发表机构
ASTRON, Netherlands Institute for Radio Astronomy; Anton Pannekoek Institute for Astronomy, University of Amsterdam; MIT Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology; Department of Physics, Massachusetts Institute of Technology（荷兰射电天文研究所; 阿姆斯特丹大学安东·潘内科克天文学研究所; 麻省理工学院卡弗里天体物理学与空间研究研究所; 麻省理工学院物理学系）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本文介绍 CHIME/FRB Outrigger 中 Hat Creek Outrigger 的调试，采用高斯过程回归校准方案缓解射频干扰，将点源灵敏度提升约 1.69-1.87 倍，并验证了该框架对大型干涉阵列的适用性。
AI 中文摘要
本工作介绍了 Hat Creek Outrigger（HCO）的调试，这是一个双极化 256 单元射电干涉仪，是加拿大氢强度映射实验快速射电暴（CHIME/FRB）Outrigger 项目的一部分。鉴于复杂的射频干扰（RFI）环境持续污染 HCO 约 40% 的可用带宽，我们采用高斯过程回归实现了一种改进的校准方案，以在受 RFI 污染的通道上恢复复增益解。为验证我们的方法，我们使用已知瞬变源和连续谱源，在快速瞬变研究相关的时间尺度（≲秒）上测试了阵列的性能。我们发现，更新后的校准方案使阵列的点源灵敏度提高了约 1.69 倍至 1.87 倍，同时保持了与热统计一致的噪声特性。因此，我们发现阵列在 HCO 带通约 80% 以上的范围内表现持续符合理论预期。我们还观察到，在应用最近开发的空间滤波技术进行 RFI 缓解后，干涉测量性能有所改善，该技术依赖于准确的校准解来有效去除不需要的干扰。我们得出结论，我们的方法为在受 RFI 污染的通道上改进大型 N 干涉阵列的校准解提供了一个有效的框架。我们的工作激励了未来开发更复杂的技术，以在受 RFI 污染的通道中恢复天体物理信息，摒弃了历史上直接丢弃这些通道的做法。
英文摘要
This work presents commissioning of the Hat Creek Outrigger (HCO), a dual-polarization 256-element radio interferometer that is part of the Canadian Hydrogen Intensity Mapping Experiment Fast Radio Burst (CHIME/FRB) Outrigger project. Driven by a complex radio-frequency interference (RFI) environment that consistently contaminates $\sim40\%$ of HCO's usable bandwidth, we implement an improved calibration scheme using Gaussian Process Regression to recover complex gain solutions over RFI contaminated channels. To validate our method, we test the performance of the array using known transients and continuum sources over relevant timescales used for fast-transient research ($\lesssim$ seconds). We find that our updated calibration scheme results in a $\sim1.69\times~\mathrm{to}~1.87\times$ improvement in the array's point-source sensitivity, while simultaneously maintaining noise properties consistent with thermal statistics. As a result, we find that the array performs consistently within theoretical expectations across $\gtrsim80\%$ of HCO's bandpass. We further observe an improvement in the interferometric performance after applying recently developed spatial filtering techniques for RFI mitigation, which rely on accurate calibration solutions for effective removal of unwanted interference. We conclude that our approach provides a valid framework for improving calibration solutions over RFI contaminated channels for large-$N$ interferometric arrays more broadly. Our work motivates future development of more sophisticated techniques to recover astrophysical information in RFI-contaminated channels, departing from the historical practice of discarding them outright.
Comments29 pages, 14 figures, submitted to AJ
