  The CORNISH project is the highest resolution radio continuum survey of the
Galactic plane to date. It is the 5 GHz radio continuum part of a series of
multi-wavelength surveys that focus on the northern GLIMPSE region (10 deg < l
< 65 deg), observed by the Spitzer satellite in the mid-infrared. Observations
with the Very Large Array in B and BnA configurations have yielded a 1.5"
resolution Stokes I map with a root-mean-squared noise level better than 0.4
mJy/beam. Here we describe the data-processing methods and data
characteristics, and present a new, uniform catalogue of compact
radio-emission. This includes an implementation of automatic deconvolution that
provides much more reliable imaging than standard CLEANing. A rigorous
investigation of the noise characteristics and reliability of source detection
has been carried out. We show that the survey is optimised to detect emission
on size scales up to 14" and for unresolved sources the catalogue is more than
90 percent complete at a flux density of 3.9 mJy. We have detected 3,062
sources above a 7-sigma detection limit and present their ensemble properties.
The catalogue is highly reliable away from regions containing poorly-sampled
extended emission, which comprise less than two percent of the survey area.
Imaging problems have been mitigated by down-weighting the shortest spacings
and potential artefacts flagged via a rigorous manual inspection with reference
to the Spitzer infrared data. We present images of the most common source types
found: regions, planetary nebulae and radio-galaxies. The CORNISH data and
catalogue are available online at http://cornish.leeds.ac.uk
