Canada–France–Hawaii Telescope, Optical telescope facility on Mauna Kea summit, Hawaii, US

The Canada-France-Hawaii Telescope is a research facility on Mauna Kea's summit featuring a 3.6-meter optical and infrared telescope positioned at approximately 4,200 meters elevation. The installation enables observations through specialized instruments that detect different wavelengths of light from space.

Built in 1977 by a non-governmental corporation of Canadian, French and University of Hawaii astronomers, the telescope saw first light on 6 August 1979, then the sixth-largest optical telescope in the world. In 1999 astronomer Vladimir Krasnopolsky used it to confirm methane in the Martian atmosphere. A proposed Maunakea Spectroscopic Explorer upgrade is on hold, and the telescope is to keep operating into the 2030s.

The name marks a tripartite agreement between the University of Hawaii at Manoa, Canada's National Research Council and France's CNRS; China, Taiwan, Brazil and Korea later joined as associate partners, and observing time is shared among scientists from all seven countries. The public-outreach site "Hawaiian Starlight", run with Coelum Astronomia, distributes high-quality CFHT images and a yearly calendar.

Observing time is allocated to scientists from the seven partner countries, while European Union astronomers can apply through the OPTICON access programme. The telescope sits at 4,204 m near Mauna Kea's summit, so the thin air demands acclimatisation before any work on site.

The MegaCam instrument captures sky images with a resolution of 378 megapixels across a field of view spanning one degree. This combination of high resolution and wide viewing angle allows astronomers to gather large amounts of data efficiently.