2018ApJS..235...29J

The Gemini/HST Galaxy Cluster Project (GCP) covers 14 z = 0.2-1.0 clusters with X-ray luminosity of L₅₀₀≥ 10⁴⁴ergs^–1 in the 0.1-2.4 keV band. In this paper, we provide homogeneously calibrated X-ray luminosities, masses, and radii, and we present the complete catalog of the ground-based photometry for the GCP clusters. The clusters were observed with either Gemini North or South in three or four of the optical passbands g', r', i', and z'. The photometric catalog includes consistently calibrated total magnitudes, colors, and geometrical parameters. The photometry reaches ≃25 mag in the passband closest to the rest-frame B band. We summarize comparisons of our photometry with data from the Sloan Digital Sky Survey. We describe the sample selection for our spectroscopic observations, and establish the calibrations to obtain rest-frame magnitudes and colors. Finally, we derive the color-magnitude relations for the clusters, and briefly discuss these in the context of evolution with redshift. Consistent with our results based on spectroscopic data, the color-magnitude relations support passive evolution of the red sequence galaxies. The absence of change in the slope with redshift constrains the allowable age variation along the red sequence to <0.05 dex between the brightest cluster galaxies and those four magnitudes fainter. This paper serves as the main reference for the GCP cluster and galaxy selection, X-ray data, and ground-based photometry.