$\star$ Construction of the chart of the dead pixels

Cameras CCD present pixels, even columns of dead pixels. They thus should be detected to prevent that they are not used in the continuation of the reduction. The dead zones are defined as being those where the pixels present a flux which differs of more than 40% of the average value of the quantum chart of effectiveness of the CCD smoothed (the chart is realised by limp of 64 pixels on side).

The result of this procedure is the production for each CCD of a binary card of the pixels declared dead.