October 2007, Nikon Kenkyukai
October 2007, Nikon Kenkyukai

The Spilit of Nippon Kogaku Tokyo

October 13, 2007
Nikon Kenkyukai Tokyo Meeting
Historical Nikon 91cm
Photographic Reflector

Nikon Kenkyukai Dodaira Meeting

The Dodaira Astronomical Observatory is located in the Mt. Dodaira above sea level 876 m in Saitama Prefecture near Tokyo. There is a 36-inch astronomical reflector dome. This astronomical dome was constructed in November 1962 by the Mitsui shipyard. The special research team of the Nikon Kenkyukai visited Dodaira Observatory to meet the big Nikon 36-inch astronomical reflector.

This dome was built in the Mitsui shipyard

The DODAIRA's Observatory Dome

Nikon 91cm Astronomical Photographic Reflector

The Nikon 91cm Astronomical Photographic Reflector

You can remember the Dodaira Astronomical Observatory by the report of the Nikon Kenkyukai June 2005 meeting . The Nikon 91cm astronomical photographic reflector is set up in a beautiful dome. The performance of Nikon 91cm astronomical reflector is still big excellent. The Dodaira Astronomical Observatory is the science facilities with historical value very much.

Beautiful Nikon 91cm Reflector and Dome

Historical Nikon 91cm Astronomical Photographic Reflector

Left: Dome Controller, Right: Telescope Controllers

Technical data of the Nikon 91cm

(1) Specifications

- Main telescope

   Diameter of primary mirror :  914 mm
   Focal length :  4.6 meters
   Max. aperture :  f/5
   Weight :  About 290 kg

- Finder

   Type :  Refraction
   Installed number :  2
   Diameter :  150 mm
   Focal length :  2.25 meters
   Eyepiece :  25mm and 80 mm
   With crosshair and adjustable lighting

- Equatorial mount

   Type :  English style
   Latitude :  36 degrees 2 minutes

(2) Drawing

Dimensions of Nikon 91cm Astronomical Photographic Reflector
Copyright (c) 1961, Nippon Kogaku Kogyo K. K. , All Rights Reserved.

Optical path diagram of Nikon 91cm Astronomical Photographic Reflector
Copyright (c) 1961, Nippon Kogaku Kogyo K. K. , All Rights Reserved.

NHK TV Program

The NHK news gathering crew visited the the Dodaira Astronomical Observatory on the day when Nikon Kenkyukai members gathered in that place. The report of that day was broadcast in the Japanese whole country on October 19, 2007.

Staff in TV Station

They were interested in the big telescope

The staff in the TV station interviewed Nikon Kenkyukai

Dinner at the Astronomical Observatory

We enjoyed ourselves over dinner at a restaurant Dodaira Observatory. We toasted with the beer for a beautiful star. Cheers!

Dinner in Astronomical Observatory

Delicious Beer of Local, OGAWA

Great Seeing by Nikon

A big dome in the astronomical observatory opens quietly, and the cold night sky appeared. We watched the brilliant star by the Nikon big telescope.

Very Excellent Big Telescope Nikon 91cm

You can see the stellar light directly

Cold Saturn

Hot Venus

Grand Reflector Nikon 91cm Super Light

The Brilliant Nippon Kogaku Tokyo Crest

Historical Value of Dodaira Observatory

A lot of cost is necessary to maintain an old astronomical observatory. However, the astronomical observatory with the history is valuable existence. Please assist in DODAIRA to the Nikon fan in the world so that the Dodaira Astronomical Observatory may live for a long time. The photograph below is Koichiro Tomita and scientists in Tokyo Astronomical Observatory.

Koichiro Tomita and scientists in Tokyo astronomical observatory
Photo: Copyright (c) 2008, Tokigawa Town, All Rights Reserved.

Attached to the bottom of the 91 cm reflector is a multicolor polarization photometer. This photo was taken in the 1970s. Koichiro Tomita is the person on the far left in the front row. He wears a woolen hat and black-rimmed glasses. Sen Kikuchi of the Tokyo Astronomical Observatory, second from the right in the front row, has long hair and glasses. He is the main researcher who developed this polychromatic polarimeter.



The Japanese science magazine NIKKEI SCIENCE is the Japanese version of SCIENTIFIC AMERICAN magazine. It was good news for 2022. Part of the web article of the Japanese version of the Nikon Kenkyukai was quoted and published in the NIKKEI SCIENCE magazine.


Nippon Astronomical Heritage 35th, Former Tokyo Astronomical Observatory Dodaira Observatory. The essay contributed by astronomer Hiroki Kousai was quoted in NIKKEI SCIENCE March 2022.


Nippon Astronomical Heritage 38th, Dodaira Schmidt Telescope. The essay contributed by Dr. Junichi Watanabe of the National Astronomical Observatory of Japan (NAOJ) was quoted in NIKKEI SCIENCE August 2022.

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Copyright Michio Akiyama, Tokyo Japan 2008, 2023