Code overview - askap-craco/CELEBI GitHub Wiki

This page contains an abridged overview of CELEBI's code and how it fits together. For a full technical description, see Scott et al. (2023), references to which are denoted in this page by a §, e.g. §4.1 is a reference to Scott et al. (2023) section 4.1.

CELEBI operates on voltages containing Fast Radio Bursts (FRBs) captured in ASKAP antennas. For each FRB, there are three sets of voltages: the FRB itself, a "flux" calibrator, and a polarisation calibrator. CELEBI correlates these data to produce visibilities and perform interferometric imaging and localisation of the FRB, and inverts ASKAP's polyphase filterbank to produce polarimetric FRB data at ~3 ns time resolution.

CELEBI is composed of Python and Bash code, linked together into a single pipeline with Nextflow. It is split into three major workflows: fluxcal, polcal, and FRB. These are linked by a main workflow, a data-flow diagram (DFD) of which is shown below:

fluxcal produces frequency-dependent complex gain solutions from the “fluxcal” calibrator voltages. These solutions are used in polcal and FRB for imaging and beamforming.

polcal produces polarisation calibration solutions that correct for the small delay and leakage between the two nominally orthogonal polarisation bases of the ASKAP antennas from the polarisation calibrator voltages.

FRB takes the solutions from the other major workflows and processes the FRB voltages to determine an arcsecond-precision localisation of the FRB and produce a set of high-time resolution polarimetric data.