Mount Laguna Observatory is an astronomical observatory owned and operated by San Diego State University . The telescope was operated in partnership with the University of Illinois at Urbana-Champaign until 2000. MLO is located approximately 75km east of downtown San Diego, California on the eastern edge of the Cleveland National Forest in the Laguna Mountains and near the hamlet of Mount Laguna. MLO was dedicated on June 19, 1968, seven years after SDSU's Department of Astronomy became an independent academic department of SDSU's College of Sciences. The dedication took place during the 1968 summer meeting of the Astronomical Society of the Pacific.Telescopes The 1.06m MLO 40-inch Telescope is a Cassegrain reflector built by Astro Mechanics in 1966. It was originally fitted with a 1.02m primary mirror which has since been replaced. It is known informally as the Illinois telescope because it was located at UIUC's Prairie Observatory until 1981. The 0.6m Clifford Smith 24-inch Telescope is a Cassegrain reflector. It was built by the SDSU Department of Astronomy and used at the main campus from 1961 to 1966. In 1971 it was installed at MLO after modifications. The 0.52m Reginald Buller 21-inch Visitors' Telescope was built in 1950 by J.W. Fecker, Inc. It was donated to SDSU by Reginald Buller and dedicated at MLO in 1988. It is used primarily by students for direct viewing, and for outreach.
