2014 XL7

On 1 September 2014, the asteroid passed about 0.259 AU (38,700,000 km; 24,100,000 mi) from Earth,^[9] but remained undetected as at that time the asteroid had an apparent magnitude of 25 and was roughly 25° from the Sun.^[10] It was discovered on 11 December 2014, by the Mount Lemmon Survey at an apparent magnitude of 20 using the Steward Observatory's 1.52-meter (60 in) reflecting telescope at Mount Lemmon Observatory near Tucson, Arizona, and received the provisional designation 2014 XL₇.^[1]

With an observation arc of only 19 days, it had a cumulative Palermo Scale rating of –2.85 and was briefly the 9th most dangerous asteroid known.^[7] It was calculated that on 4 June 2065, there was a 1 in 270,000 chance of impact and on 4 June 2076, there was a 1 in 137,000 chance of impact.^[4] On 15 January 2015, the asteroid was recovered by Cerro Paranal Observatory which extended the observation arc to 35 days,^[2] and 2014 XL₇ was subsequently removed from the Sentry Risk Table using JPL solution 9.^[8]

As of 2021^[update], and last observed in November 2016, the asteroid has a better constrained orbit with an observation arc of 713 days and an uncertainty parameter of 2, which ranges from 0 (good) to 9 (highly uncertain).^[2][3] It has an apparent magnitude of 25.82,^[6] and orbits the Sun at a distance of 0.77–2.5 AU once every 2 years and 2 months (777 days; semi-major axis of 1.65 AU). Its orbit has an eccentricity of 0.53 and an inclination of 8° with respect to the ecliptic.^[3] The potentially hazardous asteroid has a minimum orbit intersection distance with Earth of 0.00217 AU (325,000 km; 0.844 LD), or less than the distance to the Moon. Its closest encounter with Earth will occur on 29 May 2046, at a nominal distance of 13,875,000 km; 8,622,000 mi (0.09275 AU).^[9] With an absolute magnitude of 21,^[3] the asteroid is approximately 170–380 meters (560–1,200 feet) in diameter.^[5][a]