The optical properties of the atmosphere are important considerations in the design of infrared remote sensing systems. For example, the selections of the appropriate spectral region, spectral resolution or filter bandpass and the calculations of system performance all require data on background radiance and atmospheric transmittance. This paper will present previously unpublished high resolution (0.07, 0.44 cm-1) measured and computer modeled atmospheric transmittance and sky radiance data in the infrared. Included also is discussion of measurement methods and calculation procedures.