1246 Chaka
Discovery[1]
Discovered byC. Jackson
Discovery siteJohannesburg Obs.
Discovery date23 July 1932
Designations
(1246) Chaka
Named after
Shaka (King of the Zulus)[2]
1932 OA
main-belt[1][3] · (middle)
background[4][5]
Orbital characteristics[3]
Epoch 27 April 2019 (JD 2458600.5)
Uncertainty parameter 0
Observation arc86.29 yr (31,519 d)
Aphelion3.4329 AU
Perihelion1.8068 AU
2.6198 AU
Eccentricity0.3103
4.24 yr (1,549 d)
128.91°
0° 13m 56.64s / day
Inclination16.004°
290.52°
54.847°
Physical characteristics
Mean diameter
17.634±0.498 km[6][7]
17.73±3.89 km[8]
18.11±0.9 km[9]
19.596±0.035 km[10]
20.84±1.39 km[11]
25.462±0.001 h[lower-alpha 1]
0.195[11]
0.2045[10]
0.2351[9]
0.26[8]
0.310[6]
A (S3OS2-TH)[12]
Sl (S3OS2-BB)[12]
10.8[8][11]
10.9[1][3][6][9][10]

    1246 Chaka, provisional designation 1932 OA, is a background asteroid from the central regions of the asteroid belt, approximately 18 kilometers (11 miles) in diameter. It was discovered on 23 July 1932, by South African astronomer Cyril Jackson at the Union Observatory in Johannesburg.[1] The uncommon A/Sl-type asteroid has a longer than average rotation period of 25.5 hours.[13] It was named for the Zulu King Shaka.[2]

    Orbit and classification

    Chaka is a non-family asteroid from the main belt's background population.[4][5] It orbits the Sun in the central asteroid belt at a distance of 1.8–3.4 AU once every 4 years and 3 months (1,549 days; semi-major axis of 2.62 AU). Its orbit has an eccentricity of 0.31 and an inclination of 16° with respect to the ecliptic.[3] The body's observation arc begins with its first observation at Johannesburg on 4 July 1932, three weeks prior to its official discovery observation.[1]

    Naming

    This minor planet was named after Shaka (c.1787–1828), also Chaka or Tchaka, founder and one of the most influential monarchs of the Zulu Kingdom. The official naming citation was mentioned in The Names of the Minor Planets by Paul Herget in 1955 (H 115).[2]

    Physical characteristics

    Chaka's spectral type has been determined during the Small Solar System Objects Spectroscopic Survey (S3OS2). In the Tholen-like taxonomic variant of the survey, the asteroid is a rare A-type, while in the SMASS-like variant it is a Sl-subtype, that transitions between the common S- and uncommon L-type asteroids.[4][12]

    Rotation period

    In October 2013, a rotational lightcurve of Chaka was obtained from photometric observations by Joe Garlitz at his Elgin Observatory. Lightcurve analysis gave a well-defined rotation period of 25.462±0.001 hours with a brightness amplitude of 0.18 magnitude (U=3).[lower-alpha 1] Other period determinations were made by European astronomers (20 h; Δ0.2) at OHP and La Silla in October 1996 (U=2),[14] and by Andrea Ferrero (25.44 h; Δ0.25) at the Italian Bigmuskie Observatory (B88) in November 2013 (U=2).[15]

    Diameter and albedo

    According to the surveys carried out by the Infrared Astronomical Satellite IRAS and the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Chaka measures between 17.63 and 20.84 kilometers in diameter and its surface has an albedo between 0.195 and 0.310.[6][7][8][9][10][11] The Collaborative Asteroid Lightcurve Link adopts the results obtained by IRAS, that is, an albedo of 0.2351 and a diameter of 18.11 kilometers based on an absolute magnitude of 10.9.[13]

    Notes

    1. 1 2 Joe Garlitz (2013; web) observations of (1246) Chaka at the Elgin Observatory from October 2013. Posted data on the web site of the Collaborative Asteroid Lightcurve Link. Results: rotation period of 25.462±0.001 hours with a brightness amplitude of 0.18±0.02 mag. Quality code is 3. Summary figures at the LCDB. Also see Observers homepage.

    References

    1. 1 2 3 4 5 "1246 Chaka (1932 OA)". Minor Planet Center. Retrieved 14 December 2018.
    2. 1 2 3 Schmadel, Lutz D. (2007). "(1246) Chaka". Dictionary of Minor Planet Names – (1246) Chaka. Springer Berlin Heidelberg. p. 115. doi:10.1007/978-3-540-29925-7_1247. ISBN 978-3-540-00238-3.
    3. 1 2 3 4 "JPL Small-Body Database Browser: 1246 Chaka (1932 OA)" (2018-10-20 last obs.). Jet Propulsion Laboratory. Retrieved 14 December 2018.
    4. 1 2 3 "Asteroid 1246 Chaka". Small Bodies Data Ferret. Retrieved 14 December 2018.
    5. 1 2 "Asteroid (1246) Chaka". AstDyS-2, Asteroids – Dynamic Site. Retrieved 14 December 2018.
    6. 1 2 3 4 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 14 December 2018.
    7. 1 2 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. S2CID 119293330.
    8. 1 2 3 4 Nugent, C. R.; Mainzer, A.; Masiero, J.; Bauer, J.; Cutri, R. M.; Grav, T.; et al. (December 2015). "NEOWISE Reactivation Mission Year One: Preliminary Asteroid Diameters and Albedos". The Astrophysical Journal. 814 (2): 13. arXiv:1509.02522. Bibcode:2015ApJ...814..117N. doi:10.1088/0004-637X/814/2/117. S2CID 9341381.
    9. 1 2 3 4 Tedesco, E. F.; Noah, P. V.; Noah, M.; Price, S. D. (October 2004). "IRAS Minor Planet Survey V6.0". NASA Planetary Data System – IRAS-A-FPA-3-RDR-IMPS-V6.0: IRAS–A–FPA–3–RDR–IMPS–V6.0. Bibcode:2004PDSS...12.....T. Retrieved 14 December 2018.
    10. 1 2 3 4 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. S2CID 35447010. (catalog)
    11. 1 2 3 4 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. S2CID 46350317.
    12. 1 2 3 Lazzaro, D.; Angeli, C. A.; Carvano, J. M.; Mothé-Diniz, T.; Duffard, R.; Florczak, M. (November 2004). "S3OS2: the visible spectroscopic survey of 820 asteroids" (PDF). Icarus. 172 (1): 179–220. Bibcode:2004Icar..172..179L. doi:10.1016/j.icarus.2004.06.006. Retrieved 14 December 2018.
    13. 1 2 "LCDB Data for (1246) Chaka". Asteroid Lightcurve Database (LCDB). Retrieved 14 December 2018.
    14. ↑ Florczak, M.; Dotto, E.; Barucci, M. A.; Birlan, M.; Erikson, A.; Fulchignoni, M.; et al. (November 1997). "Rotational properties of main belt asteroids: photoelectric and CCD observations of 15 objects". Planetary and Space Science. 45 (11): 1423–1435. Bibcode:1997P&SS...45.1423F. doi:10.1016/S0032-0633(97)00121-9.
    15. ↑ Ferrero, Andrea (July 2014). "Period Determination of Six Main Belt Asteroids". The Minor Planet Bulletin. 41 (3): 184–185. Bibcode:2014MPBu...41..184F. ISSN 1052-8091.
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