Coudé Auxiliary Telescope, Research telescope at Mount Hamilton, California, US

The Coudé Auxiliary Telescope is a 0.6-meter reflecting telescope housed at Lick Observatory on Mount Hamilton. Its fixed optical path directs light to stationary instruments, allowing detailed spectral analysis of distant stars from a stable platform.

Completed in 1969, this telescope introduced advanced spectrographic capabilities to Lick Observatory. It allowed astronomers to analyze stellar composition and physical properties with greater precision than previously available methods.

The CAT sits just south of the Shane Dome on Tycho Brahe Peak, named for the 16th-century Danish astronomer whose precise observations of Mars let Kepler derive his laws of planetary motion. The peak's name ties the site to that observational tradition, and the CAT's fixed coudé focus continues it with a 0.6 m mirror.

Located at 1,280 meters (4,200 feet) elevation, the site sits where dry mountain conditions favor clear observations. Visitors should expect cooler temperatures and note that access may be limited depending on active research schedules.

The telescope uses a Coudé mounting that redirects light multiple times before analysis. This unusual design lets researchers use heavy spectral equipment without constantly repositioning instruments.