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969 Leocadia
969 Leocadia (prov. designation: A921 VC or 1921 KZ) is a very dark background asteroid from the inner regions of the asteroid belt, approximately 19 kilometers (12 miles) in diameter. It was discovered on 5 November 1921, by Russian astronomer Sergey Belyavsky at the Simeiz Observatory on the Crimean peninsula.[1] The uncommon F-type asteroid (FX) has a rotation period of 6.9 hours and is likely regular in shape.[10] Any reference of the asteroid's name to a person is unknown.[3] Orbit and classificationLeocadia is a non-family asteroid of the main belt's background population when applying the hierarchical clustering method to its proper orbital elements.[5][6] It orbits the Sun in the inner main-belt at a distance of 2.0–3.0 AU once every 3 years and 10 months (1,411 days; semi-major axis of 2.46 AU). Its orbit has an eccentricity of 0.21 and an inclination of 2° with respect to the ecliptic.[4] The body's observation arc begins at Uccle Observatory in February 1933, more than a decade after its official discovery observation Simeiz Observatory on 5 November 1921.[1] NamingThis minor planet is named after a Feminine Russian first name. Any reference of this name to a person or occurrence is unknown.[3] Unknown meaningAmong the many thousands of named minor planets, Leocadia is one of 120 asteroids, for which no official naming citation has been published. All of these low-numbered asteroids have numbers between 164 Eva and 1514 Ricouxa and were discovered between 1876 and the 1930s, predominantly by astronomers Auguste Charlois, Johann Palisa, Max Wolf and Karl Reinmuth.[12] Physical characteristicsIn the Tholen classification (FXU:), Leocadia is an uncommon and dark F-type asteroid, somewhat similar to that of an X-type, though with an unusual (U) and noisy (:) spectra.[4] Rotation periodIn December 2006, a rotational lightcurve of Leocadia was obtained from photometric observations by Italian amateur astronomers Roberto Crippa and Federico Manzini at the Sozzago Astronomical Station (A12). Lightcurve analysis gave a rotation period of 6.87±0.01 hours with a brightness amplitude of 0.14±0.01 magnitude (U=2), which is indicative of a rather spherical, non-irregular shape.[10][11] Diameter and albedoAccording to the surveys carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer (WISE), the Japanese Akari satellite, and the Infrared Astronomical Satellite IRAS, Leocadia measures 17.321±0.218, 19.37±0.22 and 19.51±0.7 kilometers in diameter, and its surface has a very low albedo of 0.019±0.005, 0.0435±0.003 and 0.045±0.001, respectively.[7][8][9] Additional measurements by the WISE telescope were published giving a mean diameter as low as 13.58±3.09 km.[11] The Collaborative Asteroid Lightcurve Link adopts the result from IRAS, that is, an albedo of 0.0435 and a diameter of 19.51 kilometers based on an absolute magnitude of 9.22.[11] An asteroid occultation on 19 August 2013, gave a best-fit ellipse dimension of 19.0 × 19.0 kilometers.[6] These timed observations are taken when the asteroid passes in front of a distant star. However the measurements for Leocadia were of poor quality.[6] References
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