In-orbit performance of the gas imaging spectrometer onboard ASCA

Kazuo Makishima, Makoto Tashiro, Ken Ebisawa, Hajime Ezawa, Yasushi Fukazawa, Shuichi Gunji, Masaharu Hirayama, Eriko Idesawa, Yasushi Ikebe, Manabu Ishida, Yoshitaka Ishisaki, Naoko Iyomoto, Tsuneyoshi Kamae, Hidehiro Kaneda, Ken'ichi Kikuchi, Yoshiki Kohmura, Hidetoshi Kubo, Kyoko Matsushita, Keiichi Matsuzaki, Tatehiro MiharaKen'ichiro Nakagawa, Takaya Ohashi, Yoshitaka Saito, Yutaro Sekimoto, Tadayuki Takahashi, Takayuki Tamura, Takeshi Tsuru, Yoshihiro Ueda, Noriko Y. Yamasaki

Research output: Contribution to journalArticlepeer-review

213 Citations (Scopus)


The in-orbit performance and calibration of the Gas Imaging Spectrometer (GIS), located on the focal plane of the X-ray astronomy satellite ASCA, are described. An extensive in-orbit calibration has confirmed its basic performance, including a position resolution of 0.6 mm (FWHM) and an energy resolution of 7.8% (FWHM), both at 6 keV. When combined with the X-ray telescope, the GIS sensitivity range becomes 0.7-10 keV. The in-orbit non X-ray background of the GIS has been confirmed to be as low as (5-9) × 10-4 c s-1 cm-2 keV-1 over the 1-10 keV range. The long-term detector gain has been stable within a few % for nearly 3 years. Extensive observations of the Crab Nebula and other sources have provided accurate calibrations of the position response, photometric capability, dead time, and timing accuracy of the GIS. Furthermore, the overall energy response, including the temporal and positional gain variations and the absolute gain scale, has been calibrated to ∼ 1%. Thus, the GIS is working as an all-round cosmic X-ray detector, capable of X-ray imagery, fine X-ray spectroscopy, X-ray photometry with a flux dynamic range covering more than 5 orders of magnitude, and fast X-ray photometry with a time resolution up to 60 μs.

Original languageEnglish
Pages (from-to)171-189
Number of pages19
JournalPublications of the Astronomical Society of Japan
Issue number2
Publication statusPublished - 1996
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


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