Southern Reference Stars (SRS)

Southern Reference Stars (SRS) is a list of 20,488 stars in the southern hemisphere intended to supplement the AGK3R in the north, to extend coverage of reference stars across the whole sky for calibrating photographic surveys. Observations of stars, mostly of magnitudes 7.5 to 9.5, were made at a dozen observatories between 1961 and 1973, and coordinated at the U.S. Naval Observatory and Pulkovo Observatory.