(Subaru Prime Focus Camera)
(Subaru Prime Focus Camera)
The Widest Field of View on an 8-10 m Telescope
Subaru is the only 8-meter class telescope in the world with the ability to mount an instrument at prime focus, which has an extremely large field of view. Suprime-Cam is an 80 million pixel digital camera designed to take advantage of Subaru’s prime focus for efficient deep imaging of a large area of sky, with a 30 by 24 arcminute field of view, each image covers an area comparable to the size of the full moon. It is an effective tool for detecting small bodies at the outskirts of the solar system (Kuiper Belt objects), studying the birth and evolution of galaxies, and probing the large-scale structure of our Universe.
Even though Suprime-Cam's field of view is large as the size of the full moon, there is no compromise in sensitivity or the finest details it can capture. The faintest details visible in this color image are about 1000 million times fainter than what can been seen with the unaided eye. The brightest features in the image are stars belonging to our own Milky Way Galaxy. (The streaks running vertically from these stars are artifacts created when the detector is over exposed.) The majority of the remaining faint objects are external galaxies outside the Milky Way. In total, approximately 30,000 galaxies are found in this image. The close-up view (right panel) shows a previously unknown cluster of galaxies. The distance between the Earth and the cluster is estimated to be approximately 5 billion light years.
This small fuzzy object is a galaxy 12.6 billion light years from Earth. It shows evidence of forming stars rapidly at a time when the Universe was about a billion years old. Very distant galaxies are brightest at a particular wavelength that corresponds to their distance from Earth. By using special filters that select light at a particular wavelength, researchers are scouring the Universe for faint galaxies. Suprime-Cam’s efficiency in deep imaging of a large area of sky makes it a favorite tool for finding the most distant galaxies in the Universe.
At the end of their lives, both massive and light weight stars return much of their material back interstellar space. Light weight stars that weight between 0.8 to 8 times the Sun end their life by losing a large fraction of their weight by repeatedly expanding and shrinking until only their naked hot cores remain. Here, Suprime-Cam has captured the intricate detail of ripples and shells of the Ring Nebula.
The support astronomer’s main job is to understand what researchers want to observe, and to give them advice on how to achieve their goals.
Suprime-Cam is a super-large digital camera for studying very faint astronomical objects. Subaru is the only 8-meter class telescope with a prime focus. Suprime-Cam takes advantage of this unique capability. Smaller telescope or cameras with a smaller field of view take a much longer time to do what Suprime-Cam can do in a single exposure.
Putting a prime-focus instrument on a large telescope is a huge technological challenge. It is extremely unlikely that any existing 8-meter class telescope could develop similar capabilities. Subaru took on this difficult challenge to distinguish itself from other 8-meter class telescope, and it has succeeded.
With any sophisticated instrument, there is occasional hardware trouble, which we handle through everyday maintenance. Suprime-Cam does have some unique complications. Getting to the instrument while it is in the telescope is cumbersome. We need to tip the telescope and climb into a crane to reach the instrument, before performing delicate manual repairs mid-air.
(From a late 2002 interview with Suprime-Cam support astronomer Yutaka Komiyama.)