1803 Zwicky

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1803 Zwicky
Discovery [1]
Discovered byP. Wild
Discovery siteZimmerwald Obs.
Discovery date6 February 1967
MPC designation(1803) Zwicky
Named after
Fritz Zwicky[2]
(Swiss astronomer)
1967 CA · 1931 DL
main-belt · Phocaea[3][4]
Orbital characteristics[1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc86.21 yr (31,488 days)
Aphelion2.9317 AU
Perihelion1.7665 AU
2.3491 AU
3.60 yr (1,315 days)
0° 16m 25.32s / day
Physical characteristics
Dimensions9.20±0.24 km[5]
9.934±0.080 km[6]
10.06 km (calculated)[3]
10.229±0.082 km[7]
27.1±0.1 h[8]
0.23 (assumed)[3]
S (assumed)[3]
12.00[5] · 12.1[7] · 12.2[1][3]

1803 Zwicky, provisional designation 1967 CA, is a stony Phocaea asteroid from the inner regions of the asteroid belt, approximately 10 kilometers in diameter. It was discovered on 6 February 1967, by Swiss astronomer Paul Wild at Zimmerwald Observatory near Bern, Switzerland.[9] It was later named after Swiss astronomer Fritz Zwicky.[2]

Classification and orbit[edit]

Zwicky is a member of the Phocaea family (701),[4] an asteroid family with two thousand members, named after their largest member, 25 Phocaea. It orbits the Sun in the inner main-belt at a distance of 1.8–2.9 AU once every 3 years and 7 months (1,315 days). Its orbit has an eccentricity of 0.25 and an inclination of 22° with respect to the ecliptic.[1] It was first identified as 1931 DL at Lowell Observatory in 1931, extending the body's observation arc by 36 years prior to its official discovery observation.[9]

Physical characteristics[edit]

Zwicky is an assumed stony S-type asteroid, in line with the overall spectral type for Phocaea family.[3]


In March 2003, a fragmentary lightcurve of Zwicky was obtained from photometric observations by French amateur astronomer Laurent Bernasconi. It gave a rotation period of 27.1 hours with a brightness amplitude of 0.08 magnitude (U=1).[8] As of 2017, no other rotational lightcurves have been obtained.

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, Zwicky measures between 9.2 and 10.2 kilometers in diameter, and its surface has an albedo between 0.25 and 0.34.[5][6][7] The Collaborative Asteroid Lightcurve Link assumes a standard albedo for Phocaea asteroids of 0.23, and calculates a diameter of 10.54 kilometers based on an absolute magnitude of 12.2.[3]


This minor planet was named after Swiss astronomer Fritz Zwicky (1898–1974), who was a professor at Caltech and a pioneer in many fields, most notably in the study of galaxy clusters and supernovas, in high-energy astrophysics, and in developing jet propulsion for spacecraft and airplanes.[2] He was the first to infer the existence of unseen matter and coined the term Dark matter. The lunar crater Zwicky is also named in his honour. The official naming citation was published by the Minor Planet Center before November 1977 (M.P.C. 4156).[10]


  1. ^ a b c d "JPL Small-Body Database Browser: 1803 Zwicky (1967 CA)" (2017-05-04 last obs.). Jet Propulsion Laboratory. Retrieved 3 June 2017.
  2. ^ a b c Schmadel, Lutz D. (2007). "(1803) Zwicky". Dictionary of Minor Planet Names – (1803) Zwicky. Springer Berlin Heidelberg. p. 144. doi:10.1007/978-3-540-29925-7_1804. ISBN 978-3-540-00238-3.
  3. ^ a b c d e f g "LCDB Data for (1803) Zwicky". Asteroid Lightcurve Database (LCDB). Retrieved 16 December 2016.
  4. ^ a b "Small Bodies Data Ferret". Nesvorny HCM Asteroid Families V3.0. Retrieved 1 November 2017.
  5. ^ 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 16 December 2016. Online catalog
  6. ^ 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.
  7. ^ 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.
  8. ^ a b Behrend, Raoul. "Asteroids and comets rotation curves – (1803) Zwicky". Geneva Observatory. Retrieved 16 December 2016.
  9. ^ a b "1803 Zwicky (1967 CA)". Minor Planet Center. Retrieved 16 December 2016.
  10. ^ "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 16 December 2016.

External links[edit]