F.W.A. Argelander

The Positions and Brightness of the Stars

F.W.A. Argelander Portrait

F.W.A. Argelander (1799-1875), Astronomer

Friedrich Wilhelm August Argelander was born at the 22nd of March 1799 in Memel (Klaipeda). At this time the town related to Prussia and the largest Prussian neighbortown was Königsberg (Kaliningrad), where in 1817 Argelander started an education in court yard sciences.

1810 in Königsberg Friedrich Wilhelm Bessel (1784-1846) had become director of the observatory and professor of astronomy at the university. Argelander was filled for enthusiasm for astronomy by Bessel, became student of Bessel and 1820 assistant at the Königsberg observatory. He made his Ph.D. in 1822 with a critical review of the observations by John Flamsteed (1646-1719), who had published an uncorrected and not levelled summary of his celestial observations from 1676 to 1705 in 1712. This was the base for a posthum published, famous star catalog of 1725, extended in 1728, about 2848 exact fix star positions. This was one of the first star maps after the invention of the telescope. Flamsteed also had introduced a new system for numbering the stars within their constellations, which is in use today, still. - The next larger star catalog was made by Johann Elert Bode (1747-1826) in 1801 named "Uranographia, sive astrorum descriptio", including ca. 17000 stars.

Bessel mediated Argelander 1823 a job as an observator at the university observatory of Turku (Åbo) in Finnland. Argelander became director of the observatory and 1828 he also became professor for astronomy at the university of Åbo. Four years later the university was moved to Helsinki (Helsingfors) because of a fire which destroyed most of the buildings of the Åbo university. Argelander followed the university to Helsinki. Already in Åbo he had worked on the motion of the stars, where he wrote down the results in 1837 in the book "About the Proper Motion of the Solar System".

From 1836/7 he began with the first plans on an observatory in Bonn, which should be financed by Friedrich Wilhelm IV. (1795-1861), who became king in 1840 and who arranged a Cologne Dome Festivity in 1842 and a Millennium Celebration of the German Reich in 1843, marking his nationalistic intends. But the Bonn observatory had to wait and was ready in the middle of 1844 and inaugurated in 1845.

While the construction time in 1843 Argelander published a catalog of the fixstars visible by the naked eye, where he created a unique method for estimating the brightness of the stars in relation to one another. He called the catalog "Uranometria nova", maybe in memoriam of the star atlas "Uranometria" by Johannes Bayer (1572-1625) from 1603. The method for the estimation of the brightness of stars is also called "Argelander stepwise estimation method"(?). This estimation method he also used at a collection of 22 known variable stars published in 1850.

For the determination of the proper motion of the solar system related to the surrounding universe Argelander came to the conclusion that he had not enough data for the exact answer to the question, around what center the Sun and the other stars move, if there would be any center. Therefore he worked on the exact determination of the positions of the stars at the Northern sky from 1852 on in Bonn.

At the WFS:

Titlepage of the Atlas of the Northern Starry Sky of 1899, Polaroid

Within eleven years he measured the position and brightness of 324,198 stars between +90° and -2° declination with his assistants Eduard Schönfeld (1828-1891) and Aldalbert Krüger (1832-1896) at least twice and collected this in an index numbered by declination. So the Northstar Polaris, named alpha Ursa Minoris according to the catalog of Bayer and 1 Ursa Minor according to the catalog of Flamsteed, has the index number 88°8 in the catalog by Argelander. Nowadays (epoch 2000) Polaris has the declination 89°16' and the rectascension 2h31.5m, but at the time of Argelander (epoch 1800) Polaris was to find at 88°15' declination and 0h52.5m rectascension, and therefore Polaris is sorted under the declination of 88 degrees.

This 1863 first published catalog became famous as the "Bonner Durchmusterung" (Bonn Survey, abbrevated BD). In the same year Argelander became founder of the Astronomical Society together with Wilhelm Foerster (1832-1921) and others. Within this society of European astronomer the international zone effort was started. The goal of this effort was the complete survey of the celestial sky. The society published independently a catalog of stars between 80° and -23° declination at 1887, containing ca. 200,000 stars, known as Astronomische Gesellschaft Katalog (AGK). Until 1868 a second edition of the Bonn survey was published.

Argelander died with nearly 76 years February the 17th 1875. His assistant Eduard Schönfeld extended the catalog by 133.659 stars of the zone from -2° to -22° declination until 1886. In this the Bonn catalog added survey also the brightest fixstar of the nightsky, Sirius aka Alpha Canis Majoris aka 1 Canis Major is included as -16°1591.

Under the direction of J.M. Thome (1843-1908) from 1892 on the southern sky was mapped at the observatory of Cordoba (Argentina). Thome didn't see the completion of this souther sky atlas anymore. It was not done until 1914, when 578,802 stars from declination -22° to -90° were collected as the "Cordoba Durchmusterung" (CD). Together with the Bonner Durchmusterung it built a systematical catalog of more than one million stars up to tenth magnitude, made before the age of the photographic surveys.

Sources:
Joachim Herrmann (Ed.): Das große Lexikon der Astronomie, Orbis Verlag 1996
Jacqueline Mitton: Penguin Dictionary of Astronomy - in Redshift 2, Maris Multimedia 1995
Fritz Krafft, Adolf Meyer-Abich (Ed.): Große Naturwissenschaftler - Biographisches Lexikon, Fischer Handbuch 1970
Hans F. Müller, Bertelsmann Lexikon Institut (Ed.): Das moderne Lexikon, Bertelsmann Lexikon-Verlag 1970


Page history:
created 1998-12-03 F.W.A. Argelander
modified 1998-12-08 to Argelander.html
modified 1998-12-10 translated
modified 1998-12-13 final translations
modified 1998-12-16 atlas image
modified 2000-02-08 small changes

To the Sky over Berlin...To the astronomy links...-- jd --