Vignetting Effect in the Soft X-Ray Telescope Onboard Yohkoh: I. Numerical Simulation
Vignetting Effect in the Soft X-Ray Telescope Onboard Yohkoh: I. Numerical Simulation
复制标题
Yohkoh星上软X射线望远镜的渐晕效应：一、数值模拟
DOI：
10.1007/s11207-013-0292-x
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发表时间：
2015
期刊：
影响因子：
2.8
通讯作者：
T.
中科院分区：
文献类型：
--
作者：
Shin;J.;Sakurai;T.
用数值模拟的方法研究了软X射线望远镜Yohkoh上的晕效应。视场有效区域的离轴变化表明，用一维轴对称模型不能很好地描述SXT中的晕晕现象。我们的模型假定X射线反射镜的响应函数是关于光学中心对称的，以及由于其他望远镜结构的掩星效应是关于几何中心对称的；晕影是这两个贡献的结果。我们发现，SXT有效面积的旋转不对称分布主要是由于光学中心相对于望远镜几何中心的偏移。由偏移量引起的旋转对称性偏离在视场外围最为明显，当考虑为一维分布时，这导致有效面积的色散。由于SXT的拟合误差大于测量误差，该模型不能完全描述SXT的晕晕现象。我们最终需要一个完整的二维模型来制作SXT中的晕影。
Using a numerical simulation method, we examine the vignetting effect in theSoft X-ray Telescope(SXT) onboardYohkoh. The off-axis variation of the effective area in the field-of-view shows that the vignetting in SXT cannot be described properly with a one-dimensional axisymmetric model. Our model assumes a response function of the X-ray mirror that is symmetric about the optical center, and an effect of occultation due to other telescope structures that is symmetric about the geometrical center; the vignetting is the result of these two contributions. We found that a rotationally non-symmetric distribution of the SXT effective area is mostly due to the offset of the optical center from the geometrical center of the telescope. The deviation from rotational symmetry due to the offset is most noticeable at the outskirts of the field-of-view, which results in the dispersion of effective area when considered as a one-dimensional distribution. The model cannot completely describe the vignetting in SXT because the fitting errors are larger than the measurement errors. We ultimately need a fully two-dimensional model for the vignetting in SXT.