AKARI Produces Two New Infrared All-Sky Catalogues

Two new infrared catalogues, containing more than 1.3 million celestial sources, have been made public. The AKARI All-Sky Catalogues, based on the first all-sky infrared survey in more than a quarter of a century, will provide important new data for a wide range of studies that cover topics ranging from the properties of nearby stars, to the formation of planetary systems, and the star formation history of the distant Universe.
All-sky surveys are an essential tool for astronomers. The large numbers of objects that are detected in these surveys lend themselves to classification and statistical analyses of celestial bodies. The astronomical census that results from a multi-wavelength, all-sky survey provides a firm framework on which to build a deeper understanding of the formation and evolution of galaxies, stars and planetary systems. For more than 25 years astronomers have relied on the IRAS all-sky atlas, based on observations made in 1983 with the InfraRed Astronomical Satellite, to provide this type of information at infrared wavelengths. Today, the scientific community has an important new tool for this work: the AKARI all-sky catalogues.

AKARI, the first Japanese infrared astronomical satellite, was launched in February 2006 and surveyed the entire sky between May 2006 and August 2007. The two catalogues that are released publicly contain the positions and flux values (at 6 wavelengths) for more than 1.3 million celestial sources detected by two instruments carried by AKARI: the Infrared Camera (IRC) detected ~870,000 objects in two bands (9 and 18 micrometres), and the Far-Infrared Surveyor (FIS, sensitive to 65, 90, 140, and 160 micrometres) detected ~430,000 celestial sources.

These new catalogues, the AKARI-IRC Point Source Catalogue and the AKARI-FIS Bright Source Catalogue, are a significant improvement upon the previous all-sky infrared survey that was produced with IRAS. AKARI can pinpoint the location of a star to an accuracy of arcseconds (compared to arcminutes with IRAS), and it is about 10 times more sensitive (at 18 micrometres) than IRAS. These improvements will have a significant impact on the science that can be performed with these all-sky surveys.

"The release of the catalogues is very timely", notes Alberto Salama, Project Scientist for AKARI at ESA. "Many of the objects detected by AKARI and contained in these catalogues will be prime candidates for future investigation at far-infrared and submillimetre wavelengths with Herschel. These catalogues will be very useful for astronomers preparing for the next opportunity, in May, to propose observations with Herschel."

Some preliminary scientific studies using these new AKARI catalogues have been carried out by AKARI team members. These touch on: studies of the star formation history in the Universe, properties of star-forming galaxies, and searches for evidence of dust associated with planet formation in the debris disks around stars other than the Sun. These early studies, described in the accompanying article "Selected highlights from early studies with the AKARI all-sky catalogues" (see link in right-hand menu)demonstrate the role and importance of infrared observations in exploring a wide variety of astronomical topics.