AKARI

List all AKARI datasets

AKARI (ASTRO-F)

Mission Descriptions

Overview

"Akari" (AKARI, ASTRO-F) is an infrared astronomical observation satellite developed primarily by the Institute of Space and Astronautical Science (ISAS) in Japan. The main objective of its mission was to observe infrared radiation from space with high sensitivity and resolution, and to create an infrared map of the entire sky. It was launched on February 22, 2006, and completed its scientific observations in June 2011.

The satellite, weighing approximately 960 kg and measuring 1.9 × 1.9 × 3.2 meters, orbited in a sun-synchronous polar orbit at an altitude of about 750 km, with a period of approximately 100 minutes.

The astronomical goals were diverse, but the most significant were:

  • Understanding the formation and evolution of galaxies
  • Elucidating the process of star formation and the subsequent formation of planets around them

To achieve these, the satellite conducted the following observations:

  • An unbiased all-sky survey at wavelengths of 50-180 μm
  • Imaging and spectroscopic observations with higher sensitivity than the survey, covering wavelengths of 2-180 μm

Observation Phases

The observations by "Akari" were divided into the following three phases, depending on the status of the telescope's cooling system:

  • Phase 1: The initial six months focused on the all-sky survey (May 8, 2006 - November 9, 2006)
  • Phase 2: The period until the depletion of the cooling liquid helium (November 10, 2006 - August 26, 2007)
  • Phase 3: The period after the depletion of the cooling liquid helium (June 1, 2008 - May 14, 2010)

Observation Instruments

The satellite was equipped with a 68.5 cm aperture Ritchey-Chrétien reflector telescope, which hosted two observation instruments on its focal plane: the Far-Infrared Surveyor (FIS) and the InfraRed Camera (IRC). Both instruments could perform observations in imaging and spectroscopic modes.

A cooling system using liquid helium was also installed, maximizing the performance of the observation instruments.

Far-Infrared Surveyor (FIS)

The FIS was designed primarily for conducting an all-sky survey in the far-infrared region. In imaging mode, it observed in four wavelength bands, covering a total range of 50 - 180 μm through a combination of filters and detectors. In spectroscopic mode, it formed a Fourier spectrometer using a combination of polarizers and detectors, covering the wavelength range of 80-170 μm for spectroscopic imaging observations.

InfraRed Camera (IRC)

The IRC was an observation instrument mainly used for pointed observations in the near- to mid-infrared regions. It consisted of three independent camera systems (NIR, MIR-S, MIR-L), covering a combined wavelength range of 1.7 - 26.5 μm. In imaging mode, it observed in a total of nine wavelength bands by switching filters. In spectroscopic mode, it conducted low-dispersion spectroscopic observations by using prisms and grisms instead of filters.

Achievements

Notable achievements of "Akari" include the following:

  • Completion of the All-Sky Infrared Survey: "Akari" observed over 96% of the entire sky more than twice, creating an all-sky infrared map and identifying numerous previously unknown infrared sources.
  • Detailed Observation of Star Formation Regions: Observations across the near- to far-infrared spectrum provided detailed profiles of star formation regions.
  • Infrared Observations of Comets and Asteroids: The satellite provided data to understand the physical properties of comets and asteroids within the solar system.

Additionally, based on "Akari" observation data, many data products such as all-sky infrared maps and various catalogs have been created. These observation data and products provide valuable information on the formation processes of stars and galaxies, and the evolution of the universe.

Refereneces

Datasets