(5646) 1990 TR

(5646) 1990 TR is a probable rare-type binary[4] asteroid classified as near-Earth object of the Amor group, approximately 2.3 kilometers in diameter. It was discovered on 11 October 1990, by Japanese astronomers Seiji Ueda and Hiroshi Kaneda at Kushiro Observatory near Kushiro, in eastern Hokkaido, Japan.[2]

(5646) 1990 TR
Discovery [1]
Discovered byS. Ueda
H. Kaneda
Discovery siteKushiro Obs.
Discovery date11 October 1990
Designations
(5646) 1990 TR
1990 TR
Amor · NEO [1][2]
Orbital characteristics [1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc26.90 yr (9,825 days)
Aphelion3.0791 AU
Perihelion1.2087 AU
2.1439 AU
Eccentricity0.4362
3.14 yr (1,147 days)
218.56°
0° 18m 50.4s / day
Inclination7.9118°
14.141°
335.68°
Known satellites1 [3][4]
Earth MOID0.2112 AU · 82.3 LD
Physical characteristics
Dimensions2.03±0.52 km[5]
2.30 km (derived)[6]
2.50±0.05 km[7]
2.723±0.525 km[8]
4.3 km (dated)[1]
3.1999±0.0002 h[3]
3.204±0.002 h[9]
6.25 h[10]
0.18 (assumed)[6]
0.19±0.03[7]
0.454±0.194[8][11]
0.65±0.43[5]
0.66±0.42[12]
SMASS = U [1]
Q [13] · S [14] · U [6]
14.3[8] · 15.00[14] · 15.4[1] · 15.45[7] · 15.67[6][10]

    Orbit

    The asteroid orbits the Sun at a distance of 1.2–3.1 AU once every 3 years and 2 months (1,147 days). Its orbit has an eccentricity of 0.44 and an inclination of 8° with respect to the ecliptic.[1] The body's observation arc begins with its first observation at the Siding Spring Observatory, five months prior to its official discovery observation at Kushiro.[2]

    Lightcurve

    In December 2012, the so far best rated rotational lightcurve was obtained by American astronomer Brian Warner at his Palmer Divide Observatory in Colorado. Lightcurve analysis gave a rotation period of 3.1999 hours with a brightness variation of 0.12 magnitude (U=3). Photometric observations also gave a period of 19.47 hours for a probable asteroid moon, with a measured diameter-ratio of 0.18±0.02, which translates into a diameter of 400 meters for its moon.[3]

    Diameter and albedo

    According to the surveys carried out by the Spitzer Space Telescope and NASA's Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, the asteroid measures 2.03 and 2.723 kilometers in diameter and its surface has an albedo of 0.19 and 0.66.[5][7][8][11] The Collaborative Asteroid Lightcurve Link assumes an albedo of 0.18 and derives a diameter of 2.3 kilometers based on an absolute magnitude of 15.67.[6]

    References
    1. "JPL Small-Body Database Browser: 5646 (1990 TR)" (2017-03-27 last obs.). Jet Propulsion Laboratory. Retrieved 26 May 2017.
    2. "5646 (1990 TR)". Minor Planet Center. Retrieved 12 February 2017.
    3. Warner, Brian D. (April 2013). "Seeing Double Old and New: Observations and Lightcurve Analysis at the Palmer Divide Observatory of Six Binary Asteroids". The Minor Planet Bulletin. 40 (2): 94–98. Bibcode:2013MPBu...40...94W. ISSN 1052-8091. PMID 32259164.
    4. Dr. Lance A. M. Benner (18 November 2013). "Binary and Ternary near-Earth Asteroids detected by radar". NASA/JPL Asteroid Radar Research. Retrieved 1 March 2014.
    5. Mueller, Michael; Delbo', M.; Hora, J. L.; Trilling, D. E.; Bhattacharya, B.; Bottke, W. F.; et al. (April 2011). "ExploreNEOs. III. Physical Characterization of 65 Potential Spacecraft Target Asteroids" (PDF). The Astronomical Journal. 141 (4): 9. Bibcode:2011AJ....141..109M. doi:10.1088/0004-6256/141/4/109.
    6. "LCDB Data for (5646)". Asteroid Lightcurve Database (LCDB). Retrieved 12 February 2017.
    7. Nugent, C. R.; Mainzer, A.; Bauer, J.; Cutri, R. M.; Kramer, E. A.; Grav, T.; et al. (September 2016). "NEOWISE Reactivation Mission Year Two: Asteroid Diameters and Albedos". The Astronomical Journal. 152 (3): 12. arXiv:1606.08923. Bibcode:2016AJ....152...63N. doi:10.3847/0004-6256/152/3/63. S2CID 119289027.
    8. Mainzer, A.; Grav, T.; Masiero, J.; Hand, E.; Bauer, J.; Tholen, D.; et al. (November 2011). "NEOWISE Studies of Spectrophotometrically Classified Asteroids: Preliminary Results". The Astrophysical Journal. 741 (2): 25. arXiv:1109.6407. Bibcode:2011ApJ...741...90M. doi:10.1088/0004-637X/741/2/90. S2CID 118700974.
    9. Warner, Brian D. (April 2016). "Near-Earth Asteroid Lightcurve Analysis at CS3-Palmer Divide Station: 2015 October-December". The Minor Planet Bulletin. 43 (2): 143–154. Bibcode:2016MPBu...43..143W. ISSN 1052-8091. PMC 7243997. PMID 32455373.
    10. Wisniewski, Wieslaw Z. (December 1992). "The unusual lightcurve of 1990 TR". In Lunar and Planetary Inst.: 653. Bibcode:1992acm..proc..653W.
    11. Mainzer, A.; Grav, T.; Bauer, J.; Masiero, J.; McMillan, R. S.; Cutri, R. M.; et al. (December 2011). "NEOWISE Observations of Near-Earth Objects: Preliminary Results". The Astrophysical Journal. 743 (2): 17. arXiv:1109.6400. Bibcode:2011ApJ...743..156M. doi:10.1088/0004-637X/743/2/156. S2CID 239991.
    12. Thomas, C. A.; Trilling, D. E.; Emery, J. P.; Mueller, M.; Hora, J. L.; Benner, L. A. M.; et al. (September 2011). "ExploreNEOs. V. Average Albedo by Taxonomic Complex in the Near-Earth Asteroid Population". The Astronomical Journal. 142 (3): 12. Bibcode:2011AJ....142...85T. doi:10.1088/0004-6256/142/3/85.
    13. Thomas, Cristina A.; Emery, Joshua P.; Trilling, David E.; Delbó, Marco; Hora, Joseph L.; Mueller, Michael (January 2014). "Physical characterization of Warm Spitzer-observed near-Earth objects". Icarus. 228: 217–246. arXiv:1310.2000. Bibcode:2014Icar..228..217T. doi:10.1016/j.icarus.2013.10.004. S2CID 119278697.
    14. Carry, B.; Solano, E.; Eggl, S.; DeMeo, F. E. (April 2016). "Spectral properties of near-Earth and Mars-crossing asteroids using Sloan photometry". Icarus. 268: 340–354. arXiv:1601.02087. Bibcode:2016Icar..268..340C. doi:10.1016/j.icarus.2015.12.047. S2CID 119258489.
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