Astronomische Gesellschaft Katalog

The AGK2 is an accurate star catalog of about 200,000 fixed stars, on the initiative of the Astronomical Society was established in the 1930s as a cooperative project of several observatories.

The Astronomical Society ( AG) as one of the oldest scientific associations in Europe was founded in 1800. Around 1860, she initiated the main star catalog this time, lent their name to AGK. It was expanded in 1929 to AGK2 - with newer data astrometry and precise account of the proper motions. This AGK2 is to this day (along with the newer version AGK3 ) a significant data base for astronomy, celestial mechanics and orbit determination.

Astrometric methodology

The measurement was made of the star positions of AKG2

  • In cooperation of three observatories, including those in Hamburg- Bergedorf
  • With unified instrument - "AG- astrographs " specially developed ( three astro cameras with about 2 m focal length ) and the AG - comparator for evaluation of thousands of photographic plates
  • On the basis of an improved system of astronomical fundamental constants were measured using modern semi-automated meridian circles

The resulting therefrom in about 10 years of work AGK2 includes over 200,000 stars (down to 9 to 10 size) and with position accuracies better than 1 ". Until the 1980s it was an important base for the astrometry and evaluations in the context of satellite geodesy - and was against 1960, the "father " of the SAO catalog with 250,000 stars.

International Cooperation

A monograph of the Hamburg Observatory describes the evolution in more detail. At the Potsdam Meeting of the Astronomical Society in 1921 Richard Schorr and other astronomers presented the request to repeat the observations 50 years after the first star catalog AGK. The 1869 adopted catalog of the Astronomical Society had become a standard work for the sky survey. 12 observatories in various countries from 1868 to 1908 had involved and surveyed more than 100,000 star positions. They were published as 15bändiges work in the "Catalogue of the Astronomical Society, 1st Division ".

The Neubeobachtung from 1921 and the extension to more than 200,000 stars was in the " zone companies of the Astronomical Society ". The new item catalog was especially important because the position of the Earth's axis in space continuously changed by small increments ( precession ) and because the positions of stars within the Milky Way long-term shift ( proper motions ).

The new star catalog was adopted as a joint project of the Observatories Hamburg, Bonn and Pulkovo. New in the work was the recording and measurement technology: photo plates on special wide- angle cameras ( astrographs ), which were then measured at very precise measuring machines in the laboratory.

  • Astronomical data collection
  • Star catalog
  • Abbreviation