Since the catalogue by Perek and Kohoutek (PK) has been printed in 1967, numerous observations and theoretical studies have been made, and new planetary nebulae (NP) have been discovered, in addition to the 1036 PN indexed by PK. We have compiled a bibliographic index from 1965, covering about 80 papers per year; a catalogue of 1455 PN and a bibliographic index have been established (Acker, Marcout, Ochsenbein, 1981).
Now, two important catalogues are being compiled which result from the joint work of the Observatories of Strasbourg, Bordeaux, Marseille, the Laboratory of Astronomy of Montpellier, and the Observatory of Haute Provence.