The AARTFAAC All-Sky Monitor: System Design and Implementation

Abstract

The Amsterdam-ASTRON Radio Transients Facility And Analysis Center (AARTFAAC) all sky monitor is a sensitive, real time transient detector based on the Low Frequency Array (LOFAR). It generates images of the low frequency radio sky with spatial resolution of 10s of arcmin, MHz bandwidths, and a time cadence of a few seconds, while simultaneously but independently observing with LOFAR. The image timeseries is then monitored for short and bright radio transients. On detection of a transient, a low latency trigger will be generated for LOFAR, which can interrupt its schedule to carry out follow-up observations of the trigger location at high sensitivity and resolutions. In this paper, we describe our heterogeneous, hierarchical design to manage the 240 Gbps raw data rate, and large scale computing to produce real-time images with minimum latency. We discuss the implementation of the instrumentation, its performance, and scalability.

Improved upper limits on the 21 cm signal power spectrum of neutral hydrogen at z ≈ 9.1 from LOFAR

“…Improving the NCP sky model -Finally, a complete review of our current sky model will be carried out, investigating as well the inclusion of diffuse Stokes I, Q and U emission as observed using the AARTFAAC 21 HBA system (Prasad et al 2016;.…”

Constraining coherent low-frequency radio flares from compact binary mergers

“…LOFAR also has an all-sky radio monitor known as the Amsterdam ASTRON Radio Transient Facility and Analysis Center (AARTFAAC), which runs as a parallel backend when the LOFAR Low Band Array (LBA; 10-90 MHz) is operating (Prasad et al 2014(Prasad et al , 2016. This facility samples the sky on 1 s timescales using the inner-most 6 LOFAR core stations and 16 subbands (AARTFAAC-6; a total of 3.12 MHz of processed bandwidth centred around 60 MHz), with plans to upgrade to AARTFAAC-12 with the addition of 6 more core stations and another 16 subbands.…”

AARTFAAC flux density calibration and Northern hemisphere catalogue at 60 MHz

“…In this paper, we describe the next step in achieving the goal of continuous all-sky monitoring with AARTFAAC. Previously, we described the basic properties of the AARTFAAC system and its real-time calibration and technical commissioning (Prasad et al 2014), as well as the system design and correlator (Prasad et al 2016), and TraP, the transients detection pipeline also used for LOFAR transient searches (Swinbank et al 2015). In this paper, we describe the results of the first practical commissioning runs.…”