39890 Bobstephens

39890 Bobstephens, provisional designation 1998 FA3, is a stony asteroid from the middle region of the asteroid belt, approximately 2 kilometers in diameter. The asteroid was discovered on 23 March 1998, by Czech astronomer Petr Pravec at Ondřejov Observatory near Prague in the Czech Republic.[5] It was named for American astronomer Robert Stephens.[2]

39890 Bobstephens
Discovery [1]
Discovered byP. Pravec
Discovery siteOndřejov Obs.
Discovery date23 March 1998
Designations
(39890) Bobstephens
Named after
Robert D. Stephens
(American astronomer)[2]
1998 FA3
main-belt · (middle)
Orbital characteristics [1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc21.25 yr (7,760 days)
Aphelion3.1534 AU
Perihelion2.0287 AU
2.5910 AU
Eccentricity0.2170
4.17 yr (1,523 days)
201.46°
0° 14m 10.68s / day
Inclination5.4950°
161.73°
95.752°
Physical characteristics
Dimensions2.06 km (calculated)[3]
9.55±0.01 h[4]
0.20 (assumed)[3]
S [3]
15.8[3] · 15.9[1]

    Orbit and classification

    Bobstephens orbits the Sun in the central main-belt at a distance of 2.0–3.2 AU once every 4 years and 2 months (1,523 days). Its orbit has an eccentricity of 0.22 and an inclination of 5° with respect to the ecliptic.[1] It was first imaged at Steward Observatory in 1995. This precovery extends the body's observation arc by 3 years prior to its official discovery observation.[5]

    Physical characteristics

    Rotation period

    In August 2008, a rotational lightcurve of Bobstephens was obtained from photometric observations by American amateur astronomer Daniel Coley at the Center for Solar System Studies in California. Light-curve analysis gave a rotation period of 9.55 hours with a brightness variation of 0.20 magnitude (U=2).[4]

    Diameter and albedo

    The Collaborative Asteroid Lightcurve Link assumes a standard albedo for stony asteroids of 0.20 and calculates a diameter of 2.06 kilometers with an absolute magnitude of 15.8.[3]

    Naming

    This minor planet was named for Californian amateur astronomer and photometrist Robert D. Stephens (born 1955), who is an expert in lightcurve photometry of minor planets since 1999.[2] The official naming citation was published by the Minor Planet Center on 24 July 2002 (M.P.C. 46112).[6]

    References
    1. "JPL Small-Body Database Browser: 39890 Bobstephens (1998 FA3)" (2017-01-23 last obs.). Jet Propulsion Laboratory. Retrieved 28 June 2017.
    2. Schmadel, Lutz D. (2007). "(39890) Bobstephens". Dictionary of Minor Planet Names – (39890) Bobstephens. Springer Berlin Heidelberg. p. 894. doi:10.1007/978-3-540-29925-7_10020. ISBN 978-3-540-00238-3.
    3. "LCDB Data for (39890) Bobstephens". Asteroid Lightcurve Database (LCDB). Retrieved 27 December 2016.
    4. Coley, Daniel (January 2012). "Asteroid Lightcurve Analysis at the Danhenge Observatory Apr - Aug 2011". The Minor Planet Bulletin. 39 (1): 23–24. Bibcode:2012MPBu...39...23C. ISSN 1052-8091. Retrieved 27 December 2016.
    5. "39890 Bobstephens (1998 FA3)". Minor Planet Center. Retrieved 27 December 2016.
    6. "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 27 December 2016.

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