GALEX Arecibo SDSS Survey

The GALEX Arecibo SDSS Survey (GASS) was a survey of HI emissions from over a thousand galaxies. Galaxies were chosen from SDSS and GALEX, so that cross correlations can be made. Observations were made in 2008-2009 at Arecibo, using the 21-cm line to detect HI. Three data releases followed, the final one 2013. A later extension covering over a thousand additional galaxies was xGASS (for Extended GALEX Arecibo SDSS Survey). Follow-up surveys estimating galaxies' molecular hydrogen were COLD GASS and xCOLD GASS.

Note that the acronym GASS is also used for the Galactic All-sky Survey.