Precision calibration of radio interferometers using redundant baselines
Precision calibration of radio interferometers using redundant baselines
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DOI：
10.1111/j.1365-2966.2010.17174.x
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发表时间：
2010-01
影响因子：
4.8
通讯作者：
Adrian Liu;Max Tegmark;S. Morrison;A. Lutomirski;M. Zaldarriaga
中科院分区：
文献类型：
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作者：
Adrian Liu;Max Tegmark;S. Morrison;A. Lutomirski;M. Zaldarriaga
人们对21厘米断层成像的兴趣与日俱增，导致了低噪声、中等角度分辨率、高光谱分辨率和大视场的宽带无线电干涉仪的设计和建造。这些干涉仪的特性与传统无线电仪器略有不同，可能需要新的校准技术才能达到它们的设计灵敏度。自校准或冗余校准技术允许仪器根据复杂的天空发射结构进行校准，是理想的。特别是，这些新仪器拥有大量冗余基线，这使得冗余校准成为一个特别有吸引力的选择。在本文中，我们通过仿真研究了现有冗余校准方案的误差和偏差，并展示了如何消除统计偏差。我们还发展了一个通用的定标公式，包括冗余基线方法和基点源校准法作为特例，并说明了如何考虑与理想冗余和共面的微小偏差。
Growing interest in 21-cm tomography has led to the design and construction of broad-band radio interferometers with low noise, moderate angular resolution, high spectral resolution and wide fields of view. With characteristics somewhat different from traditional radio instruments, these interferometers may require new calibration techniques in order to reach their design sensitivities. Self-calibration or redundant calibration techniques that allow an instrument to be calibrated off complicated sky emission structures are ideal. In particular, the large number of redundant baselines possessed by these new instruments makes redundant calibration an especially attractive option. In this paper, we explore the errors and biases in existing redundant calibration schemes through simulations, and show how statistical biases can be eliminated. We also develop a general calibration formalism that includes both redundant baseline methods and basic point source calibration methods as special cases, and show how slight deviations from perfect redundancy and coplanarity can be taken into account.