  We conducted a deep spectroscopic survey, named SSA22-HIT, in the SSA22 field
with the DEep Imaging MultiObject Spectrograph (DEIMOS) on the Keck telescope,
designed to tomographically map high-z HI gas through analysis of Lya
absorption in background galaxies' spectra. In total, 198 galaxies were
spectroscopically confirmed at 2.5 < z < 6 with a few low-z exceptions in the
26 x 15 arcmin^2 area, of which 148 were newly determined in this study. Our
redshift measurements were merged with previously confirmed redshifts available
in the 34 x 27 arcmin^2 area of the SSA22 field. This compiled catalog
containing 730 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. 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 extragalactic survey fields in
terms of a combination of wide area and high surface number density of objects
at z > 2. About 40 % of the spectroscopically confirmed objects in SSA22-HIT
show reasonable quality of spectra in the wavelengths shorter than Lya when a
sufficient amount of smoothing is adopted. Our data set enables us to make the
HI tomographic map at z > 3, which we present in a parallel study.
