Arthur Auwers , German astronomer, was the son of Gottfried Daniel Auwers and his wife Emma Christiane Sophie, born Borkenstein. His full names were Arthur Julius Georg Friedrich, but he used only the first of these. He studied at the University of Göttingen from 1857 to 1859 and then at the University of Königsberg (now Kaliningrad, Russia) where he submitted his doctoral dissertation on the proper motion of Procyon in 1862. After some years (1862-1866) as an observer at Gotha Observatory (at Thuringen, Germany) he was appointed as astronomer and became a member of the Berlin Academy of Sciences in 1866. Much of his research dealt with the accurate determination of the positions and proper motions of the stars, the production of star catalogues, and with planetary astronomy. In his early publications he discussed, among others, parallax determinations with the Königsberg heliometer (1863), the constant of aberration (1869), and the variability of the solar diameter (1873). He observed the transit of Venus on 8 December 1874 at Luxor, Egypt, as a member of the German transit of Venus expedition. Later he was a member of a similar expedition to observe the next transit at Punta Arenas in South America, in 1882. His observations led to an undated publication on the derivation of the solar parallax from heliometer observations during the two transits, and another on the derivation of the diameters of the sun and Venus from the same observations (1891). Meanwhile he also published papers on Algol variables (1881), the determination of a fundamental meridian for Australia (1884), and observations of a solar eclipse at Berlin on 16 May 1882. More important was his Fundamental-catalog fuer die zonen-beobachtungen nordlichen himmel, published in Leipzig in 1879. Around this time he was professor of astronomy at Berlin and worked at the Berlin Observatory.
Auwers's observational experience made him an ideal collaborator in some of the work carried out by Dr David Gill* at the Royal Observatory, Cape of Good Hope. He visited the observatory from 24 May to 5 September 1889 and with Gill made extensive observations of the minor planet Victoria. Gill's determination of the solar parallax from observations of the minor planets required that the positions of a number of comparison stars needed to be accurately known. The positions of these stars were determined from observations made at various observatories, and after his return to Germany Auwers undertook the reduction of these observations and sent Gill the results. Auwers also collaborated in the publication of Gill's A determination of the solar parallax and mass of the moon, from heliometer observations of the minor planets Iris, Victoria and Sappho made in the years 1888 and 1889 at the Royal observatory, Cape of Good Hope (London, 1897).
At this time Auwers also published his Fundamental-catalog fuer die zonen-beobachtungen am suedhimmel und suedlicher-Polar-Catalog fuer die Epoche 1900 (Kiel, 1897). Several of his other publications dealt with the compilation of star catalogues, the positions of fundamental stars, and tables for reducing stellar observations. He discussed the proper motions of the 3240 stars catalogued by Bradley at Greenwich in 1759-1763, finding that about half of them have proper motions of 5 arc seconds per century or more.
Auwers and Gill were firm friends and regular correspondents. He was a prodigious worker who took great pains to achieve the greatest possible accuracy of his results. He was widely known and honoured, among others as a recipient of the gold medal of the Royal Astronomical Society, a member and perpetual secretary of the Academy of Sciences of Berlin and a corresponding member of the French Academy of Sciences.
