Karl Nikolaus Adalbert Krueger (9 December 1832 – 21 April 1896) was a German

astronomer An astronomer is a scientist in the field of astronomy who focuses on a specific question or field outside the scope of Earth. Astronomers observe astronomical objects, such as stars, planets, natural satellite, moons, comets and galaxy, galax ...

. Born in Marienburg,

Prussia Prussia (; ; Old Prussian: ''Prūsija'') was a Germans, German state centred on the North European Plain that originated from the 1525 secularization of the Prussia (region), Prussian part of the State of the Teutonic Order. For centuries, ...

(now Malbork,

Poland Poland, officially the Republic of Poland, is a country in Central Europe. It extends from the Baltic Sea in the north to the Sudetes and Carpathian Mountains in the south, bordered by Lithuania and Russia to the northeast, Belarus and Ukrai ...

), he was editor of ''

Astronomische Nachrichten ''Astronomische Nachrichten'' (''Astronomical Notes''), one of the first international journals in the field of astronomy, was established in 1821 by the German astronomer Heinrich Christian Schumacher. It claims to be the oldest astronomical jour ...

''from 1881 until his death. Krueger died of a heart condition in

Kiel Kiel ( ; ) is the capital and most populous city in the northern Germany, German state of Schleswig-Holstein. With a population of around 250,000, it is Germany's largest city on the Baltic Sea. It is located on the Kieler Förde inlet of the Ba ...

at the age of 63.

Life and work

In 1851, Krueger entered the University of Berlin where he studied mathematics and science. In 1853, showing a special preference for astronomical studies, Krueger moved to the

University of Bonn The University of Bonn, officially the Rhenish Friedrich Wilhelm University of Bonn (), is a public research university in Bonn, North Rhine-Westphalia, Germany. It was founded in its present form as the () on 18 October 1818 by Frederick Willi ...

and became an assistant to the astronomer

Friedrich Wilhelm Argelander Friedrich Wilhelm August Argelander (22 March 1799 – 17 February 1875) was a German astronomer. He is known for his determinations of stellar brightnesses, positions, and distances. Life and work Argelander was born in Memel in the Kingd ...

at the Bonn Observatory. Under Argelander's supervision he produced data for the comprehensive astrometric

star catalogue A star catalogue is an astronomical catalogue that lists stars. In astronomy, many stars are referred to simply by catalogue numbers. There are a great many different star catalogues which have been produced for different purposes over the year ...

known as the

Bonner Durchmusterung In astronomy, Durchmusterung or Bonner Durchmusterung (BD) is an astrometric star catalogue of the whole sky, published by the Bonn Observatory in Germany from 1859 to 1863, with an extension published in Bonn in 1886. The name comes from ('run-t ...

, together with fellow student

Eduard Schönfeld Eduard Schönfeld (22 December 18281 May 1891) was a German astronomer. Education Schönfeld was born at Hildburghausen, in the Duchy of Saxe-Meiningen, where he had a distinguished career at the gymnasium. On leaving the gymnasium, he desired t ...

. Starting in Bonn, he undertook a lifelong study of the orbit of the minor planet

Themis In Greek mythology and religion, Themis (; ) is the goddess and personification of justice, divine order, law, and custom. She is one of the twelve Titan children of Gaia and Uranus, and the second wife of Zeus. She is associated with oracles a ...

, whose perturbations by Jupiter eventually enabled him in 1873 (while at Helsinki Observatory) to determine the mass of the latter planet. He was awarded his doctorate by the University of Bonn in August 1854 for his dissertation titled "''De ascensionibus rectis, a Flamsteedio quadrantis muralis ope observatis''". In 1858 a

heliometer A heliometer (from Greek ἥλιος ''hḗlios'' "sun" and ''measure'') is an instrument originally designed for measuring the variation of the Sun's diameter at different seasons of the year, but applied now to the modern form of the instrumen ...

previously used by Friedrich Winnecke came into his hands, and was successfully employed in a series of parallax determinations. Krueger was made ''

Privatdozent ''Privatdozent'' (for men) or ''Privatdozentin'' (for women), abbreviated PD, P.D. or Priv.-Doz., is an academic title conferred at some European universities, especially in German-speaking countries, to someone who holds certain formal qualifi ...

