Key points are not available for this paper at this time.
This paper presents data and finding charts for the Guide Star Photometric Catalog (GSPC), which is an all-sky set of 1477 pohotoelectrically determined BV sequences covering the magnitude range from 9 to 15. The GSPC was created to provide photometric calibrators for the Guide Star Catalog, which is a catalog of approximately 2 x 10 to the 7th objects needed to support the pointing of the Hubble Space Telescope. For declinations greater than +3 deg, the sequences generally lie near the centers of the original (Palomar Observatory-National Geographic Society) Sky Atlas, while for smaller declinations they lie near the centers for the ESO/SERC Southern Sky Atlas. The sequences nominally contain (at least) six stars, each with a photometric precision of 0.05 mag. In practice, a small number of sequences contains fewer stars, and the precisions achieved for the faintest stars are more nearly 0.1 mag.
Lasker et al. (Thu,) studied this question.