Guide Star Catalog
The Hubble Guide Star Catalog , GSC for short , is an extremely comprehensive star catalog in two parts.
In the second part, the GSC-II, stars are recorded with their color index , location and brightness , 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 magnitude , but the new one extends up to 19. 1400 historical photo plates were digitized for the GSC-I for the GSC-II there were 4400 more plates that had been newly recorded in the northern and southern hemispheres.
Almost a billion stars and galaxies are contained in the eight terabyte database. In addition to Hubble, many large telescopes on earth also use the GSCs, and the data itself is a treasure trove of stellar statistics.
numbers
- 998,402,801 objects
- 455,851,432 objects whose position, classification and apparent brightness are known
- the first catalog (GSC 1.x) contains 20,000,000 objects
future
All stars up to the 20th magnitude are to be recorded for the third version of the GSC (a further doubling of the catalog size) as well as their own movements in the sky.