Asteroid 2015 DG198 passed by the Earth at a distance of 12 300 000 km (32.0 times the average distance between the Earth and the Moon, or 8.22% of the average distance between the Earth and the Sun), slightly before 9.10 pm GMT on Sunday 15 March 2015. There was no danger of the asteroid hitting us, though had it done so it would have presented only a minor threat. 2015 DG198 has an estimated equivalent diameter of 26-82 m (i.e. it is estimated that a spherical object with the same volume would be 26-82 m in diameter), and an object of this size would be expected to explode in an airburst (an explosion caused by superheating from friction with the Earth's atmosphere, which is greater than that caused by simply falling, due to the orbital momentum of the asteroid) in the atmosphere between 20 and 1 km above the ground, with only fragmentary material reaching the Earth's surface, although since an object at the upper end of this range would be expected to release an amount of energy equivalent to about 25 megatons of TNT (roughly 425 000 times the energy released by the Hiroshima bomb), then being directly underneath it might be fairly unpleasant.
The calculated orbit of 2015 DG198. JPL Small Body Database.
2015 DG198 was discovered on 23 February 2015 (twenty days after its closest approach to the Earth) by the University of Hawaii's PANSTARRS telescope on Mount Haleakala on Maui. The designation 2015 DG198 implies that it was the 4957th asteroid (asteroid G198) discovered in the second half of February 2015 (period 2015 D).
While 2015 DG198 occasionally comes near to the Earth, it does not actually cross our orbital path. It has an elliptical 799 day orbit, at an angle of 7.62° to the plane of the Solar System, that takes it from 1.06 AU from the Sun (1.06 times the average distance at which the Earth orbits the Sun), slightly outside our orbit, to 2.31 AU from the Sun, (2.31 times the distance at which the Earth orbits the Sun and considerably more than the distance at which the planet Mars orbits the Sun). As a Near Earth Object that remains strictly outside the orbit of the Earth it is classed as an Amor Family Asteroid.
See also...
Asteroid 2015 FS passed by the Earth at a distance of 16 620 000 km (43.4 times the average distance between the Earth and the Moon, or 11.1% of the average distance between the Earth and the Sun), slightly after 11.40 pm GMT on Saturday 14...
Asteroid 2015 EU passed by the Earth at a distance of 9 359 000 km (24.7 times the average distance between the Earth and the Moon, or 6.26% of the average distance between the Earth and the Sun), slightly after 2.40 am GMT on Thursday 12 March 2015.
Asteroid 2015 FD passed by the Earth at a distance of 4 212 000 km (11.0 times the average distance between the Earth and the Moon, or 2.82% of the average distance between the Earth and the Sun), slightly before 2.10 am GMT on Wednesday 11 March 2015...
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