  FastSound is a galaxy redshift survey using the near-infrared Fiber
Multi-Object Spectrograph (FMOS) mounted on the Subaru Telescope, targeting
H$\alpha$ emitters at $z \sim 1.18$--$1.54$ down to the sensitivity limit of
H$\alpha$ flux $\sim 2 \times 10^{-16} \ \rm erg \ cm^{-2} s^{-1}$. The primary
goal of the survey is to detect redshift space distortions (RSD), to test
General Relativity by measuring the growth rate of large scale structure and to
constrain modified gravity models for the origin of the accelerated expansion
of the universe. The target galaxies were selected based on photometric
redshifts and H$\alpha$ flux estimates calculated by fitting spectral energy
distribution (SED) models to the five optical magnitudes of the Canada France
Hawaii Telescope Legacy Survey (CFHTLS) Wide catalog. The survey started in
March 2012, and all the observations were completed in July 2014. In total, we
achieved $121$ pointings of FMOS (each pointing has a $30$ arcmin diameter
circular footprint) covering $20.6$ deg$^2$ by tiling the four fields of the
CFHTLS Wide in a hexagonal pattern. Emission lines were detected from $\sim
4,000$ star forming galaxies by an automatic line detection algorithm applied
to 2D spectral images. This is the first in a series of papers based on
FastSound data, and we describe the details of the survey design, target
selection, observations, data reduction, and emission line detections.
