Lowell Observatory telescope, Flagstaff, Arizona, USA. This 13 inch photographic telescope is called the Abbot L. Lowell Astrograph and was installed at Lowell Observatory in 1928. Clyde Tombaugh (1906-1997), US astronomer, discovered Pluto with it in 1930 after becoming an assistant at the observatory in 1929. In the course of his searches, he also discovered some 3000 asteroids. The observatory, founded in 1894 by Percival Lowell, now operates eight telescopes in the Flagstaff area and one in Western Australia.