Showing posts with label infrared sky. Show all posts
Showing posts with label infrared sky. Show all posts

Wednesday, March 14, 2012

NASA Releases New WISE Mission Catalog of Entire Infrared Sky

This is a mosaic of the images covering the entire sky as observed by the Wide-field Infrared Survey Explorer (WISE), part of its All-Sky Data Release. Image Credit: NASA/JPL-Caltech/UCLA. Full image and caption - Rectangular view

Over 11,000 years ago, a massive, supergiant star came to the end of its life. The star's core collapsed to form an incredibly dense ball of neutrons, and its exterior was blasted away in an immense release of energy astronomers call a supernova. Image Credit: NASA/JPL-Caltech/UCLA. Full image and caption - enlarge image

PASADENA -- NASA unveiled a new atlas and catalog of the entire infrared sky today showing more than a half billion stars, galaxies and other objects captured by the Wide-field Infrared Survey Explorer (WISE) mission.

"Today, WISE delivers the fruit of 14 years of effort to the astronomical community," said Edward Wright, WISE principal investigator at UCLA, who first began working on the mission with other team members in 1998.

WISE launched Dec. 14, 2009, and mapped the entire sky in 2010 with vastly better sensitivity than its predecessors. It collected more than 2.7 million images taken at four infrared wavelengths of light, capturing everything from nearby asteroids to distant galaxies. Since then, the team has been processing more than 15 trillion bytes of returned data. A preliminary release of WISE data, covering the first half of the sky surveyed, was made last April.

The WISE catalog of the entire sky meets the mission's fundamental objective. The individual WISE exposures have been combined into an atlas of more than 18,000 images covering the sky and a catalog listing the infrared properties of more than 560 million individual objects found in the images. Most of the objects are stars and galaxies, with roughly equal numbers of each. Many of them have never been seen before.

WISE observations have led to numerous discoveries, including the elusive, coolest class of stars. Astronomers hunted for these failed stars, called "Y-dwarfs," for more than a decade. Because they have been cooling since their formation, they don't shine in visible light and could not be spotted until WISE mapped the sky with its infrared vision.

WISE also took a poll of near-Earth asteroids, finding there are significantly fewer mid-size objects than previously thought. It also determined NASA has found more than 90 percent of the largest near-Earth asteroids.

Other discoveries were unexpected. WISE found the first known "Trojan" asteroid to share the same orbital path around the sun as Earth. One of the images released today shows a surprising view of an "echo" of infrared light surrounding an exploded star. The echo was etched in the clouds of gas and dust when the flash of light from the supernova explosion heated surrounding clouds. At least 100 papers on the results from the WISE survey already have been published. More discoveries are expected now that astronomers have access to the whole sky as seen by the spacecraft.

"With the release of the all-sky catalog and atlas, WISE joins the pantheon of great sky surveys that have led to many remarkable discoveries about the universe," said Roc Cutri, who leads the WISE data processing and archiving effort at the Infrared and Processing Analysis Center at the California Institute of Technology in Pasadena. "It will be exciting and rewarding to see the innovative ways the science and educational communities will use WISE in their studies now that they have the data at their fingertips."

NASA's Jet Propulsion Laboratory (JPL) in Pasadena, Calif., manages and operates WISE for NASA's Science Mission Directorate in Washington. The mission was competitively selected under NASA's Explorers Program, which is managed by NASA's Goddard Space Flight Center in Greenbelt, Md. The science instrument was built by the Space Dynamics Laboratory in Logan, Utah, and the spacecraft was built by Ball Aerospace and Technologies Corp., in Boulder, Colo. Science operations, data processing and archiving take place at the Infrared Processing and Analysis Center at the California Institute of Technology in Pasadena. Caltech manages JPL for NASA.

For a collection of WISE images released to date, visit: http://wise.ssl.berkeley.edu/gallery_images.html

An introduction and quick guide to accessing the WISE all-sky archive for astronomers is online at: http://wise2.ipac.caltech.edu/docs/release/allsky/

For more information about WISE, visit: http://www.nasa.gov/wise


Whitney Clavin 818-354-4673
Jet Propulsion Laboratory, Pasadena, Calif.
whitney.clavin@jpl.nasa.gov

J.D. Harrington 202-358-5241
NASA Headquarters, Washington
j.d.harrington@nasa.gov

Wednesday, March 31, 2010

AKARI produces two new infrared all-sky catalogues

AKARI's view of the infrared sky: sources found at 9 micrometres are represented in blue, at 18 micrometres in green, and at 90 micrometres in red. Credit: JAXA - Hi-Res [jpg] 3,523.43 kb

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 today 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.

