Apertif, Phased Array Feeds for the Westerbork Synthesis Radio Telescope

TL;DR

Apertif is a significant upgrade to the Westerbork Synthesis Radio Telescope, employing phased array feeds to enable wide-field, high-sensitivity radio imaging and transient surveys, resulting in increased survey speed and new scientific capabilities.

Contribution

Introduction of a novel phased array feed system that transforms the Westerbork telescope into a wide-field, high-sensitivity radio survey instrument with multiple simultaneous beams.

Findings

Formation of up to 40 overlapping beams on the sky.

Execution of a large-area imaging survey covering 2300 deg2.

Ongoing transient and pulsar survey covering 15,000 deg2.

Abstract

We describe the APERture Tile In Focus (Apertif) system, a phased array feed (PAF) upgrade of the Westerbork Synthesis Radio Telescope which has transformed this telescope into a high-sensitivity, wide field-of-view L-band imaging and transient survey instrument. Using novel PAF technology, up to 40 partially overlapping beams can be formed on the sky simultaneously, significantly increasing the survey speed of the telescope. With this upgraded instrument, an imaging survey covering an area of 2300 deg2 is being performed which will deliver both continuum and spectral line data sets, of which the first data has been publicly released. In addition, a time domain transient and pulsar survey covering 15,000 deg2 is in progress. An overview of the Apertif science drivers, hardware and software of the upgraded telescope is presented, along with its key performance characteristics.