In 1998, a large scale, optical infrared telescope, named “Subaru”, was established at the top of Mt. Mauna Kea in Hawaii Island by the National Astronomical Observatory.
Its diameter is 8.3m and, being a one-piece mirror, is the largest in the world; so big, in fact, that it takes 7 years to polish. Subaru’s average margin of error is 12mm. Its accuracy is so good that it can be used to see a ball at the top of Mt. Fuji from the center of Tokyo. Subaru has 261 actuators on the back side of the reflector to control movement.