'' in the University in 1860. In 1862 Krueger was appointed Professor of Astronomy and Director of the Helsinki Observatory, working there for 14 years. At the time of his appointment he married Maria Wilhelmina Amalia, the eldest daughter of Friedrich Argelander. While in Helsinki, Krueger carefully determined the position of the stars of the

Double Cluster The Double Cluster, also known as Caldwell 14, consists of the open clusters NGC 869 and NGC 884 (often designated h Persei and χ (chi) Persei, respectively), which are close together in the constellation Perseus. Both visible to the ...

Perseus In Greek mythology, Perseus (, ; Greek language, Greek: Περσεύς, Romanization of Greek, translit. Perseús) is the legendary founder of the Perseid dynasty. He was, alongside Cadmus and Bellerophon, the greatest Greek hero and slayer of ...

. The large

proper motion Proper motion is the astrometric measure of changes in the apparent places of stars or other celestial objects as they move relative to the center of mass of the Solar System. It is measured relative to the distant stars or a stable referenc ...

of the star

Groombridge 34 Groombridge 34 is a binary star system in the northern constellation of Andromeda. It was listed as entry number 34 in ''A Catalogue of Circumpolar Stars'', published posthumously in 1838 by British astronomer Stephen Groombridge. Bas ...

was first detected by him. He also performed observations of

variable star A variable star is a star whose brightness as seen from Earth (its apparent magnitude) changes systematically with time. This variation may be caused by a change in emitted light or by something partly blocking the light, so variable stars are ...

s, several comets and minor planets, in addition to his theoretical work. After leaving Helsinki, Krueger directed the

Gotha Gotha () is the fifth-largest city in Thuringia, Germany, west of Erfurt and east of Eisenach with a population of 44,000. The city is the capital of the district of Gotha and was also a residence of the Ernestine Wettins from 1640 until the ...

Observatory (1876-1880), succeeding the recently deceased

Peter Andreas Hansen Peter Andreas Hansen (born 8 December 1795, Tønder, Schleswig, Denmark; died 28 March 1874, Gotha, Thuringia, Germany) was a Danish-born German astronomer. Biography The son of a goldsmith, Hansen learned the trade of a watchmaker at Flensburg, ...

. In Gotha he continued to record data for the

Astronomische Gesellschaft Katalog The ''Astronomische Gesellschaft Katalog'' (AGK) is an astrometric star catalogue of the Northern hemisphere. It was published in 3 versions from 1890 until 1975, named AGK1, AGK2 and AGK3. History Compilation for the first version, Astronomische ...

, an astrometric star catalogue. Krueger was appointed as Director of the Royal Prussian Observatory in Kiel in 1880. In 1881, with the approval of the

Astronomical Society A list of notable groups devoted to promoting astronomy research and education. International * Astronomers for Planet Earth (A4E) * Astronomers Without Borders (AWB) *International Astronomical Union (IAU) *International Meteor Organization * Ne ...

(''Astronomische Gesellschaft''), Krueger became the editor of one of the foremost astronomical journals of the day, ''

''; following the death of the former editor Christian Peters the year before. Following the death of Krueger in 1896, the editorship passed to his former assistant and son-in-law

Heinrich Kreutz Heinrich Carl Friedrich Kreutz (September 8, 1854 – July 13, 1907) was a German astronomer, most notable for his studies of the orbits of several sungrazing comets, which revealed that they were all related objects, produced when a very lar ...

References

External links

Obituaries
listed in the

Astrophysics Data System The SAO/NASA Astrophysics Data System (ADS) is a digital library portal for researchers on astronomy and physics, operated for NASA by the Smithsonian Astrophysical Observatory. ADS maintains three bibliographic collections containing over 15 ...

List of Adalbert Krueger's publications
in the Astrophysics Data System * Obituary printed in ''Astrophysical Journal'' * Obituary printed in ''Astronomical Journal'' {{DEFAULTSORT:Kruger, Adalbert 1832 births 1896 deaths Astronomers from the Kingdom of Prussia People from Malbork Scientists from the Province of Prussia 19th-century German astronomers