(152680) 1998 KJ9

(152680) 1998 KJ9
Discovery[1]
Discovered by LINEAR (704)
1.0-m Reflector
Discovery site Lincoln Lab's ETS
Discovery date 27 May 1998
Designations
MPC designation (152680) 1998 KJ9
NEO · PHA · Apollo [2]
Orbital characteristics[2]
Epoch 13 January 2016 (JD 2457400.5)
Uncertainty parameter 0
Observation arc 7706 days (21.10 yr)
Aphelion 2.3742 AU (355.18 Gm) (Q)
Perihelion 0.52125 AU (77.978 Gm) (q)
1.4477 AU (216.57 Gm) (a)
Eccentricity 0.63995 (e)
1.74 yr (636.25 d)
6.2670° (M)
0° 33m 56.952s / day (n)
Inclination 10.932° (i)
98.675° (Ω)
259.95° (ω)
Earth MOID 0.00552 AU (826,000 km)
Physical characteristics
Dimensions ~500 meters[3]
Mass 7.87×1010 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]

    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.[5] It was recovered on 28 December 2003 which extended the observation arc by 5 years.[6] Two precovery images from January 1990 extended the observation arc by 8 years.[5]

    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).[7] 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.[8]

    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 KJ91914-12-310.6060.6040.60819.4279–900data
    (458732) 2011 MD51918-09-170.9110.9090.91317.9556–1795data
    (163132) 2002 CU111925-08-300.9030.9010.90518.5443–477data
    69230 Hermes1937-10-301.9261.9261.92717.5700-900[9]data
    69230 Hermes1942-04-261.6511.6511.65117.5700-900[9]data
    (27002) 1998 DV91975-01-311.7621.7611.76218.1507–1637data
    2002 NY402002-08-181.3711.3711.37119.0335–1082data
    2004 XP142006-07-031.1251.1251.12519.3292–942data
    2015 TB1452015-10-311.2661.2661.26620.0620-690data
    (137108) 1999 AN102027-08-071.0141.0101.01917.9556–1793data
    (153814) 2001 WN52028-06-260.6470.6470.64718.2921–943data
    99942 Apophis2029-04-130.09810.09630.100019.7310–340data
    2017 MB12072-07-261.2161.2152.75918.8367–1186data
    2011 SM682072-10-171.8751.8651.88619.6254–820data
    (163132) 2002 CU112080-08-311.6551.6541.65618.5443–477data
    (416801) 1998 MZ2116-11-261.0681.0681.06919.2305–986data
    (153201) 2000 WO1072140-12-010.6340.6310.63719.3427–593data
    (276033) 2002 AJ1292172-02-081.7831.7751.79218.7385–1242data
    (290772) 2005 VC2198-05-051.9511.7912.13417.6638–2061data
    (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. 1 2 "MPEC 1998-K31 : 1998 KJ9". IAU Minor Planet Center. 1998-05-29. Retrieved 2011-11-15. (J98K09J)
    2. 1 2 3 4 5 "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. 1 2 "Near Earth Asteroids (NEAs)" (Version 20.1). International Astronomical Union. 13 October 2011. Retrieved 2011-10-30.
    4. ↑ "Asteroid General Data - 1998 KJ9 (152680)". Catalogue of the Solar System Small Bodies Orbital Evolution. Retrieved 2011-11-15.
    5. 1 2 "(152680) = 1998 KJ9 Orbit" (2011-02-06; arc=7706 days). Minor Planet Center. Retrieved 2013-09-24.
    6. ↑ "MPEC 2003-Y87 : 1998 KJ9". IAU Minor Planet Center. 2003-12-29. Retrieved 2013-09-24.
    7. ↑ "JPL Close-Approach Data: 152680 (1998 KJ9)" (last observation: 2011-02-06; arc: 21.1 years). Retrieved 2011-11-15.
    8. ↑ "1998KJ9 Ephemerides for 31 December 1914". NEODyS (Near Earth Objects - Dynamic Site). Retrieved 2011-11-15.
    9. 1 2 Marchis, F.; et al. "Multiple asteroid systems: Dimensions and thermal properties from Spitzer Space Telescope and ground-based observations". Icarus. 221 (2): 1130–1161. Retrieved 24 August 2018.
    Preceded by
    		 Large NEO Earth close approach
    (inside the orbit of the Moon)
    31 December 1914    		 Succeeded by
    (163132) 2002 CU11
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