Bonner Durchmusterung

In astronomy, Durchmusterung or Bonner Durchmusterung (BD) is an astrometric star catalogue of the whole sky, published by the Bonn Observatory in Germany from 1859 to 1863, with an extension published in Bonn in 1886. The name comes from Durchmusterung ('run-through examination'), a German word used for a systematic survey of objects or data. The term has sometimes been used for other astronomical surveys, including not only stars, but also the search for other celestial objects. Special tasks include celestial scanning in electromagnetic wavelengths shorter or longer than visible light waves. The Bonner Durchmusterung (abbreviated BD), was initiated by Friedrich Argelander and using observations largely carried out by his assistants, which resulted in a catalogue of the positions and apparent magnitudes of 342,198 stars down to approximate apparent magnitude 9.5 and covering the sky from 90°N to 2°S declination. The catalogue, published in three parts, was accompanied by charts plotting the positions of the stars, and was the basis for the Astronomische Gesellschaft Katalog (AGK) and Smithsonian Astrophysical Observatory Star Catalog (SAO) catalogues of the 20th century. In 1886 Eduard Schönfeld, also in Bonn, published an extension from 2°S to 23°S declination. (A further extension from an observatory in Cordoba Argentina was published in five parts between 1892 and 1932 to cover the southern sky from 22°S to 90°S declination.) BD star numbers are still used and allow the correlation of the work with modern projects. The format of a BD number is exemplified by "BD−16 1591", which is the BD number of Sirius. This number signifies that in the catalog, Sirius is the 1591st star listed in the declination zone between −16 and −17 degrees, counting from 0 hours right ascension. Stellar positions and zone boundaries use an equinox for the epoch of B1855.0. Many astronomical research projects—from studies of celestial mechanics and the Solar System, up to the nascent field of astrophysics—were made possible by the publication of the atlas and data of the Bonner Durchmusterung.