The molecular environment of the Galactic star forming region
  G19.61-0.23
  We present single-dish (sub)millimeter observations of gas and dust in the
Galactic high-mass star-forming region G19.61-0.23, with the aim of studying
the large-scale properties and physical conditions of the molecular gas across
the region. The final aim is to compare the large-scale (about 100 pc)
properties with the small-scale (about 3 pc) properties and to consider
possible implications for extragalactic studies. We have mapped CO
isotopologues in the J=1-0 transition using the FCRAO-14m telescope and the
J=2-1 transition using the IRAM-30m telescope. We have also used data from the
ATLASGAL survey and from the BU-FCRAO Galactic Ring Survey, as well as the
Spitzer infrared Galactic plane surveys GLIMPSE and MIPSGAL to characterize the
star-formation activity within the molecular clouds. We reveal a population of
molecular clumps in the 13CO(1-0) emission. Our analysis of the 13CO suggests
that the virial parameter (ratio of kinetic to gravitational energy) varies
over an order of magnitude between clumps that are unbound and some that are
apparently "unstable". This conclusion is independent of whether they show
evidence of ongoing star formation. We find that the majority of ATLASGAL
sources have MIPSGAL counterparts with luminosities in the range 10^4 - 5 10^4
Lsun and are presumably forming relatively massive stars. We compare our
results with previous extragalactic studies of the nearby spiral galaxies M31
and M33; and the blue compact dwarf galaxy Henize2-10. We find that the main
giant molecular cloud surrounding G19.61-0.23 has physical properties typical
for Galactic GMCs and which are comparable to the GMCs in M31 and M33. However,
the GMC studied here shows smaller surface densities and masses than the clouds
identified in Henize2-10 and associated with super star cluster formation.
