Willem Hendrik van den Bos (25 September 1896 – 30 March 1974) was a Dutchastronomer who worked at theUnion Observatory in South Africa and became its director in 1941. He discovered nearly3000 newdouble stars, made more than71000 astronomical measurements and compiled a catalogue of Southern hemisphere double stars.^[1][2] He computed the orbits of more than 100 double stars using a method he invented^[3] and which later became the accepted standard.^[1]

Van den Bos was born inRotterdam in 1896. He studiedastronomy atLeiden University and worked at theLeiden Observatory. In 1925 he completed his PhD in astronomy under the supervision ofWillem de Sitter and was invited byR.T.A. Innes to join theUnion Observatory inJohannesburg for a three-year appointment as assistant to the director,H.E. Wood. Innes was eager to have an experienced observer of double-stars to share the workload on the newly erectedtelescope.^[1]

Van den Bos extended his appointment at the Union Observatory indefinitely and in 1941 was appointed Director of the observatory. He retired from the observatory in 1956 but continued his observations both in South Africa and theUnited States until 1966 when he was forced to stop owing to severe illness.^[1]

During the 31 years of his career he discovered2895 newdouble stars^[4] and made71929 astronomical measurements.^[4] He compiled a catalogue from previous observations of southern hemisphere double stars that was incorporated into theIndex Catalog of Visual Double Stars^[5][6], published in 1963, with the collaboration of H.M. Jeffries and F.M. Greeby of theLick Observatory,California.^[1] The catalogue later became theWashington Double Star Catalog.^[6]

Van den Bos developed his own method^[3] of measuring the orbits of double stars and used it to measure the orbits of more than 100binary stars. His method became the accepted standard procedure.^[1]

• President of the Double Star Commission of theInternational Astronomical Union for 14 years.^[1]
• Royal Danish Academy Gold Medal
• Gill Medal from the Astronomical Society of Southern Africa
• President of the Astronomical Society of Southern Africa in 1943 and 1955
• The 1969 Double-star Colloquium of the International Astronomical Union inNice was dedicated to Van den Bos.
• The asteroid1663 van den Bos is named after him, as is the lunar cratervan den Bos.^[7]

Publications by Willem Hendrik Van den Bos atResearchGate

• 1896 births
• 1974 deaths
• 20th-century Dutch astronomers
• Dutch emigrants to South Africa
• Leiden University alumni
• South African astronomers
• Scientists from Rotterdam

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