Not sure whether it's ok to post it here. I just got a Musser Copernican planetarium model 500, which was made in 1960s by Scientific Space Industries, a division of Hughes Aircraft Company. It's a very interesting planetarium and still amazing to me today. I would like to see if anyone else owns it and can share more information with me, or have spare overlay disks to sell.
For information, I found David Webb's website with some detailed introduction of it.