Pit,

Thanks for the challenging test!

Re the lines not matching the star movement, my guess is this: You have a huge error, 17 degrees. I implemented drawing a straight line in image space (2D projection of the actual 3D curve) between the start point and the solution point. This projection is likely fine for most use cases, but when your error is that large, the projection probably doesn't match the geodesic as well as you'd like. You're the expert in this kind of math, so let me know if you disagree.

I'd expect that this isn't a problem as (a) it led to the solution iteratively anyway, and (b) with a compass and an astro setup, most folks should start much closer to the solution, even with that poor a view of the night sky.

If there was good reason, I could switch from a single projected line, to a series of line segments that better match the geodesic, but I think that would be overkill for almost all use cases. Again, let me know what you think.

Hy

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