This has some great background on Forth's history and use at observatories.

"The evolution of Forth | History of programming languages---II" - https://dl.acm.org/doi/10.1145/234286.1057832

I know of one: the U.S. Naval Observatory near Flagstaff, Arizona. I lived in Flagstaff in 1979. I knew the astronomer and visited him at the observatory at night. He showed me a terminal running Forth that could control the telescope.

I’m sure there were many other sites.