The Australian SKA Pathfinder

The Australian Square Kilometre Array Pathfinder (ASKAP) will be the fastest cm-wave survey instrument in radio astronomy. ASKAP will consist of 36 12-meter 3-axis antennas, each with a large checkerboard phased array feed (PAF) operating from 0.7 to 1.8 GHz, and digital beamformer preceding the correlator. The 96 dual-polarization elements (192 receivers) of the PAF and the subsequent beamformer will provide about 30 beams (at 1.4 GHz) to produce a 30 square degree field of view, allowing rapid, deep sky surveys. The large data rates involved (∼ 2 Tb/sec per antenna) and the need to do pipeline processing has led to the antenna incorporating a third axis to fix the parallactic angle with respect to the entire optical system (blockage and phased array feed).