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Spectrometry of Celestial X-Rays 2-30 KeV (S77)

NSSDCA ID: 1972-014A-04

Mission Name: TD 1A
Principal Investigator:Dr. Jacques Labeyrie


A 100-sq-cm proportional counter was used to measure the spectra of celestial X-ray sources in 10 channels between 2 and 30 keV. The proportional counter was located behind a crossed pair of slot collimators, which together yielded a 5- by 1-deg field of view. The proportional counter had a 0.5-mm beryllium window and a xenon filler gas. It was constructed in two parts, which were then anticoincidenced to remove the background due to cosmic-ray particles. Several months after launch the experiment was switched off when problems were encountered with the spacecraft's encoder. During the second scan period, on July 1, 1973, the experiment was successfully switched on. Calibration showed that the instrument had not suffered any degradation in sensitivity nor in energy resolution and the experiment was able to fulfill its scientific mission. During spin-up mode the experiment scanned the earth as well as the sky and was able to monitor X-ray radiation from the auroral zones.

Alternate Names

  • S 77
  • Spectrometry of Extraterrestrial X-Rays
  • TD1A/SpectrometryofCelestialX-Rays2-30KeV_S77_


  • Solar Physics: X-Ray

Additional Information

Questions and comments about this experiment can be directed to: Coordinated Request and User Support Office



NameRoleOriginal AffiliationE-mail
Dr. Jacques LabeyriePrincipal InvestigatorCentre d'Etudes Nucleaires de Saclay
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