X-Ray Astronomy Study with the Astro-D Satellite

ASCA(ASTRO-D)是ISAS的第四颗X射线天文卫星，于1993年2月20日成功发射。它带有嵌套的薄箔X射线反射镜，在0.5到10keV的宽能量范围内提供了很大的有效面积。一组CCD相机和成像气体闪烁正比计数器放置在焦平面上。ASCA是一个拥有这些仪器的高通量成像和光谱X射线天文台。日美两国科学家在X射线望远镜、X射线CCD相机和计算机软件的联合开发方面进行了广泛的合作。ASCA是一个X射线天文天文台，首次能够在0.5-10keV的宽能量范围内同时进行成像和光谱观测。ASCA仪器覆盖了等离子体诊断最重要的能带，因为在不同电离阶段从氧到铁的所有K线和K吸收边缘都在这个带内。ASCA的CCD摄像机可以单独解析所有主要线条。从谱线能量的多普勒频移可以明显地测量到1000公里/S量级或以上的等离子体运动。ASCA的这些能力使诊断在中子星和黑洞等致密天体周围吸积的物质成为可能。ASCA的空间分辨光谱也为研究超新星遗迹、星系和星系团中的扩展等离子体提供了强有力的手段。ASCA的关键元素正在成功地在轨道上工作。ASCA已经取得了几项显著的科学成果。其中大部分是由于日美在这一国际科学研究计划的帮助下进行的合作，作为科学研究的助学金。

ASCA (ASTRO-D), the fourth X-ray astronomy satellite of ISAS,was successfully launched on February 20,1993. It carries nested thin-foil X-ray mirrors providing a large effective area over a wide energy range from 0.5 to 10keV.A set of CCD cameras and imaging gas scintillation proportional counters are placed on the focal plane. ASCA is a high-throughput imaging and spectroscopic X-ray observatory with these instruments.An extensive collaboration between Japanese and U.S.scientists has been carried out in the joint developments of the X-ray telescopes, the X-ray CCD cameras, and computer software. It is continuing in the maintenance and the in-flight calibration of the instruments, and also in the data analysis and the following scientific activities.ASCA is an X-ray astronomy observatory which is, for the first time, capable of performing imaging and spectroscopic observations simultaneously over a wide energy range 0.5-10keV.The ASCA instruments cover the most important energy band for plasma diagnostics, because all the K-lines and the K-absorption edges from oxygen through iron at various ionization stages lie within this band. The CCD camera of ASCA can resolve all major lines individually. Motion of plasma of the order or greater than 1000km/s can be measured significantly from Doppler shift of the line energies. These capabilities of ASCA allow diagnostics of accreting matter around such compact objects as neutron stars and black holes. Spatially-resolved spectroscopy with ASCA also provides powerful means for the investigations of extended plasmas in supernova remnants, galaxies, and clusters of galaxies.The key elements of ASCA are succesfully working in orbit. ASCA has already obtained several remarkable scientific results. Most of them are due to the Japan-US collaboration with the help of this International Scientific Research Program as A Grant-in Aid for Scientific Research.