a) level 1 intensity (intensity range of 0 to 25); b) temporal variation of intensity at points a) and b); c) histograms of the intensities at points a) and b); d) the mean background value (intensity range of 0 to 25); e) the background model (intensity range of 0 to 50), f) the histogram of the model values minus the mean background; g) the 2D distribution of the difference between the model and mean background (colour range between −2 and 2 with white lines showing the boundary between regions with and without data) and h) the level 1 intensity minus the background model (intensity range of 0 to 25).