National Astronomical Observatory of Japan Mitaka Campus

In short

The ​National Astronomical Observatory of Japan Mitaka Campus​ is the headquarters of the National Astronomical Observatory of Japan, located in Mitaka City, Tokyo. The campus is open to the public as an accessible research facility, and observation buildings from the time the observatory moved to Mitaka still remain. Several buildings, including the First Equatorial Building, are Registered Tangible Cultural Properties of Japan.

• ​First Equatorial Building​​: Completed in 1921, this is the oldest observation building on the campus. Inside is a 20-centimeter aperture telescope made by Zeiss in Germany.
• ​Observatory History Museum​​: Formerly the Large Equatorial Building, its wooden dome houses a 65-centimeter aperture telescope, which is the largest refracting telescope in Japan.
• ​Solar Tower Telescope​​: A building where the entire tower serves as the barrel of a telescope, also known as the "Einstein Tower."

History and Highlights

The ​National Astronomical Observatory of Japan Mitaka Campus​ serves as the headquarters of the National Astronomical Observatory of Japan. While conducting astronomical research and developing new observation equipment, it is open to the public as an accessible research facility.

Its predecessor, the Tokyo Astronomical Observatory, was located in Azabu-Iigura, near present-day Tokyo Tower. Because the site became too cramped and city lights made observations difficult, it was decided to relocate to Mitaka Village. When the observatory in Azabu suffered heavy damage in the 1923 Great Kanto Earthquake, the relocation progressed rapidly, moving in 1924 (Taisho 13).

Observation buildings from that era still remain on the campus. The Large Equatorial Building, completed in 1926, is a wooden dome built with the help of shipyard engineers to fully house a telescope with a focal length of 10 meters. Today, it serves as the Observatory History Museum. The Solar Tower Telescope, completed in 1930, functions with the entire tower acting as the telescope's barrel. It is also called the "Einstein Tower" because it was built for the same research purpose as the Einstein Tower in Germany. Along with the First Equatorial Building, both the Large Equatorial Building and the Solar Tower Telescope are Registered Tangible Cultural Properties of Japan.

The Meridian Circle Museum houses the Repsold Transit Instrument, made in Germany in 1880, which is an Important Cultural Property of Japan. When it was in Azabu, it was mainly used for observations to determine the time. Based on that time, a noon gun was fired at the former site of the Edo Castle main keep.

Viewing and Experience Highlights

• ​First Equatorial Building​​: Completed in 1921, this is the oldest observation building on the campus. Inside its 6-meter diameter dome is a 20-centimeter aperture telescope made by Zeiss in Germany, which was used for 61 years starting in 1938 to sketch sunspots. Solar observation sessions are held on select Saturdays and Sundays.
• ​Observatory History Museum​​: The 65-centimeter aperture refracting telescope was made by Zeiss in Germany and has the largest aperture among refracting telescopes in Japan. The observation floor on the second story could move up and down like an elevator, allowing observers to look through the telescope comfortably no matter which direction it faced. It is currently fixed in place.
• ​4D2U Dome Theater​​: Shows supercomputer simulations and data from the latest observation equipment as 3D images. Prior reservations are required for regular public showings.

Visitor Tips

When visiting, stop by the guardhouse just inside the main gate to sign the register, and affix the visitor sticker provided to a visible place on your clothing. Because this is a research facility, do not enter areas, buildings, or grassy fields outside the designated visitor route. The Solar Tower Telescope can only be viewed from the outside.

Inside the campus, you will also find the Mitaka City House of Stars, Forest and Picture Books. The Mitaka City Osawa-no-Sato Watermill Farmhouse is about 610 meters west-northwest from here.