Discovery date December 2015 Minor planet category Hungaria group Discovered December 2015 | MPC designation 2015 YU9
2015 YB Observation arc 23 days Asteroid group Hungaria family | |
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Aphelion 2.0204 AU (302.25 Gm) (Q) Perihelion 1.7794 AU (266.19 Gm) (q) | ||
2015 YU9, better known as 2015 YB and WY032FF, is a Hungaria group inner main-belt asteroid discovered in December 2015. Pan-STARRS precovery images from 8 December 2015 have been located. At the time of discovery the asteroid was 0.8 AU (120,000,000 km; 74,000,000 mi) from Earth which is close to the Earth minimum orbit intersection distance (MOID). The asteroid came to perihelion (closest approach to the Sun) around 28 December 2015.
When the asteroid was first detected and it had an observation arc less than 1 day, the asteroid was suspected of being a Near-Earth asteroid that would make a close approach to Earth on 19 December 2015. But that orbit solution used an erroneous observation from the Catalina Sky Survey causing an incorrect orbit determination. The asteroid is not a near-Earth object.
With an absolute magnitude of 19.2, the inner main-belt asteroid is about 380–860 meters in diameter. Initial mass media reports for the size of the asteroid were incorrectly based on the assumption the asteroid was 0.02AU from Earth and not 0.8AU from Earth.
On 31 December 2015 the asteroid received the provisional designation 2015 YU9.