polar alignment in Kstars/Ekos compared with Astrometry.net
I have a simple setup as just starting out - an old Canon DSLR (600D) attached to a Sky Watcher EQ-AL55i equatorial mount (no scope), using Kstars/Ekos to control on an old Macbook Pro running Ubuntu 24.04. The camera has a Canon EF-S18-55mm f/3.5-5.6 lens. Currently I'm just exploring the Milky Way and other stars looking south while trying to learn the software (and starware!)
After some struggling with Kstars/Ekos I am trying its polar alignment module, which I think is pretty impressive. Last night it aligned to about 40 arc-seconds which I was very happy with. So I then took some images of the SCP without moving the mount and uploaded them to Astrometry.net to check (what a great service!). I used their grid overlay which shows where they calculate the SCP to sit. I've attached a screenshot of the output.
According to Astrometry.net the SCP is not at the centre of the image, yet Ekos says I'm within 1 arc-minute of polar alignment. It's possible that the camera isn't perfectly aligned on the mount, as it's done by eye, but it's the same for both procedures.
What am I missing here? Should I not even expect them to show the same alignment?
Thanks for any thoughts and comments,
Tony
