Zone catalog
As Zone catalog in which is position astronomy and Astrometrie a star catalog or a screening referred to the skies either only in certain zones declination -regions comprises or is composed of individual such zones.
Since an observatory can only optimally observe those sections of the sky that reach an elevation angle of at least 45 ° at their culmination , an exact star or nebula catalog must include observations from different geographical latitudes . The measurement results of these zones are then combined using identical objects ( reference stars in the overlaps, fundamental stars ) to form the complete catalog.
The first zone catalog was that of Caroline Herschel on the star cluster and nebula observations of her brother Wilhelm Herschel , followed by individual works by astronomers such as Bessel, Struve, etc. The Córdoba survey (observatory in Argentina), which complements the Bonn Survey of some 100,000 stars in the southern sky .
Strictly speaking, many later star atlases and catalogs such as the AGK2 and AGK3 were also created from zone data, but are only rarely given that name. As a result of astrophotography , which does not cover the starry sky by declination zones, but by means of overlapping photo plates , the use of a zone catalog is unnecessary.