ASKAP-FLASH (the First Large Absorption Survey in HI) is one of nine Survey Science Projects which will be carried out with the Australian SKA Pathfinder (ASKAP) radio telescope.

ASKAP is an array of 36 antennas each 12m in diameter, capable of high dynamic range imaging and using wide-field-of-view phased array feeds. ASKAP is intended to be a world-class telescope in its own right as well as a pathfinder instrument for the Square Kilometre Array.

ASKAP's large spectral bandwidth (288 MHz bandwidth over the frequency range 700-1800 MHz) and wide field of view (30 square degrees) will open up a completely new parameter space for large, blind HI absorption-line surveys using background radio continuum sources. Since the detection limit for such surveys is independent of redshift, ASKAP-FLASH will allow us to learn about the neutral gas content of galaxies in the poorly-explored redshift range 0.4 < z < 1.0, where the HI emission line is too weak to be detectable in even the deepest ASKAP surveys.