Heckmann was born in 1901 in Opladen the son of a notary. He studied mathematics, physics and astronomy in Bonn and was after his graduation in 1925 assistant at the Bonn Observatory. In 1927 he went to Göttingen, where he habilitated in 1929. Although one of the most talented among the younger German astronomer, stopped his scientific career after 1933, because he at the Nazi colleagues and the Reich Education Ministry (SEM) as representatives of the relativity theory ( " Jewish " ) physics and politically was considered "left" center man. Nevertheless, he was on 11 November 1933, the signatories of the commitment of the professors at German universities and colleges to Adolf Hitler and the Nazi state. He was also a member of the Nazi party to mitigate its negative political assessment by the NSD covenant. In 1935, he was an adjunct professor, and in 1939 head of the Göttingen Observatory. The appeal process at the Hamburg Observatory retired since 1938 years back; he could reach it only by distancing himself in cryptic words of the theory of relativity. Heckmann was in 1939 preferred candidate of the Hamburg Observatory, after Walter Baade had canceled. The NSD federal government tried to impose instead Heckmanns several astronomers who were tight on NS line. In January 1942 he was appointed Director of the Hamburg Observatory, of which he held until 1962.
Even if he had behaved very opportunistic against the Nazi system in Göttingen with his appointment to the observatory, he did not hesitate to defend his scientific attitude to the theory of relativity open. On November 15, 1940 Heckmann was one of a group of modern physicist (including Carl Friedrich von Weizsäcker ), the supporters of Deutsche Physik turned on the subject of relativity theory and quantum physics. Following this meeting, the supporters of Deutsche Physik in Germany were isolated.
Towards the end of the war years succeeded Heckmann, a young woman with Jewish families successfully deal at the observatory without revealing their identity.
After the end of the Nazi state Heckmann justified himself for his opportunistic concessions to the Nazi party or their academic life.
In the postwar years, he gained international recognition. In 1953 he was at the congress in Leiden German representative, where the project of European Southern Observatory was initiated and discussed. Heckmann was a driving force in building the ESO, the first Director-General, he was then from 1962 to 1969. From 1952 to 1956 he was president of the Astronomical Society, 1955-1961 Deputy and 1967-1970 President of the International Astronomical Union. In 1961 he was awarded the James Craig Watson Medal, in 1962 with the Jules Janssen Award and in 1964 with the Bruce Medal.
He died during a trip to his son in Regensburg in the family circle.
Heckmann's scientific interests and publications ranged from astrometry to cosmology.
The asteroid (1650) Heckmann is named after him.
Writings (selection )
- Theories of cosmology. Springer, Berlin, 1942, and 1968.
- Stars, cosmos, world models. Piper, Munich, 1976.