The ALFA Ultra Deep Survey (AUDS)

The “ALFA Ultra Deep Survey” (AUDS) is the most sensitive 21cm line survey to be conducted with the new Arecibo 300 MHz spectrometer. The survey will search for 21cm HI line emission at redshifts between 0 and 0.16 with an unprecedented sensitivity. The main scientific goals of the survey are to investigate the evolution of HI gas in the universe and explore the low‐density gas around the edges of galaxies. Precursor observations with a total integration time of 60 hours were carried out to test the feasibility of the project. Results from these observations are briefly discussed.