The Virtual Telescope Project says it tracked the apparent motion of the asteroid, which resulted in an image in which it appears distinctly.
"This is why stars leave long trails, while the asteroid looks like a sharp dot of light in the center of the image," the project's website said, explaining its technique. The sighting comes from a telescope at the Tenagra Observatories in Arizona.
The International Astronomical Union's Minor Planet Center says the asteroid could be as small as 13 feet (4 meters) in size, about the size of a classic Volkswagen Beetle. The Virtual Telescope Project estimates it to be about 33 feet (10 meters), which would put it closer to the size of a double-decker bus.
As you've likely noticed by now, the asteroid passed by us by with no ill effects.