An Overview of FAST Real-time Fast Radio Burst Searching System

In this paper, we report a real-time Fast Radio Burst(FRB) searching system that has been successfully implemented with the 19 beam receiver of the Five-hundred-meter Aperture Spherical radio Telescope(FAST).The relatively small field of view of FAST makes the search for new FRBs challenging, but its high sensitivity significantly improves the accuracy of FRB localization and enables the detection of high-precision neutral hydrogen absorption lines generated by FRBs. Our goal is to develop an FRB searching system capable of realtime detection of FRBs that allows high-time resolution spectro-temporal studies among the repeated bursts, as well as detailed investigations of these bursts and exploration of FRB progenitor models. The data from each beam of the 19-beam receiver are fed into a high-performance computing node server, which performs real-time searches for pulses with a wide dispersion measure(DM) range of 20–10,000 pc cm-3with step efficiency of 25% in real time. Then, the head node server aggregates all the candidate signals from each beam within a given time,determining their authenticity based on various criteria, including arrival time, pulse width, signal-to-noise ratio and coincidence patterns among the 19 beams. Within the 1.05–1.45 GHz operating bandwidth of the FAST 19beam receiver, the system achieves a frequency resolution of 122.07 kHz and a time resolution of 270.336 μs.Subsequently, our team detected a series of bursts with a DM of 566 on 2019 August 30 confirming them as FRB121102. The FRB searching system enables the 19-beam receiver of FAST to detect repeated/one-off pulses/bursts in real time.