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Planetary Nebulae (PNe) are highly representative of the lastest stages of intermediate mass stellar evolution. However, there are still many unresolved questions in their evolutionary scheme. Mass loss processes during the Asymptotic Giant Branch (AGB) are not fully understood. Binarity, rotation and magnetic fields may play an important role in PNe formation. The morphological study of PNe will help us to address those questions, and therefore a rationale and homogeneous data base is needed. Searching in the literature we have not found a homogeneous catalogue of northern PNe. There are some incomplete works of a few dozen PNe (Balick 1987; Chu et al 1987), and also an incomplete catalogue of southern PNe (Schwarz et al. 1992).
We aim at filling the gap, carring out a complete Catalogue of extended northern PN. This catalogue will have the following characteristics: \\ \hspace*{0.3cm} (a) It will be homogeneous (all the images are being obtained with the same telescope and instrument), and complete for all the PNe with $-$10$^{\circ} < \delta < +80^{\circ}$ and with diameters larger than {12\arcsec}, because stellar PNe cannot be used for this kind of study. \\ \hspace*{0.3cm} (b) In order to obtain a sharp image of the different ionized regions, images are obtained through narrow band filters: H$\alpha$+[N~{\sc ii}] (FWHM=100 {\AA}) and [O~{\sc iii}] $\lambda$ 5007 \AA (FWHM=30 {\AA}). \\ \hspace*{0.3cm} (c) It will exclude all the objects with doubtful classifications, as well as the PNe included in Balick (1987) and Schwarz et al. (1992).
Since the summer 1993, 120 PNe have been observed at the 0.8 m IAC-80 telescope, at the Observatorio del Teide (Tenerife). The spatial scale on the detector, a 1024$\times$1024 Thomson CCD, is {0{\farcs}435}, the field of view being {7{\farcm}4}. It lacks 30 PNe more to finish the sample which is expected to be finished after the summer 1995, and will published as a book by the IAC. As a glimpse of the future catalogue, we present composite real color images of some PNe, produced by combining the H$\alpha$ + [N~{\sc ii}] with red, and the [O~{\sc iii}] with green.
