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ASCA: The Advanced Satellite for Cosmology and Astrophysics

artist concept of ASCA

The Advanced Satellite for Cosmology and Astrophysics, ASCA, is Japan's fourth cosmic X-ray astronomy mission, and the second for which the United States is providing part of the scientific payload. The satellite was successfully launched on February 20, 1993. ASCA operated successfully till July 15 2000 when it was transferred into a safe-hold mode. The satellite re-entered on March 2, 2001 after 7 and half years of scientific observations. ASCA was the first satellite to use CCD detectors for X-ray astronomy.

Mission Characteristics

* Lifetime: February 20, 1993 - March 2, 2001
* Energy Range: 0.4 - 10 keV
* Special Features: First X-ray mission to combine imaging capability with broad pass band, good spectral resolution, and a large effective area
* Payload:
  • Four X-ray telescopes each composed of 120 nested gold-coated aluminum foil surfaces (total eff area 1,300 cm2 @ 1 keV, spatial resolution 3´ half power diameter, FOV 24´ @ 1 keV) working in conjunction with one of the following detectors:
    • a Gas Imaging Spectrometer (GIS; 0.8-12 keV)
      Two Imaging Gas Scintillation Proportional Counters (IGSPC)
      FOV 50´,
      spatial resolution ~0.5' at 5.9 keV,
      and energy resolution of 8 % at 5.9 keV,
      Eff area (GIS+XRT) 50 cm2 @ 1 keV
    • Solid-state Imaging Spectrometer (SIS; 0.4-12 keV)
      Two CCD arrays of four 420 X 422 square pixel chips,
      FOV 22´ X 22´,
      Spatial resolution 30",
      energy resolution of 2 % at 5.9 keV ,
      Eff area (SIS+XRT) 105 cm2
* Science Highlight: * Archive: Catalogs, Spectra, Lightcurves, Images and Raw data

[ASCA Guest Observer Facility] (

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