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1803 Zwicky, prov. designation: 1967 CA, is a stony Phocaea asteroid and binary system from the inner regions of the asteroid belt, approximately 10 kilometers (6.2 miles) in diameter. It was discovered on 6 February 1967, by Swiss astronomer Paul Wild at Zimmerwald Observatory near Bern, Switzerland. It was later named after Swiss astronomer Fritz Zwicky. The discovery of a 2.5-kilometer sized companion was announced on 8 March 2021.

Classification and orbit

Zwicky is a member of the Phocaea family (701), 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 (1,316 days; semi-major axis of 2.35 AU). Its orbit has an eccentricity of 0.25 and an inclination of 22° with respect to the ecliptic. 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.

Naming

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. 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 on 18 April 1977 (M.P.C. 4156).

Physical characteristics

Zwicky is a bright, stony S-type asteroid, in line with the overall spectral type for members of the Phocaea family.

Lightcurves

In July 2018, a rotational lightcurve of Zwicky was obtained from photometric observations by the TESS-team which gave a rotation period of (2.73364±0.00005) hours and an amplitude of (0.06±0.01) magnitude (U=2). Observations by Tom Polakis, who also discovered a satellite (see below) determined a very similar period of (2.7329±0.0002) hours with a brightness variation of (0.105±0.035) (U=2). These more recent result are replacing a previous observation from March 2003, of a fragmentary lightcurve by French amateur astronomer Laurent Bernasconi that gave a tentative period of 27.1 hours and an amplitude of 0.08 (U=1).

Diameter and albedo

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 9.20±0.24 and 9.934±0.080 kilometers in diameter, and its surface has an albedo of 0.337 and 0.259±0.038, respectively. The Collaborative Asteroid Lightcurve Link assumes a standard albedo for Phocaea asteroids of 0.23, and calculates a diameter of 10.06 kilometers based on an absolute magnitude of 12.2. The WISE team also published an alternative mean-diameters of (8.03±1.37) and (10.229±0.082) kilometers with a corresponding albedo of (0.35) and (0.2466).

Satellite

Photometric observations at the Command Module Observatory (V02) by Tom Polakis on 21 February 2021 revealed, that Zwicky has a satellite in its orbit. The moon has a diameter of approximately 2.50 kilometers, or 26% of that of its primary, and an orbital period of 28.46 hours.

References

1. ^ "1803 Zwicky (1967 CA)". Minor Planet Center. Retrieved 27 June 2021.
2. ^ Schmadel, Lutz D. (2007). "(1803) Zwicky". Dictionary of Minor Planet Names. Springer Berlin Heidelberg. p. 144. doi:10.1007/978-3-540-29925-7_1804. ISBN 978-3-540-00238-3.
3. ^ "JPL Small-Body Database Browser: 1803 Zwicky (1967 CA)" (2021-03-23 last obs.). Jet Propulsion Laboratory. Retrieved 27 June 2021.
4. ^ "Asteroid 1803 Zwicky – Nesvorny HCM Asteroid Families V3.0". Small Bodies Data Ferret. Retrieved 26 October 2019.
5. ^ "LCDB Data for (1803) Zwicky". Asteroid Lightcurve Database (LCDB). Retrieved 27 June 2021.
6. ^ Johnston, Wm. Robert (14 March 2021). "Asteroids with Satellites Database – (1803) Zwicky". Johnston's Archive. Retrieved 26 June 2021.
7. ^ 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 27 June 2021. (online, AcuA catalog p. 153)
8. ^ Mainzer, A. K.; Bauer, J. M.; Cutri, R. M.; Grav, T.; Kramer, E. A.; Masiero, J. R.; et al. (June 2016). "NEOWISE Diameters and Albedos V1.0". NASA Planetary Data System. Bibcode:2016PDSS..247.....M. Retrieved 27 June 2021.
9. ^ 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. S2CID 119293330.
10. ^ Pál, András; Szakáts, Róbert; Kiss, Csaba; Bódi, Attila; Bognár, Zsófia; Kalup, Csilla; et al. (March 2020). "Solar System Objects Observed with TESS—First Data Release: Bright Main-belt and Trojan Asteroids from the Southern Survey". The Astrophysical Journal Supplement Series. 247 (1): 26. arXiv:2001.05822. Bibcode:2020ApJS..247...26P. doi:10.3847/1538-4365/ab64f0. ISSN 0067-0049. S2CID 210718903.
11. ^ Popescu, M.; Licandro, J.; Carvano, J. M.; Stoicescu, R.; de León, J.; Morate, D.; et al. (September 2018). "Taxonomic classification of asteroids based on MOVIS near-infrared colors". Astronomy and Astrophysics. 617: A12. arXiv:1807.00713. Bibcode:2018A&A...617A..12P. doi:10.1051/0004-6361/201833023. ISSN 0004-6361. S2CID 119030733. (VizieR online cat)
12. Schmadel, Lutz D. (2009). "Appendix – Publication Dates of the MPCs". Dictionary of Minor Planet Names – Addendum to Fifth Edition (2006–2008). Springer Berlin Heidelberg. p. 221. Bibcode:2009dmpn.book.....S. doi:10.1007/978-3-642-01965-4. ISBN 978-3-642-01964-7.
13. Behrend, Raoul. "Asteroids and comets rotation curves – (1803) Zwicky". Geneva Observatory. Retrieved 16 December 2016.
14. 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. S2CID 35447010. Retrieved 27 June 2021.
15. 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. S2CID 9341381.

External links

• Minor Planet 1803 Zwicky -- Discovery of Binary Companion, Tom Polakis on YouTube
• Lightcurve Database (LCDB), query form (info)
• Dictionary of Minor Planet Names, Google books
• Asteroids and comets rotation curves, CdR – Geneva Observatory, Raoul Behrend
• Discovery Circumstances: Numbered Minor Planets (1)-(5000) – Minor Planet Center
• 1803 Zwicky at AstDyS-2, Asteroids—Dynamic Site
  • Ephemeris · Observation prediction · Orbital info · Proper elements · Observational info
• 1803 Zwicky at the JPL Small-Body Database
  • Close approach · Discovery · Ephemeris · Orbit viewer · Orbit parameters · Physical parameters

• Minor planet object articles (numbered)
• Phocaea asteroids
• Discoveries by Paul Wild (Swiss astronomer)
• Named minor planets
• Binary asteroids
• Astronomical objects discovered in 1967