Langley Voltage Offset or V0 (referred to as V naught) represents a hypothetical voltage reading that the detector amplifier system would have if it were making its measurement at the top of the atmosphere where the optical depth is zero. This instrument characteristic is used to derive a responsivity of the respective channels assuming the extraterrestrial solar spectral irradiance is known and constant.


These graphs display the Langley voltage intercepts collected for each channel, for the instrument and board settings in use at the site on the requested date. The Langley method is described in Harrison and Michalsky (1994). Points falling more than two standard deviations from the regression line were omitted.