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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. The asteroid was named for JPL engineer Bobby Williams.

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. 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.

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).

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.

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, The official naming citation was published by the Minor Planet Center on 28 July 1999 (M.P.C. 35483).

References

1. ^ "JPL Small-Body Database Browser: 5642 Bobbywilliams (1990 OK1)" (2017-03-29 last obs.). Jet Propulsion Laboratory. Retrieved 21 June 2017.
2. ^ 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. ^ "5642 Bobbywilliams (1990 OK1)". Minor Planet Center. Retrieved 1 August 2016.
4. ^ "LCDB Data for (5642) Bobbywilliams". Asteroid Lightcurve Database (LCDB). Retrieved 1 August 2016.
5. ^ 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.

External links

• Asteroid Lightcurve Database (LCDB), query form (info Archived 16 December 2017 at the Wayback Machine)
• Dictionary of Minor Planet Names, Google books
• Asteroids and comets rotation curves, CdR – Observatoire de Genève, Raoul Behrend
• Discovery Circumstances: Numbered Minor Planets (5001)-(10000) – Minor Planet Center
• 5642 Bobbywilliams at AstDyS-2, Asteroids—Dynamic Site
  • Ephemeris · Observation prediction · Orbital info · Proper elements · Observational info
• 5642 Bobbywilliams at the JPL Small-Body Database
  • Close approach · Discovery · Ephemeris · Orbit viewer · Orbit parameters · Physical parameters

• Minor planet object articles (numbered)
• Mars-crossing asteroids
• Discoveries by Henry E. Holt
• Named minor planets
• Astronomical objects discovered in 1990