993 Moultona

993 Moultona, provisional designation 1923 NJ, is a Koronian asteroid from the outer regions of the asteroid belt, approximately 14 kilometers (8.7 miles) in diameter. It was discovered on 12 January 1923, by astronomer George Van Biesbroeck at the Yerkes Observatory in Williams Bay, Wisconsin, in the United States.[1] The likely elongated asteroid has a rotation period of 5.3 hours.[8] It was named after American astronomer Forest Ray Moulton.[10]

993 Moultona
Discovery [1]
Discovered byG. van Biesbroeck
Discovery siteYerkes Obs.
Discovery date12 January 1923
Designations
(993) Moultona
Named after
Forest Ray Moulton 
(American astronomer)
1923 NJ · 1928 BA
1960 WD · 1964 PQ
1967 CN
main-belt [1][2] · (outer)
Koronis [3][4]
Orbital characteristics [2]
Epoch 23 March 2018 (JD 2458200.5)
Uncertainty parameter 0
Observation arc86.00 yr (31,410 d)
Aphelion2.9991 AU
Perihelion2.7218 AU
2.8604 AU
Eccentricity0.0485
4.84 yr (1,767 d)
272.19°
0° 12m 13.32s / day
Inclination1.7799°
184.26°
249.56°
Physical characteristics
Mean diameter
12.43±1.13 km[5][6]
15.15±1.17 km[7]
5.2712±0.0007 h[8][9]
0.147[7]
0.315[5][6]
S (assumed)[8]
11.4[1][2][5][6][8]
11.80[7]

    Orbit and classification

    Moultona is a core member of the Koronis family (605),[3][4] a very large outer asteroid family with nearly co-planar ecliptical orbits.[11] It orbits the Sun in the outer main-belt at a distance of 2.7–3.0 AU once every 4 years and 10 months (1,767 days; semi-major axis of 2.86 AU). Its orbit has an eccentricity of 0.05 and an inclination of 2° with respect to the ecliptic.[2] The body's observation arc begins with a precovery taken at the Lowell Observatory on October 1931, more than 12 years after to its official discovery observation at Williams Bay.[1]

    Naming

    This minor planet was named after Forest Ray Moulton (1872–1952), an American astronomer and mathematician known for research in celestial mechanics. The official naming citation was mentioned in The Names of the Minor Planets by Paul Herget in 1955 (H 50). The lunar crater Moulton was also named in his honor.[10]

    Physical characteristics

    Moultona is an assumed S-type asteroid.[8]

    Rotation period

    In December 2014, a rotational lightcurve of Moultona was obtained from photometric observations by French amateur astronomer Laurent Bernasconi. Lightcurve analysis gave a well-defined rotation period of 5.2712±0.0007 hours with a high brightness amplitude of 0.73 magnitude, indicative of an non-spherical, elongated shape (U=3)

    Diameter and albedo

    According to the surveys carried out by the Japanese Akari satellite and the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Moultona measures between 12.43 and 15.15 kilometers in diameter and its surface has an albedo between 0.147 and 0.315.[6][5][7] The Collaborative Asteroid Lightcurve Link assumes an albedo of 0.24 and calculates a diameter of 14.24 kilometers based on an absolute magnitude of 11.4.[8]

    References
    1. "993 Moultona (1923 NJ)". Minor Planet Center. Retrieved 19 July 2018.
    2. "JPL Small-Body Database Browser: 993 Moultona (1923 NJ)" (2017-10-29 last obs.). Jet Propulsion Laboratory. Retrieved 19 July 2018.
    3. "Asteroid 993 Moultona". Small Bodies Data Ferret. Retrieved 19 July 2018.
    4. "Asteroid (993) Moultona – Proper elements". AstDyS-2, Asteroids – Dynamic Site. Retrieved 25 May 2018.
    5. Mainzer, A. K.; Bauer, J. M.; Cutri, R. M.; Grav, T.; Kramer, E. A.; Masiero, J. R.; et al. (June 2016). "NEOWISE Diameters and Albedos V1.0". NASA Planetary Data System: EAR-A-COMPIL-5-NEOWISEDIAM-V1.0. Bibcode:2016PDSS..247.....M. Retrieved 19 July 2018.
    6. Masiero, Joseph R.; Mainzer, A. K.; Grav, T.; Bauer, J. M.; Cutri, R. M.; Nugent, C.; et al. (November 2012). "Preliminary Analysis of WISE/NEOWISE 3-Band Cryogenic and Post-cryogenic Observations of Main Belt Asteroids". The Astrophysical Journal Letters. 759 (1): 5. arXiv:1209.5794. Bibcode:2012ApJ...759L...8M. doi:10.1088/2041-8205/759/1/L8.
    7. Usui, Fumihiko; Kuroda, Daisuke; Müller, Thomas G.; Hasegawa, Sunao; Ishiguro, Masateru; Ootsubo, Takafumi; et al. (October 2011). "Asteroid Catalog Using Akari: AKARI/IRC Mid-Infrared Asteroid Survey". Publications of the Astronomical Society of Japan. 63 (5): 1117–1138. Bibcode:2011PASJ...63.1117U. doi:10.1093/pasj/63.5.1117. Retrieved 19 July 2018. (online, AcuA catalog p. 153)
    8. "LCDB Data for (993) Moultona". Asteroid Lightcurve Database (LCDB). Retrieved 19 July 2018.
    9. Behrend, Raoul. "Asteroids and comets rotation curves – (993) Moultona". Geneva Observatory. Retrieved 19 July 2018.
    10. Schmadel, Lutz D. (2007). "(993) Moultona". Dictionary of Minor Planet Names – (993) Moultona. Springer Berlin Heidelberg. p. 86. doi:10.1007/978-3-540-29925-7_994. ISBN 978-3-540-00238-3.
    11. Nesvorný, D.; Broz, M.; Carruba, V. (December 2014). Identification and Dynamical Properties of Asteroid Families. Asteroids IV. pp. 297–321. arXiv:1502.01628. Bibcode:2015aste.book..297N. doi:10.2458/azu_uapress_9780816532131-ch016. ISBN 9780816532131.

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