The 75 - 170 metre wide asteroid 2013 RF will make a close pass (16.1 lunar distances, 0.0413 AU), travelling at 19.15 km/second, to the Earth-Moon system on the 7th September, 2013 @ 19:10 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).