Extended fight sources

A fight wave is considered to be spatially coherent if there is a constant phase difference between different points of observation. Ligtit that is emitted from different parts of a conventional fight source is not phase-related. Therefore, the fight from an extended fight som ce will not be spatially coherent at close distances. 

Unlike stellar spectroscopy, the analysis of meteoritic grains and inclusions can provide an extremely precise isotopic breakdown. The weak point of this technique, however, is that the exact characteristics of the stars from which the grains formed can only be inferred. When we detect fight, we can deduce its celestial source by extending back its fine of incidence and we can determine the composition of the source from the spectral lines it contains. But we do not know where the meteorite grains came from, and only their composition can tell us anything of their origins. 

For relatively small facilities, battery-powered fights, continuously cormected to a charging source and which automatically come on when the power fads, are often used. Units are available which have extended useful lifetimes of 10 years or more. As with any other standby device, it is necessary to test... 

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