Examination of Characteristics of Atmosphere Fluctuations of Importance to Ground-Based Astronomy

该奖项支持对穿过大气的光路波动性质的测量和分析。 研究结果对于优化自适应光学、大型望远镜和地面空间干涉仪的设计具有重要意义。 测量将使用目前安装在威尔逊山上的红外空间干涉仪（ISI）进行，该仪器已经在启动此类测量中发挥了作用。 初步测量似乎表明，对于地面天文学中遇到的条件，光程波动通常与基于柯尔莫哥洛夫湍流标准模型和泰勒近似的预期显着不同。 此外，这些偏差可能对未来大孔径仪器的设计及其向红外区域的扩展产生重大影响。 该程序将测量从恒星物体到两个望远镜的光程差的波动，以及两个望远镜位置附近地面的波动。 这些将与风速、一天中的时间、天文视宁度和云量等参数相关。 测量结果将产生时间、艾伦方差和功率谱的结构函数。 此外，检查激光干涉仪和各种望远镜间隔的红外干涉条纹信号之间的相关性将提供有关距离结构函数的直接信息。 为了获得足够的统计样本，需要在一段时间内和在适用于地面天文观测的各种条件下进行观测。

This award supports measurement and analysis of the nature of fluctuations in optical paths through the atmosphere. The results should be of importance for optimizing designs for adaptive optics, for large telescopes, and for spatial interferometers operating from the ground. Measurements will be made with the Infrared Spatial Interferometer (ISI) now installed on Mount Wilson, which has already been useful in initiating such measurements. The initial measurements appear to show that for conditions encountered in ground-based astronomy, pathlength fluctuation often differ significantly from those expected on the basis of the standard model of Kolmogorov turbulence and Taylor's approximation. Furthermore, these deviations can have a significant bearing on the design of future large aperture instruments and their extension into the infrared region. The program will measure fluctuations in pathlength differences from a stellar object to the two telescopes and also fluctuations near the ground at the position of the two telescopes. These will be correlated with such parameters as wind speed, time of day, astronomical seeing, and cloud cover. The measurements will yield the structure function of time, Allan variances, and power spectra. In addition, examination of correlations between the laser interferometers and the IR interference fringe signals with various telescope separations will provide direct information on the structure function of distance. Observations over a period of time and under various conditions applicable to astronomical observations from the ground are needed in order to obtain an adequate statistical sample.