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(152680) 1998 KJ9

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(152680) 1998 KJ9
Discovery[1]
Discovered byLINEAR (704)
1.0-m Reflector
Discovery siteLincoln Lab's ETS
Discovery date27 May 1998
Designations
(152680) 1998 KJ9
NEO · PHA · Apollo [2]
Orbital characteristics[2]
Epoch 13 January 2016 (JD 2457400.5)
Uncertainty parameter 0
Observation arc7706 days (21.10 yr)
Aphelion2.3742 AU (355.18 Gm) (Q)
Perihelion0.52125 AU (77.978 Gm) (q)
1.4477 AU (216.57 Gm) (a)
Eccentricity0.63995 (e)
1.74 yr (636.25 d)
6.2670° (M)
0° 33m 56.952s / day (n)
Inclination10.932° (i)
98.675° (Ω)
259.95° (ω)
Earth MOID0.00552 AU (826,000 km)
Physical characteristics
Dimensions~500 meters[3]
Mass7.87×1010 kg[4]
19.4[2]

(152680) 1998 KJ9 is a sub-kilometer asteroid, classified as near-Earth object and potentially hazardous asteroid of the Apollo group.[2] Based on absolute magnitude, it is the third largest asteroid known to have passed closer than the Moon.[5]

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.[1] It was tracked through 9 June 1998.[6] It was recovered on 28 December 2003 which extended the observation arc by 5 years.[7] Two precovery images from January 1990 extended the observation arc by 8 years.[6]

Based on an absolute magnitude of 19.4,[2] the asteroid has an estimated diameter of about 500 metres (1,600 ft).[3] (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).[8] 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.[9]

History of close approaches of large near-Earth objects since 1908 (A)
PHA Date Approach distance in lunar distances Abs. mag
(H) 		Diameter (C)
(m) 		Ref (D)
Nominal(B) Minimum Maximum
(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[10] data
69230 Hermes 1942-04-26 1.651 1.651 1.651 17.5 700-900[10] 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 CU11 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

References

  1. ^ a b "MPEC 1998-K31 : 1998 KJ9". IAU Minor Planet Center. 29 May 1998. Retrieved 15 November 2011. (J98K09J)
  2. ^ a b c d e "JPL Small-Body Database Browser: 152680 (1998 KJ9)" (last observation: 2011-02-06; arc: 21.1 years). Jet Propulsion Laboratory. Retrieved 7 April 2016.
  3. ^ a b "Near Earth Asteroids (NEAs)" (Version 20.1). International Astronomical Union. 13 October 2011. Retrieved 30 October 2011.
  4. ^ "Asteroid General Data - 1998 KJ9 (152680)". Catalogue of the Solar System Small Bodies Orbital Evolution. Retrieved 15 November 2011.
  5. ^ NEO Earth Close Approaches @ JPL CNEOS
    Select "Nominal dist <= 1 LD", "Past only", Sort by "H (mag)"
  6. ^ a b "(152680) = 1998 KJ9 Orbit" (2011-02-06; arc=7706 days). Minor Planet Center. Retrieved 24 September 2013.
  7. ^ "MPEC 2003-Y87 : 1998 KJ9". IAU Minor Planet Center. 29 December 2003. Retrieved 24 September 2013.
  8. ^ "JPL Close-Approach Data: 152680 (1998 KJ9)" (last observation: 2011-02-06; arc: 21.1 years). Retrieved 15 November 2011.
  9. ^ "1998KJ9 Ephemerides for 31 December 1914". NEODyS (Near Earth Objects - Dynamic Site). Retrieved 15 November 2011.
  10. ^ a b Marchis, F.; et al. "Multiple asteroid systems: Dimensions and thermal properties from Spitzer Space Telescope and ground-based observations". Icarus. 221 (2): 1130–1161. Bibcode:2012Icar..221.1130M. doi:10.1016/j.icarus.2012.09.013. Retrieved 24 August 2018.
Preceded by
 Large NEO Earth close approach
(inside the orbit of the Moon)
31 December 1914 		Succeeded by
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