The SSA22 HI Tomography Survey (SSA22-HIT). I. Dataset and compiled
  redshift catalog
  We conducted a deep spectroscopic survey, named SSA22-HIT, in the SSA22 field
with DEIMOS on the Keck telescope, designed to tomographically map of high-$z$
HI gas through analysis of Ly$\alpha$ absorption in background galaxies'
spectra. In total, 203 galaxies were spectroscopically confirmed at $2.5 < z <
6$ in the $26 \times 15$ arcmin$^2$ area, of which 150 were newly determined in
this study. Our redshift measurements were merged with previously confirmed
redshifts available in the $34 \times 27$ arcmin$^2$ area of the SSA22 field.
This compiled catalog containing $\sim 740$ galaxies of various types at $z >
2$ is useful for various applications, and it is made publicly available. Our
SSA22-HIT survey has increased by approximately twice the number of
spectroscopic redshifts of sources at $z > 3.2$ in the observed field. This
greatly benefits the HI tomographic mapping of the proto-cluster region at $z =
3.1$, which we present in a parallel study. From a comparison with publicly
available redshift catalogs, we show that our compiled redshift catalog in the
SSA22 field is comparable to those among major extra-galactic survey fields in
terms of a combination of wide area and high surface number density of objects
at $z > 2$.
