Orbital elements:
2013 OS3 Earth MOID = 0.1751 AU
Epoch 2013 July 7.0 TT = JDT 2456480.5 MPC
M 185.13762 (2000.0) P Q
n 0.51686203 Peri. 195.63408 -0.60780471 -0.70005168
a 1.5377520 Node 293.36946 +0.76530308 -0.39046990
e 0.4829238 Incl. 24.10008 +0.21185994 -0.59788034
P 1.91 H 18.8 G 0.15
From 7 observations 2013 July 16-18.