Optical rotation velocities and images of the spiral galaxy NGC 3198

H-alpha rotation velocities obtained from an echelle spectrogram to a radius of 2 arcmin for the spiral galaxy NGC 3198 agree well with the 21 cm rotation velocities of van Albada et al. (1985). The rotation curve is typical of Sc type galaxies in spite of NGC 3198's extended H I disk. From optical R and H-alpha-emission images, used to search for star-forming regions in the outer parts of this galaxy, several H-alpha knots are identified as far out as the Holmberg radius. With increasing radial distance out to 2 arcmin, the R-band surface brightness falls, the H-alpha is approximately constant, and the H I surface brightness rises.