First Deployment of a Novel Imaging Correlator for Radio Astronomy with the Long Wavelength Array

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Astronomical radio interferometry means combining signals from multiple radio telescopes to form a single coherent image. Advances in computer hardware enable increasingly large-scale interferometers. Such instruments will probe the early Universe and explore the radio sky in real-time. This project will implement a new algorithm to enable computationally efficient interferometry on large arrays. The algorithm has been shown to be effective in theory. Thyagarajan and collaborators will demonstrate it on real data. They will use the Long Wavelength Array in La Sevilleta, New Mexico. They will encode this algorithm in specialized hardware to enable a survey of astronomical radio transients. In addition to benefitting astronomy, this algorithm may find application wherever interferometry is used. Applications include radar, acoustic interferometry used in oceanography, national security applications and medicine.Coming advances in radio astronomy will be enabled by extremely large interferometers driven by high-performance, low-cost digital signal processing. Progress toward large scale interferometry requires rethinking the correlator of an interferometer. The correlator is the radio equivalent of a camera in an optical system. It cross-correlates signals from pairwise combinations of antennae. Its computational requirements scale as O(N^2), where N is the number of antennae. It dominates the cost and power consumption of large arrays. This project will implement the Modular Optimal Frequency Fourier (MOFF) correlator concept, in which spatial Fast Fourier Transforms in the aperture plane reduce the computational complexity to O(N log N). This potentially transformative advance enables larger arrays and the study of fast transients. This project will implement the algorithm and demonstrate it on real-world data from the Long Wavelength Array at La Sevilleta, deploy a Graphical Processing Unit (GPU) based implementation, and use this method to demonstrate a transient search pipeline. This project will demonstrate feasibility for future large scale interferometry projects such as HERA phase III.