It is shown that the retrieval of temperature and pressure profiles can be obtained from vertically resolved limb emission measurements without requiring absolute radiance calibration. Only relative spectral and spatial response functions are required. The retrieved temperature and pressure profiles define the thermal IR source function, allowing absolute calibration of the flux input to channels sensing gases with known spectral parameters and mixing ratio. These calibration concepts have now been demonstrated using data from the Limb Infrared Monitor of the Stratosphere instrument on Nimbus 7.© (2000) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.