| Minorplanet: | yes |
| Background: |
|
| Discovered: | 18 July 1999 |
| Epoch: | 27 April 2019 (JD 2458600.5) |
| Uncertainty: | 4 |
| Observation Arc: | 9.21 yr (3,363 d) |
| Perihelion: | 37.200 AU |
| Semimajor: | 38.107 AU |
| Eccentricity: | 0.0238 |
| Period: | 235.24 yr (85,921 d) |
| Mean Motion: | / day |
| Inclination: | 3.9954° |
| Asc Node: | 127.44° |
| Arg Peri: | 285.68° |
| Satellites: | 1 |
| Mass: | (system) |
| Albedo: | 0.1 0.225 |
| Spectral Type: | B–V 1.68 V–R 0.682 |
| Abs Magnitude: | 7.1 |
(provisional designation ) is a trans-Neptunian object and binary system from the classical Kuiper belt, located in the outermost region of the Solar System. The bright cubewano belongs to the cold population and measures approximately 75km (47miles) in diameter. It was first observed at Mauna Kea Observatory on 18 July 1999. Discovered in 2005, its minor-planet moon is just 3 kilometers smaller than its primary and has an orbital period of 84 days.
orbit characterizes it as a classical Kuiper Belt object, or cubewano. Due to its nearly circular orbit and low inclination, it is also in the "cold" population of cubewanos. As a result, it is likely reddish in color.
has one moon, S/2005 1. This moon was discovered by the Hubble Space Telescope on 5 October 2013. It orbits away from 1999 OJ4, completing one orbit every . The orbit has an eccentricity of .
At about 72 km, it is nearly the same size as . From the surface of 1999 OJ4, S/2005 (1999 OJ4) 1 would have an apparent diameter of roughly 8.11°,[1] over fourteen times the apparent size of the Sun from Earth.