Category of Astronomical Heritage: tangible immovable
Mitaka Observatory, Tokyo National Astronomical Observatory of Japan

Description

Geographical position

Mitaka Observatory Campus (1924), Tokyo National Astronomical Observatory of Japan (Part of NAOJ, 1988),
2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan, IAU code 388

Tokyo Astronomical Observatory (before 1938), IAU code 389

Location

Latitude 35°40’30,8’’ N, Longitude 139°32’17,1’’ E, Elevation ...m above mean sea level.

IAU observatory code

388

Description of (scientific/cultural/natural) heritage

The Tokyo Meteorological Observatory (TMO) was already founded in 1875.

Fig. 1a. Mintaka Observatory Entrance - National Astronomical Observatory of Japan (CC3, O muko-san-shibo)

Fig. 1b. Mintaka Observatory Campus - National Astronomical Observatory of Japan (credit: NAOJ)

"In 1888 (Meiji era 21), three organizations
- the Astronomical Observatory of Tokyo Imperial University,
- the Naval Meteorological Observatory, and
- the Geographical Bureau of the Ministry of Home Affairs --
merged to form Tokyo Astronomical Observatory (TAO) in Iikura, Azabu Ward (destroyed by an earthquake in 1923), where the Naval Meteorological Observatory was originally located." (History of NAOJ)

Fig. 2a. Transit Instrument, made by A. Repsold & Söhne of Hamburg (1888), (credit: NAOJ)

Fig. 2b. Edo Castle, Tokyo, (CC)

In that observatory, timekeeping was started with the Repsold Transit Instrument. A time signal cannon fired each day at noon; it was places at the main tower (Tenshu) of the Tokyo Imperial Palace (since 1869), the former Edo castle (35°41’N, 139°45’ E), the residence of the Tokugawa Shogunate, in Chiyoda, now in the centre of Tokyo.

A new observatory was planned outside of the centre of Tokyo in Mitaka in 1909. The Mitaka Observatory was moved in 1924 (Taisho era 13), built until 1935.

History

Fig. 3a. Einstein Solar Tower, Mintaka Observatory, Carl Zeiss of Jena (1930), (credit: NAOJ)

Fig. 3b. Dome of the 20cm-telescope, Carl Zeiss Jena (1921, installed in 1938), (credit: NAOJ)

Telescopes, Mintaka Observatory

20-cm-Equatorial -Telescope (359-cm-focal length), Carl Zeiss Jena (1921, installed in 1938), weight-driven clockwork drive,
White Light Telescope for sunspot and faculae observations (solar image with a diameter of 24cm),
Dome (1926) (diameter 6m, height 7.8m), 1998 retired
New system: 10cm refractor equipped with CCD (1997).
The sunspot relative numbers are reported to the Solar Influences Data Analysis Center (SIDC) in the Royal Observatory of Belgium.
Solar Tower Telescope ("Einstein Tower") for Solar spectroscopy, built by Carl Zeiss of Jena (1926-1930) - cf. Einstein Tower of the Astrophysical Observatory Potsdam,
Coelostat aperture 60cm, Cassegrain Reflector Telescope aperture 48cm, focal length 22m, Dome (diameter 5m, height 20m), constructed by the Nakamura Komusho Company (height 20m, diameter 5m),
Building embellished with terracotta tiles with scratched patterns.
1957 upgraded to the current optical system,
1968 (Showa Year 43) retired from operation.
Solar-Flare-Telescope: H-alpha Flare Patrol Telescope
STEP Full-Disk Magnetograph

$65-cm-Refractor, Carl Zeiss Jena (1929), (CC3, Kes$

Fig. 4b. 65-cm-Refractor, Carl Zeiss Jena (1929), (CC3, Kestrel)

$Dome of the 65-cm-Refractor, Carl Zeiss Jena (1929$

Fig. 4a. Dome of the 65-cm-Refractor, Carl Zeiss Jena (1929), (credit: NAOJ)

