1 Introduction

Kinematical studies of the stellar populations in the inner parts of the Milky Way have mainly used RGB and AGB stars, observed in strategically chosen low-extinction windows (Morrison et al. 1990; Menzies 1990; Minniti 1994; Izumiura et al. 1995; Sevenster et al. 1997). These stars are both bright and numerous, and their metallicity covers a large range, allowing one to study the correlations between the kinematics and the chemical abundances in the Galaxy (Lewis & Freeman 1989; Ibata & Gilmore 1995). Recently, proper motions for some K giants have become available which provide the first striking signature of the bulge triaxiality (Zhao et al. 1994).

Planetary nebulae (hereafter PNe) trace a closely related stellar population which can also be used for such studies. They originate from intermediate and low initial-mass stars and therefore constitute a relatively old population. The optical spectrum of a PN is dominated by bright emission lines [recombination (H, He, a.o.) and collisionally excited ([OIII], a.o.) lines] allowing highly accurate radial velocity determinations. The observable life time is short, typically a few times 10⁴ years. Therefore PNe are not very numerous in the Galaxy: the total population in the Galactic disk is estimated to be around 23$\,$000 with an additional 2$\,$000 in the bulge (Zijlstra & Pottasch 1991); older determinations range between 7$\,$000 and 70$\,$000 (see the compilation in Peimbert 1992) but with large dependencies on adopted distance scales. To date, about 1700 PNe are known in the Galaxy, classified in the Strasbourg-ESO Catalogue (Acker et al. 1992, hereafter SECAT) and its first supplement (Acker et al. 1996).

Although this suggests that PNe are useful tracers of Galactic kinematics, so far few papers have directly studied the kinematics of the PNe population. Schneider et al. (1983a; hereafter STPP83) made a compilation of all known PNe radial velocities at that time, correcting for systematic offsets between different sources. In a follow-up paper, Schneider & Terzian (1983b) derived a rising rotation curve in the outer Galaxy from 252 disk PNe. Kinman et al. (1988; hereafter KFL88) found evidence for bulge rotation from PNe radial velocities.

Since the compilation of STPP83, further radial velocity determinations of PNe have become available. Meatheringham et al. (1988; hereafter MWF88) presented radial and expansion velocities of 64 southern galactic planetary nebulae. In the same year KFL88 published radial velocities of 23 PNe (although with low accuracy), 15 of which were newly discovered. More recently, Kohoutek & Pauls (1995) presented well-determined radial velocities for 76 nebulae in the direction of the Galactic centre. Spyromilio (1995) gave accurate velocities for a few non-bulge PNe. Dopita & Hua (1997) measured radial velocities and fluxes of 52 southern PNe. Beaulieu (1996) made a deep and uniform narrow-band H$\alpha$imaging survey for PNe in the southern Galactic bulge; she measured radial velocities of 56 newly discovered PNe and also re-determined velocities for 317 previously known PNe. Finally, Zijlstra et al. (1997) presented high-accuracy velocities for 71 Galactic bulge PNe. There is significant overlap between these samples. Combined, there is now a larger and more accurate set of data available especially for the central regions of the Galaxy.

In this paper we present a new, up-to-date and homogeneous compilation of all PNe kinematical data known at the present time. A large number of new and previously unpublished measurements are included. The paper is presented as follows: Sect. 2 presents new radial velocities coming from our recent observations. In Sect. 3 the catalogue is presented, with a brief overview of its main characteristics. Finally, in Sect. 4, a preliminary study of the kinematics of the disk and the bulge is made.