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Images created from the
third DCE when about half the Moon was sunlit are shown above. The temperatures for the portion of the
Moon that are still in eclipse continue to decline, while the temperatures on
the sunlit side of the Moon rise rapidly.
The 4.3 µm spectral bands go into soft saturation, which is designated
by the white region. The black band
are regions with the warmest temperatures and are hard saturated.
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Interference filters such
as the ones used for the 4.3 µm arrays scatter radiation from a bright
sources7 and such scattering for the 4.3 µm filters
was mapped in detail during the ground calibration. The scattering is evident by the band of
lighter color between the eclipsed and sunlit portions of the Moon as well as
the response outside the edge of the lunar disk. Scattering would most
strongly effect the brightness temperature contrast between the bright
craters and their immediate surrounding. The ground calibration
indicates that the scattering decreasing rapidly in the cross-scan direction
with a Lorentzian profile with a characteristic width of 5”. A correction to
the scattering contribution has been applied to the final data
products and the brightness temperature maps displayed in view graph
12. The correction changed the
brightness temperatures of the brighter regions by < 2° K
while the coolest regions are more strongly effected with as much as a 10K
decrease for measurements just above the noise floor.
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7Stierwalt,
D.L., and W.J. Eisenman, 1978, Problems in using cold spectral filters with
LWIR detectors, Proc. SPIE, 132, 134 – 140.
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