A very sensitive electronic device that is revolutionizing astronomy in the 1990s. CCD cameras are composed of silicon chips that are sensitive to light, changing detected photons of light into electronic signals that can then be used to make images of astronomical objects or to analyze how much light is being received from such objects. CCDs require computers for reduction of data, so the expense can be much greater than for, say, photography --- but CCDs can detect much fainter objects than can photographs. Unfiltered CCDs tend to be more red-sensitive than the human eye.