Kwasan and Hida Observatories, Graduate School of Science, Kyoto University japanese Home page

The "Main Building" at the Kwasan Observatory.

The 45cm Refractor Telescope.

The telescope was initially bought by the Department of Astronomy, Kyoto University in 1927, and was installed in the Kwasan Observatory when it was founded two years later.

At that time, this telescope was equipped with a 30cm diameter lens. However, a new 45cm lens manufactured by Carl Zeiss replaced the original lens in order to improve performance. This replacement required a longer focal length, and thus necessitated minor changes in the telescope design. For example, the light which enters the telescope is first reflected by a mirror at the bottom, and then by a second mirror to form an image at the exit of an imaging lens mounted in the middle of the telescope.

Such changes made the telescope's appearance quite unique.

The tracking system is powered by gravity, which is the same method that is often used in antique clocks.

The performance
Aperture450 mm
Focal length6750 mm
F ratio15
Resolution0.29 arcsec
Light gathering power4130
Limiting visual magnitude16.0
Tracking systemGravitational

Path of the light

Path of the light Detailed information is available here.

The gravitational clock (Tracking system)

Gravitational Clock Click here for more detailed information.