5256 Farquhar

5256 Farquhar, provisional designation 1988 NN, is a stony Eunomian asteroid from the middle regions of the asteroid belt, approximately 12 kilometers in diameter. It was discovered on 11 July 1988, by American astronomers Eleanor Helin, Celina Mikolajczak and Robert Coker at the Palomar Observatory in California.[8] The asteroid was later named for American NASA specialist Robert W. Farquhar.[2]

5256 Farquhar
Discovery [1]
Discovered byE. F. Helin
C. Mikolajczak
R. Coker
Discovery sitePalomar Obs.
Discovery date11 July 1988
Designations
(5256) Farquhar
Named after
Robert W. Farquhar
(NASA specialist)[2]
1988 NN · 1955 HK
main-belt · Eunomia [3]
Orbital characteristics [1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc61.27 yr (22,379 days)
Aphelion3.0639 AU
Perihelion2.0426 AU
2.5532 AU
Eccentricity0.2000
4.08 yr (1,490 days)
46.478°
0° 14m 29.76s / day
Inclination14.956°
219.35°
88.805°
Physical characteristics
Dimensions11.990±0.126 km[4]
12.09 km (calculated)[3]
12.949±0.140 km[5]
11.513±0.001 h[6]
0.1275±0.0198[5]
0.148±0.020[4]
0.21 (assumed)[3]
S [3]
11.8[1] · 11.9[3] · 12.3[5] · 12.41±0.63[7]

    Orbit and classification

    Farquhar is a member of the Eunomia family, the most prominent family in the intermediate main-belt, which mostly consists of stony S-type asteroids. It orbits the Sun in the central main-belt at a distance of 2.0–3.1 AU once every 4 years and 1 month (1,490 days). Its orbit has an eccentricity of 0.20 and an inclination of 15° with respect to the ecliptic.[1] The first observation was made at the U.S. Goethe Link Observatory in 1955, extending the asteroid's observation arc by 33 years prior to its discovery.[8]

    Physical characteristics

    Rotation period

    In November 2013, a rotational lightcurve of Farquhar was obtained from photometric observations at the Phillips Academy Observatory (I12), Massachusetts, and at the HUT Observatory (H16), Colorado. The bimodal lightcurve gave a rotation period of 11.513 hours with a very low brightness variation of 0.07 in magnitude (U=2).[6] A low brightness amplitude typically indicates a rather spheroidal shape.

    Diameter and albedo

    According to the surveys carried out by NASA's Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, Farquhar measures 12.0 and 12.9 kilometers in diameter and its surface has an albedo of 0.148 and 0.128, respectively.[4][5] The Collaborative Asteroid Lightcurve Link assumes an albedo of 0.21, derived from the family's largest member and namesake, 15 Eunomia, and calculates a diameter of 12.1 kilometers with an absolute magnitude of 11.9.[3]

    Naming

    This minor planet was named for American NASA mission design specialist Robert W. Farquhar (1932–2015). At the Goddard Space Flight Center, he designed low-cost spacecraft and missions to explore the Solar System.[2]

    Farquhar was known for his international collaborations and for designing missions to comets and minor planets using inventive alternative trajectories.[2] The approved naming citation was published by the Minor Planet Center on 10 November 1992 (M.P.C. 21134).[9]

    References
    1. "JPL Small-Body Database Browser: 5256 Farquhar (1988 NN)" (2016-08-03 last obs.). Jet Propulsion Laboratory. Retrieved 21 June 2017.
    2. Schmadel, Lutz D. (2007). "(5256) Farquhar". Dictionary of Minor Planet Names – (5256) Farquhar. Springer Berlin Heidelberg. p. 451. doi:10.1007/978-3-540-29925-7_5084. ISBN 978-3-540-00238-3.
    3. "LCDB Data for (5256) Farquhar". Asteroid Lightcurve Database (LCDB). Retrieved 9 September 2016.
    4. Masiero, Joseph R.; Grav, T.; Mainzer, A. K.; Nugent, C. R.; Bauer, J. M.; Stevenson, R.; et al. (August 2014). "Main-belt Asteroids with WISE/NEOWISE: Near-infrared Albedos". The Astrophysical Journal. 791 (2): 11. arXiv:1406.6645. Bibcode:2014ApJ...791..121M. doi:10.1088/0004-637X/791/2/121. Retrieved 9 September 2016.
    5. 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.
    6. Odden, Caroline E.; Bond, J. Brooke; Aggarwal, Ashok K.; Seokjun, Yoon; Chapman, Kathryn J.; Fortin, Liam G.; et al. (October 2014). "Lightcurve Analysis for Three Asteroids: 4000 Hipparchus, 5256 Farquhar and 5931 Zhvanetskij". The Minor Planet Bulletin. 41 (4): 274–275. Bibcode:2014MPBu...41..274O. ISSN 1052-8091. Retrieved 9 September 2016.
    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 9 September 2016.
    8. "5256 Farquhar (1988 NN)". Minor Planet Center. Retrieved 9 September 2016.
    9. "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 9 September 2016.

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