1187 Afra

1187 Afra (prov. designation: 1929 XC) is a dark background asteroid from the central regions of the asteroid belt. It was discovered by Germany astronomer Karl Reinmuth at Heidelberg Observatory on 6 December 1929.[1] The X-type asteroid has a rotation period of 14.1 hours and measures approximately 32 kilometers (20 miles) in diameter. The origin of the asteroid's name remains unknown.

1187 Afra
Modelled shape of Afra from its lightcurve
Discovery [1]
Discovered byK. Reinmuth
Discovery siteHeidelberg Obs.
Discovery date6 December 1929
Designations
(1187) Afra
Named after
unknown[2]
1929 XC
Orbital characteristics [3]
Epoch 31 May 2020 (JD 2459000.5)
Uncertainty parameter 0
Observation arc90.16 yr (32,932 d)
Aphelion3.2285 AU
Perihelion2.0523 AU
2.6404 AU
Eccentricity0.2227
4.29 yr (1,567 d)
52.040°
0° 13m 46.92s / day
Inclination10.697°
327.16°
74.956°
Physical characteristics
Mean diameter
  • 31.83±3.9 km[6]
  • 31.96±0.33 km[7]
  • 32.348±0.299 km[8]
  • 14.06993±0.00001 h[9]
  • 14.0701±0.0005 h[10]
  • 14.09±0.02 h[11]
  • 14.645±0.006 h[12]
SMASS = X [3]
11.50[1][3]

    Orbit and classification

    Afra is a non-family asteroid of the main belt's background population when applying the hierarchical clustering method to its proper orbital elements.[4][5] It orbits the Sun in the central asteroid belt at a distance of 2.1–3.2 AU once every 4 years and 3 months (1,567 days; semi-major axis of 2.64 AU). Its orbit has an eccentricity of 0.22 and an inclination of 11° with respect to the ecliptic.[3] The body's observation arc begins at Heidelberg in January 1930, seven weeks after its official discovery observation.[1]

    Naming

    It is not known to what person, group of persons, or occurrence the name "Afra" refers to.[2]

    Unknown meaning

    Among the many thousands of named minor planets, Afra is one of 120 asteroids, for which no official naming citation has been published. All of these low-numbered asteroids have numbers between 164 Eva and 1514 Ricouxa and were discovered between 1876 and the 1930s, predominantly by astronomers Auguste Charlois, Johann Palisa, Max Wolf and Karl Reinmuth (also see category).[13]

    Physical characteristics

    The lightcurve of Afra shows a periodicity of 14.09±0.02 hours, during which time the brightness of the object varies by 0.40±0.02 in magnitude.[11][14]

    References
    1. "1187 Afra (1929 XC)". Minor Planet Center. Retrieved 14 March 2020.
    2. Schmadel, Lutz D. (2007). "(1187) Afra". Dictionary of Minor Planet Names. Springer Berlin Heidelberg. p. 100. doi:10.1007/978-3-540-29925-7_1188. ISBN 978-3-540-00238-3.
    3. "JPL Small-Body Database Browser: 1187 Afra (1929 XC)" (2020-02-04 last obs.). Jet Propulsion Laboratory. Retrieved 14 March 2020.
    4. "Asteroid 1187 Afra – Proper Elements". AstDyS-2, Asteroids – Dynamic Site. Retrieved 14 March 2020.
    5. "Asteroid 1187 Afra". Small Bodies Data Ferret. Retrieved 14 March 2020.
    6. Tedesco, E. F.; Noah, P. V.; Noah, M.; Price, S. D. (October 2004). "IRAS Minor Planet Survey V6.0". NASA Planetary Data System. 12: IRAS-A-FPA-3-RDR-IMPS-V6.0. Bibcode:2004PDSS...12.....T. Retrieved 14 March 2020.
    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 14 March 2020. (online, AcuA catalog p. 153)
    8. 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. Bibcode:2016PDSS..247.....M. Retrieved 14 March 2020.
    9. Ďurech, J.; Hanuš, J.; Oszkiewicz, D.; Vančo, R. (March 2016). "Asteroid models from the Lowell photometric database". Astronomy and Astrophysics. 587: A48. arXiv:1601.02909. Bibcode:2016A&A...587A..48D. doi:10.1051/0004-6361/201527573. ISSN 0004-6361.
    10. Behrend, Raoul. "Asteroids and comets rotation curves – (1187) Afra". Geneva Observatory. Retrieved 14 March 2020.
    11. Menke, John; Cooney, Walt; Gross, John; Terrell, Dirk; Higgins, David (October 2008). "Asteroid Lightcurve Analysis at Menke Observatory" (PDF). Minor Planet Bulletin. 35 (4): 155–160. Bibcode:2008MPBu...35..155M. ISSN 1052-8091.
    12. Clark, Maurice (July 2019). "Asteroid Photometry from the Preston Gott Observatory" (PDF). Minor Planet Bulletin. 46 (3): 346–349. Bibcode:2019MPBu...46..346C. ISSN 1052-8091.
    13. Schmadel, Lutz D. (2007). "Appendix 11 – Minor Planet Names with Unknown Meaning". Dictionary of Minor Planet Names – Fifth Revised and Enlarged revision. Springer Berlin Heidelberg. pp. 927–929. ISBN 978-3-540-00238-3.
    14. "LCDB Data for (1187) Afra". Asteroid Lightcurve Database (LCDB). Retrieved 14 March 2020.
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