Subaru Telescope - Overview

Overview

Subaru is a Ritchey-Chretien reflecting telescope. Instruments can be mounted at a Cassegrain focus below the primary mirror, in enclosures on either of two Nasmyth focal points on the sides of the telescope mount, to which light can be directed with a tertiary mirror, or, in an arrangement rare on large telescopes, at the prime focus, in lieu of a secondary mirror, to provide a wide field of view suited to deep wide-field surveys.

In 1984, the University of Tokyo formed an engineering working group to study the concept of a 7.5-metre telescope. In 1985, the astronomy committee of Japan's science council gave top priority to the development of a "Japan National Large Telescope" (JNLT), and in 1986, the University of Tokyo signed an agreement with the University of Hawaii to build the telescope in Hawaii. In 1988, the National Astronomical Observatory of Japan was formed through a reorganization of the University's Tokyo Astronomical Observatory, to oversee the JNLT and other large national astronomy projects.

Construction of the telescope began in April 1991, and later that year, a public contest gave the telescope its official name, "Subaru Telescope." Construction was completed in 1998, and the first scientific images were taken in January 1999. In September 1999, Princess Sayako of Japan dedicated the telescope.

A number of state-of-the-art technologies were worked into the telescope. For example, 261 computer-controlled actuators press the main mirror from the back to correct its distortion when the telescope changes its orientation. The telescope enclosure building is also shaped to minimize air turbulence, to improve the quality of astronomical images.

Subaru is one of the few state-of-the-art telescopes to have ever been used with the naked eye. For the dedication, an eyepiece was constructed so that Princess Sayako could look through it directly. It was enjoyed by the staff for a few nights until it was replaced with the much more sensitive working instruments.