2011 XC2

DiscoveredbyLINEAR (704)

Discoverydate8 December 2011

MPCdesignation

2011 XC₂

Minorplanet category

Apollo
NEO^[2]

2011 XC₂

Discovery[1]
Discovered by	LINEAR (704)
Discovery date	8 December 2011
Designations
MPC designation	2011 XC2
Minor planet category	Apollo NEO[2]
Orbital characteristics[2]
Epoch 13 January 2016 (JD 2457400.5)
Uncertainty parameter 7
Observation arc	22 days
Aphelion	3.1579 AU (472.42 Gm) (Q)
Perihelion	0.83844 AU (125.429 Gm) (q)
Semi-major axis	1.9982 AU (298.93 Gm) (a)
Eccentricity	0.58040 (e)
Orbital period (sidereal)	2.82 yr (1031.7 d)
Mean anomaly	176.76° (M)
Mean motion	0° 20m 56.184s /day (n)
Inclination	28.768° (i)
Longitude of ascending node	70.686° (Ω)
Argument of perihelion	306.58° (ω)
Earth MOID	0.00132534 AU (198,268 km)
Jupiter MOID	2.67756 AU (400.557 Gm)
Physical characteristics
Dimensions	~85 meters (279 ft)[3] 60–140 meters[4]
Mass	8.4×108 kg (assumed)[3]
Absolute magnitude (H)	23.2[2]

2011 XC₂ (also written 2011 XC2) is a near-Earth asteroid roughly 60–140 meters (200–460 ft) in diameter that passed less than 1 lunar distance from Earth on 3 December 2011.^[5]

From mid October 2011 until 3 December 2011 15:00 UT the small dim asteroid had an elongation less than 60 degrees from the Sun.^[6] (While less than 18 degrees from the Sun any dim asteroid can be lost in astronomical twilight, and many observatories can not see below ~40 degrees from the horizon.) On 3 December 2011 at 15:20 UT the asteroid passed 0.0023 AU (340,000 km; 210,000 mi) from Earth and at 16:20 UT passed 0.0016 AU (240,000 km; 150,000 mi) from the Moon.^[5] The asteroid was then discovered on 8 December 2011 by Lincoln Near-Earth Asteroid Research (LINEAR) at an apparent magnitude of 19 using a 1.0-meter (39 in) reflecting telescope.^[1] At the time of discovery the asteroid was near opposition to the Sun.^[6]

It has an observation arc of 22 days with an uncertainty parameter of 7.^[2] Virtual clones of the asteroid that fit the uncertainty region in the known trajectory show a 1 in 455,000 chance that the asteroid will impact Earth on 2 December 2056.^[3] With a 2056 Palermo Technical Scale of −4.35,^[3] the odds of impact by 2011 XC₂ in 2056 are about 22387 times less^[7] than the background hazard level of Earth impacts which is defined as the average risk posed by objects of the same size or larger over the years until the date of the potential impact.^[8] Using the nominal orbit, JPL Horizons shows that the asteroid will be 3.8 AU (570,000,000 km; 350,000,000 mi) from Earth on 2 December 2056.^[9]