5357 Sekiguchi

5357 Sekiguchi (prov. designation: 1992 EL) is an Eos asteroid from the outer region of the asteroid belt, approximately 15 kilometers (9 miles) in diameter. It was discovered on 2 March 1992, by Japanese amateur astronomers Tetsuya Fujii and Kazuro Watanabe at the Kitami Observatory in eastern Hokkaidō, Japan. The asteroid was later named after Japanese astronomer Tomohiko Sekiguch.[2]

5357 Sekiguchi
Shape model of Sekiguchi from its lightcurve
Discovery [1]
Discovered byT. Fujii
K. Watanabe
Discovery siteKitami Obs.
Discovery date2 March 1992
Designations
(5357) Sekiguchi
Named after
Tomohiko Sekiguch
(Japanese astronomer)[2]
1992 EL · 1969 TB4
1971 BE3 · 1981 BH
1990 VJ4 · 1990 WU13
main-belt · (outer)[3]
Eos [4]
Orbital characteristics [1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc67.13 yr (24,518 days)
Aphelion3.2966 AU
Perihelion2.6794 AU
2.9880 AU
Eccentricity0.1033
5.17 yr (1,887 days)
75.618°
0° 11m 26.88s / day
Inclination9.0838°
301.97°
116.81°
Physical characteristics
Mean diameter
13.948±0.118 km[5]
14.281±0.193 km[6]
14.52±0.65 km[7]
15.19±1.13 km[8]
5.4048±0.0011 h[9]
5.4100±0.0011 h[9]
5.41±0.01 h[10]
0.192±0.032[5][7]
0.334±0.052[8]
0.3829±0.0259[6]
C [3]
10.9[6][8] · 11.60[7] · 11.624±0.002 (R)[9] · 11.7[1][3] · 11.719±0.003 (R)[9]

    Orbit and classification

    Sekiguchi is a member the Eos family (606),[4] the largest asteroid family of the outer main belt consisting of nearly 10,000 asteroids.[11]:23 It orbits the Sun at a distance of 2.7–3.3 AU once every 5 years and 2 months (1,887 days). Its orbit has an eccentricity of 0.10 and an inclination of 9° with respect to the ecliptic.[1] The first precovery was obtained at Goethe Link Observatory in 1950, extending the asteroid's observation arc by 42 years prior to its discovery.[2]

    Naming

    This minor planet was named in honor of Japanese astronomer Tomohiko Sekiguch (born 1970), associate professor at Hokkaido University. From 1998 to 2001, he had been observing minor planets at the European Southern Observatory.[2] The official naming citation was published by the Minor Planet Center on 6 April 2012 (M.P.C. 79102).[12]

    Physical characteristics

    Rotation period

    In October 2005, a rotational lightcurve of Sekiguchi was obtained from photometric observations by French amateur astronomers René Roy and Laurent Bernasconi. Lightcurve analysis gave a well-defined rotation period of 5.41 hours with a brightness variation of 0.72 magnitude (U=3).[10]

    In October 2010 and November 2011, two more lightcurves were obtained at the Palomar Transient Factory, rendering a period of 5.4048 and 5.4100 hours with an amplitude of 0.58 and 0.27 magnitude, respectively (U=2/2).[9]

    Diameter and albedo

    According to the surveys carried out by the Japanese Akari satellite and NASA's Wide-field Infrared Survey Explorer with its NEOWISE mission, Sekiguchi measures between 13.9 and 15.2 kilometers in diameter and its surface has an albedo between 0.192 and 0.3829.[6][7][8] The Collaborative Asteroid Lightcurve Link assumes a standard albedo for carbonaceous asteroids of 0.057 and consequently calculates a larger diameter of 25.4 kilometers with an absolute magnitude of 11.7.[3]

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    References
    1. "JPL Small-Body Database Browser: 5357 Sekiguchi (1992 EL)" (2017-03-29 last obs.). Jet Propulsion Laboratory. Retrieved 20 June 2017.
    2. "5357 Sekiguchi (1992 EL)". Minor Planet Center. Retrieved 3 May 2016.
    3. "LCDB Data for (5357) Sekiguchi". Asteroid Lightcurve Database (LCDB). Retrieved 3 May 2016.
    4. "Asteroid 5357 Sekiguchi – Nesvorny HCM Asteroid Families V3.0". Small Bodies Data Ferret. Retrieved 27 October 2019.
    5. 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.
    6. 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.
    7. 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.
    8. 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 17 October 2019. (online, AcuA catalog p. 153)
    9. Waszczak, Adam; Chang, Chan-Kao; Ofek, Eran O.; Laher, Russ; Masci, Frank; Levitan, David; et al. (September 2015). "Asteroid Light Curves from the Palomar Transient Factory Survey: Rotation Periods and Phase Functions from Sparse Photometry". The Astronomical Journal. 150 (3): 35. arXiv:1504.04041. Bibcode:2015AJ....150...75W. doi:10.1088/0004-6256/150/3/75.
    10. Behrend, Raoul. "Asteroids and comets rotation curves – (5357) Sekiguchi". Geneva Observatory. Retrieved 3 May 2016.
    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.
    12. "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 3 May 2016.
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