COLD GASS

COLD GASS (for CO Legacy Database for GASS) is an Institut de radioastronomie millimétrique (IRAM) survey of carbon monoxide (CO) in a selection of over 350 massive galaxies identified both in Sloan Digital Sky Survey (SDSS) (in the optical) and the Galaxy Evolution Explorer (GALEX) (in ultraviolet). The goal is estimates of their molecular hydrogen (through the use of alpha CO with detected CO spectral lines) and its ratio with atomic hydrogen (based on the 21-cm line). The galaxies were drawn from the GALEX Arecibo SDSS Survey (GASS).

xCOLD GASS (for Extended CO Legacy Database for GASS) is a follow-on effort extending the survey to include galaxies of a smaller mass range (from the xGASS survey), bringing the total above 500.