Wind-driven halo in high-contrast images I. Analysis of the focal-plane images of SPHERE
Wind-driven halo in high-contrast images I. Analysis of the focal-plane images of SPHERE
复制标题
高对比度图像中的风驱动晕 一、SPHERE 焦平面图像分析
DOI：
10.1051/0004-6361/201937397
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发表时间：
2020
影响因子：
6.5
通讯作者：
Cantalloube F
中科院分区：
文献类型：
--
作者：
Cantalloube F
风力驱动的光环是最新一代地面仪器提供的图像中观察到的一个特征，这些仪器配备了极端自适应光学系统和日冕仪，如甚大望远镜（VLT）的SPHERE。当大气湍流条件的变化快于自适应光学环路可以校正的速度时，就会出现这种特征。风驱动的晕被观察为点扩散函数沿着不同方向的径向延伸（这有时被称为蝴蝶图案）。当存在这种情况时，它会显著限制仪器的对比度能力，并阻止在近距离处提取信号或扩展信号，如拱星盘。这种限制是必然的，因为它污染的数据的相当一部分的时间：约30%的数据产生的VLT/SPHERE仪器的影响，由风驱动halo.AimsThis本文回顾了风驱动halo的原因，并提出了一种方法，直接从科学图像分析其贡献。它对原始对比度和后处理后的最终对比度的效果demonstrated.MethodsWe使用模拟和对天空的SPHERE数据来验证，用我们的方法提取的参数可以描述图像中的风驱动晕。我们研究了这些参数的时间，空间和光谱的变化，指出其有害影响的最终contrast.ResultsThe数据驱动的分析，我们提出了准确地描述风驱动的晕贡献的图像中提供的信息。这种分析证实，这是一个根本的限制，最终达到的对比performance.ConclusionsWith既定的程序，我们将分析一个大样本的SPHERE提供的数据，以提出后处理技术，是量身定制的，以消除风驱动的光环。
ContextThe wind-driven halo is a feature that is observed in images that were delivered by the latest generation of ground-based instruments that are equipped with an extreme adaptive optics system and a coronagraphic device, such as SPHERE at the Very Large Telescope (VLT). This signature appears when the atmospheric turbulence conditions vary faster than the adaptive optics loop can correct for. The wind-driven halo is observed as a radial extension of the point spread function along a distinct direction (this is sometimes referred to as the butterfly pattern). When this is present, it significantly limits the contrast capabilities of the instrument and prevents the extraction of signals at close separation or extended signals such as circumstellar disks. This limitation is consequential because it contaminates the data for a substantial fraction of the time: about 30% of the data produced by the VLT/SPHERE instrument are affected by the wind-driven halo.AimsThis paper reviews the causes of the wind-driven halo and presents a method for analyzing its contribution directly from the scientific images. Its effect on the raw contrast and on the final contrast after post-processing is demonstrated.MethodsWe used simulations and on-sky SPHERE data to verify that the parameters extracted with our method can describe the wind-driven halo in the images. We studied the temporal, spatial, and spectral variation of these parameters to point out its deleterious effect on the final contrast.ResultsThe data-driven analysis we propose provides information to accurately describe the wind-driven halo contribution in the images. This analysis confirms that this is a fundamental limitation of the finally reached contrast performance.ConclusionsWith the established procedure, we will analyze a large sample of data delivered by SPHERE in order to propose post-processing techniques that are tailored to removing the wind-driven halo.