1. 1 Fast conversion factor measurement of a CCD using Images with vertical gradient Charge Transfer Efficiency based on The variance of the signal in flat Field images, gain correction

2. 2 Fast conversion factor measurement of a CCD using Images with vertical gradient Introduction Fast way to realize Photon Transfer Curve Appropriate to use this technique during CCD tuning The method Im 1 + Im 2 For each line i of Im: The mean is calculated (S i ) 2 Im = Is = Im 1 - Im 2 For each line i of Is: The variance is calculated (σ i 2 ) Each (S i, σ i 2 ) pair is plotted Im 1 and Im 2, two TDI images

3. 3 Results. 1.Preliminary work. Mask cosmetic defects. 2.Flat Field of TDI images. 3.Weighted least square method. 4.Automatic detection of the beginning of the non linearity regime. 5.User friendly program. Future work.

4. 4 Charge Transfer Efficiency based on the variance of the signal in flat Field images, gain correction. Change in Variance in Flat Field (CVF) Method. Is = Im 1 - Im 2 For each line (column) i of Is: The variance is calculated (σ i 2 ) Each (i, σ i 2 ) pair is plotted Results

5. 5 How can I correlate previous plots to the CTE? Expression of the variance affected by the CTE (a = 1- b) Conclusion The best fit line of the previous plot: Gives us the Charge Transfer Efficiency:

6. 6 Results, Simulated data. Results, Real data. Conclusion Results promising. Mask cosmetic defects Work in 2d instead of 1d Direct comparison CVF versus ESO Fe55 setup User friendly program