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12564 Ikeller, provisional designation 1998 SO49, is a stony Koronian asteroid from the outer region of the asteroid belt, approximately 5 kilometers in diameter.

12564 Ikeller
Discovery [1]
Discovered byW. Bickel
Discovery siteBergisch Gladbach Obs.
Discovery date22 September 1998
MPC designation(12564) Ikeller
Named after
Ingeborg Bickel–Keller
(discoverer's wife)[2]
1998 SO49 · 1988 RA7
1991 EG5 · 1993 SK13
main-belt · Koronis[3]
Orbital characteristics[1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc27.90 yr (10,190 days)
Aphelion2.9423 AU
Perihelion2.7273 AU
2.8348 AU
4.77 yr (1,743 days)
0° 12m 23.4s / day
Physical characteristics
Dimensions5.17 km (calculated)[3]
5.369±0.259 km[4][5]
7.0321±0.0196 h (R)[6]
7.0423±0.0196 h (S)[6]
0.24 (assumed)[3]
13.6[1][3][4] · 13.644±0.003 (R)[6] · 14.16±0.23[7] · 14.282±0.007 (S)[6]

The asteroid was discovered by German amateur astronomer Wolf Bickel at his private Bergisch Gladbach Observatory on 22 September 1998. It was named after the discoverer's wife, Ingeborg Bickel–Keller.[2]

Orbit and classificationEdit

Ikeller is a member of the Koronis family, a group of stony asteroids in the outer main-belt named after 158 Koronis. It orbits the Sun at a distance of 2.7–2.9 AU once every 4 years and 9 months (1,743 days). Its orbit has an eccentricity of 0.04 and an inclination of 2° with respect to the ecliptic.[1]

The body's observation arc begins 10 years prior to its official discovery observation, with its identification as 1988 RA7 at ESO's La Silla Observatory in September 1988.[2]

Physical characteristicsEdit

According to the survey carried out by the NEOWISE mission of NASA's space-based Wide-field Infrared Survey Explorer, Ikeller measures 5.4 kilometers in diameter and its surface has an albedo of 0.22,[4] while the Collaborative Asteroid Lightcurve Link assumes a standard albedo for Koronian asteroids of 0.24 and thus calculates a smaller diameter of 5.2 kilometers, as the higher the albedo (reflectivity), the smaller a body's diameter at a certain absolute magnitude (brightness).[3]


In August 2012, a photometric lightcurve of Ikeller was obtained from photometric observations by astronomers at the Palomar Transient Factory in California. Lightcurve analysis gave a rotation period of 7.0423 hours with a brightness variation of 0.44 magnitude (U=2).[6]


This minor planet was named by the discoverer after his wife, Ingeborg Bickel–Keller (born 1941).[2] The approved naming citation was published by the Minor Planet Center on 16 January 2014 (M.P.C. 86713).[8]


  1. ^ a b c d "JPL Small-Body Database Browser: 12564 Ikeller (1998 SO49)" (2016-08-03 last obs.). Jet Propulsion Laboratory. Retrieved 24 June 2017.
  2. ^ a b c d "12564 Ikeller (1998 SO49)". Minor Planet Center. Retrieved 5 April 2016.
  3. ^ a b c d e f "LCDB Data for (12564) Ikeller". Asteroid Lightcurve Database (LCDB). Retrieved 17 May 2016.
  4. ^ a b c d 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. Retrieved 17 May 2016.
  5. ^ a b Masiero, Joseph R.; Mainzer, A. K.; Grav, T.; Bauer, J. M.; Cutri, R. M.; Dailey, J.; et al. (November 2011). "Main Belt Asteroids with WISE/NEOWISE. I. Preliminary Albedos and Diameters". The Astrophysical Journal. 741 (2): 20. arXiv:1109.4096. Bibcode:2011ApJ...741...68M. doi:10.1088/0004-637X/741/2/68. Retrieved 4 December 2016.
  6. ^ a b c d e 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. Retrieved 17 May 2016.
  7. ^ 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 17 May 2016.
  8. ^ "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 17 May 2016.

External linksEdit