Candidate planetary nebulae in the IPHAS photometric catalogue
  Context. We have carried out a semi-automated search for planetary nebulae
(PNe) in the INT Photometric H-Alpha Survey (IPHAS) catalogue. We present the
PN search and the list of selected candidates. We cross correlate the selected
candidates with a number of existing infrared galactic surveys in order to gain
further insight into the nature of the candidates. Spectroscopy of a subset of
objects is used to estimate the number of PNe present in the entire candidate
list.
  Aims. The overall aim of the IPHAS PN project is to carry out a deep census
of PNe in the northern Galactic plane, an area where PN detections are clearly
lacking.
  Methods. The PN search is carried out on the IPHAS photometric catalogues.
The candidate selection is based on the IPHAS and 2MASS/UKIDSS colours of the
objects and the final candidate selection is made visually.
  Results. From the original list of ~600 million IPHAS detections we have
selected a total of 1005 objects. Of these, 224 are known objects, leaving us
with 781 PN candidates. Based on the initial follow-up spectroscopy, we expect
the list to include very young and proto-PNe in addition to genuine, normal PNe
(~16 %) and emission line objects other than PNe. We present additional
criteria to select the most probable PN candidates from our candidate list.
