CCD CHARGE TRANSFER EFFICIENCY (CTE) DERIVED FROM SIGNAL VARIANCE IN FLAT FIELD IMAGES

This paper describes a novel technique for estimating the CTE of a CCD. It is based on the change in variance with CCD row or column in simple flat field images, and uses the fact that imperfect charge transfer during readout has a smoothing effect on the final image. The data used to test the procedure are acquired with the ESO test bench, in the context of characterizing the OmegaCAM CCDs. For nine CCDs results from the CTE measurements by e2v and with the variance based technique developed in this paper were compared. Results are promising. This technique, still under development, proved reliable and can be used for simple and efficient CTE measurements.