Abstract: The SE-590 Reflectance Factors and Radiances Measured from a Helicopter Data Set were collected using the helicopter-borne SE-590 during Intensive Field Campaign 5 (IFC-5) in 1989. These data were collected at 17 different grid locations within the FIFE study area. Data were collected on 6 days from July 28, 1989 through August 8, 1989, when sky conditions were clear. The helicopter missions were ... designed to provide a means of spectrally characterizing each FIFE site and provide an intermediate scale of sampling between that of the surface measurements and the higher altitude aircraft and spacecraft multispectral imaging devices. The SE-590 instrumentation was chosen to provide compatibility with surface-based radiometers and TM spacecraft sensors. Off-nadir measurements were made as a means of providing more accurate estimates of hemispherical reflectance and for use with bi-directional reflectance models.