Aitken, Robert Grant (1864–1951)

US astronomer. He discovered and observed thousands of double stars. From 1895 he worked at the Lick Observatory on Mount Hamilton, California, and was its director 1930–35.

Aitken was born in Jackson, California. In 1891 he became professor of mathematics at the University of the Pacific.

He began a survey of double stars 1899, not finished until 1915. During the early years of the project he was assisted by W J Hussey (1862–1926), and between them they discovered nearly 4,500 new binary systems. Their primary tool was the 91-cm/36-in refractor. Aitken then carried out a thorough statistical examination of this vast amount of information, which he published as Binary Stars 1918 and, revised, as New General Catalogue of Double Stars 1935. His work lay not merely in the discovery of new binary stars, but also in determining their motions and orbits.