The Group Evolution Multiwavelength Study (GEMS): the Sample and   Datasets
  Galaxy groups have been under-studied relative to their richer counterparts -- clusters. The Group Evolution Multiwavelength Study (GEMS) aims to redress some the balance. Here we describe the GEMS sample selection and resulting sample of 60 nearby (distance < 130 Mpc) galaxy groups and our multiwavelength dataset of X-ray, optical and HI imaging. ROSAT X-ray images of each group are presented. GEMS also utilizes near-infrared imaging from the 2MASS survey and optical spectra from the 6dFGS. These observational data are complemented by mock group catalogues generated from the latest LCDM simulations with gas physics included. Existing GEMS publications are briefly highlighted as are future publication plans. 
Duncan A. Forbes, Trevor Ponman, Frazer Pearce, John Osmond, Virginia   Kilborn, Sarah Brough, Somak Raychaudhury, Carole Mu...