GOME-2 was one of the most extended calibration campaigns within TNO. The measurements took more than five months. Within this period the instrument was calibrated at three different optical bench temperatures and two different detector temperatures. Special effort was put into the radiometric calibration and the slit-function characterization. For the radiometric calibration NASA and NPL were invited to calibrate their sources alongside of the TNO sources. The slit-function was measured using a dedicated source, which enabled a characterization at sub-pixel level. This was a large improvement over the previous method were only a few points of the slit-function where measured. This improved slit-function knowledge is a major improvement for the retrieval of science products. TNO also collaborated with the scientist of the University of Bremen for a three week measurement campaign with their Cat-Gas set-up. With this set-up the instrument 'looked' at a controlled atmospheric condition to characterize instrument behavior for different atmospheric compositions. These measurements will be used for retrieval algorithms.