Launch date: May 23, 1969

Lifetime: 10 years

Energy range: 3 to 750 kev (very "hard" x-rays to gamma rays)

Science Highlights:

  • One of the first satellites to detect gamma-ray bursts.
  • Long lifetime allowed for study of long-term variability of x-ray binaries and x-ray transients.
  • Co-discovered (with ANS) x-ray bursts.


    Launch date: Dec. 12, 1970

    Lifetime: Two years

    Energy range: 2 to 20 keV

    Science Highlights:

  • First earth orbiting mission to be entirely devoted to x-ray astronomy.
  • First comprehensive and uniform all sky survey.
  • Detected 339 x-ray sources, including binaries, supernova remnants, Seyfert galaxies and clusters of galaxies.
  • Discovery of the diffuse x-ray emission from clusters of galaxies.


    Launch date: August 21, 1973

    Lifetime: about nine years

    Energy range: 0.5 to 10 keV (x-ray only)

    Science Highlights:

  • Discovery of several log-period pulsars (e.g., X Per).
  • Discovery of absorpton dips in Cyg X-1.
  • Long-term monitoring of pulsars and other bright x-ray binaries.

  • Observed rapid intensity variability from Cen A.


    Launch date: October 15, 1974

    Lifetime: About six years

    Energy range: 0.3 to 40 kev

    Science Highlights:

  • Long-term monitoring of numerous x-ray sources.
  • Discovery of several long-period (minutes) x-ray pulsars.
  • Discovery of several bright x-ray transients probably containing a black hole (e.g., A0620-00=Nova Mon 1975).
  • Established that Seyfert I galaxies (Active Galactic Nuclei) are a class of x-ray emitters.
  • Discovery of iron line emission in extragalactic sources.


    Launch date: June 21, 1975

    Lifetime: About three years E

    nergy range: 0.15 Kev to 1 MeV (well into gamma-ray)

    Science Highlights:

  • Iron-line detection in the x-ray spectra of a cluster of galaxies.
  • Detection of black-body spectrum from x-ray bursts.
  • Set upper limit on the polarization of radiation from several x-ray binaries.


    Launch date: August 12, 1977

    Lifetime: about one year and half.

    Energy range: 0.2 keV to 10 MeV

    Science Highlights:

  • Complete flux-limited High Galactic Latitude Survey.
  • Measurement of x-ray background from 3 to 50 keV.
  • Comprehensive catalog of x-ray sources (one for each experiment).
  • Several hundred optical companions and source classifications based on x-ray source positions.
  • Monitored variability of a variety of objects from AGNs to x-ray binaries.
  • Studied aperiodic variability in Cyg X-1 on time scales on a few milliseconds
  • Discovered the first eclipse seen in a low-mass x-ray binary.


    Launch date: November 12, 1978

    Lifetime: About two and a half years

    Energy range: 0.2 keV to 20 keV

    First imaging x-ray telescope in space.

    High-resolution Solid State Spectrometer (0.5 to 4.5 keV).

    Science Highlights:

  • First high resolution spectroscopy and morphological studies of supernova remnants.
  • Recognized that coronal emissions in normal stars are stronger than expected.
  • Resolved numerous x-ray sources in the Andromeda Galaxy and the Magellanic Clouds.
  • First study of the x-ray-emitting gas in galaxies and clusters of galaxies revealing cooling inflow and cluster evolution.
  • Detected x-ray jets from Cen A and M87 aligned with radio jets.
  • First medium and deep x-ray surveys.
  • Discovery of thousands of "serendipitous" sources.
  • Marked a "turning point" in x-ray astronomy. After Einstein, X-ray astronomy is completely established.


    Tenma: February, 20, 1983, through November, 22 1985

    EXOSAT: May 26, 1983, through April 9, 1986

    GINGA: February 5, 1987, through November 1, 1991

    ROSAT: 1 June 1990, through 12 February 1999

    ASCA: February 20, 1993, through March 2, 2001

    RXTE: December 30, 1995, to the present

    BeppoSax: April 30, 1996, through 30 April 2002

    Chandra: July 23, 1999 (nominal five-year mission)

    XMM-Newton: December 10, 1999 (nominal 10-year mission)

    SOURCE:High-Energy Astrophysics Science Archive Research Center

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