I have two stellar databases that I'm trying to combine. Each is obviously from a different vantage point, because of the different X, Y, Z coordinates of identical stars.

So, I thought I'd take a vector derived from 0, 0, 0 to a reference star in each database and back out the rotation angle of the second reference star using 3-d rotation transform formulas. Then, I'd take the derived rotation, apply it as a transform to the entire database to make it like the first one, and then I should be able to combine the two with a minimum of error.

But, it's becoming a headache. It seems I've forgotten more than I thought from college and not using the math in my job to reinforce it, doesn't help.

I've seen transforms to rotate a vector; anyone have a quick and easy formula to back out the angle of transformation?

Thanx!