The VLA Low‐Band Ionosphere and Transient Experiment (VLITE): Ionospheric Signal Processing and Analysis

Abstract

AbstractThis paper describes in detail the automated pipeline used for ionospheric processing and analysis by the Very Large Array (VLA) Low‐band Ionosphere and Transient Experiment (VLITE). VLITE is a prototype system that continuously acquires data streams at 320–384 MHz from 18 of the 27 antennas comprising one of the world's most powerful radio telescopes, the VLA. VLITE independently samples and processes these signals without interfering with primary VLA observations, taking advantage of a unique feature of the optical design of its parabolic antennas. These signals are processed and analyzed with an automated pipeline to characterize ionospheric fluctuations toward cosmic sources. In particular, “low‐band” (<500 MHz) observations with the VLA are quite sensitive to the horizontal gradient in the total electron content (TEC). Such observations toward a strong cosmic source can be used to characterize fluctuations with amplitudes TECU per km. In near real time, the pipeline generates time series and corresponding fluctuation spectra to characterize as fully as possible the observed field of TEC gradient fluctuations. The pipeline is optimized to highlight the VLA's ability to sense fluctuations on small temporal (∼seconds), spatial (∼few km), and amplitude (∼10−3–10−4 TECU per km) scales. The paper thoroughly describes the processing and analysis steps involved, including illustrative examples of each step and potential scientific applications of the resulting data products.