Fig. 1. Diagram of experimental setup for scaling the spectral irradiance of mercury lamps

Fig. 2. Irradiance values for each wavelength of mercury lamps

Fig. 3. Irradiance ratio values for each wavelength

Fig. 4. Flow chart of calibration scheme combining mercury lamp and tungsten lamp

Fig. 5. Actually measured irradiance degradation results varying with time in visible band

Fig. 6. Plot of actual irradiance degradation over time in visible band obtained after correction with tungsten lamps only

Fig. 7. Plot of visible band irradiance degradation results varying with time using combined correction of mercury and tungsten lamps

Fig. 8. Plot of in-orbit tungsten lamp irradiance data over time

Fig. 9. Plot of ratio of measured values of tungsten lamp 1 to tungsten lamp 2 as a function of time