The HectoMAP Redshift Survey: First Data Release
  HectoMAP is a dense, red-selected redshift survey to a limiting $r = 21.3$
covering 55 square degrees in a contiguous 1.5$^\circ$ strip across the
northern sky. This region is also covered by the Subaru/Hyper Suprime-Cam (HSC)
Subaru Strategic Program (SSP) photometric survey enabling a range of
applications that combine a dense foreground redshift survey with both strong
and weak lensing maps. The median redshift of HectoMAP exceeds 0.3 throughout
the survey region and the mean density of the redshift survey is $\sim 2000$
galaxies deg$^{-2}$. Here we report a total of 17,313 redshifts in a first data
release covering 8.7 square degrees. We include the derived quantities
D$_{n}4000$ and stellar mass for nearly all of the objects. Among these
galaxies, 8117 constitute a 79\% complete red-selected subsample with $r \leq
20.5$ and an additional 4318 constitute a 68\% complete red-selected subsample
with $20.5 < r < 21.3$. As examples of the strengths of HectoMAP data we
discuss two applications: refined membership of redMaPPer photometrically
selected clusters and a test of HSC photometric redshifts. We highlight a
remarkable redMaPPer strong lensing system. The comparison of photometric
redshifts with spectroscopic redshifts in a dense survey uncovers subtle
systematic issues in the photometric redshifts.
