Hartwig, (Carl) Ernst (Albrecht)

(b. Frankfurt am Main, Germany, 14 January 1851; d. Bamberg, Germany, 3 May 1923)

astronomy.

After graduating from the renowned Melanchthon Gymnasium in Nuremberg, Hartwig studied mathematics, physics, and astronomy at the universities of Erlangen, Leipzig, Göttingen, and Munich. In 1874 he became assistant astronomer at the observatory of the University of Strasbourg, where he obtained the Ph.D. degree in 1880. Soon afterward he was sent officially to study modern observatories in Austria, Russia, Finland, Sweden, and Denmark. In 1882-1883 Hartwig was the leader of the German astronomical expedition for observing the transit of Venus at Bahia Blanca, Argentina.

Hartwig spent the next two years as associate astronomer and lecturer at the University of Dorpat (now Tartu, Estonia). In 1886, because of his great experience in practical astronomy, he was charged with the directorship of the observatory at Bamberg, which was erected, under his supervision, with funds from the will of Carl Remeis, an enthusiastic amateur astronomer. Hartwig spent the rest of his life at the observatory in scientific contact with the astrophysical observatory in Potsdam and the nearby University of Erlangen. The latter conferred on him the title of honorary professor (1916) and the degree of D.D. honoris causa (1921). He married Nanette Müller in 1889.

Hartwig’s work was devoted to two main branches of research: the measurement of stars and planets and the observation of variable stars. In his astrometric observations he preferred the heliometer, an instrument specially designed to measure small spherical distances with the highest precision attainable at that time. Hartwig was familiar with the heliometer from Strasbourg and Dorpat, and he had such an instrument, one of the largest ever constructed, at his disposal at Bamberg. He performed a most valuable series of measurements of the diameters of planets and of the physical libration of the moon. He also measured the positions and parallaxes of stars and, occasionally, the positions of planets and comets, two of which he discovered.

Equally valuable are Hartwig’s contributions in the field of variable stars, which he observed according to Argelander’s method and also, from 1913 to 1923, photographically. In 1885 he independently discovered S Andromedae, the first known extragalactic supernova. He made many series of observations of long-period variables and of U-Geminorum stars. From 1891 he published an annual catalog of variable stars with approximate ephemerides for the Astronomische Gesellschaft, and, in collaboration with Gustav Müller of Potsdam, he compiled the fundamental work Geschichte und Literatur der veränderlichen Sterne (Leipzig, 1918).

BIBLIOGRAPHY

I. Original Works. Hartwig’s books are Heliometriche Untersuchungen der Durchmesser von Venus und Mars, vol. XV of Publikationen der Astronomischen Gesellschaft (Leipzig, 1879); Beitrag zur Bestimmung der physischen Libration des Mondes aus Heliometerbeobachtungen (Karlsruhe, 1881); Die Physik im Dienste der Wissenschaft, der Kunst und des praktischen Lebens (Stuttgart, 1884), written with G. Krebs et al.; and Geschichte und Literatur des Lichtwechsels der bis Ende 1915 als sicher veränderlich anerkannten Sterne (Leipzig, 1918), written with G. Müller.

Among Hartwig’s papers are “Physical Libration of the Moon,” in Monthly Notices of the Royal Astronomical Society, 41 (1881), 375; and “Katalog und Ephemeriden veränderlicher Sterne,” in Vierteljahresschrift der Astronomischen Gesellschaft, 26-55 (1891-1920). A great number of his other papers and short notes, concerned with variable stars, the moon, and planets, were published in Vierteljahresschrift der Astronomischen Gesellschaft, 13-22 (1878-1887); Astronomische Nachrichten, 95-217 (1879-1923); Berichte der Naturforschenden Gesellschaft in Bamberg, 16-21 (1893-1910); and Veröffentlichungen der Remeis-Stern warte zu Bamberg, 1st ser. (1910-1923); 2nd ser., 1 (1923).

Moreover, there are a great number of unpublished notes on observations of comets, lunar occultations, eclipses, variable stars, and novae, preserved at the Remeis-Sternwarte.

II. Secondary Literature. For information on Hartwig, see Cuno Hoffmeister, “Ernst Hartwig,” in Vierteljahresschrift der Astronomischen Gesellschaft, 59 (1924), 70; E. Heise, “Ernst Hartwig,” in Deutsches biographisches Jahrbuch (1923); and in Astronomische Nachrichten, 219 (1923), 185.

Konradin Ferrari d’Occhieppo