5642 Bobbywilliams
Discovery [1]
Discovered byH. E. Holt
Discovery sitePalomar Obs.
Discovery date27 July 1990
Designations
(5642) Bobbywilliams
Named after
Bobby G. Williams
(JPL engineer)[2]
1990 OK1
Mars-crosser [1][3][4]
Orbital characteristics [1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc41.97 yr (15,330 days)
Aphelion3.0867 AU
Perihelion1.5454 AU
2.3161 AU
Eccentricity0.3327
3.52 yr (1,287 days)
235.13°
0° 16m 46.56s / day
Inclination24.956°
310.12°
39.038°
Physical characteristics
Dimensions4.71 km (calculated)[4]
4.8341±0.0003 h[5]
0.20 (assumed)[4]
S [4]
14.0[1][4] · 14.24±0.23[6]

    5642 Bobbywilliams, provisional designation 1990 OK1, is an eccentric, stony asteroid and Mars-crosser from the inner regions of the asteroid belt, approximately 4.7 kilometers in diameter.

    It was discovered on 27 July 1990, by American astronomer Henry E. Holt at Palomar Observatory in California, United States.[3] The asteroid was named for JPL engineer Bobby Williams.[2]

    Orbit and classification

    Bobbywilliams orbits the Sun in the inner main-belt at a distance of 1.5–3.1 AU once every 3 years and 6 months (1,287 days). Its orbit has an eccentricity of 0.33 and an inclination of 25° with respect to the ecliptic.[1] A first precovery was taken at the Australian Siding Spring Observatory in 1975, extending the body's observation arc by 15 years prior to its official discovery at Palomar.[3]

    Physical characteristics

    Rotation period

    In July 2011, a rotational lightcurve of Bobbywilliams was obtained from photometric observations by astronomer Julian Oey at both the Australian Kingsgrove (E19) and Leura (E17) observatories. Lightcurve analysis gave a well-defined rotation period of 4.8341 hours with a brightness variation of 0.05 magnitude (U=3).[5]

    Diameter and albedo

    The Collaborative Asteroid Lightcurve Link assumes a standard albedo for stony asteroids of 0.20 and calculates a diameter of 4.71 kilometers with an absolute magnitude of 14.0.[4]

    Naming

    This minor planet was named for Jet Propulsion Laboratory engineer Bobby G. Williams (born 1951), specialized in celestial mechanics and the navigation of space probes. He has been a leading navigation manager when NEAR Shoemaker had its rendezvous with the asteroids 253 Mathilde and 433 Eros,[2] The official naming citation was published by the Minor Planet Center on 28 July 1999 (M.P.C. 35483).[7]

    References

    1. 1 2 3 4 5 "JPL Small-Body Database Browser: 5642 Bobbywilliams (1990 OK1)" (2017-03-29 last obs.). Jet Propulsion Laboratory. Retrieved 21 June 2017.
    2. 1 2 3 Schmadel, Lutz D. (2007). "(5642) Bobbywilliams". Dictionary of Minor Planet Names – (5642) Bobbywilliams. Springer Berlin Heidelberg. pp. 478–479. doi:10.1007/978-3-540-29925-7_5346. ISBN 978-3-540-00238-3.
    3. 1 2 3 "5642 Bobbywilliams (1990 OK1)". Minor Planet Center. Retrieved 1 August 2016.
    4. 1 2 3 4 5 6 "LCDB Data for (5642) Bobbywilliams". Asteroid Lightcurve Database (LCDB). Retrieved 1 August 2016.
    5. 1 2 Oey, Julian (July 2012). "Lightcurve Analysis of Asteroids Observed in 2011 from Leura and Kingsgrove Observatories". The Minor Planet Bulletin. 39 (3): 145–147. Bibcode:2012MPBu...39..145O. ISSN 1052-8091. Retrieved 1 August 2016.
    6. ↑ 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 1 August 2016.
    7. ↑ "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 1 August 2016.
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