The SSBUV experiment wavelength scale and stability: 1988 to 1994

A solar backscatter ultraviolet experiment flies regularly on the Space Shuttle to help validate and maintain the calibrations of several satellite-borne stratospheric ozone monitoring instruments. The Shuttle Solar Backscatter Ultraviolet (SSBUV) programme incorporates multiple radiometric standards and redundant calibration checks which have allowed the tracking of long-term changes in the calibration of the SSBUV instrument to within 1% over six flights. The reduction of uncertainties in SSBUV wavelength calibration has recently been emphasized because of an increasing need to improve precision and accuracy. Therefore, selected solar spectral features are now used to monitor intra- and inter-flight changes in that wavelength calibration. The results of applying this technique to the six SSBUV Shuttle missions are presented, together with a comparison of these results with results from two traditional approaches in which laboratory and on-board spectral line sources, respectively, are used to determine and monitor the SSBUV wavelength scale. Long-term wavelength calibration change is less than 0,02 nm, and intra-flight wavelength change is 0,05 nm or less.