1150 Achaia

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1150 Achaia
Discovery [1]
Discovered by K. Reinmuth
Discovery site Heidelberg Obs.
Discovery date 2 September 1929
MPC designation (1150) Achaia
Pronunciation /əˈkə/
Named after
Achaea (Greek region)[2]
1929 RB · 1955 SZ1
main-belt · Flora[3]
Orbital characteristics[1]
Epoch 16 February 2017 (JD 2457800.5)
Uncertainty parameter 0
Observation arc 86.78 yr (31,696 days)
Aphelion 2.6392 AU
Perihelion 1.7424 AU
2.1908 AU
Eccentricity 0.2047
3.24 yr (1,184 days)
0° 18m 14.04s / day
Inclination 2.3929°
Earth MOID 0.7366 AU
Physical characteristics
Dimensions 7.689±0.020 km[4]
7.82 km (calculated)[3]
7.928±0.036 km[5]
7.96±0.25 km[6]
8.16±0.25 km[7]
60.99±0.05 h[a]
61.071±0.001 h[8]
61.072±0.005 h[9]
0.24 (assumed)[3]
12.60[7] · 12.7[1][3][5][6] · 12.98±0.41[10]

1150 Achaia (/əˈkə/), provisional designation 1929 RB, is a stony Florian asteroid from the inner regions of the asteroid belt, approximately 7.8 kilometers in diameter. It is named for the Greek region of Achaia.[2]


Achaia was discovered on 2 September 1929, by German astronomer Karl Reinmuth at Heidelberg Observatory in southwest Germany.[11] Ten nights later, it was independently discovered by Friedrich Schwassmann and Arno Wachmann at Bergedorf.[2]

The body's observation arc begins at Heidelberg, five days after its official discovery observation. No precoveries were taken, and no prior identifications were made.[11]

Orbit and classification[edit]

Achaia is a stony S-type asteroid and a member of the Flora family, one of the largest families of the main-belt. It orbits the Sun at a distance of 1.7–2.6 AU once every 3 years and 3 months (1,184 days). Its orbit has an eccentricity of 0.20 and an inclination of 2° with respect to the ecliptic.[1]

Physical characteristics[edit]


A rotational lightcurve of Achaia was obtained by Czech astronomer Petr Pravec at Ondřejov Observatory in October 2007.[b] It gave a well-defined rotation period of 60.99 hours with a brightness variation of 0.72 magnitude (U=3).[a]

Published in 2016, two additional lightcurves were derived from modeled photometric data using various sources. They gave a sidereal rotation period of 61.071 and 61.072 hours, as well as a spin axis of (5.0°, −65.0°) and (20.0°, −69.0°) in ecliptic coordinates, respectively.[8][9]

While not being a slow rotator, Achaia has a notably longer period than the vast majority of asteroids, which typically rotate every 2 to 20 hours once around their axis. Also, the body's changes in brightness are relatively high and indicate that it has a non-spheroidal shape.

Diameter and albedo[edit]

According to the surveys carried out by the Japanese Akari satellite and NASA's Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, Achaia measures between 7.689 and 8.16 kilometers in diameter, and its surface has an albedo between 0.234 and 0.251.[4][5][6][7] The Collaborative Asteroid Lightcurve Link assumes an albedo of 0.24 – taken from 8 Flora, the family's principal body and namesake – and calculates a diameter of 7.82 kilometers based on an absolute magnitude of 12.7.[3]


This minor planet is named for the region Achaea (or "Achaia") in Western Greece. It is located in the northern part of the Peloponnese peninsula and borders on the gulfs of Patras and Corinth.[2] Naming citation was first mentioned in The Names of the Minor Planets by Paul Herget in 1955 (H 107).[2]


  1. ^ a b Pravec (2007) web: rotation period 60.99±0.05 hours with a brightness amplitude of 0.72 mag. Quality code of 3. Summary figures at Collaborative Asteroid Lightcurve Link (CALL) for (1150) Achaia and Pravec, P.; Wolf, M.; Sarounova, L. (2007)
  2. ^ (1150) Achaia: Lightcurve Plot analysis on 23 October 2007 by Pravec and Galad. ProjectID: Modra, Kharkiv. Comment: Error of 0.02 h is formal, real error perhaps a couple times greater.


  1. ^ a b c d "JPL Small-Body Database Browser: 1150 Achaia (1929 RB)" (2016-06-13 last obs.). Jet Propulsion Laboratory. Retrieved 2 February 2017.
  2. ^ a b c d e Schmadel, Lutz D. (2007). Dictionary of Minor Planet Names – (1150) Achaia. Springer Berlin Heidelberg. p. 97. ISBN 978-3-540-00238-3. Retrieved 2 February 2017.
  3. ^ a b c d e f "LCDB Data for (1150) Achaia". Asteroid Lightcurve Database (LCDB). Retrieved 2 February 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 2 February 2017.
  5. ^ 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 2 February 2017.
  6. ^ a b c d 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 2 February 2017.
  7. ^ a b c d 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. Retrieved 2 February 2017.
  8. ^ a b Durech, J.; Hanus, J.; Oszkiewicz, D.; Vanco, R. (March 2016). "Asteroid models from the Lowell photometric database". Astronomy and Astrophysics. 587: 6. arXiv:1601.02909. Bibcode:2016A&A...587A..48D. doi:10.1051/0004-6361/201527573. Retrieved 2 February 2017.
  9. ^ a b Hanus, J.; Durech, J.; Oszkiewicz, D. A.; Behrend, R.; Carry, B.; Delbo, M.; et al. (February 2016). "New and updated convex shape models of asteroids based on optical data from a large collaboration network" (PDF). Astronomy and Astrophysics. 586: 24. arXiv:1510.07422. Bibcode:2016A&A...586A.108H. doi:10.1051/0004-6361/201527441. Retrieved 2 February 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 2 February 2017.
  11. ^ a b "1150 Achaia (1929 RB)". Minor Planet Center. Retrieved 2 February 2017.

External links[edit]