NORAD uses four high-tech systems to track Santa; radar, satellites, Santa Cams and fighter jets.
Tracking Santa starts with the NORAD radar system called the North Warning System. This powerful radar system consists of 47 installations strung across the northern border of North America. On December 24th, NORAD monitors the radar systems continuously for indications that Santa Claus has left the North Pole.
The moment that radar indicates Santa has lifted off, we use our second detection system. Satellites positioned in geo-synchronous orbit at 22,300 miles from the Earth’s surface are equipped with infrared sensors, which enable them to detect heat. Amazingly, Rudolph's bright red nose gives off an infrared signature, which allows our satellites to detect Rudolph and Santa.
To see exactly where Santa is at this moment, click here: http://www.noradsanta.org/en/how.html