Auwers, Arthur Julius Georg Friedrich von

(b. Göttingen, Germany, 12 September 1838; d. Lichterfelde bei Berlin, Germany, 24 January 1915)

astronomy.

The son of Gottfried Daniel Auwers, the riding master of Göttingen University, Auwers attended the gymnasia in Gottingen and Schulpforta from 1847 to 1857. He made a great number of observations and calculations of planets, comets, and variable stars as early as 1857–1859, his first years at Göttingen University. During his term as assistant at Königsberg (1859–1862) he made heliometric observations of double stars, which led him to his dissertation Untersuchungen ünder veränderliche Eigenbewegungen (1862). Bessel’s assumption that certain changes in the proper motions of the stars Sirius and Procyon are based on the presence of invisible companion stars had opened a new field in celestial mechanics. Auwers was able to derive the orbits for both Sirius and Procyon as weakly eccentric ellipses, corresponding to the motion of the visible principal stars around the center of gravity of the double star system in forty or fifty years, respectively. A few years later it became possible also to observe their very faint companions by optical means.

Auwers then spent four years with Hansen at the Gotha observatory, for the most part determining parallaxes of the fixed stars. On Hansen’s recommendation, in 1866 Auwers was appointed astronomer of the Berlin Academy, where he displayed great scientific and organizational ability during the next five decades. In 1878 the Academy appointed him as its permanent secretary, a position he held until his death. He was elected secretary of the Astronomical Society (founded in 1865) at its first meeting, and from 1881 to 1889 he was its president. Later he was awarded the Ordre pour le Mérite, grade of chancellor, and in 1912 was elevated to the hereditary nobility.

Auwers’ lifework was the meticulous observation and calculation necessary to draw up star catalogs with highly accurate positions of stars. Since this required exact knowledge of the proper motions of the fixed stars, he also made new reductions of previous observations. Therefore, from 1865 to 1883 he undertook the laborious task of making a completely new reduction of Bradley’s Greenwich observations, the oldest measurements of tolerable precision. The result was the publication of three volumes of Bradley’s observations (1882–1903), the basis of all modern star positions and proper motions.

Auwers participated in the Zonenunternehmen der Astronomischen Gesellschaft, a project which had as its aim the observation and cataloging of all stars in the Bonner Durchmusterung up to the ninth magnitude. He not only observed the half of the zone for which Berlin was responsible but also took over the secretaryship of the zone commission appointed by the Astronomical Society to coordinate this task and to perform the final reduction. He also demonstrated his great organizational talents when he was in charge of the German expeditions that observed the transits of Venus in 1874 and 1882 in order to determine the sun’s parallaxes. On the first expedition Auwers observed in Luxor, and on the second one in Punta Arenas, Chile. He published the results of both expeditions in six volumes (1887–1898).

In 1889 the opposition of the minor planet Victoria gave Auwers the opportunity to undertake the determination of the sun’s parallax once again. He made the complete reduction of the meridian observations done in this connection by twenty-two other observatories, and obtained a surprisingly good determination of the sun’s distance, considering the relatively great distance of the planet from the earth.

His incomparable experience and his remarkable endurance enabled Auwers to establish extremely accurate fundamental catalogs of positions of selected bright stars that had been observed for hundreds of years. These efforts led to the Neue Fundamental-catalog der Astronomischen Gesellschaft, the foundation of all present precise measurements. Here his talent for the detection and elimination of systematic errors in observations was brought to the fore. Auwers also initiated the Geschichte des Fixsternhimmels, an extensive reduction and listing of all meridian observations of fixed stars from 1743 to 1900. Thus he must be considered the one who completed Bessel’s epoch of classical astronomy in the second half of the nineteenth century. His participation in the founding of the astrophysical observatory in Potsdam bears witness also to his receptivity to the new science of astrophysics.

BIBLIOGRAPHY

I. Original Works. Auwers’ writings include Untersuchungen über veränderliche Eigenbewegungen, 2 vols. (Königsberg, 1862; Leipzig, 1868); Bericht über die Beobachtung des Venusdurchgangs 1874 in Luxor (Berlin, 1878); Fundamentalcatalog für die Zonenbeobachtungen am nördlichen Himmel (Leipzig, 1879); Neue Reduktion der Bradleyschen Beobachtungen 1750 bis 1762, 3 vols. (St. Petersburg, 1882–1903); Die Venusdurchgänge 1874 und 1882, 6 vols. (Berlin, 1887–1898); Fundamentalcatalog für die Zonenbeobachtungen am südlichen Himmel (Kiel, 1897); Bearbeitung der Bradleyschen Beobachtungen an der Greenwicher Sternwarte (Leipzig, 1912–1914); and many other works.

II. Secondary Literature. Articles on Auwers are in Neue deutsche Biographie, I 462; The Observatory, 38 (1915), 177–181; Poggendorff, Vols. III, IV, V; and Vierteljahrschrift der Astronomischen Gesellschaft, 53 (1918), 15–23.

Bernhard Sticker