Parkes observations for project P1375 semester 2026APRS_01

Rotating radio transients (RRATs) are Galactic neutron stars that emit sporadic radio pulses, and the question of whether apparently one-off sources truly repeat remains unresolved. With the discovery of numerous fast radio bursts (FRBs), the paradigm of 'one detection defines an astrophysical source' has shifted. However, the distinction between truly non-repeating Galactic transients and insufficiently observed repeating sources remains critical. Recent high-sensitivity follow-up observations with FAST have revealed that multiple apparent one-off RRATs originally detected by Parkes are in fact repeating sources, with fainter pulses hundreds of times weaker than their initial bright detections. This discovery raises a fundamental question: are many one-off RRATs simply the result of insufficient observational sensitivity, or do they represent intrinsically catastrophic transient events. We propose deep follow-up monitoring of four apparent one-off RRATs using the Parkes Ultra-Wideband receiver system, which offers 1.7-3.4 times higher sensitivity than the Multibeam discovery data. These observations will constrain the pulse repetition rates and energy distributions of these sources, examine the extreme variability seen in some RRATs and pulsars that exhibit pulses differing by >500 times in brightness, and test whether hidden repeating emission explains the apparent one-off nature of these sources.