光束偏斜和Stokes V，带离轴馈电
Beam squint and Stokes V with off-axis feeds
摘要：
具有离轴馈源的射电望远镜，例如（E）VLA，遭受“波束斜视”，其中两个正交的圆偏振采样在天空上具有不同的指向中心。它的影响在波束中心附近很弱，但在天线功率方向图的边缘变得越来越重要，在那里，在给定的天空位置处的两个极化中的增益显著不同。这种效应限制了圆偏振（Stokes V）的VLA测量，并在Stokes I中制作的图像中引入了动态范围限制和宽场伪影。我们提出了一个适应的基于能力的反卷积清洁方法，可以纠正这个缺陷“在飞行中”，同时成像，纠正以及相关的自校准。我们提出了两个例子，这种技术使用的程序“斜视”的Obit包，允许在斯托克斯V和斯托克斯I减少伪影的宽场成像。我们讨论了这些例子中的残余误差以及未来纠正这些错误的计划。这种技术可以推广到实现时间和空间可变的校正，如指向和交叉偏振泄漏误差。
英文摘要：
Radio telescopes with off-axis feeds, such as the (E)VLA, suffer from "beam squint" in which the two orthogonal circular polarizations sampled have different pointing centers on the sky. Its effects are weak near the beam center but become increasingly important towards the edge of the antenna power pattern where gains in the two polarizations at a given sky position are significantly different. This effect has limited VLA measurements of circular polarization (Stokes V) and introduced dynamic range limiting, wide-field artifacts in images made in Stokes I. We present an adaptation of the visibility-based deconvolution CLEAN method that can correct this defect "on the fly" while imaging, correcting as well the associated self-calibration. We present two examples of this technique using the procedure "Squint" within the Obit package which allows wide-field imaging in Stokes V and reduced artifacts in Stokes I. We discuss the residual errors in these examples as well as a scheme for future correction of some of these errors. This technique can be generalized to implement temporally- and spatially-variable corrections, such as pointing and cross-polarization leakage errors.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
