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The EXOSAT Observatory

artist concept of EXOSAT in space
Credit: European Space Agency (ESA)

The European Space Agency's X-ray Observatory, EXOSAT, was operational from May 1983 to April 1986. During that time, EXOSAT made 1780 observations of a wide variety of objects, including active galactic nuclei, stellar coronae, cataclysmic variables, white dwarfs, X-ray binaries, clusters of galaxies, and supernova remnants.

Mission Characteristics

* Lifetime: May 26, 1983 - April 9, 1986
* Energy Range: 0.05-50 keV
* Special Features: 90 Hours highly-eccentric Earth orbit
* Payload:
  • 2 Wolter Type I grazing incidence Low Energy (LE; 0.05-2 keV) Imaging Telescopes, FOV ~ 2°, peak effective area 10 cm2 each with
    • Channel Multiplier Array (CMA; 0.05-2.0keV)
      eff. area 0.4 - 10 cm2, FOV ~2°, ~18 arcsecond spatial resolution
    • Position Sensitive Detector (PSD)
    • Transmission Gratings (TGS)
      500 lines mm-1(LE2), 1000 lines mm-1(LE1). Used in conjunction with the CMA detectors.
  • A Medium Energy (ME) Proportional Counter
    1-50 keV, FOV 45 arcmin, 1600 cm2
  • A Gas Scintillation (GS) Proportional Counter
    2-20 keV, 100 cm2
* Science Highlights:
  • Discovery of the Quasi Period Oscillations in LMXRB and X-ray Pulsars
  • Comprehensive study of AGN variability
  • Observing LMXRB and CV over many orbital periods
  • Measuring iron line in galactic and extra galactic sources
  • Obtaining low-energy high-resolution spectra
* Archive: Catalogs, Spectra, Lightcurves, Images and Raw data

[About EXOSAT] ( [Archive] ( [Software] ( [Gallery] ( [Publications] (

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Acting Project Leader: Dr. Barbara Mattson
All material on this site has been created and updated between 1997-2012.

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