Any-Plate Polar Alignment Helper

User story

As a user in a hemisphere without a view of the polar sky, I want visual feedback when polar aligning my mount.

Background

The Polar Alignment view can already measure PA error for each axis. Most equatorial mounts that I’m familiar with use imprecise mechanisms to align their Altitude/Azimuth. Usually just a pair of push/pull bolts turned by hand. The current PA tool becomes difficult to use once error is below ~10s of arc-minutes.

At this point the lack of visual feedback and the nature of the mount Alt/Az mechanisms makes it very frustrating to get closer.

There are plenty of other PA methods, but most require a clear view of the polar (southern or northern) sky. Or have the same drawback of no visual feedback when adjusting.

Proposal

PA view can already measure axis error. What if:

1. The user is instructed to slew to the appropriate region of the sky.

2. The user is then instructed to center their FoV on some star in the appropriate region of the sky

   1. This is technically optional, but will make later steps much easier for the user to perform

3. The user can then choose to measure the error

4. Once measured calculate a new offset target accounting for the error
5. The user can then choose to slew the mount to that location

6. The user is instructed to use the appropriate axis mechanism to center the current view back to the location chosen in Step 2.

   1. This is where choosing and centering on a star in Step 2. is useful

7. After the adjustment perform a Solve and Sync

The user could choose to take individual subs or use live view to confirm their position during or after the adjustment.

- I am willing to submit a PR for the proposed feature