Palomar Observatory telescope. Historical artwork of the dome at Palomar Observatory that houses the Hale telescope. This reflector telescope was named after the astronomer George Ellery Hale when it was completed in 1948. At about five metres (200 inches), it is the second largest single fixed mirror telescope in the world. Many important advances in astronomy took place here, such as the first observation of a brown dwarf star. The dome sits at an elevation of 1867 metres within the Palomar mountain range in San Diego County, California, USA.