(524366) 2001 XR254
, 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 cubewano belongs to the cold population and measures approximately. It was first observed on 10 December 2001, by astronomers at the Mauna Kea Observatory, Hawaii. Its 140-kilometer sized companion was discovered by the Hubble Space Telescope in June 2006.
Discovery and orbit
was discovered on 10 December 2001 by David C. Jewitt, Scott S. Sheppard and Jan Kleyna using 2.2-meter University of Hawaii reflector on Mauna Kea. belongs to the dynamically cold population of the classical Kuiper belt objects, with small orbital eccentricities and inclinations. Their semi-major axes reside mainly in the interval 40–45 AU.Satellite
is a binary consisting of two components of approximately equal size. Assuming that both components have the same albedo, the primary is estimated to be about 170 km in diameter. The size of the secondary in this case is estimated at about 140 km. The total mass of the system is about 4 kg. The average density of both components is about 1 g/cm3.| Semi-major axis | Eccentricity | Period | Inclination |
| 9311 ± 52 | 0.5561 ± 0.0047 | 125.579 ± 0.048 | 41.08 ± 0.22 |