(148975) 2001 XA255

, provisional designation:, is a dark minor planet in the outer Solar System, classified as centaur, approximately 38 km in diameter. It was discovered on 9 December 2001, by David C. Jewitt, Scott S. Sheppard, and Jan Kleyna observing from the Mauna Kea Observatory. The object is currently trapped in a 1:1 mean-motion resonance with Neptune following a path of the horseshoe type.

Orbit and classification
follows a very eccentric orbit (0.68) with perihelion just inside the orbit of Saturn, aphelion in the trans-Neptunian belt and a semi-major axis of 28.9 AU. The orbital inclination of this object is moderate at 12.6º.

Resonance with Neptune
was identified as trapped in a 1:1 mean-motion resonance with Neptune and 1:2 with Uranus by T. Gallardo in 2006. The object is dynamically unstable and it entered the region of the giant planets relatively recently, perhaps 50,000 years ago, from the scattered disk. It follows a short-lived horseshoe orbit around Neptune.

Physical characteristics
The object has an estimated diameter of 12.5 km and it was classified as an inactive centaur by David Jewitt. Observations by the NEOWISE mission gave a larger diameter of 37.7 kilometers and an albedo of 0.041. It has an absolute magnitude is 11.1.