Wide-Field $^{12}$CO ($J=2-1$) and $^{13}$CO ($J=2-1$) Observations
  toward the Aquila Rift and Serpens Molecular Cloud Complexes. I. Molecular
  Clouds and Their Physical Properties
  We present results of wide-field $^{12}$CO ($J = 2 - 1$) and $^{13}$CO ($J =
2 - 1$) observations toward the Aquila Rift and Serpens molecular cloud
complexes (25$^\circ < l < 33^\circ$ and $1^\circ < b < 6^\circ$) at an angular
resolution of 3$'$.4 ($\approx$ 0.25 pc) and at a velocity resolution of 0.079
km s$^{-1}$ with the velocity coverage of $-5$ km s$^{-1} < V_{\rm LSR} <$ 35
km s$^{-1}$. We found that the $^{13}$CO emission better traces the structures
seen in the extinction map and derived the $X_{\rm ^{13}CO}$-factor of this
region. Applying \texttt{SCIMES} to the $^{13}$CO data cube, we identified 61
clouds and derived their masses, radii, and line widths. The line-width-radius
relation of the identified clouds basically follows those of nearby molecular
clouds. Majority of the identified clouds are close to virial equilibrium
although the dispersion is large. By inspecting the $^{12}$CO channel maps by
eye, we found several arcs which are spatially extended to 0.2 $-$ 3 degree in
length. In the longitude-velocity diagrams of $^{12}$CO, we also found the two
spatially-extended components which appear to converge toward Serpens South and
W40 region. The existence of two components with different velocities and arcs
suggests that large-scale expanding bubbles and/or flows play a role in the
formation and evolution of the Serpens South and W40 cloud.
