Subaru Deep Field
September 16, 1999
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Object Name: Subaru Deep Field
Telescope: Subaru Telescope / Cassegrain Focus
Filter: J (1.25micron), K'(2.13micron)
Color: Blue (J), Green (J+K'), Red (K')
Date: UT1999 April 3,4,29,30; May 1,2,6,7,8,11,27; June 6,7,9
Exposure: 12.1 hours (J), 9.7 hours (K')
Field of View: about 2 arcmins
Orientation: North up, east left
Position: RA(J2000.0)=13h24m21.3s, Dec(J2000.0)=+27d29m23s (Coma Berenices)
To best observe distant parts of our Universe, we need to look as far as possible away from the plane of our own Galaxy to avoid the interstellar dust and great myriad of stars that comprise the Milky Way. The island of Hawaii where Subaru Telescope is located is well situated for making these kinds of observations as the North Galactic Pole (as far away as you can get from the plane of our Galaxy) passes nearly directly overhead. This is where the influence of the atmosphere is smallest and the number of hours available for observing is relatively large. The Subaru Telescope has plans to observe a one-degree wide field near the North Galactic Pole called the "Subaru Deep Field" to study in great detail the contents of this distant part of our Universe.
The image shows the first observations made by Subaru of the "Subaru Deep Field." The image is composed of two infrared images taken with CISCO attached to the Subaru Telescope. We could successfully observe the faintest objects on a large infrared image.
Faint blue objects are expected to be small young galaxies about 3 billion light years away from the Earth, while faint red objects are thought to be fairly old galaxies about 7 billion light years away. The faintest white objects may be more than 10 billion light years away from the Earth, but observations at visible wavelengths are needed to confirm the distances. In addition, some of the reddest objects may be unusual, very dusty galaxies.
Due to the expansion of the Universe, distant objects have their visible light redshifted into the infrared part of the spectrum. Infrared observations are therefore essential for studying the most distant regions of the Universe, beyond 10 billion light years. It is thought that many of the faint objects in the figure may be at such distances. Further observations with visible-light cameras and infrared spectrographs will provide us with further details about each object and increase our understanding about star formation and galaxy evolution.