1389 Onnie

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1389 Onnie
1389Onnie (Lightcurve Inversion).png
Light-curve-based 3D-model of Onnie
Discovery [1]
Discovered byH. van Gent
Discovery siteJohannesburg Obs.
(Leiden Southern Station)
Discovery date28 September 1935
MPC designation(1389) Onnie
Named after
A. Kruyt (relative of G. Pels)[2]
1935 SS1 · 1949 QV1
1955 XB1
main-belt · Koronis[3]
Orbital characteristics[1]
Epoch 16 February 2017 (JD 2457800.5)
Uncertainty parameter 0
Observation arc80.87 yr (29,539 days)
Aphelion2.9118 AU
Perihelion2.8183 AU
2.8650 AU
4.85 yr (1,771 days)
0° 12m 11.52s / day
Physical characteristics
Dimensions12.46 km (derived)[3]
13.772±0.184 km[4]
14.737±0.159 km[5]
22.5 h[6]
23.0447±0.0005 h[7]
0.24 (assumed)[3]
B–V = 0.810[1]
LS [8] · S[3][6]
11.64[1] · 11.69[3][5][6] · 11.74±0.40[8]

1389 Onnie, provisional designation 1935 SS1, is a stony Koronian asteroid from the outer region of the asteroid belt, approximately 13 kilometers in diameter. It was discovered on 28 September 1935, by Dutch astronomer Hendrik van Gent at Leiden Southern Station, annex to the Johannesburg Observatory in South Africa.[9]

Orbit and classification[edit]

The stony S-type asteroid belongs to the Koronis family, a group consisting of few hundred known bodies with nearly ecliptical orbits. Onnie orbits the Sun at a distance of 2.8–2.9 AU once every 4 years and 10 months (1,771 days). Its orbit has an eccentricity of 0.02 and an inclination of 2° with respect to the ecliptic.[1] As no precoveries were taken, and no prior identifications were made, the body's observation arc begins with its official discovery observation at Johannesburg.[9]


American astronomer Richard P. Binzel obtained a rotational light-curve of Onnie from photometric observations in September 1983. It gave a longer-than average rotation period of 22.5 hours with a change in brightness of 0.34 magnitude (U=2). In 2011 and 2013, respectively, a modeled light-curve using data from the Uppsala Asteroid Photometric Catalogue and other sources gave a period 23.0447 hours, as well as a spin axis of (183.0°, -75.0°) in ecliptic coordinates (U=n.a.).[7][10]

Diameter and albedo[edit]

According to the 2014-published result by NASA's Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, Onnie measures 13.77 kilometers in diameter, and its surface has an albedo of 0.198.[4] The Collaborative Asteroid Lightcurve Link assumes a standard albedo for stony Koronian asteroids of 0.24 and derives a diameter of 12.46 kilometers based on an absolute magnitude of 11.69.[3]


This minor planet was named for A. Kruyt, sister-in-law of astronomer G. Pels (1893–1966). Pels, who proposed the minor planet's name, was as a lifelong member of the Leiden Observatory's staff, observer of minor planets at Leiden, as well as an orbit computer for many of Hendrik van Gent's made discoveries.[2] The minor planet 1667 Pels was named in his honour.[11]


  1. ^ a b c d e "JPL Small-Body Database Browser: 1389 Onnie (1935 SS1)" (2016-08-12 last obs.). Jet Propulsion Laboratory. Retrieved 11 January 2017.
  2. ^ a b Schmadel, Lutz D. (2007). "(1389) Onnie". Dictionary of Minor Planet Names – (1389) Onnie. Springer Berlin Heidelberg. p. 112. doi:10.1007/978-3-540-29925-7_1390. ISBN 978-3-540-00238-3.
  3. ^ a b c d e f "LCDB Data for (1389) Onnie". Asteroid Lightcurve Database (LCDB). Retrieved 11 January 2017.
  4. ^ a b c 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. Retrieved 11 January 2017.
  5. ^ a b c 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.
  6. ^ a b c Binzel, R. P. (October 1987). "A photoelectric survey of 130 asteroids". Icarus. 72 (1): 135–208. Bibcode:1987Icar...72..135B. doi:10.1016/0019-1035(87)90125-4. ISSN 0019-1035. Retrieved 11 January 2017.
  7. ^ a b Hanus, J.; Durech, J.; Broz, M.; Warner, B. D.; Pilcher, F.; Stephens, R.; et al. (June 2011). "A study of asteroid pole-latitude distribution based on an extended set of shape models derived by the lightcurve inversion method". Astronomy & Astrophysics. 530: 16. arXiv:1104.4114. Bibcode:2011A&A...530A.134H. doi:10.1051/0004-6361/201116738. Retrieved 11 January 2017.
  8. ^ a b Veres, Peter; Jedicke, Robert; Fitzsimmons, Alan; Denneau, Larry; Granvik, Mikael; Bolin, Bryce; et al. (November 2015). "Absolute magnitudes and slope parameters for 250,000 asteroids observed by Pan-STARRS PS1 – Preliminary results". Icarus. 261: 34–47. arXiv:1506.00762. Bibcode:2015Icar..261...34V. doi:10.1016/j.icarus.2015.08.007. Retrieved 11 January 2017.
  9. ^ a b "1389 Onnie (1935 SS1)". Minor Planet Center. Retrieved 11 January 2017.
  10. ^ Hanus, J.; Durech, J.; Broz, M.; Marciniak, A.; Warner, B. D.; Pilcher, F.; et al. (March 2013). "Asteroids' physical models from combined dense and sparse photometry and scaling of the YORP effect by the observed obliquity distribution". Astronomy and Astrophysics. 551: 16. arXiv:1301.6943. Bibcode:2013A&A...551A..67H. doi:10.1051/0004-6361/201220701. Retrieved 11 January 2017.
  11. ^ Schmadel, Lutz D. (2007). "(1667) Pels". Dictionary of Minor Planet Names – (1667) Pels. Springer Berlin Heidelberg. p. 132. doi:10.1007/978-3-540-29925-7_1668. ISBN 978-3-540-00238-3.

External links[edit]