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Subaru Telescope

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The Subaru Telescope is a massive scientific instrument used for astronomical observation. It is operated by the National Astronomical Observatory of Japan. The telescope is located at the Mauna Kea Observatory on the island of Hawaii. Its name is taken from the Pleiades, which is a well-known open star cluster. For many years, it held the title of the world's largest monolithic primary mirror. This means it had the largest single-piece mirror used in a telescope. It remained the largest until the Large Binocular Telescope opened in 2005.

The Keck Subaru and Infrared obervatories
The Keck Subaru and Infrared obervatories

This instrument is a Ritchey-Chretien reflecting telescope. This design uses mirrors to bounce and focus light to a specific point. Scientists can mount different tools, called instruments, at four distinct focal points. One location is the Cassegrain focus, which sits below the primary mirror. Two other locations are called Nasmyth focal points, located on the sides of the mount. Light reaches these points using a tertiary mirror. A fourth location is the prime focus, which is located where the secondary mirror would normally be. This prime focus setup is rare for large telescopes. It allows the telescope to perform wide-field surveys, which means looking at very large areas of the sky at once.

To keep the images sharp, the telescope uses very advanced technology. The primary mirror is supported by 261 computer-controlled actuators. These actuators are small devices that press against the mirror from underneath. They correct for distortion in the mirror that happens when the telescope changes its orientation. The telescope enclosure, or the building, is also specifically shaped. This shape helps minimize the effects of atmospheric turbulence, which is the shaking of air in the sky. Without these technologies, the images of stars would appear blurry.

The Keck Subaru and Infrared obervatories
The Keck Subaru and Infrared obervatories

The history of the Subaru Telescope began with planning in the 1980s. In 1984, an engineering working group at the University of Tokyo started studying the concept. By 1985, Japan's science council gave high priority to a "Japan National Large Telescope." In 1986, the University of Tokyo signed an agreement to build the telescope in Hawaii. Construction officially began in April 1991. The telescope was named "Subaru" after a public contest held in 1991. Construction was completed in 1998, and the first scientific images were captured in January 1999. In September 1999, Princess Sayako of Japan dedicated the telescope. She even used a special eyepiece to look through the telescope with her own eyes.

Subaru uses a wide variety of specialized instruments for different types of science. The Hyper Suprime-Cam (HSC) is a 900-megapixel ultra-wide-field camera. It was used to create a dark matter map in 2018.

HSCSDMmap2018
HSCSDMmap2018

Another tool is the SCExAO, which is a high-contrast imaging system. It uses a Phase Induced Amplitude Apodization (PIAA) design. This allows it to image exoplanets, which are planets orbiting other stars, much closer to their host stars than older designs. Other instruments include the MOIRCS, which is a wide-field camera and spectrograph. There is also the FMOS, an infrared spectrograph that can study up to 400 objects at once using movable fiber optics.

The telescope is currently a vital tool in several major space searches. It is a primary instrument used in the search for Planet Nine. This search is being conducted by two different research groups. One group is led by Konstantin Batygin and Michael Brown. The other group is led by Scott Sheppard and Chad Trujillo. This search is expected to take up to five years to complete. Subaru is particularly good at this because its field of view is 75 times larger than the Keck telescopes. This large view helps scientists scan the sky for the faint signals of a distant planet.

Subaru has also contributed to finding new worlds in our universe. In 2024, working with the TESS space telescope, it helped discover the planet Gliese 12 b. The telescope's ability to gather light and see wide areas makes it unique. It connects many different fields of study, from studying dark matter to finding new planets. Even though it has faced challenges, like a coolant leak in 2011 and a sensor mishap in 2023, it remains a cornerstone of global astronomy. It continues to help humans understand the vast systems of our universe.

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File:The Keck Subaru and Infrared obervatories.JPG
The Keck Subaru and Infrared obervatories.JPG
File:HSCSDMmap2018.gif
HSCSDMmap2018.gif
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