How do you guide/track when shooting Polaris?

It’s difficult as all the errors you might not notice in other parts of the sky start to add up, small movements and errors make big changes, sort of like using an alt/az mount at the zenith. The longer the FL, the harder it is.

Polar alignment has to be a accurate as is mechanically possible with your mount and diffraction has to be taken into account. If you use a guide scope it must be aligned with the optical axis of the OTA. Cone error needs to be minimized by making sure that the optical axis of the OTA is the same as the RA axis of the mount.

The meridian flip is almost not needed and really doesn’t gain anything. If you start from dead east you can go 12 hours or more without any worries about mechanical interference.

Not sure how it would effect guiding, my guess is that you want to make sure to get a good calibration after all your other adjustments. Backing off on aggressiveness and exposure frequency might also be helpful.

Last thing, try to compose your shot so that you are centered as far from the NCP as you can.

I had intended on replying when you first posted the question, but I held off to see what others had to say since I have never actually attempted this…. but I do know a few things and hopefully these pointers will assist you:

My train of thought….. polar alignment will be important due to cone error and a likely increase in field rotation due to this. To image it, I would slew to home position, or frame up your image how you want it. DO NOT PLATE SOLVE AND SYNC. From there, I would manually rotate your scope on the RA axis to the eastern most position that you feel comfortable. Since your scope will be pointing at polaris, there should be no requirement for a meridian flip. If you started the night on east side of pier as low as possible, you will not have any issues imaging for at least 12-14 hours which will put you on the opposite side of the pier by morning.

Where it’s going to get tricky: Guiding. I’ve never tried it at NCP. In most cases it should work, but I imagine the longer you do it, cone error is going to come into play. You may need to disable guiding on one axis, or possibly altogether. Cone error will probably shift the axis of movement throughout the night, I could see PHD getting confused. Reality is, you really shouldn’t need guiding at the NCP, but I feel like it’s worth attempting to run on the declination axis only in an attempt to correct for cone error and keep your image framed properly.

Dithering. You’re gonna need it. PHD needs to be actively guiding to dither…. if PHD can’t guide throughout the night, then you’ll want to use ‘Mount Dither’ in NINA to manually bump the scope around a bit. Probably want a larger amount of dither than normal just to be safe. Walking noise will probably appear more like a giant circle pattern here, instead of the normal straight line noise.

The biggest key takeaway from this is you cannot let your software plate solve and sync. Some folks learn this early on, others later in life… but you’ll end up in an endless loop of the mount flipping back and forth between each side of pier constantly because it can’t center the image thanks to cone error. You should be able to initial manual slews if you want however.

Most of this is educated speculation. I’ve never tried this. Cone error is going to get you, but the wider your field…the easier this will be. Good luck.