Guide Star Catalog

The Hubble Guide Star Catalog, GSC short, is a very extensive star catalog in two parts.

In the second part, the GSC -II stars with color index, location and brightness are recorded, more than 20 times as many as in the first part, the GSC -I. This catalog, which was created in 1989 primarily to align the Hubble Space Telescope was - in just one color - complete up to the 15th star size, the new but reaches up to 19 for the GSC -I had 1400 historical photographic plates digitized been, for the GSC- II still 4400 more disks that were newly added to the northern and southern hemispheres.

Almost a billion stars and galaxies are included in the eight- terabyte database. Besides Hubble also be operated many large telescopes on Earth the GSCs, and the data itself represent a treasure trove stellarstatistische


  • 998 402 801 objects
  • 455 851 432 objects whose position classification and Apparent magnitude is known
  • The first catalog (GSC 1.x) comprises 20,000,000 items


All the stars up to 20th magnitude to be recorded for the third version of the GSC ( a re- doubling of the catalog scope ) as well as their proper motions in the sky.