Delporte, Eugène Joseph

(b. Genappe, Belgium, 10 January 1882; d. Uccle, Belgium, 19 October 1955)

astronomy.

Delporte graduated from Brussels University and obtained the doctorate in physics and mathematics with high honors in 1903, at the age of twenty-one. He immediately joined the Royal Observatory of Belgium in Uccle as a volunteer assistant. In 1904 he became assistant, in 1909 associate astronomer, and in 1923 astronomer. He was appointed to the directorship of the observatory in 1936 and retired from official duty in 1947.

From 1903 to 1919 Delporte was attached to the department of meridian astronomy. He made thousands of transit observations of reference stars, among them 3,533 stars for the zones + 21° and + 22° of the Carte du ciel, and conducted careful investigations of the errors of the divisions of the meridian circle. He determined the difference of longitude between the observatories of Paris and Uccle in 1910 and in 1920, and he supervised the installation of the time service at the observatory.

In 1919 Delporte transferred to the department of equatorials and dedicated himself to systematic observations of comets and asteroids. These observations were first performed visually with the thirty-eightcentimeter Cooke refractor; but about 1925, when first the thirty-centimeter-aperture Zeiss astrograph and then the double Zeiss astrograph with forty-centimeter-aperture objectives were installed, a definite investigation of these bodies was organized. The first discovery was the planet Belgica. It was followed by many more discoveries, including Amor and Adonis, which approach nearest to the earth. Delporte’s name is also linked with the independent discovery of the comet Dutoit-Neujmin-Delporte. New techniques for accurate determination of position were investigated; and the precise positions were sent regularly to the Astronomisches Rechen-Institut at Heidelberg, where they were used in the determinations of orbits.

In 1930 Delporte edited two volumes for the International Astronomical Union entitled Scientific Delimitation of Constellations, with text, maps, and celestial atlas. These volumes fixed the limits of constellations for the entire sky.

Delporte was actively interested in expanding the work of the observatory. The institution was provided with a reflecting telescope one meter in aperture (this was recently enlarged to 1.20 meters and provided with a Schmidt combination), the double astrograph with a forty-centimeter aperture (already mentioned), and an Askania meridian circle with a nineteen-centimeter aperture. He was also responsible for providing the Cooke visual refractor, which had an aperture of thirty-eight centimeters, with a Zeiss objective forty-five centimeters in diameter.

Delporte was an enthusiastic observer, and he inspired many younger astronomers who are continuing his work. After his official retirement he continued to examine plates of asteroids at the observatory, and it was while pursuing this task that he died suddenly.

Delporte received prizes of the Royal Academy of Sciences of Belgium and was a member of the National Committee on Astronomy from its founding in 1919, its vice-chairman in 1930, and its chairman from 1949 until his death. In addition, he was president of the Commission on the Observation of Planets, Comets and Satellites and Ephemerides of the Internation Astronomical Union, corresponding member of the Bureau des Longitudes in Paris, corresponding member of the Academy of Sciences in Paris, and an associate member of the Royal Astronomical Society. He was secretary-editor of the journal Ciel et terre of the Belgian Astronomical Society.

BIBLIOGRAPHY

The following major articles appeared in Annales de l’observatoire de Belgique: “Observations méridiennes faites au cercle méridien de Repsold,” 2nd ser., 10–12 (1907–1910); “Différence de longitude entre Paris et Uccle,” ibid., 14 (1913); “Catalogue de 3533 étoiles de repère de la zone + 21°. + 22°,” 2nd ser., 13 (1914); with H. Philippot, “Étude de la division du cercle méridien de Repsold,” ibid., 14 (1918); “Forme des tourillons du cercle méridien de Repsold,” 3rd ser., 1 (1921); with Philippot, “Positions moyennes pour 1914 d’étoiles de comparaison de la comète 1913 f (Delavan),” ibid., 1 (1922).

See also “Observations de la lune et de planètes en 1906 et 1907, et comparaison avec la Connaissance des temps et le Nautical Almanach,” in Astronomische Nachrichten, 178 (1908); “Observations du soleil, de la lune et de planètes en 1908, et comparaison avec la Connaissance des temps et le Nautical Almanach,” ibid., 181 (1909); “Observations photographiques de petites planètes avec l’astrographe Zeiss de l’Observatoire d’Uccle,” in Journal des observateurs, 7 (1924); “Petites planetes découvertes à l’Observatoire royale de Belgique,” in Bulletin de la classe des sciences de l’Académie royale de Belgique (1926).

H. L. Vanderlinden