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The Extreme Ultraviolet Spectrometer (EUVS) was used to observe
the variations in the solar EUV flux in the wavelength range
from 140 to 1850 A and the atmospheric attenuation at various
fixed wavelengths. This provided quantitative atmospheric
structure and composition data. The instrument consisted of 24
grazing-incidence grating monochromators, using parallel-slit
systems for entrance collimation and photoelectric detectors at
the exit slits. Twelve of these monochromators had wavelength
scan capability, each with 128 selectable wavelength positions,
which could also automatically step scan through these
positions. The other 12 monochromators operated at fixed
wavelengths with fields of view smaller than the full solar disk
to aid in the atmospheric absorption analysis. The spectral
resolution varied from 2 to 54 A depending upon the particular
instrument. The field of view varied from 60 x 60 down to 3 x 6
arc min. All 24 monochromator-entrance axes were co-aligned
parallel. A solar pointing system could point to 256 different
positions, execute a 16-step one-dimensional sc an or a full
256-step raster. The time resolution varied from 0.5 s for
observing 12 fixed wavelengths up to 256 s for programming the
EUVS through all possible modes.
[Summary provided by NASA]
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