[5] A close encounter with the Earth on 14 December 2015 caused the value of the semi-major axis of 2015 XX169 to drift slowly upwards, and the object evolved from an Aten asteroid to an Apollo asteroid about a year after this close approach.
2015 XX169 was discovered on 9 December 2015 by R. G. Matheny observing with the 1.5-m reflector telescope at the Mount Lemmon Survey.
[2] 2015 XX169 is currently an Apollo asteroid (Earth-crossing but with a period greater than a year).
Its semi-major axis (currently 1.00096 AU) is similar to that of Earth (1.00074 AU), but it has a relatively low eccentricity (0.18431) and moderate orbital inclination (7.640°).
Asteroid 2015 XX169 follows an asymmetrical horseshoe path with respect to our planet; the value of its relative mean longitude oscillates about 180°, but enclosing 0°.