Comparison of the SAO and AGK3R star catalogues

The SAO star catalog positions from the GC and the AGK2 and Yale photographic catalogs are compared with the AGK3R catalog. Both catalogs are alleged to be on the system of the FK4. When the differences are considered as accidental errors, the mean errors deduced for positions from the SAO at the epoch 1958.5 range from 0.61 seconds to 0.25 seconds. The systematic differences in right ascension between SAO and AGK3R positions to the north of 60 deg declination indicate that each SAO source represents the FK4 somewhat differently than the AGK3R.