[sneaks (Paul)]

I have what I think is a good polar alignment, and decided to track a star in Orion to test how long it would remain centered while on max zoom.

With the mount completely off, the star drifts in my image from bottom to top. Turning sidereal tracking on almost perfectly nullifies this drift, which is great.

However, the star slowly but surely also drifts from right to left in the image. And I don't know what the cause of this is. It is drifting slower than sidereal rate for sure, but has definitely moved after 60 seconds or so, enough to make a long exposure blurred.

Thankful for any advice you can give!
Paul.