  The planetary nebula populations of relatively nearby galaxies can be easily
observed and provide both a distance estimate and a tool with which dynamical
information can be obtained. Usually the requisite radial velocities are
obtained by multi-object spectroscopy once the planetary nebulae have been
located by direct imaging. Here we report on a technique for measuring
planetary nebula kinematics using the double-beam ISIS spectrograph at the
William Herschel Telescope in a novel slitless mode, which enables the
detection and radial velocity measurements to be combined into a single step.
The results on our first target, the Sab galaxy NGC 4736, allow the velocity
dispersion of the stellar population in a disk galaxy to be traced out to four
scale lengths for the first time and are consistent with a simple isothermal
sheet model.
