1151 Ithaka

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1151 Ithaka
Discovery [1]
Discovered by K. Reinmuth
Discovery site Heidelberg Obs.
Discovery date 8 September 1929
MPC designation (1151) Ithaka
Named after
Ithaca (Greek Ionian Island)[2]
1929 RK · 1966 LA
main-belt · (inner)[3]
Orbital characteristics[1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc 87.63 yr (32,007 days)
Aphelion 3.0719 AU
Perihelion 1.7417 AU
2.4068 AU
Eccentricity 0.2763
3.73 yr (1,364 days)
0° 15m 50.4s / day
Inclination 6.5616°
Earth MOID 0.7459 AU · 290.6 LD
Physical characteristics
Dimensions 8.97±2.41 km[4]
12.120±0.100 km[5][6]
14±3 km[7]
14.37 km (derived)[3]
20.46±4.51 km[8]
4.93115±0.00011 h[7]
4.9314±0.0003 h[a]
4.932±0.001 h[9]
0.057 (assumed)[3]
12.90±0.56[10] · 12.94[3] · 12.94±0.03[7] · 13.10[4][6] · 13.12[8] · 13.2[1]

1151 Ithaka, provisional designation 1929 RK, is a carbonaceous asteroid from the inner regions of the asteroid belt, approximately 14 kilometers in diameter. It was discovered by Karl Reinmuth at the Heidelberg-Königstuhl State Observatory in 1929, and later named for the Greek island of Ithaca.[11]


Ithaka was discovered on 8 September 1929, by German astronomer Karl Reinmuth at the Heidelberg Observatory in southwest Germany.[11] Five nights later, it was independently discovered by Soviet astronomer Grigory Neujmin at Simeiz Observatory on the Crimean peninsula.[2] Only the first discoverer is acknowledged by the Minor Planet Center.[11] The body's observation arc begins with its official discovery observation at Heidelberg.[11]

Orbit and classification[edit]

Ithaka is a non-family asteroid from the background population. It orbits the Sun in the inner main-belt at a distance of 1.7–3.1 AU once every 3 years and 9 months (1,364 days). Its orbit has an eccentricity of 0.28 and an inclination of 7° with respect to the ecliptic.[1]

Physical characteristics[edit]

Ithaka is an assumed carbonaceous C-type asteroid,[3] untypical for inner-belt asteroids.

Rotation period[edit]

In 2011, three rotational lightcurves of Ithaka were obtained from photometric observations. Lightcurve analysis gave a well-defined rotation period between 4.93115 and 4.932 hours with a brightness amplitude of 0.12 to 0.15 magnitude (U=3/3/3).[7][9][a]

Diameter and albedo[edit]

According to the survey carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Ithaka measures between 8.97 and 20.46 kilometers in diameter and its surface has an albedo between 0.02 and 0.13.[4][5][6][8] A collaboration of Italian and American photometrists estimate a diameter of 14±3 kilometers,[7] and the Collaborative Asteroid Lightcurve Link assumes a standard albedo for carbonaceous asteroids of 0.057 and derives a diameter of 14.37 kilometers based on an absolute magnitude of 12.94.[3]


This minor planet was named after the Greek Ionian Island of Ithaca located in the Ionian Sea. In Greek mythology, the legendary hero Odysseus was the King of Ithaca (also see 1143 Odysseus). The official naming citation was mentioned in The Names of the Minor Planets by Paul Herget in 1955 (H 107).[2]


  1. ^ a b Pravec (2011), lightcurve plot of (1151) Ithaka. Observation: 14 September 2011. Rotation period 4.9314±0.0003 hours with a brightness amplitude of 0.12±0.01 mag. Quality Code of 3. Summary figures at Ondrejov Asteroid Photometry Project and LCDB


  1. ^ a b c d "JPL Small-Body Database Browser: 1151 Ithaka (1929 RK)" (2017-04-26 last obs.). Jet Propulsion Laboratory. Retrieved 8 September 2017.
  2. ^ a b c Schmadel, Lutz D. (2007). Dictionary of Minor Planet Names – (1151) Ithaka. Springer Berlin Heidelberg. p. 97. ISBN 978-3-540-00238-3. Retrieved 8 September 2017.
  3. ^ a b c d e f g "LCDB Data for (1151) Ithaka". Asteroid Lightcurve Database (LCDB). Retrieved 8 September 2017.
  4. ^ a b c d 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. Retrieved 8 September 2017.
  5. ^ a b c 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 8 September 2017.
  6. ^ 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" (PDF). The Astrophysical Journal. 741 (2): 25. arXiv:1109.6407. Bibcode:2011ApJ...741...90M. doi:10.1088/0004-637X/741/2/90. Retrieved 8 September 2017.
  7. ^ a b c d e Franco, Lorenzo; Ferrero, Andrea; Durkee, Russell I. (April 2012). "Lightcurve Photometry and H-G Parameters for 1151 Ithaka". The Minor Planet Bulletin. 39 (2): 47–48. Bibcode:2012MPBu...39...47F. ISSN 1052-8091. Retrieved 8 September 2017.
  8. ^ a b c d Nugent, C. R.; Mainzer, A.; Bauer, J.; Cutri, R. M.; Kramer, E. A.; Grav, T.; et al. (September 2016). "NEOWISE Reactivation Mission Year Two: Asteroid Diameters and Albedos". The Astronomical Journal. 152 (3): 12. arXiv:1606.08923. Bibcode:2016AJ....152...63N. doi:10.3847/0004-6256/152/3/63. Retrieved 8 September 2017.
  9. ^ a b Aymami, Josep Maria (January 2012). "CCD Photometry and Lightcurve Analysis of Main Belt Asteroids 1077 Campanula and 1151 Ithaka from Observatori Carmelita". The Minor Planet Bulletin. 39 (1): 29. Bibcode:2012MPBu...39...29A. ISSN 1052-8091. Retrieved 8 September 2017.
  10. ^ 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 8 September 2017.
  11. ^ a b c d "1151 Ithaka (1929 RK)". Minor Planet Center. Retrieved 8 September 2017.

External links[edit]