V-FASTR: The VLBA Fast Radio Transients Experiment

TL;DR

V-FASTR is a novel experiment utilizing the VLBA to detect fast transient radio signals in real-time, offering advantages over single-dish methods such as larger field of view and precise localization, by processing data in a commensal mode during regular observations.

Contribution

This paper introduces V-FASTR, a new method for blind detection of fast radio transients using VLBA data processed in real-time during standard operations.

Findings

Successfully detected pulsar signals during test observations.

Demonstrated the ability to localize events with milliarcsecond accuracy.

Showed the feasibility of real-time transient detection with VLBA.

Abstract

Recent discoveries of dispersed, non-periodic impulsive radio signals with single-dish radio telescopes have sparked significant interest in exploring the relatively uncharted space of fast transient radio signals. Here we describe V-FASTR, an experiment to perform a blind search for fast transient radio signals using the Very Long Baseline Array (VLBA). The experiment runs entirely in a commensal mode, alongside normal VLBA observations and operations. It is made possible by the features and flexibility of the DiFX software correlator that is used to process VLBA data. Using the VLBA for this type of experiment offers significant advantages over single-dish experiments, including a larger field of view, the ability to easily distinguish local radio-frequency interference from real signals and the possibility to localize detected events on the sky to milliarcsecond accuracy. We describe our software pipeline, which accepts short integration (~ms) spectrometer data from each antenna in real time during correlation and performs an incoherent dedispersion separately for each antenna, over a range of trial dispersion measures. The dedispersed data are processed by a sophisticated detector and candidate events are recorded. At the end of the correlation, small snippets of the raw data at the time of the events are stored for further analysis. We present the results of our event detection pipeline from some test observations of the pulsars B0329+54 and B0531+21 (the Crab pulsar).