Artist Concept GRB (IMAGE) National Radio Astronomy Observatory Caption Artist impression of the "reverse shock" echoing back though the jets of the gamma-ray burst (GRB 161219B). Credit NRAO/AUI/NSF, S. Dagnello Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.