Optical positions for identifications from the MC2 and MC3 catalogues

Optical positions measured from the Palomar Sky Survey prints are given for objects identified with MC2 and MC3 radio sources. A comparison with other published optical positions for sources in common suggests an r.m.s. error of 0.3 seconds to 0.35 seconds arc in each coordinate. Comparison of previously published optical positions from the Sydney measuring machine with subsequent more accurate radio positions indicates an r.m.s. error of 0.28 seconds arc in each coordinate for the optical positions of stellar objects