Gamma_ray burst detection. Animation clip 1 of 11 showing a gamma_ray burst GRB being detected by a satellite as it scans the sky. GRBs are extremely energetic releases of gamma rays, visible across the universe in the direction the radiation is emitted. The GRB is shown here as a brief bright glow of light. GRBs are initially detected by satellites such as NASA磗 Swift Gamma_Ray Burst Mission known as Swift. The precise cause varies depending on the duration. Shorter ones are thought to occur during the merger of colliding neutron stars as they form a black hole. Longer ones are thought to occur during the death and collapse of massive rapidly rotating stars. Later clips in this sequence K003/2670_2660 show the process of neutron star merger in detail, as modelled by the Damiana supercomputer at Germany磗 Max Planck Institute for Gravitational Physics.