The TOP-SCOPE survey of Planck Galactic Cold Clumps: Survey overview and
  results of an exemplar source, PGCC G26.53+0.17
  The low dust temperatures (<14 K) of Planck Galactic Cold Clumps (PGCCs) make
them ideal targets to probe the initial conditions and very early phase of star
formation. TOP-SCOPE is a joint survey program targeting ~2000 PGCCs in J=1-0
transitions of CO isotopologues and ~1000 PGCCs in 850 micron continuum
emisison. The objective of the TOP-SCOPE survey and the joint surveys (SMT
10-m, KVN 21-m and NRO 45-m) is to statistically study the initial conditions
occurring during star formation and the evolution of molecular clouds, across a
wide range of environments. The observations, data analysis and example science
cases for these surveys are introduced with an exemplar source, PGCC
G26.53+0.17 (G26), which is a filamentary infrared dark cloud (IRDC). The total
mass, the length and the mean line-mass (M/L) of the G26 filament are ~6200
Msun, ~12 pc and ~500 Msun/pc, respectively. Ten massive clumps including eight
starless ones are found along the filament. The most massive Clump as a whole
may be still in global collapse while its denser part seems to be undergoing
expansion due to outflow feedback. The fragmentation in G26 filament from cloud
scale to clump scale is in agreement with gravitational fragmentation of an
isothermal, non-magnetized, and turbulent supported cylinder. A bimodal
behavior in dust emissivity spectral index ($\beta$) distribution is found in
G26, suggesting grain growth along the filament. The G26 filament may be formed
due to large-scale compression flows evidenced by the temperature and velocity
gradients across its natal cloud.
