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Guide Star Catalog

(GSC, HSTGC, Hubble Space Telescope Guide Catalog)
(catalog of stars to help aim HST)

The Guide Star Catalog (GSC or Hubble Space Telescope Guide Catalog or HSTGC) is a catalog of stars compiled to help with the use of the Hubble Space Telescope, to provide the locations of recognizable stars to be used when refining the aim at objects near these stars in the celestial sphere. To make it so-usable for accurate aiming, it favors stars over other astronomical objects, and favors non-binary stars.

GSC-I has 20 million stars of magnitudes 6 through 15, and GSC-II has nearly a billion to magnitude 21.

GSCGSC 03549-02811Guide Star Catalog 

Referenced by:
astronomical catalog
Digitized Sky Survey (DSS)
position angle