Carl Wilhelm Wirtz

Carl Wilhelm Wirtz (24 August 1876 in Krefeld - 18 February 1939 in Hamburg) was an astronomer who worked at observatories in Germany and at the Strasbourg Observatory. He systematically observed the redshift of nebulae, which in his time was difficult to interpret in terms of the cosmology of the time, according to which the universe would contain stars and nebulae uniformly.

He used the German term equivalent to K-correction. The term continues to be used in current cosmology, although the observational evidence for the expansion of the Wirtz universe is rarely mentioned in the literature.

It is not clear whether Wirtz realized the cosmological implications of the results of his observations.