A grating spectrometer which makes simultaneous measurements of the earth’s radiance near 4.3 µ (2300 cm-1) in thirty-five spectral intervals about 0.04 µ wide at 20-sec intervals has been constructed. Calibration procedures are described which permit spectral radiances to be determined to an absolute accuracy of about 3%. Measurements made during balloon flights in 1967 and 1968 illustrate the instrument performance.
P. W. Schaper and J. H. Shaw, "Performance of a Spectrometer for Measuring the Earth’s Radiance near 4.3 µ," Appl. Opt. 9, 924-928 (1970)