About the Okayama 188-cm Reflector Telescope
Located on the boundary between Asakuchi City and Yakage Town , Oda County , Okayama Prefecture, the Okayama 188-cm Reflector Telescope is one of the largest optical-infrared telescopes in Japan. When the Okayama Astrophysical Observatory (now the Okayama Branch of Subaru Telescope) opened in 1960, the 188-cm reflector telescope had the 7th largest aperture in the world, and was said to be the largest telescope in the Orient. It has produced many scientific results, such as the first extrasolar planet discovered from Japan. It has worked as a major Japanese optical infrared astronomical facility for over half a century. Since 2018, the telescope has been operated under a tripartite agreement between the Institute of Science Tokyo , Asakuchi City, and the National Astronomical Observatory of Japan. More than 60 years after its construction, the telescope is still used for cutting-edge scientific research, especially in the search for extrasolar planets, and the city of Asakuchi regularly uses it for visual observing events for the public .
Research
Currently, the Okayama 188-cm Reflector Telescope is primarily used for the exploration of exoplanets. The main instruments include an optical high-dispersion spectrograph and a three-color simultaneous photometric camera, each employing different methods to observe exoplanets. The former is used for radial velocity monitoring, while the latter is utilized for transit observations. Additionally, advanced instrument development is underway, such as the creation of an “astro comb,” a highly precise wavelength calibration standard based on quantum technology.
Researchers and graduate students from universities across the country have been involved in the development of these observation instruments, contributing to the training of many researchers in the field of optical and infrared astronomy. Furthermore, because the telescope is easily accessible within Japan and allows for relatively flexible scheduling of observation time, it is well-suited for large-scale projects. Due to these characteristics, the Okayama 188-cm Reflector Telescope plays a significant role in the education and training of young researchers.
Specifications
| Location | Honjo, Kamogata, Asakuchi, Okayama, Japan |
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| Manufacturer | Grubb Parsons (United Kingdom) |
| Effective diameter of primary mirror | 188 centimeters |
| Focal length of primary mirror | 915 centimeters |
| Body weight | 50 tons |
| Optical system | Classical Cassegrain |
| Observation wavelengths | 0.36 to 2.5 micrometers |
| Main observational instruments | HIgh Dispersion Echelle Spectrograph (HIDES) Infrared Imager/Spectrograph for the OAO 188-cm Telescope (ISLE) Kyoto Okayama Optical Low-dispersion Spectrograph (KOOLS) Multi-color Simultaneous Camera for studying Atmospheres of Transiting exoplanets (MuSCAT) |
| Characteristics | The Okayama 188-cm Reflector Telescope has a Newton focus, Cassegrain focus, and Coude focus. It can exchange observational instruments and secondary mirrors according to the needs of the observations. |
History
| 1953 | Science Council of Japan requested Japanese government construct a large telescope. |
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| October 19, 1960 | Opening ceremony held. Preliminary observation started. |
| 1994 | OASIS observation started (Comet Shoemaker–Levy 9’s collision with Jupiter was observed in the near infrared.) |
| 2000 | HIDES operation started (Full-scale high-dispersion spectroscopic observations) |
| 2006 | ISLE common use started |
| 2008 | KOOKS common use started |
| 2014 | MuSCAT first-light |
| 2018 | Open use ended |
Main Research Results
- Discovery of Multi-giant Planet System around Giant Star (Okayama Astrophysical Observatory, Japanese language only
- Farthest Giant Explosion in Universe Captured (Okayama Astrophysical Observatory, Japanese language only)
- Discovery of a Planet around a Giant Star (Okayama Astrophysical Observatory, Japanese language only)
- Timing the Shadow of a Potentially Habitable Extrasolar Planet Paves the Way to Search for Alien Life
- Sunny Super-Earth?
- Soccer Balls in Interstellar Space