This is the Health Check plot for checking saturation of GIRAFFE
flat field calibration data. 
A saturated flat field can still be used for localization of the fibre signal
(unless in extreme cases), but the information related to pixel-to-pixel gain
variations, to fringing and to fibre-to-fibre sensitivity is lost in the
saturated regions. Therefore all measured flats are monitored in terms of
saturated pixels. </font><p><font size="2">

We display the QC1 parameter qc_numsat
(QC.NUMSAT) which registers the number of pixels close or at saturation (> 60,000 ADU).
The alert level is set to 1000 ADU  which is more or  less arbitrary but
experience shows that data with higher values indeed have an issue.</font><p><font size="2">

This plot monitors <b>all</b> 
flat field data. The HC flats (L543.1) are displayed in colour.</font><p><font size="2">

The values are usually 0, a flat with saturation stands out clearly. The upper
threshold is more or less arbitrary, it is used to get an alert.