https://phys.org/news/2018-07-radio-rebound-powered-jets-gamma-ray.html

While the gamma rays from the burst disappeared from view a scant seven seconds later, longer wavelengths of light from the explosion—including X-ray, visible light, and radio—continued to shine for weeks. This allowed astronomers to study the aftermath of this fantastically energetic event, known as GRB 161219B, with many ground-based observatories, including the National Science Foundation's Very Large Array.

The unique capabilities of the Atacama Large Millimeter/submillimeter Array (ALMA), however, enabled a team of astronomers to make an extended study of this explosion at millimeter wavelengths, gaining new insights into this particular GRB and the size and composition of its powerful jets.