The Catalogs and Surveys Branch of the Space Telescope Science Institute has digitized the photographic Sky Survey plates from the Palomar and UK Schmidt telescopes to produce the "Digitized Sky Survey". These images were then processed and calibrated to produce the Guide Star Catalogs in support of HST operations.
The Guide Star Catalog I (GSC-I)
The Guide Star Catalog II (GSC-II)
The Guide Star Photometric Catalog I (GSPC-I)
The Guide Star Photometric Catalog II (GSPC-II)
These catalogs support ground and space-based telescope operations and provide a valuable scientific resource to the astronomical community.