  We present spectroscopic measurements for 71 galaxies associated with 62 of
the brightest high-redshift submillimeter sources from the Southern fields of
the Herschel Astrophysical Terahertz Large Area Survey (H-ATLAS), while
targeting 85 sources which resolved into 142. We have obtained robust redshift
measurements for all sources using the 12-m Array and an efficient tuning of
ALMA to optimise its use as a redshift hunter, with 73 per cent of the sources
having a robust redshift identification. Nine of these redshift identifications
also rely on observations from the Atacama Compact Array. The spectroscopic
redshifts span a range $1.41<z<4.53$ with a mean value of 2.75, and the CO
emission line full-width at half-maxima range between $\rm 110\,km\,s^{-1} <
FWHM < 1290\,km\,s^{-1}$ with a mean value of $\sim$ 500kms$^{-1}$, in line
with other high-$z$ samples. The derived CO(1-0) luminosity is significantly
elevated relative to line-width to CO(1-0) luminosity scaling relation, which
is suggestive of lensing magnification across our sources. In fact, the
distribution of magnification factors inferred from the CO equivalent widths is
consistent with expectations from galaxy-galaxy lensing models, though there is
a hint of an excess at large magnifications that may be attributable to the
additional lensing optical depth from galaxy groups or clusters.
