20-cm Telescope Dome
The Oldest Observation Building in Mitaka Campus
The 20-cm (7.9-inch) Telescope Dome was designed by the Construction and Repair Department of Tokyo Imperial University, and constructed by Mr. Chodayu Nishiura in 1921. This two-story building is made of reinforced concrete. The 20-cm Refractor Telescope, housed in the dome, was manufactured by the German company Carl Zeiss. Its equatorial mount has a weight-driven clockwork mechanism controlled by a governor. This telescope played a major role in sketching observations of sunspots for 61 years starting from 1938.
The 20-cm Telescope Dome is the oldest among the observation buildings in Mitaka Campus, but its design embodies functionality.
This building was listed as a Registered Tangible Cultural Property of Japan in February 2002.
Solar Observation Parties
Solar observation parties are regularly held at the 20-cm Telescope Dome. When conditions are right, participants can observe sunspots on the solar surface with the 20-cm Refractor Telescope operated by the staff.
- To prevent the spread of the novel coronavirus, solar observation parties continue to be canceled until further notice.
- Only on sunny days from 10:00 a.m. to 2:30 p.m. or from 10:00 a.m. to Noon (in July, August, and September). In the summer season, the events may be canceled due to intense heat. After the observation parties, visitors can only view the telescope (until 5:00 p.m.).
- How to Join
- No fees or reservations are required. Our staff will be waiting at the telescope dome, so feel free to ask and join the party.
|Aperture||20 cm (7.9 in)|
|Focal Length||359 cm (11.8 ft)|
|Mount||Weight-driven clockwork drive|
|Size||Diameter: 6 m (19.7 ft), Height: 7.8 m (25.6 ft)|
|Status||Registered Tangible Cultural Property|
(Taisho Year 10)
(Showa Year 2)
|Zeiss-made equatorial telescope installed|
(Heisei Year 10)
|Retired from operation|
(Heisei Year 12)
|Opened to the public|
(Heisei Year 14)
|Listed as a Registered Tangible Cultural Property|