The high-velocity cloud complex Galactic Center Negative as seen by
  EBHIS and GASS. I. Cloud catalog and global properties
  Using Milky Way data of the new Effelsberg-Bonn HI Survey (EBHIS) and the
Galactic All-Sky Survey (GASS), we present a revised picture of the
high-velocity cloud (HVC) complex Galactic Center Negative (GCN). Owing to the
higher angular resolution of these surveys compared to previous studies (e.g.,
the Leiden Dwingeloo Survey), we resolve Complex GCN into lots of individual
tiny clumps, that mostly have relatively broad line widths of more than 15
km/s. We do not detect a diffuse extended counterpart, which is unusual for an
HVC complex. In total 243 clumps were identified and parameterized which allows
us to statistically analyze the data. Cold-line components (i.e., w < 7.5 km/s)
are found in about 5% only of the identified cloudlets. Our analysis reveals
that Complex GCN is likely built up of several subpopulations that do not share
a common origin. Furthermore, Complex GCN might be a prime example for warm-gas
accretion onto the Milky Way, where neutral HI clouds are not stable against
interaction with the Milky Way gas halo and become ionized prior to accretion.
