About the Subaru Telescope

Overview of Subaru Telescope

Name Subaru Telescope
Affiliation National Astronomical Observatory of Japan (NAOJ), National Institutes of Natural Sciences (NINS)
Location ○ Hilo Base Facility
650 North A'ohoku Place, Hilo, Hawaii 96720 U.S.A
○ Summit Facility (Subaru Telescope)
Longitude and longitude: 19°49’32” N, 155°28’36” W
Altitude: 4,139m (altitude of altitude axis of telescope: 4,163m)
Principal Activities ○ Publication of results of observation using the Subaru Telescope
○ Development and manufacture of measuring instruments and related products
○ Maintenance of the Subaru Telescope
○ Fostering and education of the next generation of researchers
○ Facility observation tours, remote lectures and other public-relations activities
○ Promotional and educational activities such as astronomical events for local communities, presentations at schools, and lectures

Hilo Base Facility

Aerial View of the Hilo Office

photo: Aerial View of the Hilo Office

The NAOJ Hawaii Observatory was officially established in April 1997, following the completion of its base facility building in Hilo, Hawaii. "Subaru Telescope" can refer to the telescope itself or the entire observatory organization. Due to the difficulty of operating at high altitude, most of the support work for the telescope is conducted in Hilo by a staff of about 100 people. The Hilo Base Facility houses several research laboratories, a library, and extensive computing facilities including a supercomputer.

Hilo Office Front Sign

photo: Hilo Office Front Sign

Simulator Room

photo: Simulator Room

Remote Control Room at the Hilo Office

photo: Remote Control Room at the Hilo Office

The Subaru Telescope

Subaru Telescope under the golden sky of sunset, ready for observations

photo: Subaru Telescope under the golden sky of sunset, ready for observations

Subaru Telescope is located on the summit of Maunakea, a dormant volcano on the Big Island of Hawaii. The summit of Maunakea is an isolated peak that protrudes above most of the Earth's weather systems. The air pressure up on Maunakea is only two-third of what it is at the sea level. Clouds typically form below the summit where an inversion layer keeps the clouds from rising to the summit. Because Hawaii is isolated from any other land mass, trade winds blow smoothly over the islands, and there are few cities to pollute its dark skies.

The summit of Maunakea is one of the best astronomical observing sites in the world. With 13 telescopes from 11 countries in operation, Maunakea has more telescopes from more countries than any other observing site. Besides Subaru, there are three other 8-10 m class telescopes on Maunakea, the Gemini North telescope and the two Keck telescopes.

Maunakea is an irreplaceable natural and cultural resource. As a science reserve, development is carefully managed to balance the needs of preservation as well as exploration.

Specifications of Subaru Telescope

Subaru Telescope

Primary Mirror

Effective diameter
(diameter of light affecting area):
8.2 m (27 ft.)
Thickness: 20 cm (7.9 inches)
Weight: 22.8 metric tons (25.1 tons)
Material: ULE (ultra-low thermal expansion glass)
Mean Surface error: 0.014 microns (1/5,000,000 inch)
Focal length: 15 m (49'2")

Telescope Structure

Mounting: altitude-azimuth (Alt-Az)
Basic Optics: Ritchey-Chretian System
Foci: Four
Primary focus: F2.0 (with corrector lens)
Cassegrain focus: F12.2
Nasmyth focus (optical): F12.6
Nasmyth focus (infrared): F13.6
Height: 22.2 m (73 ft.)
Maximum width: 27.2 m (89 ft.)
Weight: 555 metric tons (612 tons)
Maximum slewing speed: 0.5 deg/sec
Tracking accuracy without guiding: 0.1”
Blind pointing accuracy: less than 1.0”
Best angular resolution achieved: 0.2"(without adaptive optics @ 2.15 μm)

Telescope Enclosure

Altitude: 4139 m (13,580 ft.)
Latitude: 19d 49m 32s N (based on NAD83)
Longitude: 155d 28m 34s W (based on NAD83)
Cylindrical enclosure rotating with the telescope
Height: 43 m (141 ft.)
Diameter at base: 40 m (131 ft.)
Weight: 2000 metric tons (2205 tons)
Outer wall: aluminum panels
  • The University of Hawaii
  • NAOJ Mitaka Campus