An imaging A-band survey-1. The catalogue, star and galaxy counts

We present results from a large area (552 arcmin2) imaging K-band survey of faint objects. The survey is a high galactic latitude blank-field sample to a 5? limit of K ? 17.3. The methods for constructing the infrared survey are described, including flatfielding, astrometry, mosaicing and photometry. Also described are optical CCD observations which cover the survey to provide optical-infrared colours of almost all the objects in the sample. Star-galaxy discrimination is performed and the results used to derive the infrared star and galaxy counts. K-band 'no-evolution' galaxy-count models are constructed and compared with the observed data. In the infrared, there is no counterpart for the large excess of faint galaxies over the no-evolution model seen in optical counts. In contrast, the K counts require little or no evolution in the luminosity or space density of galaxies, although it is shown that the count predictions can be remarkably insensitive to evolution under certain reasonable assumptions. Finally, model predictions for K-selected redshift surveys are derived.