The IPHAS catalogue of Hα emission-line sources in the northern Galactic plane

We present a catalogue of point-source Hα emission-line objects selected from the INT/WFC Photometric Hα Survey (IPHAS) of the northern Galactic plane. The catalogue covers the magnitude range 13 ≤r'≤ 19.5 and includes Northern hemisphere sources in the Galactic latitude range -5° < b < 5°. It is derived from ~1500 deg² worth of imaging data, which represents 80 per cent of the final IPHAS survey area. The electronic version of the catalogue will be updated once the full survey data become available. In total, the present catalogue contains 4853 point sources that exhibit strong photometric evidence for Hα emission. We have so far analysed spectra for ~300 of these sources, confirming more than 95 per cent of them as genuine emission-line stars. A wide range of stellar populations are represented in the catalogue, including early-type emission-line stars, active late-type stars, interacting binaries, young stellar objects and compact nebulae.