The GEEC2 spectroscopic survey of Galaxy groups at 0.8 < z < 1

We present the data release of the Gemini-South GMOS spectroscopy in the fields of 11 galaxy groups at 0.8 < z < 1, within the COSMOS field. This forms the basis of the Galaxy Environment Evolution Collaboration 2 (GEEC2) project to study galaxy evolution in haloes with M ∼ 1013 M⊙ across cosmic time. The final sample includes 162 spectroscopically confirmed members with R < 24.75, and is >50 per cent complete for galaxies within the virial radius, and with stellar mass Mstar > 1010.3 M⊙. Including galaxies with photometric redshifts, we have an effective sample size of ∼400 galaxies within the virial radii of these groups. We present group velocity dispersions, dynamical and stellar masses. Combining with the GCLASS sample …