|Discovery date 27 May 1998|
Minor planet category Apollo NEO, PHA
Discovered 27 May 1998
Absolute magnitude 19.4
|MPC designation (152680) 1998 KJ9|
Observation arc 7706 days (21.10 yr)
Earth moid 0.6 cm
Asteroid group Apollo asteroid
|Discovered by LINEAR (704)
Aphelion 2.3742 AU (355.18 Gm) (Q)
Discoverer Lincoln Near-Earth Asteroid Research
(152680) 1998 KJ9 is a near-Earth asteroid and potentially hazardous object. It has a well determined orbit with an excellent observation arc of 21 years and an Uncertainty Parameter of 0.
It was discovered on 27 May 1998 by the Lincoln Near-Earth Asteroid Research (LINEAR) at an apparent magnitude of 17.6 using a 1.0-meter (39 in) reflector. It was tracked through 9 June 1998. It was recovered on 28 December 2003 which extended the observation arc by 5 years. Two precovery images from January 1990 extended the observation arc by 8 years.
Based on an absolute magnitude of 19.4, the asteroid has an estimated diameter of about 500 metres (1,600 ft). (152680) 1998 KJ9 is noted for a close approach to the Earth on 31 December 1914 at a distance of 0.00155 AU (232,000 km; 144,000 mi). It is one of the largest objects known to have come inside the orbit of the moon. During the 1914 close approach the asteroid reached about apparent magnitude 7.7.