In radio astronomy, perytons are short man-made radio signals of a few milliseconds resembling fast radio bursts (FRB). A peryton differs from radio frequency interference by the fact that it is a pulse of several to tens of millisecond duration which sweeps down in frequency. They are further verified by the fact that they occur at the same time in many beams, indicating that they come from Earth, whereas FRB's occur in only 1 or 2 of the beams, indicating that they are of galactic origin. The first signal occurred in 2001 but was not discovered until 2007. First detected at the Parkes Observatory, data gathered by the telescope also suggested the source was local. The signals were found to be caused by premature opening of a microwave oven door nearby.