In the meantime, Professor Krueger had been called to Kiel to become the director of the Kiel Observatory. Besides this position, Krueger took over the position of the editor of the Astronomische Nachrichten. In 1883, Dr. Kreutz followed him to Kiel to work with Krueger, and accepted the position of a computer at that observatory, first an extarordinary clerk job, and in 1889 a regular appointment as second observer at the Observatory. From the beginning, Kreutz was involved in the editorial work of the A.N. also. In October, 1888 he obtained a degree as assistant professor, and in 1891 was appointed as associate professor of astronomy at the University of Kiel. About that time, he married Krueger's daughter.
When Krueger died in 1896, Kreutz succeeded him in the editorship of the Astronomische Nachrichten, a position he held for the rest of his life. He undertook the laborious durties of this position with great care, and succeeded in maintaining the high standard of this leading astronomical journal of the world at that time.
Kreutz was particularly interested in the orbits of comets, and carried out extensive computational work in this field. His most important investigation was that of the orbits of the sungrazing comets 1843 I, 1861 II, 1880 I, and 1882 II; he brought up evidence that these were probably members of a certain group of comets, now called the Kreutz group.
Heinrich Kreutz passed away on July 13, 1907 in Kiel after a long illness at age 52.
Besides the Kreutz group comets 1668 (C/1668 E1), 1695 (C/1695 U1), 1843 I, 1861 II, 1880 I, 1882 II, 1887 I and the presumable Kreutz group members X/1106 C1 and X/1702 D1, his investigations include orbital calculations for comet 1771 Messier (C/1771 G1).
Moreover, Kreutz published numerous papers, mainly in the Astronomische Nachrichten, the Vierteljahresschrift (Quarterly Journal) of the Astronomische Gesellschaft, and the Publications of the Kiel Observatory, including minor calculations as well as many contributions on cometary orbits.
As responsible editor of the Astronomische Nachrichten from volume 140 to 175, he was maintaining the most influential astronomical journal of these days. To face the increase of the number of papers, he founded the "Ergänzungshefte" or "Astronomische Abhandlungen" in 1901, to provide a platform for more comprehensive treatises; 13 issues were published until his death in 1907. He also chaired the headquarters for astronomical telegrams.
His most important work is "Untersuchungen über das System der Cometen 1843I, 1880I and 1882II.", published in 3 parts, all in German, the first two in "Publicationen III and IV" of the Kiel Observatory, the third in the first volume of his new "Astronomische Abhandlungen," or "Ergaenzungshefte Astr. Nachr.", Vol. 1 (1901) p 1-90.
Some information on Kreutz' life can be found in the obituaries, e.g.: