Crossley telescope

The Crossley telescope is a reflecting instrument with a 36-inch mirror housed within a cast iron structure at the Mount Hamilton summit observatory. Observers operated it from a raised platform positioned about 25 feet (7.6 meters) above the dome floor.

Built by Andrew Common in 1879, the telescope was later given to the observatory by Edward Crossley. It changed how astronomers could photograph distant stars that were too faint to see directly.

The telescope served as a teaching tool for astronomy students and invited the public to observe the night sky during regular viewing events at the observatory. These occasions helped people connect with what astronomers study and discover.

The telescope sits atop a high mountain site with limited access, so visitors should expect uneven ground and elevation changes during their visit. Plan your trip for clear weather when the observatory offers guided tours and observation opportunities.

The mirror received multiple coating upgrades, shifting from silver to aluminum between 1934 and 1951 through specialized processes that improved its light-gathering ability. These refinements allowed it to capture images of fainter celestial objects than ever before.

Location: Santa Clara County

Part of: Lick Observatory

Website: https://ucolick.org/public/telescopes/crossley.html

GPS coordinates: 37.33825,-121.64426

Latest update: December 12, 2025 14:24