Friedrich Wilhelm Argelander

Friedrich Wilhelm August Argelander ( born March 22, 1799 Memel, † February 17, 1875 in Bonn ) was a German astronomer. He directed the construction of several observatories in Europe, studied variable stars and led by the Bonner Durchmusterung, which he summarized 325,000 stars in a star catalog. In recognition of his work for him, the asteroid ( 1551 ) Argelander and a street in the neighborhood of Poppelsdorf were named.


Education in East Prussia

Argelander was born in Memel in East Prussia. His father, the merchant Johann Gottlieb Argelander, was of Finnish descent and his mother, Wilhelmina Dorothea Grünhagen of German origin. After the battle of Jena and Auerstedt the Prussian royal family had left Berlin and stayed temporarily lived in Memel. The Crown Prince, later King Friedrich Wilhelm IV, was therefore several times in Argelanders parents' house guest and befriended with the son.

Argelander attended high school in Elbing, and from 1813 the Collegium Fridericianum in Königsberg. In 1817 he began studying at the University of Königsberg. Here he was fascinated by the astronomical lectures of Friedrich Wilhelm Bessel, the director of the observatory Königsberg. Argelander was 1820 Bessels assistant and supported him in the exact determination of star positions, so-called Sternörtern. In 1822 he received his doctorate with a critical examination of the observations of John Flamsteed. In the same year he published the journal " studies of the orbit of the Great Comet of 1811 ," which made ​​him known in professional circles throughout Europe.

Activity in Finland

In 1823 a position as Observer at the Observatory in Turku, Finland. Bessel should propose one of his former students for this purpose. Reluctantly, he suggested Argelander, as he his best employees reluctant lost, and wrote a corresponding letter of recommendation to the authorities in Saint Petersburg. The trip to Finland was also Argelanders honeymoon; on May 2, 1823, he had married Marie Sophie Charlotte Courtan. The observatory of Turku had only recently been completed and not yet fully established. It commanded at this time by a Fraunhofer constructed by Joseph telescope with 20 cm aperture width, which was used as a transit instrument and a Heliometer. In the early years the activities of the observatory consisted mainly in the observation of comets. After 1827 a meridian circle was available, examined Argelander stars with high proper motion.

On September 4, 1827 a major fire destroyed large parts of Turku, including university buildings. The University was then transferred to Helsinki today. Although the observatory was only slightly affected by the fire due to their isolated location, the Institute has also been laid. 1828 Argelander was appointed professor at the newly established University of Helsingfors. The plans for a new observatory were before 1830. Due to unfavorable ground conditions were difficulties in the creation of the foundation and the project was delayed. Argelander used the time traveled to East Prussia and recruited new employees from the ranks of Bessel's students. As of 1833, the observatory was able to resume limited their operation. Argelander led by accurate determinations of the bright circumpolar stars and determined from the movement of 390 stars, the proper motion of the solar system.

Appeal to Bonn

1836 the Prussian government decided the establishment of an astronomical institute at the University of Bonn. The site of the observatory director was offered Argelander. In 1837 he moved to Bonn and prepared the building of an observatory before. During this time he took advantage of an old fortress on the Rhine for his observations. He determined the apparent magnitudes of all of Central Europe from the visible to the naked eye stars. He dealt in depth with variable stars, and later developed the so-called Argelander step estimation method. She proved in the subsequent period and prior to the development of photography and electronic measuring instruments, as indispensable tools for the observation of variable stars and photometry. Since the construction of the observatory reluctant progressed, built Argelander near the Rhine fortress a small observatory in which he set a comet finder of Fraunhofer and 7.7 cm opening ( three Prussian inches) and 65 cm focal length. From 1841 to 1843 he determined with the help of an assistant, the position of about 22,000 stars.

The new observatory at Bonn Poppelsdorfer Allee ( as a University Institute on 1 January 2006 merged into the Argelander Institute for Astronomy ) was completed and inaugurated in 1845 in mid 1844. In the next few years, a number of comets and asteroids was observed. In 1847 he recognized the at that time the highest proper motion of a star at Groombridge 1830. Argelander began in 1849 with a new survey of the sky. He divided the sky into 200 zones led to the May 1852 23,250 observations of 17,000 stars by. Each position and brightness determination was calibrated with known stars to achieve the highest possible degree of precision.

Bonner Durchmusterung

The screening was not yet complete, as Argelander took an even bigger project in attack. Bessel had once proposed the determination of all the stars to 9th magnitude, but not carried out. Argelander decided that " large survey " carried out, with all the stars should be covered up to the 9th magnitude in the northern hemisphere up to a declination of 2 °. Until 1863 the exact measurements Argelander and his assistants Adalbert Krüger and Eduard Schönfeld 324 198 stars and made ​​of cards. The only aids in the creation of this work was a telescope of 78 mm aperture, 630 mm focal length, and nine times magnification. The resulting star catalog is called the Bonner Durchmusterung ( the telescope from the workshop of Fraunhofer is still in Bonn and can be visited ).

1863 was Argelander one of the founders of the German Astronomical Society.

He pointed to the need to determine the set out in the Bonner Durchmusterung star positions more precisely. This task, however, would have to share several observatories. A proposal was adopted in 1867 by the Astronomical Society. The Bonn observatory was assigned a 10 ° wide zone. Argelander itself took no more to the observations, but led by measurements of stellar proper motions.

Until 1874, Argelander enjoyed excellent health. In summer, however, he contracted typhoid fever one that was rampant in the area. In the fall first was an improvement, but his powers waned in the subsequent period and he died on 17 February 1875.


He was married since 2 May 1823 Marie Sophie Charlotte Courtan ( 1801-1883 ) in Königsberg. The couple had several children, including:

  • Heinrich Lorentz (1834-1908)
  • Maria Wilhelmine Amalie (1827 - after 1883) ∞ Adalbert Krüger ( 1832-1896 ), head of the observatory in Helsinki
  • Olga Maria Elisabeth (1836-1854)
  • Anna Mathilde Auguste (1838-1872) ∞ 1865 Julius Theodor Wolff ( 1827-1899 ), astronomer in Bonn and Munich


In 1863 he was awarded the Gold Medal of the Royal Astronomical Society. In 1871 he became a corresponding member of the Bavarian Academy of Sciences. He was a member of the Order Pour le Mérite for Sciences and Arts.

At his birthplace in Memel is remembered with a large plaque on Argelander. In Bonn, the outgoing of Poppelsdorfer Allee Argelanderstraße and the Argelander Institute for Astronomy are named after him.

The lunar crater Argelander was named in 1935 by the IAU for him.

The asteroid ( 1551 ) Argelander is also named after him.


  • Observationes astronomicae in specula universitatis Fennicae factae. 3 vols Helsinki ( Helsingfors ) 1830-32
  • DLX Stellarum fixarum positiones mediae ineunte anno 1830. Helsinki 1835
  • About the own motion of the solar system. Saint Petersburg 1837
  • Survey of the northern sky between 45 ° and 80 ° north declination. Bonn 1848
  • New Uranometrie. Berlin 1843
  • Screening of the sky zone between 15 ° and 31 ° south declination. In: Astronomical observations at the observatory at Bonn, 1846-1852
  • Atlas of the northern starry sky. Bonn 1857-1863: 40 cards