RRATs are Rotating RAdio Transients which are thought to be neutron stars that emit occasional flashes of radio light at cm wavelengths at regular but sparse intervals. The total duration of emission is less than one second per day, although when “on” these sources are comparable to normal pulsars.
Current estimates suggest they may outnumber the total population of regular pulsars.
RRATs are difficult to detect at low dispersion measures, as they are difficult to discriminate from radio frequency interference (RFI). Their regular and dispersed nature helped lead to their discovery by Maura McLaughlin. Like pulsars, RRATs have a dispersion measure. At least one RRAT has been shown to be detectable in X-rays with a modulation consistent with the RRAT periodicity.
Some RRATs have subsequently been shown to emit “normal” pulsations at very low flux levels, so some RRATs are not dissimilar from pulsars with large modulation indices.