In 2015, perytons were found to be the result of premature opening of microwave oven doors at the Parkes Observatory. On March 17, 2015, 3 perytons were produced by experimentation by microwaving ceramic mugs filled with water and opening the door before the microwave had stopped operating. The microwave oven releases a frequency-swept radio pulse that mimics an FRB as the magnetron turns off. Two Matsushita microwave ovens were deemed responsible for most of the perytons. Both were functional and over 27 years old. Perytons were found to be produced about 50% of the times that the microwave door was opened before the timer expired.