OPPOLZER, THEODOR RITTER VON

(b. Prague, Bohemia [now Czechoslovakia], 26 October 1841; d. Vienna, Austria, 26 December 1886)

astronomy, geodesy.

His father, Johann von Oppolzer, was a leader of the Vienna school of medicine and professor at the universities of Prague, Leipzig, and Vienna. Oppolzer’s first teacher, Franz Jahne, discovered and encouraged his outstanding mathematical abilities. After attending the Piaristen-Gymnasium in Vienna from 1851 to 1859 he studied medicine—in accordance with his father’s wishes—and received the M.D. in 1865. Having also studied astronomy, he built a private observatory in the Josephstadt, a recently incorporated suburb of Vienna. His main instrument, a seven-inch refracting telescope, was then probably the largest in the Austrian empire. By 1866 he had published more than seventy papers on astronomy, comprising observations, computations of the orbits of comets and asteroids, and analytical investigations of related problems. In March 1866 he became lecturer on astronomy at the University of Vienna. In 1868 he participated in the Austrian expedition to Aden to observe a solar eclipse, and in 1874 he observed the transit of Venus at laṣi, Rumania.

Elected to the Imperial Academy of Sciences of Vienna in 1869, Oppolzer subsequently became a member of nearly every European and American learned society. In 1870 he was appointed associate professor and, in 1875, lull professor of astronomy and geodesy at the University of Vienna. In 1873 he became director of the Gradmessungs-Bureau, the Austrian geodetic survey, which was very active under his direction. At the eighth conference of the Internationale Erdmessung, held at Berlin in 1886, he was elected vicepresident of the International Geodetic Association. He died a few months later, after having revised the major part of the proofs of his last work, “Canon der Finsternisse.”

On 1 June 1865 Oppolzer married Coelestine Mautner von Markhof, daughter of a prominent Austrian industrialist; they had six children. Three planetoids are named for two of their three daughters, Hilda and Agatha, and for his wife. A son, Egon Ritter von Oppolzer, founded the astronomical observatory at lnnsbruck.

The great majority of Oppolzer’s more than 300 papers deal with the determination and improvement of the orbits of comets and asteroids—sometimes based on Oppolzer’s own observations—and with the computation of ephemerides derived from the orbital elements. Dissatisfied with merely routine work, Oppolzer improved existing methods: as early as 1864, for example, he developed new formulas for calculating the differential correction of planetary or cometary orbital elements directly from the deviations from the computed positions. His two-volume Lehrbuch zur Bahnbestimmung der Cometen und Planeten (1870-1880) comprises all the materials then necessary for understanding and determining both preliminary and definitive orbits: the basic concepts, mathematical tools, practically arranged formulas, extensive auxiliary tables, and examples drawn from the author’s own experience.

About 1868 Oppolzer began to study the computation of ancient and modern eclipses, intending to compile a catalog of the relevant data of all eclipses from the beginning of reliable history, whether observations of the eclipses were actually known by him. These data were to be computed on the basis of modern knowledge of the exact laws of solar and lunar motion. After several years of discouraging setbacks, Oppolzer realized the impossibility of completing the work within a reasonable time by using Hansen’s tables, then the best available. Instead of abandoning the work, however, he devised new methods and tables that, despite their greater accuracy, were much easier to use. They were published in 1881 as “Syzygien-Tafeln für den Mond nebst ausfuhrlicher Anweisung.…”

Oppolzer then organized—partly at his own expense —the immense project that resulted in the “Canon der Finsternisse.” The “Canon” contains, with minor exceptions, the relevant data of every lunar and solar eclipse, with charts of the central paths of the latter, from 1207 B.C. to A.D. 2163. Oppolzer also planned a fundamental improvement of the lunar theory. Left unfinished at his death, the expansions of the derivatives necessary for this purpose were completed under the supervision of his collaborator R. Schram, who followed Oppolzer’s ideas.

In his work in geodesy Oppolzer revealed uncommon administrative ability. He introduced technical improvements in the registration of time signals and in the use of the reversible pendulum for gravimetry. Many differences of longitude between primary stations of the European triangulation frame were determined by Oppolzer or under his supervision. He represented Austria with distinction at international conferences and soon won esteem for his profound knowledge. Apart from his admirable scientific qualities, he showed great social responsibility. Beloved for his generous liberality, he devoted his last public speech to the association for the welfare of sick students founded by his father.

BIBLIOGRAPHY

I. Original Works. Oppolzer’s works include “Entwickelung von Differentialformeln zur Verbesserung einer Planeten-oder Cometenbahn,” in Sitzungsberichte der Akademie der Wissenschaften in Wien, 49 (1864), 271-288; “Definitive Bahnbestimmung des Planeten (58) Concordia,” ibid., 57 (1868), 343-383; Lehrbuch zur Bahnbestimmung der Cometen und Planeten, 2 vol s. (Leipzig, 1870-1880; 2nd ed., rev, and enl., 1882), French trans. by Ernest Pasquier, Traité de la détermination des oṛḅites des comètes et des planètes (Paris, 1886); “Über den Venusdurchgang des Jahres 1874,” in Sitzungsberichte der Akademie der Wissenschaften in Wien, 61 (1870), 515-599; “Das Schaltbrett der österreichischen Gradmessung,” ibid., 69 (1 874), 379-398; “Entwickelung der Differentialquotienten der wahren Anomalie und des Radiusvectors nach der Excentricität in nahezu parabolischcn Bahnen,“ i n Monatsberkhte der Deutschen Akademie der Wissenschaften zu Berlin (1878), 852-859; and “Syzygicn-Tafeln für den Mond nebst ausftihrlicher Anweisung…,” in Publikatkmen der Astronomischen Gesellschaft,16 (1881).

See also “Ermittlung der Störungswerthe in den Coordinaten durch die Variation entsprechend gewählter Consianten,” in Denkschriften der Akademie der Wissenschaften46 (1882), 45-75; “Tafeln für den Planeten (58) Concordia,” ibid.,47 (1883), 149-159; ’Tafeln zur Bercchnung der Mondesfinstcrnisse,” ibid., 243-275; “Bestimmung der Schwere mit Hilfe verschiedener Apparate,” in Zeitschrift für Instrumentenkunde,4 (1884), 303-316, 379-387; “Entwurf einer Mondtheorie,” in Denkschriften der Akademie der Wissenschaften,51 (1885), 69-105; “Canon der Finsternisse,” ibid.,52 (1887), 1-376, rcpr. as Canon of Eclipses (New York, 1962), with trans, of text and pref. by Owen Gingerich and Donald H. Menzel; and “Astronoroische Refraction,” ibid., 53(1887), 1-52.

II. Secondary Literature. Robert Schram, “Nekrolog Theodor von Oppolzer,” in Vierteljahrsschrift der Astronomischen Gesellschaft,22 (1887), 177-208, contains a bibliography of Oppolzer’s work. See also Eduard Suess, “Bericht,” in Almanack der Akademie der Wissenschaften in Wien,37 (1887). 183-189, with partial bibliography.

Konradin Ferrari D’occhieppo