The Remote Sensing Group in the College of Optical Sciences at the University of Arizona is best known for its work on the in-flight, radiometric calibration of remote sensing imagers using ground-based measurements at desert test sites. Radiometric calibration in this context refers to the ability to take the data from a sensor and convert it to a standard energy scale. Such work allows for the comparison of data from an array of imagers (by last count more than 30 sensors). The methods of the group have been in use since the mid-1980s and currently provide absolute radiometric calibration to better than 3%, both in accuracy and precision in the mid-visible.