A clock for the Square Kilometre Array

Abstract

The Square Kilometre Array telescope will be the largest and most complex astronomical instrument to date, with individual antennas spread across continental scales. One of the most complex technical challenges of such an extended array is the coherent combination of astronomical signals collected independently by many remote antennas. Astronomical observations therefore must be time-stamped with clock signals of exquisite accuracy and precision. Traditionally, these signals were provided by separate atomic clocks installed at each telescope site, which are synchronised over long time scales via GPS. However, the scale of the SKA makes the cost of operating and maintaining such an ensemble of complex and expensive atomic clocks extremely difficult. The National Time and Frequency Network collaboration is developing a novel solution which turns the problem on its head. We plan to recycle the optical fibre network, used to transport the astronomical data to the Square Kilometre Array's central computer, to also distribute high-quality time and frequency signals to each antenna. We are developing and then amalgamating six techniques to enable a versatile timing and frequency network that spans continental scales. Our work brings together cutting edge technological innovations with astronomical science of the highest precision.