用数字阵列探测器观测移动目标的天体测量精度极限特征
Characterizing the astrometric precision limit for moving targets observed with digital-array detectors
摘要：
目标。我们调查的最大天体测量精度，可以达到对移动目标观测的数字传感器阵列，并提供了一个估计其最终下限的基础上的Cramér-Rao界。方法.我们扩展以前的工作一维高斯点扩散函数（PSF）专注于移动物体和扩展范围到二维阵列检测器。在这项研究中，一个固定的点源天体的点扩展函数被替换为它的卷积与线性运动，从而有效地模拟运动目标的扩展函数。结果利用该方法推导出的Cramér-Rao下限的表达式，可以详细地研究运动天体所能达到的天体测量精度的极限，并根据视宁度、探测器像素大小、偏心和源漂移引起的伸长等观测参数计算最佳曝光时间。模拟和实际数据的比较表明，我们的简单模型的预测与观测是一致的。
英文摘要：
Aims. We investigate the maximum astrometric precision that can be reached on moving targets observed with digital-sensor arrays, and provide an estimate for its ultimate lower limit based on the Cramér-Rao bound. Methods. We extend previous work on one-dimensional Gaussian point-spread functions (PSFs) focusing on moving objects and extending the scope to two-dimensional array detectors. In this study the PSF of a stationary point-source celestial body is replaced by its convolution with a linear motion, thus effectively modeling the spread function of a moving target. Results. The expressions of the Cramér-Rao lower bound deduced by this method allow us to study in great detail the limit of astrometric precision that can be reached for moving celestial objects, and to compute an optimal exposure time according to different observational parameters such as seeing, detector pixel size, decentering, and elongation of the source caused by its drift. Comparison to simulated and real data shows that the predictions of our simple model are consistent with observations.
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