The folks who keep watch over North America's skies are once again capturing the imaginations of children with their Santa Claus tracker.
It's been an annual tradition for the North American Aerospace Defence Command (NORAD) for more than half a century.
In 1955, a Sears ad in Colorado-Springs misprinted the phone number for kids to call and talk to the store's Santa.
Instead, the excited kiddies dialled up NORAD's predecessor, the Continental Air Defense Command.
The kind-hearted operator at the time told the children he'd have his staff check the radar for updates on St. Nick's progress.
"Since that time, NORAD men, women, family and friends have selflessly volunteered their time to personally respond to phone calls and e-mails from children all around the world," reads NORAD's Santa tracker site.
"In addition, we now track Santa using the Internet. Millions of people who want to know Santa's whereabouts now visit the NORAD Tracks Santa website."
The site contains a live map showing Santa's current location, as well as everywhere he's dropped off presents. Kids can time, down to the second, when he's poised to arrive in their hometowns.
"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," says NORAD.
"Amazingly, Rudolph's bright red nose gives off an infrared signature, which allows our satellites to detect Rudolph and Santa."
By Monday morning, Santa had already delivered 1.2 million gifts, the tracker showed.