Astronomical Heritage Finder


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Full Description (IAU Extended Case Study format):
Windows to the Universe (multiple locations): Mauna Kea Observatory, Hawaii, USA

Identification of the property

Country/State Party 
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United States of America


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Mauna Kea Observatory. Also known as Mauna Kea Observatories. Mauna Kea (Maunakea) is Hawaiian for “white mountain”.

(Part of Windows to the Universe: Leading Optical Observatories)


Geographical co-ordinates and/or UTM 
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Latitude 19° 49.4′ N, longitude 155° 28.4′ W, elevation 4190m.

See below for details of the precise locations of individual telescopes.


Maps and plans,
showing boundaries of property and buffer zone
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See Figs. MK.1a, MK.1b and MK.1c.


Area of property and buffer zone 
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The region of Mauna Kea designated for astronomical research has an area of 2.125 km² (525 acres). This “Astronomy Precinct” is contained within the “Mauna Kea Science Reserve” which has an area of 45.7 km² (11,288 acres). The science reserve has strict controls on usage. A pie-shaped sector of it is preserved as the “Mauna Kea Ice Age Reserve”. See Figs MK.1a and MK.1b.

Fig. MK.1c shows land ownership around Mauna Kea. A large area around the science reserve is preservation land owned by the state of Hawaii. Few people live within 25 km of the summit. Mauna Loa is a large active volcano located to the south of Mauna Kea and its upper slopes are uninhabited.


Fig. MK.1a: The astronomy precinct in relationship to the Mauna Kea Science Reserve (colored green), and the Mauna Kea Ice Age Reserve (labeled as “Natural Area Reserve”)


Fig. MK.1b: The Management Corridor, Hale Pohaku, the Mauna Kea Science Reserve, and the Mauna Kea Ice Age Natural Area Reserve


Fig. MK.1c: Land ownership around Mauna Kea



Description of the property 
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Fig. MK.2: Locations of observatories near the summit of Mauna Kea


Mauna Kea Observatory is a collection of astronomical research telescopes located close to the geographic summit of Mauna Kea on the Island of Hawai‘i.

The locations of the telescopes are shown in Fig. MK.2 and their geographical coordinates are listed in the table. The coordinates were determined from an aerial survey made on September 25, 1996, that used GPS techniques for reference points. Altitudes for the optical telescopes were determined from telescope construction plans.

The Submillimeter Array (SMA) is not shown in the table because it consists of 8 movable antennae with positions that change.



NAD 83


Latitude (North)

Longitude (West)



19 49 17.81149

155 28 15.46587



19 49 22.76784

155 28 09.96073



19 49 30.90648

155 28 07.95258



19 49 34.38594

155 28 19.19564



19 49 20.75334

155 28 13.17630



19 49 22.10741

155 28 37.20394



19 49 20.77658

155 28 31.78945


Keck 1

19 49 33.40757

155 28 28.98665


Keck 2

19 49 35.61788

155 28 27.24268



19 49 31.81425

155 28 33.66719



19 49 25.68521

155 28 08.56831



The Hawaii antenna of the Very Long Baseline Array is located away from the summit region, at 19° 48′ 05″ N, 155° 27′ 21″ W at an altitude of approximately 3,732 meters (12,240 feet).

The proposed Thirty Meter Telescope (TMT) will be built on the plateau to the north of the main collection of telescopes near the summit, at a location of approximately 19° 49′ 57″ N, 155° 28′ 55″ W, at an altitude of approximately 4,007 meters (13,150 feet).

The area of Mauna Kea designated for astronomical use stretches north to the TMT site, and encompasses the area already developed with telescopes. Existing cinder cones near the summit that do not have telescopes on them, such as the Pu‘u Wekiu (the summit), Pu‘u Poliahu (to the west) and Pu‘u Hau Kea (to the south) will not be used for telescopes.


