An ALMA survey of the SCUBA-2 Cosmology Legacy Survey UKIDSS/UDS field:
  Source catalogue and properties
  We present the catalogue and properties of sources in AS2UDS, an 870-$\mu$m
continuum survey with the Atacama Large Millimetre/sub-millimetre Array (ALMA)
of 716 single-dish sub-millimetre sources detected in the UKIDSS/UDS field by
the SCUBA-2 Cosmology Legacy Survey. In our sensitive ALMA follow-up
observations we detect 708 sub-millimetre galaxies (SMGs) at $>$\,4.3$\sigma$
significance across the $\sim$\,1-degree diameter field. We combine our precise
ALMA positions with the extensive multi-wavelength coverage in the UDS field to
fit the spectral energy distributions of our SMGs to derive a median redshift
of $z_{\rm phot}=$\,2.61$\pm$0.09. This large sample reveals a statistically
significant trend of increasing sub-millimetre flux with redshift suggestive of
galaxy downsizing. 101 ALMA maps do not show a $>$\,4.3$\sigma$ SMG, but we
demonstrate from stacking {\it Herschel} SPIRE observations at these positions,
that the vast majority of these blank maps correspond to real single-dish
sub-millimetre sources. We further show that these blank maps contain an excess
of galaxies at $z_{\rm phot}=$\,1.5--4 compared to random fields, similar to
the redshift range of the ALMA-detected SMGs. In addition, we combine X-ray and
mid-infrared active galaxy nuclei activity (AGN) indicators to yield a likely
range for the AGN fraction of 8--28\,\% in our sample. Finally, we compare the
redshifts of this population of high-redshift, strongly star-forming galaxies
with the inferred formation redshifts of massive, passive galaxies being found
out to $z\sim$\,2, finding reasonable agreement -- in support of an
evolutionary connection between these two classes of massive galaxy.
