ocr: EIT INSTRUMENT The instrument is a Ritchey-Chretien reflecting telescope with dif- ferent multilayer coatings applied to each of four quadrants of the primary mirror, and the corresponding quadrants of the secondary mirror. With a sector wheel that blocks all but one quadrant af a time, EIT-is able to image the Sun in extreme ultraviolet (EUV) spectral lines formed in a relatively small range of temperatures. EIT is the first solar EUV multilayer imaging device to fly longer than 1 5 minutes (i.e., previous instruments were carried by sounding rockets). The CCD detector is another major reason ...