(357439) 2004 BL86
is a bright sub-kilometer asteroid and binary system, classified as a near-Earth object and potentially hazardous asteroid of the Apollo group, approximately in diameter. It was discovered on 30 January 2004 by astronomers of the Lincoln Near-Earth Asteroid Research at Lincoln Laboratory's Experimental Test Site near Socorro, New Mexico. Its moon was discovered during the asteroid's close approach to the Earth in January 2015.
2015 Earth approach
On 26 January 2015 at 16:20 UTC, passed, or 3.1 lunar distances, from Earth. The asteroid briefly peaked around apparent magnitude 9 and was near the celestial equator. The asteroid was visible in telescopes with objectives of or larger; high-end binoculars under a dark sky may also have worked. Near closest approach the asteroid was moving about 2.5 degrees per hour. The asteroid came to opposition on 27 January 2015 at 04:37 UTC. Around 5:00 UTC, the asteroid was near M44.The 26 January 2015 approach of 3.1 lunar distances was the closest approach of for at least the next 200 years. For comparison,, about twice the size of, passed, or 1.3 lunar distances, from Earth on 31 October 2015.