• 17-tonne US spacecraft also called the Gamma Ray Observatory and used to observe the gamma-ray sky. Launched in 1991, it housed several instruments including BATSE, the Burst and Transient Source Experiment, for looking at short-lived gamma-ray events, the Imaging Compton telescope, EGRET, the Energetic Gamma Ray Experiment Telescope, and OSSE, the Oriented scintillation spectrometer Experiment. Its mission ended in 2000. Arthur Compton (1892–1962) was the US physicist who discovered the Compton Effect of the scattering of X and Gamma radiation by matter, the fundamental scientific finding in the field.
  • acronymGRO


  • noun a black person. The racist epithet is a clipped form of ‘negro’. In the UK groid has been used in the same way.