(190166) 2005 UP156

(190166) 2005 UP156 is a stony asteroid and binary system, classified as near-Earth object of the Apollo group, approximately 1 kilometer in diameter. It was discovered on 31 October 2005, by astronomers of the Spacewatch survey at the Kitt Peak National Observatory in Arizona, United States.[2] Its minor-planet moon with an orbital period of 40.25 hours was discovered in 2017.[4]

(190166) 2005 UP156
Radar image of the 2005 UP156 binary system taken by the Arecibo Observatory in June 2017
Discovery [1]
Discovered bySpacewatch
Discovery siteKitt Peak National Obs.
Discovery date31 October 2005
Designations
(190166) 2005 UP156
2005 UP156
NEO · Amor [1][2]
Orbital characteristics [1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc14.80 yr (5,405 days)
Aphelion3.1090 AU
Perihelion1.1221 AU
2.1155 AU
Eccentricity0.4696
3.08 yr (1,124 days)
18.539°
0° 19m 13.08s / day
Inclination4.2083°
193.41°
91.156°
Known satellites1[3][4][5]
Earth MOID0.1316 AU (51.3 LD)
Physical characteristics
Mean diameter
1.045±0.025 km[6]
1.08 km (calculated)[3]
Mean density
1.8 g/cm3 [7]
40.5±0.1 h[8][lower-alpha 1]
40.542±0.003 h[4]
40.572±0.003 h[lower-alpha 1][lower-alpha 2]
40.6±0.5 h[7]
0.20 (assumed)[3]
0.234±0.033[6]
S [3]
17.1[1][6]
17.2[3]

    Orbit and classification

    2005 UP156 is an Amor asteroid that approaches the orbit of Earth from beyond but does not cross it. It orbits the Sun at a distance of 1.1–3.1 AU once every 3 years and 1 month (1,124 days). Its orbit has an eccentricity of 0.47 and an inclination of 4° with respect to the ecliptic.[1] The body's observation arc begins with a precovery image taken by NEAT at Palomar Observatory in November 2002, almost four years prior to its official discovery observation.[2] Due to its high eccentricity, the asteroid is also a Mars-crosser, which means that it also crosses the orbit of Mars (at 1.666 AU).

    Close approaches

    This near-Earth object has an Earth minimum orbital intersection distance of 0.1316 AU (19,700,000 km) which corresponds to 51.3 lunar distances. On 10 July 2017, it approached Earth to a distance of 0.133 AU and will make its next close approach at 0.128 AU in July 2057.[1]

    Physical characteristics

    2005 UP156 is an assumed S-type asteroid.[3]

    Rotation period

    Since 2004, several rotational lightcurves of 2005 UP156 were obtained from photometric observations by French amateur astronomers David Romeuf, René Roy, as well as by American astronomer Brian Warner. Analysis of the best-rated lightcurve gave a rotation period of 40.542 hours with a brightness variation of 1.1 magnitude (U=2/3/3/2).[8][4][7][lower-alpha 1][lower-alpha 2]

    While not being a slow rotator, 2005 UP156 has a much longer rotation period than most asteroids, especially for it nearly sub-kilometer size. The lightcurve's high brightness amplitude also indicates that the body has a non-spheroidal shape.

    Diameter and albedo

    According to the survey carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, 2005 UP156 measures 1.045 kilometers in diameter and its surface has an albedo of 0.234,[6] while the Collaborative Asteroid Lightcurve Link assumes a standard albedo for stony asteroids of 0.20 and calculates a diameter of 1.08 kilometers based on an absolute magnitude of 17.2.[3] The asteroid has an estimated density of 1.8 g/cm3.[7]

    Binary system

    In May 2017, photometric observations by Brian Warner and Alan Harris revealed that 2005 UP156 is a synchronous binary system with a secondary component orbiting around the system barycenter every 40.572 hours.[4][lower-alpha 2] The secondary has been confirmed by radar observations.[5] Its provisional designation is S/2017 (190166) 1.

    Numbering and naming

    This minor planet was numbered by the Minor Planet Center on 19 August 2008.[9] As of 2018, it has not been named.[2] Up to 1900 a few hundred, and by the 1990s asteroids had been discovered and named progressing from almost planet like notoriety to one of thousands; the advent of many thousands of discoveries in the 21 century has resulted in many hundreds of thousands of unnamed minor planets.

    Notes
    1. Lightcurve plots from 2014 and 2017 by Brian D. Warner, Palmer Divide Station at the Center for Solar System Studies (CS3). Summary figures at the LCDB
    2. Warner (2017q): publication not yet indexed at ADS. Binary asteroid. Rotation period 40.572±0.003 hours with a brightness amplitude of 1.35±0.05 mag. Quality Code of 3. Summary figures for (190166) at the LCDB

    References
    1. "JPL Small-Body Database Browser: 190166 (2005 UP156)" (2017-09-11 last obs.). Jet Propulsion Laboratory. Retrieved 13 September 2017.
    2. "190166 (2005 UP156)". Minor Planet Center. Retrieved 13 September 2017.
    3. "LCDB Data for (190166) 2005 UP156". Asteroid Lightcurve Database (LCDB). Retrieved 13 September 2017.
    4. Warner, B. D.; Harris, A. W. (May 2017). "(190166) 2005 UP156". Central Bureau Electronic Telegrams. Bibcode:2017CBET.4394....1W. Retrieved 13 September 2017.
    5. Johnston, Robert (14 June 2017). "(190166) 2005 UP156". johnstonsarchive.net. Retrieved 13 September 2017.
    6. 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 13 September 2017.
    7. Behrend, Raoul. "Asteroids and comets rotation curves – (190166) 2005 UP156". Geneva Observatory. Retrieved 13 September 2017.
    8. 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 13 September 2017.
    9. "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 24 February 2018.
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