Who was F'W'A' ARGELANDER

1
Who was F.W.A. ARGELANDER ?

• Bonner Durchmusterung
• First measurements of distances of stars
• Variable stars
• Head of the Astron. Gesellschaft
• Principal of the university of Bonn (1850, 1864)

2
Argelander's youth

• 22.3.1799 born in Klaipeda (Memel), near
  Königsberg
• 1807 friend of the later king of Prussia
  (Friedrich Wilhelm IV)
• 1817 start of his university education in
  Königsberg
• 1818 fascinated by lessons of Bessel, change to
  astronomy
• 1820 first own observation

3
Collaboration with F. Bessel

• 1820 assistent with Bessel
• Bessel wanted to study motion of stars (Newtons
  law of gravitation)
• 1821 working at the Königsberger Zonen
• 1822 Argelanders PhD and venia docendi
• 1823 Argelander becomes leader of the observatory
  in Abo (Turku)

4
Argelander becomes director of Bonn observatory

• 1827 fire in Abo
• 1828 Argelander was nominated to become a
  professor in Helsingfors
• 1834 letter of Argelander's mother to the king
• 1836 nomination of Argelander to Bonn
• 1837 start of Argelander's work in Bonn

5
The new observatory of Bonn
6
The Bonner Durchmusterung

• idea of a survey of all stars up to a limiting
  magnitude (gtmlim)
• simple but effective procedure
• use of a small telescope (D7.7cm f65cm)
• two observers
• start of observations in 1852
• publication of the catalogue 1863
• 324.198 stars on 48 charts
• (Argelander, Schmidt, Thormann, Schönfeld ,
  Krüger)

7
Using the Bonner Durchmusterung

• first identification of stars
• searching for comets and minor planets
• candidates of nearby stars
• statistics of the stars in the milky way

8
Argelander andthe variable stars

• variable stars important as distance indicaters
  and for the determination of stellar parameters.
• Argelander's method of measuring variable stars
  (Stufenschätzmethode)
• systematic look for existing data and prediction
  of minima!

9
Argelanders Stufenschätzmethode

• a simple and effective method for measuring the
  brightness of stars
• up to now used by amateur astronomers

10
Argelander and the measurements of the first
parallaxes
11
The Heliometer
12
Principle of the Heliometer
13
Lalande 21185
14
Argelander not only a great scientist

• Na, Argelander, was gibt es denn Neues am
  Himmel?
• Kennen Majestät denn schon das Alte?