John Louis Emil Dreyer

Johan Ludvig Emil Dreyer ( born February 13, 1852 in Copenhagen, † 14 September 1926 in Oxford) was a Danish astronomer and historian of science.

Already during his school days in Copenhagen proved Dreyer exceptional talent in mathematics, physics and history. Astronomy and history of science were the subjects in which he was to be particularly active lately. From 1874 on, he worked on the large mirror telescope of Lord Rosse at Birr Castle, where he worked intensively with misty sky objects. 1878-1882 he worked as an assistant at Dunsink Observatory, then he was appointed as Director of the Armagh Observatory.

There he fell back on results, which he himself had already won in Birr Castle, on a number of older fog catalogs ( by William Herschel and others) and on the Second Armagh Catalogue of Stars. He gave in 1888 the New General Catalogue of Nebulae and Clusters of Stars (NGC ) with 7840 entries and their supplements, the index catalogs I ( 1895) and II ( 1908) with additional 5386 objects out. Although now a number of specialist catalogs has been issued, the NGC remained until today the reference work.

From the early days of science -driven astronomy particularly the work of his compatriot Tycho Brahe interested him. Dreyer's Tycho biography (1890) is still the standard biography of this important precursor of Johannes Kepler. It was supplemented by the comprehensive edition of the complete works of Tycho in Latin. In 1906 he published The History of the Planetary System from Thales to Kepler. In 1912 he wrote the biographical introduction to The scientific papers of Sir William Herschel. For this purpose had all of whose manuscripts are examined critically, as well as his observation notes ( Dreyer partly through its own follow-up observations added ); were added to the extensive correspondence and autobiographical notes Herschel, who had asked his family.

Dreyer was until 1916 Director of the Armagh Observatory in Northern Ireland. In 1916 he received the Gold Medal of the Royal Astronomical Society. 1923/24, was Dreyer President of the Royal Astronomical Society.