History and development 
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After a several-year period of site testing in the 1960s, two small telescopes (0.6-meter diameter) were built in 1968 and 1969. A larger 2.2-meter telescope was completed in 1970. This telescope was managed by the University of Hawaii, and built using funds from NASA. The 2.2-meter telescope showed that Mauna Kea was an excellent site for astronomy. In 1979, thee larger telescopes—the 3.6-meter United Kingdom Infrared Telescope, the 3.8-meter Canada-France Hawaii Telescope, and the 3.0-meter NASA Infrared Telescope Facilty—began observations from Mauna Kea. These were followed by two submillimeter telescopes: the James Clerk Maxwell Telescope and the Caltech Submillimeter Observatory. The 10-meter Keck-1 Telescope began observations in 1990, and its success led to the completion of the adjacent Keck-2 telescope in 1996. The Gemini-North and the Subaru telescopes were then constructed each has a monolithic primary with a diameter slightly larger than 8-meters. The Gemini Northern 8-meter telescope was built on the site of one of the original 0.6-meter telescopes, and the 0.6-meter telescope was removed. The most recent major telescope to be completed is the Submillimeter Array, which consists of 8 movable antennae, each with a diameter of 6 meters.

The University of Hawaii at Hilo has replaced the other 0.6-meter telescope with a slightly larger aperture 0.9-meter telescope in the same structure. The main purpose of this telescope will be for teaching. This telescope is still in development, and is not functioning properly at the present time.

The only telescope presently under development is the Thirty Meter Telescope.

The Caltech Submillimeter Observatory is expected to be shut down and removed within 4 years.


Justification for inscription

Comparative analysis 
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See Windows to the Universe: Leading Optical Observatories (general description)


Integrity and/or authenticity 
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See Windows to the Universe: Leading Optical Observatories (general description)


Criteria under which inscription might be proposed 
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See Windows to the Universe: Leading Optical Observatories (general description)


Suggested statement of OUV 
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See Windows to the Universe: Leading Optical Observatories (general description)


State of conservation and factors affecting the property

Present state of conservation 
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The buildings and telescopes at the Mauna Kea observatory are well maintained, consistent with the operation of a major research facility.

One of the main factors affecting astronomy on Mauna Kea is artificial lights that cause light pollution. The specific form of light pollution that affects the telescopes is increased sky glow. Artificial light sources increase the sky background level above the natural background. This diminishes astronomers’ ability to see faint objects, and effectively decreases the effective size of the telescope. Light pollution affects optical astronomy—astronomy at wavelengths where the human eye is sensitive. Light pollution does not affect infrared astronomy. However, the window of the electromagnetic spectrum where the human eye is sensitive is one of the most valuable windows available to astronomy, because Earth’s atmosphere has high transparency. The sky is particularly dark at blue and green wavelengths, below 555 nm (see Fig. MK.3).


Fig. MK.3: A spectrum of the night sky seen from Mauna Kea. Nearly all of the flux shown here is natural.
Sodium emission from low-pressure sodium street lights forms part of the emission near 589 nm.

Fortunately, a strong lighting ordinance that was enacted in 1989 has provided good protection for the telescopes from light pollution. As a result, the sky background on Mauna Kea is very close to the natural level. Fig. MK.3 shows a spectrum of the night sky seen from Mauna Kea.

The eastern side of the island is frequently covered by clouds, and these clouds help to suppress artificial lights from populated areas such as Hilo in the eastern part of the island.

The submillimeter, radio and optical telescopes on Mauna Kea also need to be protected from radio frequency interference. There is a ban on fixed radio transmitters on Mauna Kea. There is one low power radio repeater located on Mauna Kea and used by the Hawaii Volcanos Observatory for safety reasons. A second repeater can be activated in the event that the Governor of Hawaii declares an emergency.


Factors affecting the property 
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Developmental pressures

Population growth on the Island of Hawaii is relatively rapid, particularly on the western side of the island that is less frequently covered by clouds. Growth in lighting associated with this growth in population is one of the largest concerns for preservation of the dark sky over Mauna Kea, and the ability to continue to do optical astronomy from Mauna Kea.

