The 2300 - 5200 metre wide asteroid 1993 UC will make a close pass (49.0 lunar distances, 0.1260 AU), travelling at 21.88 km/second, to the Earth-Moon system on the 20th March, 2013 @ 01:34 UT ±00:01.
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The Lunar Distance (LD), the distance between Earth and the Moon, equals 384,401 km, (or 0.00256 AU).