Rotation velocities of 16 SA galaxies and a comparison of Sa, Sb, and SC rotation properties

Rotational velocities over most of the optical extent of 54 Sa, Sb, and Sc galaxies have been determined. The Sa curves exhibit a similar progression with luminosity as do the Sb and Sc galaxies, and the forms of the rotation curves exhibited by Sa's are markedly similar to those found previously for Sb and Sc galaxies. The overall similarity of forms of rotation curves for spirals of very different morphologies, coupled with the derived values for the dynamical mass-to-luminosity ratios, implies that both the dark halo mass and the disk mass contribute to the total mass distribution at all radii within the optical galaxy. While the approximately four mag range is similar within each Hubble type, the values of V(max) increase with earlier Hubble type. Absolute blue magnitude and absolute infrared magnitude are correlated for all Hubble types. The luminosity-log V(max) correlation has a slope 10 + or - 2 for each Hubble type, but with zero points displaced for each type.