Astrophysical Journal/Volume 4/Carl Nicolaus Adalbert Krueger

CARL NICOLAUS ADALBERT KRUEGER.

regret to record the death of Professor Dr. A. Krueger, Director of the Royal Observatory of the University of Kiel, and editor of the Astronomische Nachrichten.

Carl Nicolaus Adalbert Krueger was born in Marienburg, West Prussia, on December 3, 1832. After attending the Gymnasium of Elbing and later that of Wittenberg, he entered the University of Berlin in 1851, with the intention of studying astronomy. In the following year, however, he took up the practical work as a voluntary assistant in the Observatory at Bonn, where he was appointed second assistant in 1853. Almost simultaneously with Krueger's appearance at the Bonn Observatory, the great work of the "Bonner Durchmusterung" was initiated by Argelander. With Schönfeld as his fellow observer, Krueger entered upon his part of this important undertaking with characteristic energy. Between 1852 and the beginning of 1859 he observed with the comet-seeker 810 zones out of a total of 1841 in the northern sky. Of the 476 revision zones observed between 1854 and 1861 he is to be credited with 304.

In spite of the great demands made upon his time by the work of observation and computation involved in the preparation of the Durchmusterung, Krueger found opportunity to pursue investigations in other fields. In 1853 he undertook the study of the motions of the minor planet Themis, whose perturbations by Jupiter enabled him to determine the mass of the latter planet. He also carried on observations of variable stars. In 1858 the heliometer previously used by Winnecke came into his hands, and was most successfully employed in a series of parallax determinations. Four years later he was appointed Professor of Astronomy and Director of the Observatory in Helsingfors where he remained fourteen years, engaged in various theoretical and practical investigations. At the time of his appointment he married the eldest daughter of Argelander. The most important work of Krueger during his stay in Helsingfors, and later during the four years of his directorate at the Gotha Observatory, was the observation and reduction of the 14680 star places in the zone 55° to 65° of the great catalogue of the Astronomische Gesellschaft.

The death of Peters in 1880 left the Astronomische Nachrichten without an editor. The exacting demands of this position made the choice of his successor a matter of grave concern, and the Astronomische Gesellschaft paid a fitting tribute to Krueger's worth by placing the editorial supervision of the foremost journal of astronomy in his hands. his work as editor began in 1881, shortly after his acceptance of the Professorship of Astronomy in the University of Kiel. The forty volumes which have appeared under Krueger's direction remain to testify to his editorial ability. The improvements effected by him will stimulate his successor to further efforts, and here, as in other fields, the influence of his life will long be felt.