To overcome the obstacles to observing extragalactic PN kinematics, our team commissioned a special-purpose instrument, the Planetary Nebula Spectrograph (PN.S) at the WHT (Douglas et al. 2002 and this volume). Using a slitless spectroscopy technique termed counter-dispersed imaging, the efficiency of the PN.S has resulted in a breakthrough in this field: hundreds of PN velocities can be obtained in a single night's observing of a galaxy at a distance of 15 Mpc.
The primary program of the PN.S is to survey a dozen bright (mB ≤ 12), round (E0–E2), nearby (D ≲ 20 Mpc) ellipticals, obtaining 100–400 PN velocities in each. Based on the statistical distribution of galaxy shapes (Lambas et al. 1992), we estimate that by selecting for projected axis ratios q ≳ 0.8, 75% of our sample will have intrinsic gravitational potential ellipticities єΦ ≲ 0.1 and thus can be well characterized by spherical dynamical models. Other than the constraints above, our sample is designed to encompass a broad spectrum of elliptical galaxies, with a large range of stellar light parameters (luminosity, concentration, shape), rotational importance, and environment.
Our program has so far been beset by bad weather, but we have obtained extensive data on the galaxies NGC 821, NGC 3379, and NGC 4494. For each we have an initial data set of ∼ 100 PN velocities out to ∼ 5 Reff, but with additional data reduction we expect these to increase to ∼ 200 each.