Mauna Kea and above

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The UK Infrared Telescope

Mauna Kea (John Davies)

Site of the largest concentration of telescopes in the northern hemisphere, the extinct (as far as we know) volcano of Mauna Kea, on the island of Hawaii, is home to almost a dozen optical, near-infrared, sub-millimetre and' radio telescopes. When I first visited the summit, in late 1980, the only telescopes present were the UK 88-inch and 24-inch, the CFHT, NASA's IRTF and the recently-completed UKIRT: add to that list JCMT, CSO, two Kecks, Subaru and a variety of radio dishes.

The view toward Mauna Loa from UKIRT (2/11/99)

UKIRT is a 3.8 metre telescope, optimised for near-infrared work, but figured to sufficient accuracy that it can be used at optical wavelengths. It used to have to only pneumatically-driven chopping, spurting secondary in the business, but brown mirrors were decided to be a bad thing, and it's much better now.
See the Joint Astronomy Centre for up to date performance statistics.

The Canada France Hawaii telescope

The CFHT dome /em>

Reputedly the tallest point on Mauna Kea, the CFHT houses a The web-site is here .

Gemini (north) and the UH 88-inch dome from CFHT

CFHT also provides pictures of the summit weather, using a camera pointed toward the dome housing the gemini-north 8-metre (scheduled to start observing in January, 2000 - or so)./td>

NASA's Infra-red Facility (IRTF)

The IRTF with Maui in the background

The IRTF dome

The IRTF is a 3.0 metre telescope, optimised from infrared observing, and devoted to planetary observing for about 50% of the time. Pictures courtesy of IRTF gallery

Mauna Kea's crowded summit

Working from left to right, the telescope buildings enclose the JCMT, CSO submillimetre array (both in millimetre valley); Subaru, Keck I and keck II on the far ridge; the UH 24-inch, UKIRT, the IRTF (actually on a peak by itself, behind the main ridge), UH 88-inch, Gemini and the CFHT dome. The island of Maui lies in the background

The two Kecks, photographed by Richard Wainscoat from a helicopter over Mauna Kea

The Keck 10-metre telescopes are currently the largest optical telescopes in the world - and will remain the leaders for the foreseeable future. Operated jointly by the California Institute of Technology and the University of California, these two telescopes have a light grasp four times higher than the Palomar 200-inch, and can take advantage of the excellent conditions on Mauna kea (pace the sky in the CFHT photograph). At an altitude of 14,000 feet, the observatories are well above much of the water in the Earth's atmosphere, and a fair amount of the oxygen (barometric pressure is about 2/3rds that at sea level). The night-time temperature is almost always between -2 and +2 Centrigrade - not your customised picture of Hawaii, but good for astronomy. (Of course, nowadays most astronomers using the Kecks do so from the comfort of the Visitor's Quarters in Waimea - the only telescope control room where you can nip out for a Big Mac between exposures.)
See here for general information

The outstanding characteristic of the keck telescopes is the mirror construction - a sequence of 36 hexagonal mirrors, each machined to the appropriate curvature, each 2 metres across, and combining to give light grasp equivalent to a 10-meter diameter mirror. The largest dimension across the mirror is closer to 11 metres, in fact, allowing speckle interferometry to achieve that resolution.

A schematic of the light path

A view of the top end

Another view of the summit

A scenic view of the two Kecks and the Subaru enclosure with Comet Hale Bopp. by John Davies

HST - the above bit

HST in orbit

Just about the only optical telescope which receives regular use at an altitude of more than 14,000 feet, HST is a 2.5 metre telescope equipped with imaging and spectroscopic instrumentation.
See the STScI site for further documentation.