Abstract
A concave grating Wadsworth spectrometer designed to scan the UV limb of the earth was flown on a Defense Department meteorological satellite to obtain measurements of atmospheric emissions in the 85–395-nm wavelength range as a function of height above the solid earth. The instrument field of view was 0.14 × 3.8° corresponding to 6 km in the vertical and 230 km in the horizontal at the limb. The scanning motion was controlled by a momentum compensated dc-torque motor mechanism that panned the line of sight across the limb corresponding to tangent altitudes of 80–480 km. A set of three photon counting detectors, each viewing a separate exit slit, provided simultaneous coverage of the wavelength bands of 85–120 nm (EUV), 110–163 nm (far UV), and 290–395 nm (UV) at a wavelength resolution of 0.4, 0.8, and 1.2 nm, respectively. A separate photometric channel isolated the atmospheric sodium doublet at 589.0–589.6 nm. The grating position and instrument view angle were controlled by digital circuitry operating on hardwired and uplinked command instructions. The operating modes included a variety of scanning and fixed wavelength and view angle operations. A description of the instrument and several examples of the data are presented. These include the dayglow emissions from thermospheric oxygen and nitrogen that form the basis of a thermospheric density determination, auroral enhancements observed in these emissions and in hydrogen Ly-α, and nighttime sodium emissions.
© 1982 Optical Society of America
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