Stony Ridge Observatory, Astronomical observatory in Angeles National Forest, California, United States.

Stony Ridge Observatory is an amateur-run astronomical observatory at 1,730 m in the Angeles National Forest, north of Mount Wilson. Its main instrument is a 760 mm Newtonian-Cassegrain telescope with four Newtonian foci and one Cassegrain focus, housed in a dome. The site also has a 12-inch Cassegrain telescope and CCD cameras.

Stony Ridge Observatory was built in 1957 by and for amateur astronomers, and its 760 mm Newtonian-Cassegrain telescope likely ranked as the eighth largest in California at the time. In the early 1960s it took part in a lunar photography and mapping project with Lockheed, on which the choice of the lunar lander touchdown site was based. In September 2009 the Station Fire threatened the site; it escaped with minimal damage to one side of the outhouse, though ground cover and the foliage of surrounding Coulter pines burned. Restoration completed in mid-2017 reinstalled the original George Carroll-designed drive systems and re-aluminized the mirrors.

The site is run by an association of amateur astronomers, and its Minor Planet Center code is 671 Stony Ridge. The 30-inch telescope was built with a design allowing four Newtonian foci or a Cassegrain focus, and asteroid 10168 Stony Ridge is named after the site.

Stony Ridge is a remote, restricted-access site north of Mt. Wilson near Charlton Flat in Angeles National Forest; it is not open to casual visitors, so arrange any visit with the member astronomers in advance. The facility has Edison power and a landline telephone, but no running water: water must be carried in. The mountain roads are winding and weather can change quickly, so check conditions before setting out.

The Minor Planet Center credits Stony Ridge with two asteroid discoveries made in 2004, not three: 144633 Georgecarroll and 327030 Alanmaclure. A third asteroid, 10168 Stony Ridge, was named after the observatory rather than discovered there.