The Caltech Submillimeter Observatory (CSO) was formerly one
of the world's premier facilities for astronomical research
and instrumentation development at submillimeter wavelengths.
The 10.4 m diameter telescope is housed in a compact dome at
4070 m altitude near the summit of Maunakea, Hawai'i.
CSO ceased scientific operations in 2015. It will be
decommissioned and the site restored.