Tied-Array Beam Localisation of Radio Transients and Pulsars

Abstract

Multi-element interferometers such as MeerKAT, which observe with high time resolution and have a wide field-of-view, provide an ideal opportunity to perform real-time, untargeted transient and pulsar searches. However, because of data storage limitations, it is not always feasible to store the baseband data required to image the field of a discovered transient or pulsar. This limits the ability of surveys to effectively localise their discoveries and may restrict opportunities for follow-up science, especially of one-off events like some Fast Radio Bursts (FRBs). Here we present a novel maximum-likelihood estimation approach to localising transients and pulsars detected in multiple MeerKAT tied-array beams at once, which we call Tied Array Beam Localisation (TABLo), as well as a Python implementation of the method named SeeKAT. We provide real-world examples of SeeKAT's use as well as a Monte Carlo analysis to show that it is capable of localising single pulses detected in beamformed MeerKAT data to (sub-)arcsecond precision.