The 20-cm Telescope Dome was designed by Facilities Department of Tokyo Imperial University and constructed by Mr. Chodayu Nishiura in 1921. The construction of it is flat building made with reinforced concrete. The 20-cm Refractor Telescope was made by Carl Zeiss in Germany. The mount is equatorial clock drive by weight hanging system (governor style). This telescope had worked for observations through sunspot sketches for 61 years since 1938.
The 20-cm Telescope Dome is the oldest observational building in the NAOJ Mitaka campus, but the structure keeps the functionality.
This building has been registered a tangible cultural property of Japan in February, 2002.
In addition, at the 20-cm Telescope Dome, solar observation is held. On sunny days, the staff controls this 20-cm Refractor Telescope, and visitors can observe the sunspots on the surface of the sun.
Partial solar eclipse party
In the morning of January 6, 2019, a partial solar eclipse can be seen throughout Japan. We will hold a partial solar eclipse party with the 20-cm Refractor Telescope at the 20-cm Telescope Dome. No reservations are required. Anyone is welcome to come. You can see eclipse until around 11:37 a.m.
- Open-day schedule in January, 2019
- January 5, 6 (Partial solar eclipse), 7, 12, 13, 14, 19, 20, 26 and 27
- Open-day schedule in December
- December 1, 2, 9, 15, 16, 22, 23, 24, 25, 26 and 27
- Opening hours
- (July and August) From 10:00 a.m. to Noon.
It might be cancelled on intense heat days.
(Other Months) From 10:00 a.m. to 2:30 p.m.
- How to Join
- The advanced registration is not required. Everyone can join it free. The staff waits near the telescope, please feel free to ask.
|Focal length||359 cm|
|Mount||Weight clock drive equatorial|
|Target of observation||Sunspot|
|Size||Diameter 6m, Height 7.8m|
|Remarks||Registered Tangible Cultural Property (Structures)|
(Taisho era 10)
(Showa era 2)
|Installation Zeiss equatorial|
(Heisei era 10)
|Research observation end|
(Heisei era 12)
|Open to the public|
(Heisei era 14)
|Registered as Tangible Cultural Property of Japan|