(612911) 2004 XR₁₉₀

(612911) 2004 XR₁₉₀
	Hubble Space Telescope image of 2004 XR190, taken in October 2010
Discovery
Discovered by	CFEPS
Discovery site	Mauna Kea Obs.; (first observed only)
Discovery date	11 December 2004
Designations
MPC designation	(612911) 2004 XR190
Alternative designations	Buffy (nickname)
Minor planet category	TNO; detached; SDO; distant;
Orbital characteristics
	Epoch 2025 Ṃay 05 (JD 2460800.5)
	Uncertainty parameter 2
Observation arc	20.00 yr (8,036 d)
Earliest precovery date	6 December 2002
Aphelion	64.05 AU
Perihelion	51.59 AU
Semi-major axis	57.82 AU
Eccentricity	0.1077
Orbital period (sidereal)	439.7 yr (160,600 d)
Mean anomaly	287.1°
Mean motion	0° 0m 8.064s / day
Inclination	46.5065°
Longitude of ascending node	252.313°
Time of perihelion	26 May 2114; ±5 days
Argument of perihelion	280.5°
Known satellites	0
Physical characteristics
Mean diameter	335–530 km; 425–850 km; 350–784 km; 560+ km; 600±170 km;
Geometric albedo	0.04–0.16; 0.09 (assumed); 0.095±0.23 (R-band); 0.10–0.25;
Apparent magnitude	21.8±0.2 (r-band); 21.9+0.8; −1.5 (G-band); 21.85±0.35 (wide-band); 21.8+0.7; −0.4 (several other bands);
Absolute magnitude (H)	3.802±0.022 (R-band); 4.3; 4.4; 4.47; 4.50;

(612911) 2004 XR₁₉₀, informally nicknamed Buffy, is a trans-Neptunian object, classified as both a scattered disc object and a detached object, located in the outermost region of the Solar System. It was first observed on 11 December 2004, by astronomers with the Canada–France Ecliptic Plane Survey at the Mauna Kea Observatories, Hawaii, United States. It is the largest known highly inclined (> 45°) object. With a perihelion of 51 AU, it belongs to a small and poorly understood group of very distant objects with moderate eccentricities.