Hamburg Observatory
Rümker returned to Europe in 1830 and took charge of the new Hamburg Observatory after the death of Johann Georg Repsold in 1830. His chief work was concerned with the cataloging of stars: a preliminary catalogue of the stars of the Southern Hemisphere was published in 1832 at Hamburg, and from 1846 to 1852 he published his great catalogue of 12,000 stars. He served as the director of "Hamburger Sternwarte" then located at Stadtwall and funded by the city of Hamburg as Christian Karl Ludwig Rümker from 1833 to 1857.