This is the first time a traveling ionospheric disturbance caused by an extraterrestrial source like a magnetar has been detected. The source entered an active phase on 22 January 2009, during which a large number of bursts were observed by several satellites. We detected its ionospheric signature using the coherent ionospheric Doppler radar system. In general, the Earth's ionosphere is a gigantic detector that responds to the ionizing radiation emitted through high-energy astrophysical objects.