The HectoMAP Cluster Survey - I. redMaPPer Clusters
  We use the dense HectoMAP redshift survey to explore the properties of 104
redMaPPer cluster candidates. The redMaPPer systems in HectoMAP cover the full
range of richness and redshift (0.08 $< z <$ 0.60). Fifteen systems included in
the Subaru/Hyper Suprime-Cam public data release are bona fide clusters. The
median number of spectroscopic members per cluster is $\sim20$. We include
redshifts of 3547 member candidates listed in the redMaPPer catalog whether
they are cluster members or not. We evaluate the redMaPPer membership
probability spectroscopically. The scaled richness ({\lambda}rich/S) provided
by redMaPPer correlates tightly with the spectroscopic richness regardless of
the cluster redshift and appears to be a better mass proxy than the original
richness, {\lambda}rich. The purity (number of real systems) in redMaPPer
exceeds 90% even at the lowest richness; however, there is some incompleteness.
Five massive galaxy clusters (M $\gtrsim 2 \times 10^{13}$ M$_{\odot}$)
associated with X-ray emission in the HectoMAP region are missing from the
catalog.
