The Australian SKA Pathfinder

Abstract

The Australian Square Kilometre Array Pathfinder (ASKAP) will be the fastest cm-wave survey radio-telescope and is under construction on the new Murchison Radio-astronomy Observatory (MRO) in Western Australia. ASKAP consists of 36 12-meter 3-axis antennas, each with a large chequerboard phased array feed (PAF) operating from 0.7 to 1.8 GHz, and digital beamformer preceding the correlator. The PAF has 94 dual-polarization elements (188 receivers) and the beamformer will provide about 36 beams (at 1.4 GHz) to produce a 30 square degree field of view, allowing rapid, deep surveys of the entire visible sky. As well as a large field of view ASKAP has high spectral resolution across the 304 MHz of bandwidth processed at any one time generating a large data-rate (30Gb/sec in to the imaging system) that requires real-time processing of the data. To minimise this processing and maximise the field of view for long observations the antenna incorporates a third axis, which keeps the PAF field of view and sidelobes fixed relative to the sky. This largely eliminates time varying artefact in the data that is processed. The MRO is 315 kilometres north-east of Geraldton, in Western Australia’s Mid West region. The primary infrastructure construction for ASKAP and other telescopes hosted at the Murchison Radio-astronomy Observatory has now been completed by CSIRO, the MRO manager, including installation of the fibre connection from the MRO site to Perth via Geraldton. The radio-quietness of the region is protected by the Mid West Radio Quiet Zone, implemented by the Australian Federal Government, out to a radius of 260km surrounding the MRO.