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Caltech announced December 4, 2017 that it is proceeding to decommission the Caltech Submillimeter Observatory (CSO) on Maunakea on the island of Hawaiʻi.

CSO is the first telescope to be removed from Maunakea under the Decommissioning Plan for Maunakea Observatories (PDF), a sub-plan of the Maunakea Comprehensive Management Plan.

In a news release from Pasadena, California, officials at Caltech said the next steps in the decommissioning process are an environmental assessment (EA) and a conservation district use application (CDUA).

The Office of Maunakea Management (OMKM), part of the University of Hawaiʻi at Hilo, will coordinate the process.

Caltech said that as part of the EA, it is preparing plans that include scenarios for dismantling the observatory, removing it and restoring the site where it now sits. Caltech said it will abide by terms outlined in its sublease with the University of Hawaiʻi and its decommissioning plan.

The community can comment on the removal and site restoration until January 15, 2018. The community is encouraged to submit comments to Peter Young of Hoʻokuleana LLC ( by January 15, 2018.

The Caltech Submillimeter Observatory

Once drafts of the EA and CDUA are released the public will have additional opportunities to comment.

According to Caltech, once the EA process is finished, a CDUA will be filed with the State Department of Land and Natural Resources. The Board of Land and Natural Resources will then decide whether to issue a conservation district use permit.

Once the telescope is removed and the site restored, no observatory development will be permitted on the site, according to the decommissioning plan.

CSO began operations in 1987 and stopped scientific observations in September 2015.

The other two telescopes set for decommissioning are the UKIRT Observatory, formerly known as the United Kingdom Infrared Telescope, and the Hoku Kea telescope operated by UH Hilo.

Read Caltech’s announcement.

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