论文标题
概率方向依赖性电离层校准lofar-hba
Probabilistic direction-dependent ionospheric calibration for LOFAR-HBA
论文作者
论文摘要
方向依赖的校准和成像是生产具有宽场低频阵列（如Lofar）的深，高忠诚，高动态范围的无线电图像的重要组成部分。当前，基于最先进的方向依赖性校准算法取决于以下假设：异翼斑块大小比明亮的场内校准器之间的分离大得多。由于电离层的动态性质，通常会违反该假设，因此方向依赖性误差会影响校准器之间的图像质量。在本文中，我们提出了一个用于推断电离层筛选的概率物理信息模型，为视野中的所有来源提供了校准。我们将我们的方法应用于从Lofar两米的Sky Sumper档案中随机选择的观察结果，并表明校正了明亮校准器之间的几乎所有方向依赖性效应，并且在平均平均将明亮源的均方根残差降低了32 \％。
Direction dependent calibration and imaging is a vital part of producing deep, high fidelity, high-dynamic range radio images with a wide-field low-frequency array like LOFAR. Currently, state-of-the-art facet-based direction dependent calibration algorithms rely on the assumption that the isoplanatic-patch size is much larger than the separation between bright in-field calibrators. This assumption is often violated due to the dynamic nature of the ionosphere, and as a result direction dependent errors affect image quality between calibrators. In this paper we propose a probabilistic physics-informed model for inferring ionospheric phase screens, providing a calibration for all sources in the field of view. We apply our method to a randomly selected observation from the LOFAR Two-Metre Sky Survey archive, and show that almost all direction dependent effects between bright calibrators are corrected and that the root-mean-squared residuals around bright sources is reduced by 32\% on average.
