An anonymous reader writes "Asteroid 1998 QE2 has an estimated size of 1.3 km — 2.9 km (based on the object's absolute magnitude H=16.6). It was observed by the Spitzer Space Telescope by Trilling et al. (2010), who estimated that it has a diameter of 2.7 km and a dark optical albedo of 0.06. This asteroid will have a close approach with Earth at about 15.2 LD (Lunar Distances = ~384,000 kilometers) or 0.0392 AU (1 AU = ~150 million kilometers) at 2059 UT on 2013 May 31 and it will reach the peak magnitude ~10.8 on May 31 around 2300 UT."
Link to Original Source