CALIBRATION OF LOW-FREQUENCY, WIDE-FIELD RADIO INTERFEROMETERS USING DELAY/DELAY-RATE FILTERING
CALIBRATION OF LOW-FREQUENCY, WIDE-FIELD RADIO INTERFEROMETERS USING DELAY/DELAY-RATE FILTERING
复制标题
使用延迟/延迟率滤波校准低频、宽场无线电干涉仪
DOI：
10.1088/0004-6256/138/1/219
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发表时间：
2009
期刊：
影响因子：
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通讯作者：
D. Backer
中科院分区：
文献类型：
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作者：
A. Parsons;D. Backer
我们提出了一种滤波技术，可应用于宽带、宽场干涉数据的各个基线，以几何方式选择天球上包含主要校准源的区域。该技术依赖于给定基线的宽带频谱的傅里叶变换来获得一维“延迟图像”，然后对延迟图像的时间序列进行变换以获得二维“延迟/延迟率图像”。给定基线、带宽、积分时间和源位置的适当组合，可以在这些图像中选择源。由于 RFI 切除算法会删除数据，强烈且持续的射频干扰 (RFI) 限制了这种源选择的有效性。已经开发出一种一维复杂的 CLEAN 算法来补偿 RFI 切除效应。这种方法允许使用 CLEANed、源隔离数据来隔离带通和主光束增益函数。这些技术应用于探测再电离时代精密阵列的数据，证明了它们在校准具有较宽相对带宽和大视场的新一代低频射电干涉仪方面的价值。
We present a filtering technique that can be applied to individual baselines of wide-bandwidth, wide-field interferometric data to geometrically select regions on the celestial sphere that contain primary calibration sources. The technique relies on the Fourier transformation of wide-band frequency spectra from a given baseline to obtain one-dimensional “delay images,” and then the transformation of a time-series of delay images to obtain two-dimensional “delay/delay-rate images.” Source selection is possible in these images given appropriate combinations of baseline, bandwidth, integration time, and source location. Strong and persistent radio frequency interference (RFI) limits the effectiveness of this source selection owing to the removal of data by RFI excision algorithms. A one-dimensional, complex CLEAN algorithm has been developed to compensate for RFI-excision effects. This approach allows CLEANed, source-isolated data to be used to isolate bandpass and primary beam gain functions. These techniques are applied to data from the Precision Array for Probing the Epoch of Reionization as a demonstration of their value in calibrating a new generation of low-frequency radio interferometers with wide relative bandwidths and large fields of view.