Update: The 180 - 400 metre wide asteroid 2011 XC has made a close pass (73.9 lunar distances, 0.1898 AU), travelling at 11.23 km/second, to the Earth-Moon system on the 11th December, 2011 @ 21:56 UT ±00:05.
The 190 - 420 metre wide asteroid 2011 XC will make a close pass (73.7 lunar distances, 0.1893 AU), travelling at 11.24 km/second, to the Earth-Moon system on the 12th December, 2011 @ 00:00 UT ±03:04.
Orbital elements:
2011 XC Earth MOID = 0.1707 AU
Epoch 2011 Aug. 27.0 TT = JDT 2455800.5 MPC
M 235.36513 (2000.0) P Q
n 0.69815621 Peri. 63.75252 -0.69820262 -0.62011879
a 1.2584452 Node 75.67628 +0.45062331 -0.76895847
e 0.1361284 Incl. 21.66630 +0.55628386 -0.15542056
P 1.41 H 20.8 G 0.15 U 8