The Green Bank Telescope HII Region Discovery Survey II. The Source
  Catalog
  The Green Bank Telescope HII Region Discovery Survey has doubled the number
of known HII regions in the Galactic zone 343deg.\leql\leq67deg. with
|b|\leq1deg. We detected 603 discrete hydrogen radio recombination line (RRL)
components at 9GHz (3cm) from 448 targets. Our targets were selected based on
spatially coincident mid-infrared and 20cm radio continuum emission. Such
sources are almost invariably HII regions; we detected hydrogen RRL emission
from 95% of our target sample. The sensitivity of the Green Bank Telescope and
the power of its spectrometer together made this survey possible. Here we
provide a catalog of the measured properties of the RRL and continuum emission
from the survey nebulae. The derived survey completeness limit, 180mJy at 9GHz,
is sufficient to detect all HII regions ionized by single O-stars to a distance
of 12kpc. These recently discovered nebulae share the same distribution on the
sky as does the previously known census of Galactic HII regions. On average,
however, the new nebulae have fainter continuum fluxes, smaller continuum
angular sizes, fainter RRL intensities and smaller RRL line widths. Though
small in angular size, many of our new nebulae show little spatial correlation
with tracers associated with extremely young HII regions, implying that our
sample spans a range of evolutionary states. We discovered 34 first quadrant
negative-velocity HII regions, which lie at extreme distances from the Sun and
appear to be part of the Outer Arm. We found RRL emission from 207 Spitzer
GLIMPSE 8.0{\mu}m "bubble" sources, 65 of which have been cataloged previously.
It thus appears that nearly all GLIMPSE bubbles are HII regions and that
\sim50% of all Galactic HII regions have a bubble morphology at 8.0{\mu}m.
