Arecibo observed near-Earth asteroid (505657) 2014 SR339 using its NASA-funded planetary radar system on February 9, 2018. Radar images reveal 2014 SR339 to have a lumpy, elongated shape at least 1.5 km long and a rotation consistent with the 8.7 hour period determined from optical lightcurves (B.D. Warner, MoreData!). At its closest approach on February 7, the asteroid was 0.054 AU, or about 21 times the Earth-Moon distance, away from Earth. 2014 SR339 was discovered on September 20, 2014 by the NEOWISE infrared spacecraft, which originally suggested its diameter was about 1 km.
Arecibo/NASA/NSF
2018-02-09
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