In 1982, the Federal Republic of Germany joined the international Agreement on the Cooperation in Astrophysical Research between Spain, Great Britain, Sweden and Denmark.

The GCT was put into operation in 1985 and was finally dismantled in 2002, in order to make room for the new 1.5m-telescope GREGOR.

Some instruments can be combined for simultaneous observations in different parts of the solar spectrum, from the near infrared to the near UV.

With the help of adaptive optics and suitable image reconstruction techniques it is now possible to observe physical properties of small-scale objects on the solar surface with sizes of only 150 km, at the theoretical limit of the telescope.

The panel on the right shows how the plasma moves: red is downward motion and blue is upward, the total range is from -1.4 km/s to +1.4 km/s.