Thermal band characterization of LANDSAT-4 thematic mapper

The TM band 6 shutter background and the 34.7 C internal black body signal were measured over 50 day dates. Variability of the shutter background temperature was from 7 C to 11 C. For ten specific images, the digital counts of the calibration data were measured. The average pulse value of the black body peak decreased from 174 to 149 counts while the shutter background counts varied as a function of shutter temperature from 77 to 85. Relative internal gains between the four channels were calculated and compared to prelaunch values. They showed gains over 9 months of up to 5%. Frequency histograms of number of pixels vs. digital counts from a night scene were used to determine gain relative to the mean and to discern a systematic along-scan pattern in a difference between forward and reverse scan counts of up to 0.5. A corrected digital image was obtained. A temperature estimate for and area of Lake Erie of 18.5 C to 19.9 C was obtained. Local temperature records showed 21 C.