The adjacent Pohakuloa Training Area, used by the United Stated Army for military training is of particular concern as a source of artificial light. Expansion of this facility is presently occurring. Because it is located only 10 km from the observatory, lights at this location have a much higher impact than more distant lights. Additionally, because this is a federal facility, it is not regulated by the County lighting ordinance. However, the army has cooperated with the University of Hawaii by following the lighting ordinance whenever possible, and by reducing lighting to the minimum levels required.

Environmental pressures

Conservation groups are frequently opposed to astronomical development on Mauna Kea. Environmental and cultural pressures have limited future astronomical use as outlined in the Mauna Kea Master Plan.

The wekiu bug is a small insect that inhabits cinder cones close the summit. Several of the cinder cones near the summit have been developed for astronomical use, and concerns have been expressed about whether this insect has been threatened by the astronomy development. Studies of the wekiu bug are ongoing. The wekiu bug currently is not listed as a threatened or endangered species.

Natural disasters and risk preparedness

The Island of Hawaii is a very high seismic risk zone and the telescopes at the observatory are at risk from damage from earthquakes. A magnitude 6.7 earthquake on Oct 15, 2006 caused significant damage to most of the telescopes on Mauna Kea. Historical records show a magnitude 7.9 earthquake occurring on the island of Hawaii on April 2, 1868.

Mauna Kea is classified as a dormant volcano. It has not erupted since the last ice age. Any future eruption is expected to be on the south flank, and not at the summit.

The Island of Hawaii has three active volcanos—Kilauea, Mauna Loa and Hualalai. Kilauea is presently undergoing an extended eruption that is producing large amounts of volcanic gases. The volcanic gases are nearly always trapped in the lower levels of the atmosphere, and do not affect Mauna Kea. Mauna Loa erupts infrequently. An eruption from Mauna Loa may have some temporary adverse effects on the observatory, including volcanic gases and temporary sky glow. Hualalai erupts more infrequently, and is less likely to have adverse effects on Mauna Kea.

Visitor/tourism pressures

The road to the observatory is a public road that is always open unless weather conditions make it unsafe. Excessive numbers of visitors at night can cause problems from car headlights shining into telescope domes. Fortunately, at present, most visitors depart the summit area shortly after sunset, and few people travel to the summit for sunrise. The summit area is cold, often windy, and only limited shelter for tourists. Visits to the summit area by tourists are therefore usually of short duration.

Number of inhabitants

There are no permanent inhabitants at Mauna Kea Observatory. Visiting astronomers stay at Hale Pohaku, located at an altitude of approximately 2,830 meters on the southern flank of Mauna Kea, approximately 7 km from the telescopes. Hale Pohaku can accommodate up to 72 temporary residents, but occupancy has been diminishing recently because of increasing amounts of remote usage of the telescopes. Typical occupancy is now less than 30.


Protection and management

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The land where Mauna Kea Observatory is located is owned by the State of Hawaii. The Mauna Kea Science Reserve is leased to the University of Hawaii.


Protective designation 
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The Mauna Kea Science Reserve and the Mauna Kea Ice Age Natural Reserve are state conservation lands.


Means of implementing protective measures 
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A lighting ordinance is in place that restricts artificial lighting in the County of Hawaii (which encompasses the entire Island of Hawaii, where Mauna Kea Observatory is located). A state lighting law requires the state department of transportation to follow the county lighting ordinance. A new state lighting law is presently under consideration by the 2012 Hawaii State Legislature. If passed, this bill will afford further protections to the dark night sky over Mauna Kea. A state “Starlight Reserve Committee” has been established to recommend further legislation to the state government to protect the night sky over Mauna Kea and Haleakala Observatories.

A staff of Mauna Kea Rangers patrols the Mauna Kea Science Reserve. They are tasked with preservation of the natural and cultural environment, and also provide assistance to persons in trouble. Law enforcement assistance is available from the State of Hawaii Division of Conservation and Resources Enforcement, and from the County of Hawaii Police Department.


