astronomer who made a catalogue of more than 300,000 stars in the northern
hemisphere, the Bonner Durchmusterung/Bonn Survey 1859-62.
His Uranometrica nova 1843 introduced the 'estimation by steps' method
for determining stellar magnitudes with the naked eye.
Argelander was born in Memel, East Prussia (now Klaipeda in Lithuania),
and studied at Königsberg under German astronomer Friedrich Bessel.
In 1823 he went to Finland and worked as an astronomical observer in
Åbo (Turku) until the observatory was destroyed by fire 1827,
and then as professor and director of the observatory at the University
of Helsinki. In 1836 he became professor at Bonn and had a new observatory
constructed there. In Åbo, Argelander studied the proper motion
of more than 500 stars and published the most accurate catalogue of
the day on the subject.
Next, he studied the movement of the Sun through the cosmos, continuing
on and confirming work done in England by William Herschel 1783. An
extension of Bessel's study of stars in the northern sky eventually
resulted in the publication of the Bonner Durchmusterung/Bonn Survey.
This catalogued the position and brightness of nearly 324,000 stars,
and although it was the last major catalogue to be produced without
the aid of photography, its value is such that it was reprinted as recently