# (152680) 1998 KJ9

(152680) 1998 KJ$_9$ is a sub-kilometer asteroid, classified as near-Earth object and potentially hazardous asteroid of the Apollo group. Based on absolute magnitude, it is the third largest asteroid known to have passed closer than the Moon.

## Description

It was discovered on 27 May 1998, by astronomers of the Lincoln Near-Earth Asteroid Research (LINEAR) at Lincoln Laboratory's ETS near Socorro, New Mexico, 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 KJ$_9$ 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.
| PHA | Date | Approach distance in lunar distances | Approach distance in lunar distances | Approach distance in lunar distances | Abs. mag (H) | Diameter $^{(C)}$ (m) | Ref $^{(D)}$ |
| PHA | Date | Nominal$^{(B)}$ | Minimum | Maximum | Abs. mag (H) | Diameter $^{(C)}$ (m) | Ref $^{(D)}$ |
| (152680) 1998 KJ9 | 1914-12-31 | 0.606 | 0.604 | 0.608 | 19.4 | 279–900 | data |
| (458732) 2011 MD5 | 1918-09-17 | 0.911 | 0.909 | 0.913 | 17.9 | 556–1795 | data |
| (163132) 2002 CU11 | 1925-08-30 | 0.903 | 0.901 | 0.905 | 18.5 | 443–477 | data |
| 69230 Hermes | 1937-10-30 | 1.926 | 1.926 | 1.927 | 17.5 | 700-900 | data |
| 69230 Hermes | 1942-04-26 | 1.651 | 1.651 | 1.651 | 17.5 | 700-900 | data |
| 2017 NM6 | 1959-07-12 | 1.89 | 1.846 | 1.934 | 18.8 | 580–1300 | data |
| (27002) 1998 DV9 | 1975-01-31 | 1.762 | 1.761 | 1.762 | 18.1 | 507–1637 | data |
| 2002 NY40 | 2002-08-18 | 1.371 | 1.371 | 1.371 | 19.0 | 335–1082 | data |
| 2004 XP14 | 2006-07-03 | 1.125 | 1.125 | 1.125 | 19.3 | 292–942 | data |
| 2015 TB145 | 2015-10-31 | 1.266 | 1.266 | 1.266 | 20.0 | 620-690 | data |
| (137108) 1999 AN10 | 2027-08-07 | 1.014 | 1.010 | 1.019 | 17.9 | 556–1793 | data |
| (153814) 2001 WN5 | 2028-06-26 | 0.647 | 0.647 | 0.647 | 18.2 | 921–943 | data |
| 99942 Apophis | 2029-04-13 | 0.0981 | 0.0963 | 0.1000 | 19.7 | 310–340 | data |
| 2017 MB1 | 2072-07-26 | 1.216 | 1.215 | 2.759 | 18.8 | 367–1186 | data |
| 2011 SM68 | 2072-10-17 | 1.875 | 1.865 | 1.886 | 19.6 | 254–820 | data |
| (163132) 2002 CU$_{11}$ | 2080-08-31 | 1.655 | 1.654 | 1.656 | 18.5 | 443–477 | data |
| (416801) 1998 MZ | 2116-11-26 | 1.068 | 1.068 | 1.069 | 19.2 | 305–986 | data |
| (153201) 2000 WO107 | 2140-12-01 | 0.634 | 0.631 | 0.637 | 19.3 | 427–593 | data |
| (276033) 2002 AJ129 | 2172-02-08 | 1.783 | 1.775 | 1.792 | 18.7 | 385–1242 | data |
| (290772) 2005 VC | 2198-05-05 | 1.951 | 1.791 | 2.134 | 17.6 | 638–2061 | data |
| $^{(A)}$ This list includes near-Earth approaches of less than 2 lunar distances (LD) of objects with H brighter than 20. $^{(B)}$ Nominal geocentric distance from the center of Earth to the center of the object (Earth has a radius of approximately 6,400 km). $^{(C)}$ Diameter: estimated, theoretical mean-diameter based on H and albedo range between X and Y. $^{(D)}$ Reference: data source from the JPL SBDB, with AU converted into LD (1 AU≈390 LD) $^{(E)}$ Color codes: unobserved at close approach observed during close approach upcoming approaches ||||||||