Existing plans 
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The Mauna Kea Science Reserve Master Plan was adopted by the University of Hawaii Board of Regents on June 16, 2000.

The Comprehensive Management Plan (CMP) provides a management framework for the University of Hawaii (UH) to address existing and future activities in the UH Management Areas on Mauna Kea. The CMP was approved by the state Board of Land and Natural Resources (BLNR) in April 2009 on the condition that UH complete four sub-plans addressing: public access, cultural resources management, natural resources management, and decommissioning. On March 25, 2010, the BLNR voted unanimously to approve the CMP’s four sub-plans, along with the management framework and implementation for project development. The sub-plans are:

  1. Mauna Kea Public Access Plan
  2. Mauna Kea Decommissioning Plan
  3. Mauna Kea Natural Resources Management Plan
  4. Mauna Kea Cultural Resources Management Plan


Property management plan 
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The Mauna Kea Science Reserve Master Plan established the Office of Mauna Kea Management (OMKM), which is charged with the day-to-day management of the Mauna Kea Science Reserve.

The Mauna Kea Management Board (MKMB) provides advice to OMKM. The Board is comprised of seven members of the community, nominated by the Chancellor of the University of Hawaii at Hilo, and approved by the Board of Regents of the University of Hawaii.

Kahu Ku Mauna (Guardians of the Mountain) is a nine-member council named by the MKMB. The council advises OMKM, MKMB, and the University Chancellor in Hawaiian cultural matters affecting the Mauna Kea Science Reserve.

The Mauna Kea Ice Age Reserve is managed by the State of Hawaii Department of Land and Natural Resources (DLNR).

DLNR is headed by the Board of Land and Natural Resources and manages the state’s public lands. Several divisions within DLNR share management responsibility for Mauna Kea lands, including the Division of Aquatic Resources (DAR), Division of Conservation and Resource Enforcement (DOCARE), the Division of Forestry and Wildlife (DOFAW), the Natural Area Reserves Commission, the Land Division, the Office of Conservation and Coastal Lands (OCCL), and the State Historic Preservation Division (SHPD).

The Mauna Kea Observatories Oversight Committee, composed of representatives from all of the observatories including those operated by IfA, oversees MKSS activities. . Each observatory pays into accounts held by The Research Corporation of the University of Hawaii that are used to fund MKSS activities including road maintenance, snow removal, facilities maintenance and management at Hale Pōhaku, common utilities and the VIS.

Mauna Kea Observatories Support Services (MKSS) provides food and lodging facilities and common infrastructure support for the observatories.

MKSS also supports, under the direction of OMKM, ranger services.


Sources and levels of finance 
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The University of Hawaii at Hilo provides funding for the Office of Mauna Kea Management.

User fees from commercial tours of Mauna Kea also provide some funding for OMKM.

The State of Hawaii paid for the road that goes up the southern side of Mauna Kea to the summit region where the telescopes are located, with a contribution from the Keck Observatory.

The telescopes on Mauna Kea collectively fund maintenance of the roadway, and snow removal operations. The telescope organizations also provide funding for the Visitor Station.


Sources of expertise and training 
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Astronomers working for the University of Hawaii and the other telescopes on Mauna Kea are experts on the astronomy needs of the observatory.

Guidance on cultural matters comes from Kahu Ku Mauna.


Visitor facilities and infrastructure 
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A Visitor Station is located at an altitude of 2,800 meters (9,200) feet, and is part of the Hale Pohaku facility.  The Visitor Station conducts nightly stargazing, and is open every day of the year. There is presently no charge for visitors.


Presentation and promotion policies 
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The Visitor Station is operating at capacity, and is not actively being promoted. Various tourist publications and the internet promote the Visitor Station and its stargazing program to local residents and to tourists.



Photos and other AV materials 
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Entity Data

Thematic essay: ‘Windows to the universe’: Starlight, dark-sky areas and observatory sites

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