>Anything in orbit can (and is) actively tracked by amateur and professionnal astronomers around the world.

Indeed, I follow a guy on twitter that has photographed it.

Quickest link I could find to one of the photos https://www.space.com/x-37b-space-plane-skywatcher-photo.htm...

And here is his account where he also has photos of stuff like the ISS https://twitter.com/ralfvandebergh