Rotational properties of 23 SB galaxies

We have obtained major axis spectra for 23 Sb galaxies in a sample chosen to encompass a wide range of radii, masses, and luminosities. These are generally field galaxies of high inclination, and our spectrograms extend, on the average, to about three quarters of the isophotal radius, R/sub 25/. The Sb rotation curves exhibit many of the systematic trends with luminosity shown by the Sc's studied previously. Velocities in small, low-luminosity, low-mass Sb galaxies rise gently to a maximum rotational velocity in a large fraction of their isophotal radius; velocities in large, high-luminosity, high-mass Sb galaxies reach their (higher) rotational velocity in only a small fraction of their isophotal radius. However, rotational velocities span a range of higher values for Sb than for Sc galaxies.