Galactic planetary nebulae and their central stars I. An accurate and homogeneous set of coordinates

We have used the 2nd generation of the Guide Star Catalogue (GSC-II) as a reference astrometric catalogue to compile the positions of 1086 Galactic Planetary Nebulae (PNe) listed in the Strasbourg ESO Catalogue (SEC), its supplement and the version 2000 of the Catalogue of Planetary Nebulae. This constitutes about 75% of all known PNe. For these PNe, the ones with a known central star (CS) or with a small diameter, we have derived coordinates with an absolute accuracy of ≈0″.35 in each coordinate, which is the intrinsic astrometric precision of the GSC-II. For another 226, mostly extended, objects without a GSC-II counterpart we give coordinates based on the second epoch Digital Sky Survey (DSS-II). While these coordinates may have systematic offsets relative to the GSC-II of up to 5 arcsecs, our new coordinates usually represent a significant improvement over the previous catalogue values for these large objects. This is the first truly homogeneous compilation of PNe positions over the whole sky and the most accurate one available so far.