Willem Hendrik van den Bos
Willem Hendrik van den Bos ( born September 25, 1896 in Rotterdam, † March 30, 1974 in Johannesburg) was a Dutch- South African astronomer. He was mainly involved in the discovery, surveying and cataloging of visual double stars.
Van den Bos studied from 1913 ( with an interruption by military service ) in Leiden. He led the 10 ½ -inch model of the University Observatory measurements of double stars by ( 1920-1925 ) and received his doctorate in 1925 with a thesis on " micrometer measurements of double stars ."
In the same year he went as a volunteer at the Union Observatory in Johannesburg. This was done at the invitation of its director, the double star experts RTA Innes, who was looking for an experienced observer in order to support the work of the newly commissioned 26 ½ - incher.
From the originally planned three-year stay were ultimately 41 years. Van den Bos occurred after the first three years a position as assistant principal at HE Wood to, the successor of Innes. From 1941 to 1956 he was director of the observatory itself. Even after retirement, van den Bos remained active until 1966, he had to quit for health reasons his astronomical activities.
The clear air of South Africa favored extensive series of observations. The indefatigable observer van den Bos discovered a total of about 3000 new star couples and performed 74000 measurements. For almost all the observations he used the 26 ½ -inch model of the observatory, interrupted only by research at the Yerkes and the McDonald Observatory ( 1957-58 ) and the Lick Observatory ( 1961-63 ).
Van den Bos created a complete list of all 18,000 known double stars between -19 ° declination and the south celestial pole and the more than 95,000 performed on these stars measurements. This catalog was his contribution to the " Index Catalogue of Visual Double Stars, 1961.0 ," which was published in 1963 in cooperation with the Lick Observatory.
Van den Bos also devoted himself to theoretical work: He developed the method of Thiele -Innes for orbit determination of double stars on, published more than 150 sets of orbital elements ( even without the assistance of mechanical calculators ) and also worked on various other calculation methods.
From 1938 to 1952 van den Bos was president of Commission 26 (Double Stars) of the International Astronomical Union. In 1943/ 44 and 1955/56, he was president of the Astronomical Society of Southern Africa.
Van den Bos was awarded the Gold Medal of the Royal Danish Academy of Sciences and the Gill Medal of the Astronomical Society of Southern Africa. The asteroid ( 1663 ) van den Bos and a lunar crater have been named after him.