1881 Shao

1881 Shao, provisional designation 1940 PC or 1968 OO, is a background asteroid from the outer regions of the asteroid belt, approximately 25 kilometers (16 miles) in diameter. It was discovered on 3 August 1940, by German astronomer Karl Reinmuth at the Heidelberg Observatory in southwest Germany. The presumed C-type asteroid has a rotation period of 7.45 hours. It was named for Chinese astronomer Cheng-yuan Shao. == Orbit and classification == Shao is a non-family asteroid from the main belt's background population. It orbits the Sun in the outer main-belt at a distance of 2.8–3.5 AU once every 5 years and 8 months (2,062 days; semi-major axis of 3.17 AU). Its orbit has an eccentricity of 0.11 and an inclination of 10° with respect to the ecliptic. The body's observation arc begins with its official discovery observation at Heidelberg in 1940. == Physical characteristics == Shao is an assumed carbonaceous C-type asteroid. === Rotation period === In July 2013, a rotational lightcurve of Shao was obtained from photometric observations by Italian amateur astronomer Silvano Casulli. Lightcurve analysis gave a rotation period of 7.452 hours with a brightness variation of 0.15 magnitude (U=2). A second lightcurve by astronomers at the Palomar Transient Factory from December 2014, gave a shorter period of 5.61 hours and an amplitude of 0.11 (U=2), indicative for a rather spherical shape. === Diameter and albedo === According to the surveys carried out by the Japanese Akari satellite and the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Shao measures between 24.083 and 25.46 kilometers in diameter and its surface has an albedo between 0.0994 and 0.115. The Collaborative Asteroid Lightcurve Link assumes a standard albedo for a carbonaceous asteroid of 0.057, and calculates a diameter of 29.21 kilometers based on an absolute magnitude of 11.4. == Naming == This minor planet was named after Chinese astronomer Cheng-yuan Shao (born 1927), an assistant to Richard McCrosky (see previously numbered 1880 McCrosky) in Harvard's minor-planet program at the Harvard–Smithsonian Center for Astrophysics and Oak Ridge Observatory in Massachusetts, United States. Shao was also involved in the recovery of near-Earth asteroid 1862 Apollo. The official naming citation was published by the Minor Planet Center on 20 February 1976 (M.P.C. 3936). == References == == External links == 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 Archived 29 July 2016 at the Wayback Machine – Observatoire de Genève, Raoul Behrend Discovery Circumstances: Numbered Minor Planets (1)-(5000) – Minor Planet Center 1881 Shao at AstDyS-2, Asteroids—Dynamic Site Ephemeris · Observation prediction · Orbital info · Proper elements · Observational info 1881 Shao at the JPL Small-Body Database