1106 Cydonia (/saɪˈdoʊniə/), provisional designation 1929 CW, is a Eunomian asteroid from the central regions of the asteroid belt, approximately 13 kilometers (8 miles) in diameter. It was discovered on 5 February 1929, by astronomer Karl Reinmuth at the Heidelberg-Königstuhl State Observatory in Germany.^[12] The asteroid was named for the fruit-bearing tree Cydonia (quince).^[3] The S-type asteroid has a relatively short rotation period of 2.7 hours.^[4]

Cydonia is a member of the Eunomia family (502),^[4][5] a prominent family of stony asteroids and the largest one in the intermediate main belt with more than 5,000 members.^[13] It orbits the Sun in the central asteroid belt at a distance of 2.3–2.9 AU once every 4 years and 2 months (1,528 days; semi-major axis 2.60 AU). Its orbit has an eccentricity of 0.13 and an inclination of 13° with respect to the ecliptic.^[1] The body's observation arc begins with its first and official discovery observation at Heidelberg in February 1929.^[12]

In the SMASS classification, Cydonia is a stony S-type asteroid,^[1][4] in-line with the Eunomia family's overall spectral type.^[13]: 23

In December 2015, a rotational lightcurve of Cydonia was obtained from photometric observations by astronomers at the Etscorn Observatory (719) in New Mexico, United States. Lightcurve analysis gave a well-defined rotation period of 2.679 hours with a brightness variation of 0.28 magnitude (U=3).^[10] In April 2017, Spanish astronomers at Puçol Observatory (J42) and other stations of the APTOG-network measured a similar period of 2.6700 hours and an amplitude of 0.10 magnitude (U=2+).^[9]

According to the survey carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Cydonia measures between 12.140 and 12.95 kilometers in diameter and its surface has an albedo between 0.1719 and 0.241.^[6][7][8]

The Collaborative Asteroid Lightcurve Link assumes an albedo of 0.21 – derived from 15 Eunomia, the family's parent body and namesake – and calculates a diameter of 13.26 kilometers based on an absolute magnitude of 11.7.^[4]

This minor planet was named after the genus Cydonia in the family Rosaceae, with the fruit-bearing quince tree as its only member. The official naming citation was mentioned in The Names of the Minor Planets by Paul Herget in 1955 (H 104).^[3]

Due to his many discoveries, Karl Reinmuth submitted a large list of 66 newly named asteroids in the early 1930s. The list covered his discoveries with numbers between (1009) and (1200). This list also contained a sequence of 28 asteroids, starting with 1054 Forsytia, that were all named after plants, in particular flowering plants (also see list of minor planets named after animals and plants).^[14]

• Asteroid Lightcurve Database (LCDB), query form (info Archived 16 December 2017 at the Wayback Machine)
• Dictionary of Minor Planet Names, Google books
• Asteroids and comets rotation curves, CdR – Observatoire de Genève, Raoul Behrend
• Discovery Circumstances: Numbered Minor Planets (1)-(5000) – Minor Planet Center
• 1106 Cydonia at AstDyS-2, Asteroids—Dynamic Site
  • Ephemeris · Observation prediction · Orbital info · Proper elements · Observational info
• 1106 Cydonia at the JPL Small-Body Database
  • Close approach · Discovery · Ephemeris · Orbit viewer · Orbit parameters · Physical parameters