MILLISECOND IMAGING OF RADIO TRANSIENTS WITH THE POCKET CORRELATOR
MILLISECOND IMAGING OF RADIO TRANSIENTS WITH THE POCKET CORRELATOR
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DOI：
10.1088/0004-637x/742/1/12
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发表时间：
2011-06
期刊：
影响因子：
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通讯作者：
Casey J. Law;Glenn Jones;Glenn Jones;D. C. Backer;W. Barott;G. Bower;C. Gutierrez-Kraybill;Peter K. G. Williams;D. Werthimer
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文献类型：
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作者：
Casey J. Law;Glenn Jones;Glenn Jones;D. C. Backer;W. Barott;G. Bower;C. Gutierrez-Kraybill;Peter K. G. Williams;D. Werthimer
我们演示了用无线电干涉仪以毫秒速率成像天空的信号处理概念。“口袋相关器”（PoCo）将来自无线电干涉仪多个元件的信号关联起来，速度快到足以成像短暂的分散脉冲。根据干涉测量的性质，毫秒相关器的功能类似于大型单碟望远镜，但具有改进的测量速度、空间定位、校准和抗干扰能力。为了验证这个概念，我们在艾伦望远镜阵列（ATA）上安装了PoCo，使用全功率、基于可见性和图像平面技术来搜索蟹状脉冲星B0329+54和M31的分散脉冲。在1.7小时的观测中，PoCo探测到来自蟹状星云脉冲星的191个巨大脉冲，在脉冲宽度为3 ms的情况下，其亮度超过了典型的5σ灵敏度极限（60 Jy）。来自脉冲星B0329+54的大约40%的脉冲是通过使用新的基于可见性的技术检测到的。对M31的观测限制了星系周围3度区域内亮度超过190 Jy的脉冲速率小于4.3 hr−1。我们计算了各种基于可见性的脉冲搜索算法的计算需求，并演示了计算集群如何帮助满足这一需求。快速成像概念的大规模实现将对银河系内外的毫秒脉冲进行盲搜索，为星际/星系间介质提供有价值的探测，发现新的无线电瞬变现象，并对它们进行定位以约束它们的起源模型。
We demonstrate a signal-processing concept for imaging the sky at millisecond rates with radio interferometers. The “Pocket Correlator” (PoCo) correlates the signals from multiple elements of a radio interferometer fast enough to image brief, dispersed pulses. By the nature of interferometry, a millisecond correlator functions like a large, single-dish telescope, but with improved survey speed, spatial localization, calibration, and interference rejection. To test the concept, we installed PoCo at the Allen Telescope Array (ATA) to search for dispersed pulses from the Crab pulsar, B0329+54, and M31 using total-power, visibility-based, and image-plane techniques. In 1.7 hr of observing, PoCo detected 191 giant pulses from the Crab pulsar brighter than a typical 5σ sensitivity limit of 60 Jy over pulse widths of 3 ms. Roughly 40% of pulses from pulsar B0329+54 were detected by using novel visibility-based techniques. Observations of M31 constrain the rate of pulses brighter than 190 Jy in a three-degree region surrounding the galaxy to <4.3 hr−1. We calculate the computational demand of various visibility-based pulse search algorithms and demonstrate how compute clusters can help meet this demand. Larger implementations of the fast imaging concept will conduct blind searches for millisecond pulses in our Galaxy and beyond, providing a valuable probe of the interstellar/intergalactic media, discovering new kinds of radio transients, and localizing them to constrain models of their origin.