Compton Observatory Gamma-Ray

The Compton Gamma-Ray Observatory (CGRO) is an observatory launched by NASA in the family of the four “large observatories” (following the Space telescope Hubble). It was launched by the Space shuttle Atlantis (mission STS-37), the April 5th 1991. Its field of observation relates to the Gamma rays. Of an initial weight of almost 17 tons, it was at the time the satellite dedicated to astrophysics heaviest ever launched.

The name of Compton is given in the honor of Arthur Compton, Nobel Prize of physics for its work on the gamma rays.

Instruments

The instruments of the CGRO cover a vast range of the electromagnetic spectrum with high energy (of 20  keV with 30  GeV), is more than 6 orders of magnitude in Fréquence, Wavelength or energy. Four instruments were assembled on CGRO. By order ascending of energy concerned, one finds:

  • Burst and Transient Source Experiment ( BATSE , 20 keV-1 MeV) studied the sky in the search of short impulses gamma, the starts gamma. The instrument was composed of 8 detectors, each one located in a corner of the satellite (itself having the approximate form of a Parallélépipède). The part of the detector was made up of crystals of Iodure of sodium, which converted into visible Lumière the gamma rays striking it. A system of Photomultiplicateur then made it possible to study the produced light. The direction of arrival of the gamma rays was reproduced by the comparison of times of arrival of the gamma rays on the various detectors (from where the interest to move away them to the maximum by positioning them in the corners of the satellite). Each detector had two parts. One optimized for the detection of the short events and low intensity, the other for the event utilizing a greater number of photons, in order to allow to take spectroscopic measurements.
  • OSE ( Oriented Scintillation Spectrometer Experiment ) of the Naval Research Laboratory ensured the detection of gamma rays between 100  keV and 10  MeV.
  • Imaging Compton Telescope ( COMPTEL ) of the Institut Max-Planck was regulated on energies of 1-30  MeV and was able to determine the angle of arrival to a degree close and the energy of the photons of high energy with a margin of 5%.
  • Energetic Gamma Ray Experiment Telescope ( EGRET ) measured the gamma sources with highest energies (20  MeV with 30  GeV) with a precision of a fraction of degree and energy with a margin of 15%. EGRET was a collaboration of the Center of space flights Goddard, Institut Max-Planck and Université of Stanford.

Successors

In the space field, the artificial satellites SWIFT, alncé in 2004 and GLAST (launching envisaged in January 2008) are the successors of Compton GRO. On the ground, HESS strictly speaking represents the first Telescope (able to carry out astrophysical images of sources because of its angular Résolution) operative in this range wavelength.

See too

Related article

External bonds

  • Official site of Compton Gamma Ray Observatory

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