A Narrowband Burst from FRB 20190520B Simultaneously Observed by FAST and Parkes

Fast radio bursts (FRBs) are short-duration radio transients with mysterious origins. Since their uncertainty, there are very few FRBs observed by different instruments simultaneously. This study presents a detailed analysis of a burst from FRB 20190520B observed by FAST and Parkes at the same time. The spectrum of this individual burst ended at the upper limit of the FAST frequency band and was simultaneously detected by the Parkes telescope in the 1.5-1.8 GHz range. By employing spectral energy distribution (SED) and spectral sharpness methods, we confirmed the presence of narrow-band radiation in FRB 20190520B, which is crucial for understanding its radiation mechanisms. Our findings support the narrow-band characteristics that most repeaters exhibit. This work also highlights the necessity of continued multiband observations to explore its periodicity and frequency-dependent properties, contributing to an in-depth understanding of FRB phenomena.