Stony Ridge Observatory is an astronomical observatory built by and for amateur astronomers in the mountains of Los Angeles County, California, in 1957. When installed, its 760 mm (30 in) Newtonian-Cassegrain likely ranked as the largest amateur telescope in the United States. The telescope is designed so that one of four Newtonian foci, or a Cassegrain focus, can be used. Asteroids 10168 Stony Ridge and 144633 Georgecarroll were discovered at the observatory, and other scientific research (including an extensive lunar photography and mapping project in cooperation with Lockheed upon which the decision on the lunar lander touchdown site was based) has been conducted there.