- The Global Context range ring pulses like a sonar: three dim rings with a
  soft inward glow grow from the subject to 250 km, and the ring flashes as
  each one arrives. Flights, military aircraft and AIS vessels a pulse crosses
  get a brief echo around their brackets. The pulses run for about 9 s after
  a selection or camera move, dimming the ring between flashes, then rest
  with the ring steady on screen, so a parked view stops repainting. Under
  reduced motion there are no pulses and the ring stays on screen
  (manjunath22466, #1519).