Photon counting during an eclipse.
We have built an instrument that counts pulses from photomultipliers that look at four bands of solar continuum, recording the changes in intensity during an eclipse. We use a plywood spectrograph to select an ultraviolet band and interference filters for the others. The number of counts seen in 1/20 sec is displayed for the subsequent 1/20 sec on binary light-emitting diodes which are photographed. Our ex periment can attain a spatial resolution of better than 0.1 sec of arc and an accuracy in irradiance of better than 3%.
Weart
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