720 XTF Search Results (f1-spectral-Type=Gamma ray;f2-subject=Events (Historical);f3-associated-Lesson=Gamma Ray History;f4-facility=VELA satellites);f2-subject%3DEvents%20(Historical);f3-associated-Lesson%3DGamma%20Ray%20History;f4-facility%3DVELA%20satellites Results for your query: f1-spectral-Type=Gamma ray;f2-subject=Events (Historical);f3-associated-Lesson=Gamma Ray History;f4-facility=VELA satellites Thu, 01 Jan 1970 12:00:00 GMT First GRB. Gamma-ray bursts (GRBs) are sudden outbursts of gamma rays from a particular place in the sky that last a few seconds or so. These outbursts are similar to what is seen in a nuclear bomb explosion, and the first GRBs were detected by the Vela satellites that monitored nuclear testing. This graph shows the sudden increase in gamma rays recorded for the first GRB detected by the monitoring satellites in 1967. Sun, 02 Jul 1967 12:00:00 GMT