Australia's first pass at the Square Kilometre Array – the Boolardy Engineering Test Array – is about to get commissioned into a fully-live system.
The test array, known naturally enough as BETA, is part of the science-before-the-science: a proving ground for some of the new technologies being used for the SKA project, in particular, the Phased Array Feeds.
Those feeds represent a new way of getting signals from the parabolic dishes of the array: instead of the waveguides that collect signals in an old style dish (like The Dish, which recently had to cut back the number of frequencies it would install waveguides for as a cost-saving measure), PAFs put an array of receptors at the focal plane.
As BETA's operators explain in this Arxiv paper, that arrangement lets “multiple independently steerable primary beams to be synthesised electronically”, but because it's never been done before, the test deployment existed for tasks like working out how to form the beams for particular imaging tasks, measuring the pattern stability of the beams, and working out how best to arrange multiple beams into a large field of view.
Along the way, BETA is also showing off some of the other technologies that'll be fundamental for the SKA. Once signals from the telescopes have been digitised (using CSIRO-designed boards dubbed DragonFly-2), they're sent from the telescopes to a central facility for processing.
With just six antennas in placed, the central processing (handled by another board from CSIRO called Redback-2) has plenty to work with: each PAF port on each antenna produces 304 individual 1 MHz channels, with each antenna needing 16 of the Redback-2 boards and 10 GB/second communications.
Each 12 hour observation run of BETA is good for dumping nearly 154 MB/second on the facility's disk, for a total of 816 GB. The ASKAP central processor, a 472-node Cray XC30 at Perth's Pawsey Centre, is currently working hard to fill the 10 PB of Spectra Logic tape storage (duplicated for insurance) available for the facility, and that's slated for expansion to 50 PB. ®