skip to content
ASCA Guest Observer Facility

ASCA's Gas Imaging Spectrometers

ASCA's two Gas Imaging Spectrometers (GIS) were built by scientists and engineers at Tokyo University. The GIS, an imaging gas scintillation proportional counter, has two main parts: the gas cell, and the photon- sensitive phototube.

The gas cell is filled with a mixture of xenon (90 percent) and helium (10 percent). The cell has a front window made of beryllium (10 microns thick). The voltage across the gass cell is 8000 V.

The phototube was made by scientists and engineers at Hamamatsu Photonics. It has a quartz window (7.5 cm thick) and ten-stage dynodes.

The area of the GIS that is sensitive to X-rays is 50 mm in diameter. Other "vital statistics" of the GIS are as follows:

  • Energy Range : 0.7 keV to 10 keV
  • Energy Resolution: 8 percent at 5.9 keV
  • Field of View: circular, with a diameter of 50 arcmin

Effective area and energy resolution of GIS and SIS

More GIS Information

Ohashi, T. et al. 1996, "The Gas Imaging Spectrometer on Board ASCA", PASJ, 48, 157
Makishima, K. et al. 1996, "In-Orbit Performance of the Gas Imaging Spectrometer onboard ASCA ", PASJ, 48, 171
Yasushi Ikebe's doctoral thesis (1995, Univ of Tokyo), "X-ray Measurements of Mass Distribution in Clusters of Galaxies"
Tashiro, M. et al. 1995, "In-orbit performance of the GIS instrument on-board ASCA (Astro-D)", SPIE, 2518, 2
Kohmura, Y. et al. 1993, "Calibration of imaging gas scintilation proportional counters on Astro-D", SPIE, 2006, 78
Ohashi, T. et al. 1991, "Imaging gas scintillation proportional counters for Astro-D", SPIE, 1549, 9

If you have any questions concerning ASCA, visit our Feedback form.

This file was last modified on Tuesday, 19-Oct-2021 16:23:31 EDT

NASA Astrophysics

  • FAQ/Comments/Feedback
  • Education Resources
  • Download Adobe Acrobat
  • A service of the Astrophysics Science Division (ASD) at NASA/ GSFC

    ASCA Project Scientist: Dr. Nicholas E. White

    Responsible NASA Official: Dr. Andy Ptak

    Privacy Policy and Important Notices.