The distances to molecular clouds in the fourth Galactic quadrant
  Distance measurements to molecular clouds are essential and important. We
present directly measured distances to 169 molecular clouds in the fourth
quadrant of the Milky Way. Based on the near-infrared photometry from the Two
Micron All Sky Survey and the Vista Variables in the Via Lactea Survey, we
select red clump stars in the overlapping directions of the individual
molecular clouds and infer the bin averaged extinction values and distances to
these stars. We track the extinction versus distance profiles of the sightlines
toward the clouds and fit them with Gaussian dust distribution models to find
the distances to the clouds. We have obtained distances to 169 molecular clouds
selected from Rice et al. The clouds range in distances between 2 and 11 kpc
from the Sun. The typical internal uncertainties in the distances are less than
5 per cent and the systematic uncertainty is about 7 per cent. The catalogue
presented in this work is one of the largest homogeneous catalogues of distant
molecular clouds with the direct measurement of distances. Based on the
catalogue, we have tested different spiral arm models from the literature.
