Brown dwarfs in the Pleiades and the initial mass function across the stellar/substellar boundary

We present a new sample of brown dwarf (BD) candidates from a survey covering 6 degrees x 6 degrees centred on the Pleiades. The survey was constructed using I- and R-band photographic plates, from the United Kingdom Schmidt Telescope, measured using the new high-precision microdensitometer SuperCOSMOS at the Royal Observatory, Edinburgh. Objects as faint as or up to similar to 0.5 mag fainter than the Pleiades lithium boundary are selected on the basis of having extremely red photographic colours and proper motions consistent with cluster membership; follow-up near-infrared and infrared photoelectric photometry yields nine candidate ED Pleiads. Coordinates, magnitudes and finders are presented for these objects. We use these data and information on higher mass stars to construct a mass function having an increasingly shallow gradient towards and across the stellar/substellar boundary; a few of the candidates are found at distances of more than 2 degrees from the nominal cluster centre. We discuss the implications of these results for future surveys.