LOFAR's first automatic response to an astrophysical transient

© ASTRON

On Friday 6 July 2018 at 10:25am (CEST), LOFAR fully automatically responded to an astrophysical transient source for the very first time. A bight burst of gamma-rays, known as GRB 180706A, was detected by the Neil Gehrels Swift Observatory and the satellite automatically sent an urgent message to waiting facilities on the ground. In the graph at the top of the figure, the black data points show the initial flash of gamma-rays and the blue data points are the follow-up X-ray observations obtained by the satellite.

LOFAR responded to the rapid trigger alert and a 2 hour observation started within 5 minutes of the alert. The box at the bottom of the figure shows the LOFAR monitoring system receiving and observing this source. As shown by the red shaded region, these observations cover the entire 'plateau' phase in the X-ray observations and the origin of this phase is still hotly contested for these events. Our observations may hold invaluable clues to show what is happening during this phase.

This work made use of data supplied by the UK Swift Science Data Centre at the University of Leicester.