65-cm-Refractor (1021-cm-focal length), Carl Zeiss Jena (1929), used for photographic and spectroscopic observations of celestial objects,
Dome (1926) diameter 14.5m, height 19.5m, 1998 retired
Gautier Meridian Circle (20-cm, 310-cm-focal length), made by Paul Ferdinand Gautier (1842-1909) of Paris, 1903/04, mounted in the Meridian Circle Building in 1924, retired in 1983,
in 1992, equipped with a new CCD micrometer, the Gauthier Meridian Circle worked again, and for about ten years measured the precise positions of quasars and other faint objects, retired in 2000.
First and Second Meridian Mark Building for the Gautier Meridian Circle
Transit Instrument (13.5-cm, 212-cm-focal length), made by A. Repsold & Söhne of Hamburg (1880), bought for the Naval Meteorological Observatory of the Meiji government (1881),
Transit building (1925),
Display of transit instruments in the building since 2008.
Photoelectric Meridian Circle (PMC), (19cm, 257.6cm focal length) (1982),
1949 "Tokyo Mitaka Catalogue of Zodiacal Stars"
1950 "Tokyo Mitaka Catalogue of Zenith Stars"
1962 "Tokyo Mitaka Catalogue of Equatorial Stars", retired from operation in 2000.
Astronomical Instrument Museum in 2008.
50-cm Reflector Telescope (50cm, 603cm focal length) with Equatorial Fork Mount (1994), Dome (height 4.9m, diameter 4.75m), used for Regular Stargazing Parties for the public (since 1996)

Fig. 5a. Gautier Meridian Circle, Paul Ferdinand Gautier of Paris (1903/04), (credit: NAOJ)

Fig. 5b. 50-cm Reflector Telescope (credit: NAOJ)

6-m Millimeter-Wave Radio Telescope (Dish Diameter 6m), made by Kamakura Works, Mitsubishi Electric Corporation (1968/70), mounting by Norizuki Iron Works (now known as Norizuki Technical Factory),
it was the third millimeter-wave radio telescope in the world and the first in Japan.
used for Millimeter wave observations and detections of new interstellar molecules, distribution observations of interstellar molecules in the Orion Nebula and the central region of the Milky Way Galaxy, observations of master fluctuations, and VLBI observations.
Relocated to Mizusawa Astrogeodynamics Observatory (predecessor of Mizusawa VLBI Observatory), Iwate Prefecture (1988),
Relocated to Nobeyama Radio Observatory, Nagano Prefecture (1989),
Relocated to Kinkowan Park, Kagoshima Prefecture (1992),
Relocated to Mitaka Campus and preserved and exhibited in the visitors’ area (2018)
TAMA 300 - Laser Interferometer Gravitational Wave Antenna (1999) with a 300m baseline length.

Fig. 6. TAMA 300 - Laser Interferometer Gravitational Wave Antenna (1999), (credit: NAOJ)

State of preservation

The Solar Tower Telescope ("Einstein Tower") was listed as a Registered "Tangible Cultural Property of Japan" in July 1998.

In addition "Tangible Cultural Property of Japan" in the year:

- 1998 and dome in 2002 -- 65-cm-Refractor, Carl Zeiss Jena (1929)
- 2011/14 -- Repsold Transit Instrument Building
- 2014 -- Gautier Meridian Circle (1924), First and Second Meridian Mark Building, Old Library, Gate House, and Front Gate,
- 2002 -- 20-cm-Equatorial -Telescope, Carl Zeiss Jena (1921)
- 2020 -- 6-m Millimeter-Wave Radio Telescope (1968/70)
on Japan Astronomical Heritage list.

Comparison with related/similar sites

Such a large photographic 65-cm-Refractor (25.5-inch) with a 15-inch guide, Carl Zeiss of Jena, like this of Imperial University Observatory Tokyo, was also delivered as visual 65-cm-Refractor (25.5-inch), Carl Zeiss of Jena, to Belgrade, Serbia, and to Berlin-Babelsberg.
The Tokyo Solar Tower Telescope ("Einstein Tower"), built by Carl Zeiss of Jena (1926--1930) is similar (but only half the size) in comparison to the Einstein Tower of the Astrophysical Observatory Potsdam.

Threats or potential threats

no threats

Present use

The Mintaka Campus Observatory in Tokyo is used as main building of the National Astronomical Observatory Japan (NAOJ, 1988).
Some instruments with their buildings are used as museums for the public:

The Solar Tower Telescope ("Einstein Tower") (1930) was opened to the public in 2000, inside the building in 2010.
65-cm-Refractor, Carl Zeiss Jena (1929) opened as the Observatory History Museum in 2001
Repsold Transit Instrument (1880), Transit building (1925),
Display of transit instruments in the building since 2008
Photoelectric Meridian Circle (PMC), (1982),
Astronomical Instrument Museum in 2008.
Solar Tower Telescope ("Einstein Tower"), Carl Zeiss Jena (1930)
6-m Millimeter-Wave Radio Telescope (1968/70), Relocated to Mitaka Campus and preserved and exhibited in the visitors’ area (2018).

