star trails. And After I got the guiding on "track", 10 min exposure.

Good point, and it reminds me I should be more careful in what I way. Slightly off PA may help guiding but the longer the exposure, the more important the PA is. Even with good guiding, longer exposures will result in image rotation about the guide star if the PA is not very good.