Investigation of X-ray Objects with Astro-D and ROSAT

1993年2月20日，日本第四颗X射线天文卫星Astro-D成功发射，并被命名为ASCA。1993年4月，ASCA的关键部件相继在轨开机，开始了观测工作。从4月到10月进行了性能验证观测，不仅验证了科学仪器的性能，而且验证了科学能力。ASCA是第一颗能够在0.5至12 keV的宽能量范围内对X射线天空进行成像的X射线天文卫星，尽管X射线望远镜的图像大小约为1弧分半高宽。ASCA的灵敏度远优于Ginga上的大面积计数器等非成像仪器。此外，该CCD照相机首次由ASCA送入轨道，具有出色的光谱分辨率。另一方面，已在轨道上运行了大约四年的德国X射线天文卫星ROSAT在低于0.5千电子伏的能量范围内具有比ASCA好得多的成像能力和更高的灵敏度。ASCA和ROSAT是相辅相成的，在性能验证期和客户观察期已经进行了几次同时观察。ROSAT所做的全天巡天的结果也有助于ASCA的几次定点观测。1994年3月，宇宙航行科学研究所在东京都立大学举行的“X射线天文学的新地平线-ASCA的初步结果”国际专题讨论会上介绍了这些合作的成果。

The Japan's fourth X-ray astronomy satellite, Astro-D was successfully launched on Feb. 20, 1993, and was named ASCA. The key elements of ASCA were successively turned on in orbit and it started its observatory work since April, 1993. The performance verification observations were done from April to October and not only the performance of the scientific instruments but also the scientific capability wes verified. After then, the guest observations based on proposals by astronomers in the world started.ASCA is the first X-ray astronomy satellite capable of imaging the X-ray sky in the wide energy range over 0.5 to 12 keV, although the image size of the X-ray telescope is approximately 1 arcminutes FWHM. The sensitivity of ASCA is much better than that of non-imaging instruments such as the large area counters on board Ginga. Furthermore, the CCD camera was carried into orbit for the first time by ASCA and has an outstanding spectral resolution. On the other hand, the German X-ray astronomy satellite ROSAT which has been in orbit for about four years has much better imaging capability and higher sensitivity in the energy range below 0.5 keV than ASCA. ASCA and ROSAT are complementary to each other and several simultaneous observations were already performed both in the performance verification period and the guest observation period. The results of the all sky survey done by ROSAT have also been useful to several ASCA pointing observations. The yields of these collaborations were presented in the international symposium "New Horizon in X-Ray Astronomy-First Rsults from ASCA-" held at the Tokyo Metropolitan University by Institute of Space and Astronautical Science in March, 1994.