World's largest submillimeter camera set to probe outer space
By Darren Quick
December 6, 2011
Although it might sound like an oxymoron, the newly unveiled SCUBA-2 camera housed at the James Clerk Maxwell Telescope (JCMT) on Mauna Kea, Hawaii, is the world's largest submillimeter camera. Submillimeter refers not to the physical size of the new camera itself, but to the submillimeter waveband between the far-infrared and microwave wavebands that the telescope observes. Being far more sensitive and powerful than its predecessor, SCUBA-2 will be able to map areas of the sky faster than ever before and provide information about the early life of stars, planets and galaxies.
Submillimeter observations provide information about the early life of stars by allowing astronomers to examine molecular clouds and dark cloud cores that are usually obscured by the very dust and gas cloud that collapsed under its own gravity to form the star.
"When you look up at the stars, you only see the light they are emitting in the visible part of the spectrum. Many galaxies, including our own Milky Way, contain huge amounts of cold dust that absorbs visible light and these dusty regions just look black when seen through an optical telescope. The absorbed energy is then re-radiated by the dust at longer, submillimeter, wavelengths", explains Professor Gary Davis, Director of the JCMT.
As well as being the world's largest submillimeter telescope, Director of the JCMT, Professor Gary Davis says the interior of SCUBA-2 is, "colder than anything in the Universe that we know of!" To allow it to detect the extremely low energy radiation in the submillimeter waveband emitted by the very cold material associated with the earliest evolutionary stages of galaxies, stars and planets, the detectors inside SCUBA-2 have to be cooled to just 0.1 degree above absolute zero (-273.5°C or -460.3°F).
SCUBA-2 is a replacement for SCUBA (Submillimeter Common User Bolometer Array), which was retired from service in 2005. Containing more than 10,000 superconducting sensors, the 4.5-ton SCUBA-2 measures 9.8 ft (3 m) high, 7.9 ft (2.4 m) wide and 8.5 ft (2.6 m) deep. With four sub arrays of 1,280 pixels each, the submillimeter camera boasts 5,120 pixels and provides a much larger field of view and sky-background limited sensitivity and will be able to map large areas of the sky up to 1,000 times faster than its predecessor.
"With SCUBA, it typically took 20 nights to image an area about the size of the full Moon. SCUBA-2 will be able to cover the same area in a couple of hours and go much deeper, allowing us to detect faint objects that have never been seen before," said Professor Wayne Holland of the UKATC, and the SCUBA-2 Project Scientist.
SCUBA-2 will allow astronomers to map sites of star formation within our Milky Way galaxy, as well as planet formation around nearby stars. Along with surveying our galactic neighbors, it will also be able to look deep into space to examine faint, faraway galaxies and help researchers understand how galaxies evolved since the Big Bang. Its speed will also allow for speedier identification of targets for further high-resolution examination by other telescopes, such as the Atacama Large Millimeter/submillimeter Array that started operations earlier this year.
SCUBA-2 was constructed as part of an international collaboration between the UKATC in Edinburgh, four universities from Canada and Britain (British Columbia, Cardiff, Edinburgh and Waterloo), the US National Institute of Standards and Technology (NIST), and the Joint Astronomy Centre, which operates the James Clerk Maxwell Telescope.