The 730 - 1600 metre wide asteroid (250458) 2004 BO41 made a close pass (57.3 LD, 0.1473 AU) travelling at 21.39 km/second, to the Earth-Moon system on the 31st August 2015 @ 15:35 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).