Hale telescope. View of the dome of the 5 metre (200-inch) Hale telescope at Mount Palomar, California, USA. When this reflecting mirror telescope was completed in 1948, it was the world's largest optical telescope and remained so until the completion of the 6 metre Russian BTA-6 telescope in 1975. The Hale telescope is named after the astronomer George Ellery Hale. Many important astronomical discoveries have been made with this telescope, including the first observation of a brown dwarf star and the first optical spectrum obtained from a quasar. In 2007 it continues to be used for astronomical research.