indicator camera

The Ground Zero Indicator, known by the acronym GZI was a specially designed shadowgraph instrument used by the British Royal Observer Corps during the Cold War to locate the Ground Zero of any nuclear explosion. It consisted of four horizontally mounted cardinal compass point pinhole cameras within a metal drum. Flash from a nuclear explosion would produce a mark on one or multiple of the papers within the drum and its position of the mark has enabled the bearing and height of the burst to be estimated in terms of engineering. With a triangulation between both neighbouring posts these types of readings would give an considered accurate height and position, which is identified by assessing the height of the explosion imprint above the horizon level that had been pre-exposed onto the paper.

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