The scientific grade detector of LIRIS has relatively good cosmetics. The most noticeable detector flaws are (see Fig. 2):
• A shallow, fan-like feature in the lower right quadrant, detectable at low signal levels. It is not a flat-field effect but is washed out after sky subtraction.
• A bright spot (lower left quad.) plus two small scratches (outer edge of the upper left quad). They should be masked in the data reduction.
• A number of extended darker spots in the two left quadrants. This is a pure flat-field effect and is easily corrected.
• A picture frame effect, which appears as a border frame of ~15 pixels width showing an enhanced response relative to the mean illumination.
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