A typical GOME orbit had a duration of about 100 minutes. Half of that time was spent in the night side of Earth, when GOME carried out sequences of calibration measurements, i.e. dark current and LED measurements (pixel-to-pixel gain).
Once a day, solar irradiance measurements were carried out when the satellite crossed the terminator in the north polar region coming from the night side. A mean solar spectrum was constructed from the series of measurements during full disc solar viewing.
Once a month, the internal calibration lamp was switched on over an entire orbit, to investigate the long term degradation of the diffuser and update the wavelength calibration of the diode arrays
Details can be found in the GOME user manual
Validation studies are based on comparisons of GOME data with correlative observations acquired by ground-based reference instruments, i.e. Brewer and Dobson ultraviolet spectrophotometers and DOAS UV-visible spectrometers. Geophysical validation of the retrieval algorithms and ozone data products was carried out by science teams in close collaboration with the algorithm developers and the operational processing teams.
The validation reports below provide assessment of the product quality of the GOME datasets.