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last change 2005 October 17, R. Arlt

Johann Wempe

Johann Wempe was born on New Year's Eve 1906 in Bremen and originally wanted to become a school teacher. Bremen was a place for ships to go to sea which in those days needed astronomical knowledge for navigation. This apparently did the trick to attract Wempe to astronomy. In fact during his initial school years he participated in evening classes of the extramural studies, and also used the old instrument of the famous Bremen doctor and astronomer W. Olbers.

After 7 years studies of math, physics and astronomy in Goettingen, Wempe received his PhD from Goettingen in 1932 with a dissertation on the "contributions to photographic spectral photometry" working for Prof Kienle. In 1936, he became scientific assistant at Landessternwarte Heidelberg. Here he worked on eclipsing binaries (!) and asteroids (Kleinplaneten) one of which is named after him!

Because of the political climate in Heidelberg, Wempe decided in 1938 to move to Jena to join H. Siedentopf. He was fragile and not so healthy, so he did not have to go to the front (during WWII). Instead he could work on the "wavelength dependence of atmospheric extinction", the topic of his Habilitation thesis in 1944 in Jena (published in Astr. Nachrichten 275, 1, 1947). That same year 1944 he moved on to Potsdam working with his former PhD advisor Kienle who had become director of the Astrophysical Observatory Potsdam at its Telegraphenberg site. Their joint goal was a quick rebuilding of that Observatory (mainly repairing the instruments that got damaged in the war). He was appointed "Observer" in 1946, and "Lecturer" in 1947. Wempe in those days also was the head of the workers' union, perhaps the first sign of what became his will (his testament says that the money he left should be used to "improve the living conditions of the people in the observatory"). Wempe was never married. His sister helped him to get by. All his life he liked gardening (esp. sun-flowers) and music (member of the Händel society). He was a very modest man.

After the war had ended, he became a professor at Humboldt Univ. in Berlin in 1948, and in 1958 he got the chair which he held till his retirement in 1971. For 22 years, he was the editor of the journal Astronomische Nachrichten; after his retirement he became interested in the history of astronomy in Potsdam. He is said to have been a very critical and demanding teacher as well as editor. He was also known to have had a good sense of humour, despite his natural nordic reserve to people.

Two years after Prof. Grotrian's death (1954), he became director of the Astrophysical Observatory Potsdam (AOP); he also was a part-time director of the Babelsberg Sternwarte then. He likened his position to that of a "conductor of an orchestra" (quoting his own words). Under his directorship, the AOP was united with the Sonneberg Obs. to become the "institute for stellar physics" in 1967. Not much later, in 1969, the Zentralinstitut for Astrophysics was founded and Wempe became director of one of the scientific branches. It is interesting to remember that Wempe played a key role in the concept and realization of the Tautenburg 2m Schmidt mirror, which was installed in 1960. Wempe developed the idea and use of the objective prism; so, not only did he know classical astronomy (celestial mechanics etc), but also spectroscopy. Scientifically, he is probably most reknowned for his work on the "absolute calibration of the intensity distribution of an AO star", which was published in 1940 (Kienle et al.).

After he became director, he did not publish much anymore. Still he always worked late hours and cared a lot about the well-being of the employees of the observatory. He also saw to it that there would be an AOP Christmas party every year. In all his years as director, his major goal has been the the modernisation of the instrumental equipment of the AOP, to provide the younger astronomers with the best possible working conditions in astrophysics. (A good legacy indeed!)

Johann Wempe died on May 29, 1980 at the age of 73.

(compiled/translated from various obituaries by hz)

[Wempe award]

Johann Wempe