通过SHABAR系统观测帕拉纳尔白昼视宁度变化：方法描述及PoET太阳望远镜的首次测量
Daytime seeing variations in Paranal through a SHABAR system. Description of the method and first measurements from the PoET solar telescope
- Instituto de Astrofísica e Ciências do Espaço, CAUP, Universidade do Porto（波尔图大学空间科学与天体物理研究所）
- Departamento de Física e Astronomia, Faculdade de Ciências, Universidade do Porto（波尔图大学理学院物理与天文系）
- Instituto de Astrofísica e Ciências do Espaço, Universidade de Lisboa（里斯本大学空间科学与天体物理研究所）
- Departamento de Física, Faculdade de Ciências, Universidade de Lisboa（里斯本大学理学院物理系）
- University of North Carolina, Chapel Hill（北卡罗来纳大学教堂山分校）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
本文介绍与PoET太阳望远镜耦合的SHABAR系统，测量帕拉纳尔白昼视宁度，发现清晨接近1角秒，下午中位值超4角秒，37天中位视宁度为2.37角秒。
AI中文摘要：
目的：本文介绍了与最近投入使用的PoET太阳望远镜耦合的SHAdow Band Ranger（SHABAR）系统的软件及首次视宁度测量结果。该系统安装在ESO位于帕拉纳尔天文台的VLT平台上。该系统收集的视宁度测量数据在PoET的观测策略中起着关键作用，因为PoET使用1至55角秒之间的孔径来观测分辨的太阳区域。因此，较小孔径的使用依赖于良好的观测条件，这些条件通过仪器的实时测量来评估。方法：我们采用SHABAR系统，该系统由一系列非均匀间隔安装在杆上的闪烁计组成，用于测量入射光的闪烁。闪烁在单个探测器中被测量，然后用于表征在给定高度范围内的大气湍流。我们使用先前推导的公式，遵循Kolmogorov湍流模型，对收集的数据进行建模，并将其转换为视宁度测量值。结果：我们发现，在清晨，地面温度升高并在大气低层产生湍流之前，帕拉纳尔的白昼视宁度可以达到接近1角秒的值。在一天中，视宁度逐渐恶化，下午的中位视宁度值大于4角秒。我们还发现，这些变化在观测的最初几周内似乎保持稳定，比较37个独立运行日的结果时，中位视宁度为2.37角秒。
英文摘要：
Aims. In this paper we present the software and first seeing measurements from a SHAdow Band Ranger (SHABAR) system that is coupled with the recently comissioned PoET solar telescope, installed at ESO's VLT platform in the Paranal Observatory. The seeing measurements that are collected by this system play a pivotal role in the observational strategy of PoET, as it employs apertures ranging between 1 and 55 arcseconds to observe resolved solar regions. As such, the usage of the smaller apertures hinges upon good observational conditions, which are assessed through real-time measurements from the instrument. Methods. We employ a SHABAR system, consisting of a series of scintillometers that are non-uniformly spaced in a bar, measuring the scintillation of the incoming light. The scintillation is measured in individual detectors, which are then used to characterize the atmospheric turbulence at a given range of heights. We use previously derived formulations, following Kolmogorov turbulence models, to model the collected data and transform it into a seeing measurement. Results. We find that the Paranal daytime seeing can reach values close to 1 arcsecond in the early morning, before the ground temperature increases and creates turbulence in the lower layers of the atmosphere. Over the day, the seeing gradually worsens, with the median seeing reaching values larger than 4 arcseconds in the afternoon. We also find that these variations appears to be stable over the first weeks of observations, yielding compatible results when comparing 37 independent days of operations, with a median seeing of 2.37 arcseconds.