The AKARI catalogues cover the wavelengths 9, 18, 65, 90, 140 and 160 micrometres. These different wavelengths can be used to separate the various generic classes of objects, such as stars (blue) and galaxies (red), in what is called colour-colour space. This allows astronomers to select samples of the various classes of objects that they wish to study. Credit:From Pollo et al.



Most of the star formation in the Universe is hidden from our view at optical wavelengths. AKARI observations are used to peer through the dust that obscures local galaxies, revealing the star formation activity that is hidden at optical wavelengths. Credit: JAXA

Most of the star formation in the Universe is hidden from our view at optical wavelengths. AKARI observations are used to peer through the dust that obscures local galaxies, revealing the star formation activity that is hidden at optical wavelengths. Credit: JAXA

The presence of dusty material around stars is shown by higher than expected fluxes from stars at infrared wavelengths. On the left hand side the expected intensity from the visible surface (photosphere) of a star declines throughout the infrared spectral region. However, the dust grains radiate strongly at wavelengths longer than about 20 micrometres, giving rise to a prominent 'infrared excess'. Credit: JAXA

Editors notes:

AKARI, the first Japanese infrared astronomical satellite, was launched in February 2006, surveying the entire sky during its 16 month cryogenic mission lifetime between May 2006 and August 2007. The 68.5 cm diameter telescope was specially designed for infrared observations with its two instruments: the Infrared Camera (IRC), and the Far-Infrared Surveyor (FIS) instrument. In addition to the all-sky survey, AKARI performed more than 5000 pointed observations over the wavelength range 2-180 micrometres in 13 bands, providing comprehensive multi-wavelength photometric and spectroscopic coverage of a wide variety of astronomical sources: nearby solar system objects, zodiacal light, brown dwarfs, young stars, debris disks and evolved stars in our Galaxy and in other galaxies of the Local Group.

AKARI achieved its planned 'cold' lifetime of 550 days, during which it conducted the all-sky survey. AKARI also carried out more than five thousand individual pointed observations in this phase.

Its on-board supply of liquid helium ran out on 26 August 2007, and the spacecraft entered a new mission phase. The liquid helium was required to keep AKARI cold enough to observe in the far-infrared. The warm phase now uses the surviving instrument, the near-infrared mode of the infrared camera, which can operate under the warmer conditions provided by the on-board mechanical cooler, for near-infrared observations.

AKARI is a JAXA project with the participation of ESA. Development of the satellite and instruments, operation, and data reduction have been carried out in collaboration with the following institutes; Nagoya University, The University of Tokyo, National Astronomical Observatory Japan, Imperial College London, University of Sussex, The Open University (UK), University of Groningen / SRON (The Netherlands), and Seoul National University (Korea). The far-infrared detectors were developed under collaboration with The National Institute of Information and Communications Technology.

ESA's European Space Operations Centre (ESOC) in Darmstadt, Germany, provided the mission with ground support through its ground station in Kiruna, Sweden, for several passes per day in the cold phase of the mission.

ESA's European Space Astronomy Centre (ESAC) near Madrid, Spain, provided support for the sky-survey data processing through the pointing reconstruction - this allows the determination of accurate astronomical positions for each of the sources detected. ESAC also contributed to the issue of the AKARI-IRC Point Source catalogue. The AKARI survey catalogues are an important legacy for Herschel and Planck.

ESAC also provides user support for European astronomers who have been granted observing opportunities. The 10% of observing time obtained from this collaboration resulted in 400 observations in the cold phase and 844 in the warm phase, covering various fields of astronomy, from comets to cosmology.

The two catalogues that are publicly released are the AKARI-FIS Bright Source Catalogue Version 1 containing far-infrared (65, 90, 140, 160 micrometres) fluxes of 427,071 sources, and the AKARI-IRC Point Source Catalogue Version 1 containing mid-infrared (9 and 18 micrometres) fluxes of 870,973 sources. The data are provided as files (FITS/Text) as well as via the AKARI Catalogue Archive Server (AKARI-CAS) web search interface from the following websites:

For further details please contact:

Alberto Salama, ESA AKARI Project Scientist
Science Operations Department,
European Space Astronomy Centre,
Directorate of Science and Robotic Exploration
European Space Agency
Email:
Alberto.Salama@esa.int