Cerenkov radiation telescope |
 The background stars are streaks in this image of a Cerenkov radiation telescope taken in little more than starlight. |
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The reflecting telescope detects the diffuse patch of blue-violet Cerenkov radiation that accompanies a shower of relativistic electrons initiated by a TeV gamma ray (or cosmic ray) entering the atmosphere. An array of 'small' mirrors is sufficient to give a crude image of the radiation path. |