Saku observatory

Saku observatory, home to the public Usuda Star Dome, sits in Saku, Nagano Prefecture, Japan, a mountainous area known for clear, high-altitude skies.

About Saku observatory

The observatory operates as the Usuda Star Dome, a public astronomy facility built around a substantial 600 mm Cassegrain reflector from telescope maker Mitaka Kohki. Alongside the main instrument sit two smaller 200 mm refractors, giving visitors a range of views from wide star fields to closer planetary detail.

History

The facility's home city changed shape in 2005, when the former town of Usuda merged with Mochizuki and Asashina to form the new city of Saku on 1 April 2005 - carrying the observatory's name and identity forward under the newly enlarged municipality.

Telescopes & research

Beyond its main 600 mm reflector and 200 mm refractor pair, Saku observatory is equipped with a "Wonder Eye" flexible focal-extension system, designed to let visitors with mobility difficulties reach the eyepiece comfortably - a barrier-free approach to public stargazing that's relatively unusual among observatories of this size.

Location & getting there

Saku sits in Nagano Prefecture, in the mountains of central Japan, an area that historically has offered dark, high-altitude skies well suited to amateur and public observing.

Visiting Saku observatory

The observatory is open to the public daily from 10 a.m. to 10 p.m. Check ahead for any scheduling changes before you travel, especially around weather-dependent evening viewing sessions.

See your named star from here

With a 600 mm reflector and barrier-free viewing access, Saku observatory is built for genuine public stargazing. If you've named a star with us, find its coordinates in our catalogue and see how it looks through the Star Dome's telescopes on a clear Nagano night.