Discovered by K. Endate
K. Watanabe MPC designation 4607 Seilandfarm Discovered 25 November 1987 Orbits Sun Asteroid group Asteroid belt | Discovery date 25 November 1987 Minor planet category main-belt · (inner) Absolute magnitude 13.1 Discovery site Kitami Observatory | |
Named after Seilandfarm
(Japanese farm) Alternative names 1987 WR · 1951 CK1
1975 EO4 Discoverers Kin Endate, Kazuro Watanabe People also search for 5692 Shirao, Sun, 4971 Hoshinohiroba | ||
4607 Seilandfarm, provisional designation 1987 WR, is a rare-type binary asteroid from the inner regions of the asteroid belt, approximately 7 kilometers in diameter. It was discovered on 25 November 1987, by Japanese amateur astronomers Kin Endate and Kazuro Watanabe at Kitami Observatory on the Japanese island of Hokkaidō.
The reddish body is classified as a rare L-type asteroid on the SMASS taxonomic scheme. It orbits the Sun at a distance of 2.2–2.3 AU once every 3 years and 5 months (1,244 days). Its orbit has an eccentricity of 0.02 and an inclination of 2° with respect to the ecliptic. The asteroid's observation arc begins with its discovery in 1987, as the first two observations at Abastuman, Georgia, and at Crimea–Nauchnij from 1954 and 1975, respectively, remain unused.
In February 2009 and September 2014, three rotational Light-curves were obtained from photometric observations by astronomers Donald P. Pray and Petr Pravec at the U.S. Carbuncle and the Czech Ondřejov Observatory, respectively. The light-curves rendered a well-defined rotation period of 7000396810000000000♠3.9681±0.0002 and 7000396830000000000♠3.9683±0.0001 hours with a corresponding brightness variation of 0.15 and 0.17 in magnitude, indicating that the asteroid's shape is nearly spheroidal (U=3/3/3). During the photometric observations in February 2009, the asteroid was discovered to be a binary system. Its asteroid moon has an orbital period of 31.6 hours. Based on mutual eclipse/occultation events, the satellite is thought to be at least 29% the size of Seilandfarm, which would translate into a diameter of about 2 kilometers or more.
According to the survey carried out by NASA's Wide-field Infrared Survey Explorer with its NEOWISE mission, the asteroid measures between 6.3 and 7.5 and kilometers in diameter, and its surface has a corresponding albedo between 0.178 and 0.279, while the Collaborative Asteroid Lightcurve Link assumes a standard albedo for stony asteroids of 0.20 and calculates a diameter of 7.1 kilometers, in agreement with the results obtained by the space-based observations.
The minor planet was named for Seilandfarm, a 50-hectare dairy and cattle farm, located in a hilly terrain, near the Japanese city of Kitami and not far from the observatory where this minor planet was discovered (also see 3785 Kitami). The farm was established by Akio Seino in 1942, and is now operated by four members of the Seino family. Naming citation was published on 14 July 1992 (M.P.C. 20521).