(159857) 2004 LJ1

(159857) 2004 LJ1, provisional designation 2004 LJ1, is an asteroid on an eccentric orbit, classified as near-Earth object and potentially hazardous asteroid of the Apollo group, approximately 3 kilometers in diameter. The asteroid was discovered on 10 June 2004, by astronomers of the LINEAR program at Lincoln Laboratory's Experimental Test Site near Socorro, New Mexico, in the United States.[2] It is one of the largest potentially hazardous asteroids known to exist.[8]

(159857) 2004 LJ1
Discovery [1]
Discovered byLINEAR
Discovery siteLincoln Lab's ETS
Discovery date10 June 2004
Designations
(159857) 2004 LJ1
2004 LJ1
Apollo · NEO · PHA [1][2]
Orbital characteristics [1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc22.29 yr (8,141 days)
Aphelion3.6072 AU
Perihelion0.9203 AU
2.2637 AU
Eccentricity0.5935
3.41 yr (1,244 days)
286.61°
0° 17m 21.84s / day
Inclination23.140°
235.58°
139.97°
Earth MOID0.0168 AU · 6.5 LD
Physical characteristics
Mean diameter
2.47 km (calculated)[3]
3.070±1.324 km[4]
2.661±0.001 h[5][lower-alpha 1]
2.7247±0.0002 h[6]
2.76 h[lower-alpha 2]
0.130±0.158[4]
0.20 (assumed)[3]
S (assumed)[3]
15.11±0.94[7] · 15.4[1][3][4]

    Orbit and classification

    2004 LJ1 is a member of the dynamical Apollo group,[1][2] which are Earth-crossing asteroids. Apollo asteroids are the largest subgroup of near-Earth objects.

    The body orbits the Sun at a distance of 0.9–3.6 AU once every 3 years and 5 months (1,244 days; semi-major axis of 2.26 AU). Its orbit has an eccentricity of 0.59 and an inclination of 23° with respect to the ecliptic.[1] Its observation arc begins with a precovery from the Digitized Sky Survey taken at the Siding Spring Observatory, Australia, in February 1995, more than 9 years prior to its official discovery observation at Socorro.[2]

    Close approaches

    With an absolute magnitude of at least 15.4, 2004 LJ1 is one of the brightest and presumably largest known potentially hazardous asteroid (see PHA-list).[8] It has an Earth minimum orbital intersection distance of 0.0168 AU (2,510,000 km), which translates into 6.5 lunar distances (LD).[1] On 16 November 2038, this asteroid will make its closest near-Earth encounter at a nominal distance of 0.0198 AU (7.7 LD).[1] It is also classified as a Mars-crosser, crossing the orbit of the Red Planet at 1.66 AU.

    Chronology of close approaches of large near-Earth objects since 1981 (A)
    PHA Date Approach distance in lunar distances Abs. mag
    (H)    		 Diameter (C)
    (m)    		 Ref (D)
    Nominal (B) Minimum Maximum
    (143651) 2003 QO1041981-05-182.7612.7602.76116.01333–4306data
    2014 LJ211989-08-017.0346.8437.22416.01333–4306data
    4179 Toutatis1992-12-089.3999.3999.39915.302440–2450data
    4179 Toutatis2004-09-294.0314.0314.03115.302440–2450data
    (159857) 2004 LJ12038-11-167.7197.7197.71915.41746–4394data
    (4953) 1990 MU2058-06-058.9868.9848.98814.13199–10329data
    4179 Toutatis2069-11-057.7257.7247.72515.302440–2450data
    (52768) 1998 OR22079-04-164.6114.6114.61215.81462–4721data
    (415029) 2011 UL212089-06-256.9366.9356.93815.71531–4944data
    3200 Phaethon2093-12-147.7147.7097.71814.64900–5300data
    (52768) 1998 OR22127-04-166.5366.5106.56315.81462–4721data
    (A) This list includes near-Earth approaches of less than 10 lunar distances (LD) of objects with H brighter than 16.
    (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

    Physical characteristics

    2004 LJ1 is an assumed stony S-type asteroid.[3]

    Rotation period

    Three rotational lightcurves of 2004 LJ1 have been obtained from photometric observations by Johanna Torppa, Adrián Galád and Brian Warner since 2004.[5][6][lower-alpha 1][lower-alpha 2] Lightcurve analysis gave a consolidated rotation period of 2.7247 hours with a brightness amplitude between 0.15 and 0.59 magnitude (U=3).[3]

    Diameter and albedo

    According to the survey carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, 2004 LJ1 measures 3.07 kilometers in diameter and its surface has an albedo of 0.13.[4] The Collaborative Asteroid Lightcurve Link assumes a standard albedo for stony asteroids of 0.20 and calculates a diameter of 2.47 kilometers, based on an absolute magnitude of 15.4.[3]

    Numbering and naming

    This minor planet was numbered by the Minor Planet Center on 30 June 2007.[9] As of 2018, it has not been named.[2]

    Notes
    1. Lightcurve plot of (159857) 2004 LJ1 from June to July 2014, by B. D. Warner at the CS3–Palmer Divide Station in California (U82). Quality code of 2. Summary figures at the LCDB and CS3 website.
    2. Torppa (2011) web: Undated observation. Rotation period 2.76 hours with a brightness amplitude of 0.5 mag. Quality Code of 2. Summary figures at the LCDB

    References
    1. "JPL Small-Body Database Browser: 159857 (2004 LJ1)" (2017-05-19 last obs.). Jet Propulsion Laboratory. Retrieved 18 January 2018.
    2. "159857 (2004 LJ1)". Minor Planet Center. Retrieved 18 January 2018.
    3. "LCDB Data for (159857)". Asteroid Lightcurve Database (LCDB). Retrieved 18 January 2018.
    4. Nugent, C. R.; Mainzer, A.; Masiero, J.; Bauer, J.; Cutri, R. M.; Grav, T.; et al. (December 2015). "NEOWISE Reactivation Mission Year One: Preliminary Asteroid Diameters and Albedos". The Astrophysical Journal. 814 (2): 13. arXiv:1509.02522. Bibcode:2015ApJ...814..117N. doi:10.1088/0004-637X/814/2/117. Retrieved 18 January 2018.
    5. Warner, Brian D. (January 2015). "Near-Earth Asteroid Lightcurve Analysis at CS3-Palmer Divide Station: 2014 June-October". The Minor Planet Bulletin. 42 (1): 41–53. Bibcode:2015MPBu...42...41W. ISSN 1052-8091. Retrieved 18 January 2018.
    6. Galád, A.; Pravec, P.; Kusnirák, P.; Gajdos, S.; Kornos, L.; Világi, J. (October 2005). "Joint Lightcurve Observations of 10 Near-Earth Asteroids from Modra and ONDREJOV". Earth. 97 (1–2): 147–163. Bibcode:2005EM&P...97..147G. doi:10.1007/s11038-006-9066-x. Retrieved 18 January 2018.
    7. Veres, Peter; Jedicke, Robert; Fitzsimmons, Alan; Denneau, Larry; Granvik, Mikael; Bolin, Bryce; et al. (November 2015). "Absolute magnitudes and slope parameters for 250,000 asteroids observed by Pan-STARRS PS1 - Preliminary results". Icarus. 261: 34–47. arXiv:1506.00762. Bibcode:2015Icar..261...34V. doi:10.1016/j.icarus.2015.08.007. Retrieved 18 January 2018.
    8. "List of the Potentially Hazardous Asteroids (PHAs)". Minor Planet Center. Retrieved 18 January 2018.
    9. "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 24 February 2018.
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