Astronomical relevance today

Fig. 7. Okayama Astrophysical Observatory (1960), (credit: NAOJ)

Besides the Mintaka Campus Observatory (1924) exist several other sites of Tokyo Observatory,
included in the National Astronomical Observatory Japan (NAOJ, 1988)

Mizusawa Latitude Observatory (1899), Mizusawa VLBI Observatory (NAOJ), 2-12, Hoshigaoka, Mizusawa, Oshu, Iwate 023-0861, Japan -- 20-m radio telescope, a 10-m radio telescope and the observations building for the VERA Project; the old visual zenith telescope room from the time of the Mizusawa Latitude Observatory and the Kimura Hisashi Memorial Museum
Norikura Solar Observatory (1949) of Tokyo Astronomical Observatory (Norikura Mountain 2876m), IAU code 382 --
25-cm-Coronagraph, 10-cm-Coronagraph, 10-cm-New Coronagraph.

Fig. 8. 188-cm-Telescope, Grubb-Parsons of Newcastle upon Tyne (1960), Okayama Astrophysical Observatory, (credit: NAOJ)

Okayama Astrophysical Observatory (OAO), (Mt. Chikurinji 372m), Tokyo (1960), IAU code 371 --
188-cm-Telescope, Grubb-Parsons of Newcastle upon Tyne,
91-cm-Telescope, 65-cm-Coudé-Type Solar Telescope, 50cm telescope, Vector Magnetograph, for optical and infrared astronomical observation.
Dodaira Observatory of Tokyo Astronomical Observatory (1962-2000), IAU code 387

Fig. 9a. Kiso Observatory (1974) at night, (credit: NAOJ)

Fig. 9b. 105-cm-Schmidt Telescope (1974), Kiso Observatory (credit: NAOJ)

Kiso Observatory (1974), (Mount Ontake 1,130m, 35°47’50"N 137°37’32"E), University of Tokyo, IAU code 381: 105-cm-Schmidt Telescope (105cm corrector lens and 150cm spherical mirror, focal length 330cm, 6° x 6°, Cassegrain System focal length 2376cm), Kiso used for studying extra-galactic astronomical objects,
30-cm-Robotic Telescope (K.3T, 2002).
Nobeyama Radio Observatory & Nobeyama Solar Radio Observatory (1982), 1350m:
45-m-single-dish Radio telescope, Nobeyama Millimeter Array (NMA) - interferometer consisting of six 10m diameter telescopes, Nobeyama Radio Heliograph (NoRH) (1992) - an array of eighty-four, 80cm antennas, Nobeyama Radio Polarimeters.
Mizusawa VERA Observatory: 20-m-Radioteleskop, 10-m-VLBI-Radioteleskop, Dr.-Kimura-Museum
Research Institute of Atmospherics der Universität Nagoya
National Astronomical Observatory Japan (NAOJ, 1988)
Large-scale Cryogenic Gravitational Wave Telescope KAGRA, in the Kamioka mine in Kamioka, Hida, Gifu Prefecture, Japan, with a baseline length of 3 km.
Hawaii Observatory (Hawaii) --
Subaru 8-m-Telescope (1999), Hilo Base Facility (Hilo),
Precision Solar Photometric Telescope (PSPT, 15-cm refracting telescope), operated at the Mauna Loa Solar Observatory (MLSO)

Fig. 10a. Nobeyama Radio Observatory (1982), (CC3, Wiiii)

Fig. 10b. VERA Observatory, Ishigakijima Station Shisa in Ishigaki (CC2, sota)

References

Bibliography (books and published articles)

Nakajima, H. ; Nishio, M. ; Enome, S. ; Shibasaki, K. ; Takano, T. ; Hanaoka, Y. ; Torii, C. ; Sekiguchi, H. ; Bushimata, T. ; Kawashima, S. ; Shinohara, N. ; Irimajiri, Y. ; Koshiishi, H. ; Kosugi, T. ; Shiomi, Y. ; Sawa, M. ; Kai, K. : The Nobeyama radioheliograph. In: Proceedings of the IEEE 82 (1994), Issue 5, p. 705-713.
Nakayama, Shigeru: A History of Japanese Astronomy: Chinese Background and Western Impact. Cambridge, Massachusetts: Harvard University Press 1969.
Noma, S. (Hg.): National Astronomical Observatory. In: Japan. An Illustrated Encyclopedia. Kodansha 1993.