Caltech Submillimeter Observatory

The Caltech Submillimeter Observatory (CSO) was a 10.4-meter submillimeter telescope at Mauna Kea Observatories (MKO), Mauna Kea, Hawaii. It was built in 1985, ceasing operation in 2015 and removed from Mauna Kea as of July 2024, part of a deal to allow the Thirty Meter Telescope to be built at MKO. The CSO's dish is to be reused for the planned Leighton Chajnantor Telescope (LCT) at the Llano de Chajnantor Observatory in the Atacama Desert in Chile. CSO instruments:

• MUSIC - Multiwavelength Submillimeter Inductance Camera.
• SHARC II - Submillimeter High Resolution Camera.
• SHARP - SHARC II polarimeter.
• MAKO - 350 μm camera.
• Z-Spec - broadband grating spectrometer.
• ZEUS-2 - long slit echelle grating spectrometer.

Some earlier CSO instruments:

• Bolocam.
• CSO-JCMT interferometer.
• SHARC.